Ink tank with integrated filter

Abstract

An ink canister for an ink delivery system includes: a housing having an ink inlet port and an ink outlet port; an exhaust port communicating with a top space of the ink canister; a filter positioned within the housing for filtering ink supplied from the ink canister via the ink outlet port; and a baffle positioned within the housing between the ink inlet port and the filter. The baffle is configured to guide air bubbles entering the ink canister via the ink inlet port toward the top space of the ink canister. A baffle opening is positioned toward the base of the ink canister, thereby allowing ink to flow through the baffle opening from the ink inlet port toward the ink outlet port.

Description

Technical Field

[0001] This invention relates to an ink reservoir with an integrated filter for use in an ink delivery system of an inkjet printer. The invention was primarily developed to minimize problems associated with air bubbles in the ink delivery system. Background Technology

[0002] Memjet is available for purchase on the market. ® Memjet's inkjet printers are used in many different printing formats, including printers for home offices (“SOHO”), label printers, digital inkjet printers, and wide-format printers. ® Printers typically include one or more fixed inkjet printheads that are user-replaceable. For example, a desktop printer may include a single user-replaceable multicolor or monochrome printhead, a high-speed digital press may include multiple user-replaceable monochrome printheads aligned along the media feed direction, and a wide-format printer may include multiple user-replaceable printheads arranged in an overlapping manner to span the width of a wide page.

[0003] Ink is supplied to the inkjet printhead via an ink delivery system designed primarily to deliver ink to the printhead at a predetermined hydrostatic pressure. The ink delivery system typically also includes an ink filter to filter out particles from the ink.

[0004] Air bubbles are a long-standing problem in inkjet printers. Air bubbles reaching the inkjet nozzles can clog them and cause serious incomplete ink refill events. Air bubbles can also reduce the efficiency of ink filters in the ink delivery system by clogging the tiny pores in the filter material. Air bubbles can also affect the operation of ink level sensors, for example, by increasing the buoyancy of float-type sensors due to adhesion, leading to potentially inaccurate ink level readings.

[0005] To some extent, using degassed ink in a closed ink delivery system can mitigate problems associated with air bubbles. However, even with degassed ink, such a system cannot completely eliminate the issue of air bubbles. For example, when air is drawn in through the printhead, it can be intentionally introduced into the ink delivery system via a printhead fill-in-insufficient operation, allowing for printhead replacement with minimal ink contamination. This introduced air can circulate within the ink delivery system, but it can cause problems such as clogging of the ink filter. If the ink filter becomes severely clogged with air bubbles, the user will need to replace it, which is both inconvenient and time-consuming.

[0006] In some ink delivery systems described in the prior art, the ink filter is connected to a degassing pump that removes air from the filter chamber containing the filter material. The degassing pump ensures that any air bubbles trapped in the ink filter dissipate into the atmosphere, preventing long-term problems caused by the continuous accumulation of air bubbles. However, the degassing pump increases the cost and complexity of the ink delivery system.

[0007] WO 2019 / 011705 describes an ink filter that is passively degassed via a vent tube under positive ink pressure.

[0008] Therefore, it may be desirable to provide an ink can with an integrated filter that minimizes the entry of air bubbles into the filter. It may further be desirable to provide an ink can that allows for the effective removal of air bubbles. It may further be desirable to provide an ink can with an ink level sensor whose operation is not affected by air bubbles in the ink. Summary of the Invention

[0009] In a first aspect, an ink container for an ink delivery system is provided, the ink container comprising: A housing having an ink inlet port and an ink outlet port; An exhaust port, which is connected to the top space of the ink tank; A filter, positioned within the housing, for filtering ink supplied from the ink tank via the ink outlet port; and A baffle plate, positioned within the housing between the ink inlet port and the filter, is configured to guide air bubbles entering the ink tank via the ink inlet port toward the top space of the ink tank. The baffle has a baffle opening positioned toward the base of the ink tank, thereby allowing ink to flow from the ink inlet port toward the ink outlet port via the baffle opening.

[0010] Preferably, the ink container includes an upper section and a lower section, the lower section having an ink inlet port and an ink outlet port.

[0011] Preferably, the volume of the upper section is greater than the volume of the lower section.

[0012] Preferably, the cross-sectional area of ​​the upper section is greater than the cross-sectional area of ​​the lower section.

[0013] Preferably, the ink outlet port is located in the base of the housing, and the filter includes a filter drum positioned above the ink outlet port.

[0014] Preferably, the baffle extends from the base of the housing toward the top of the ink can.

[0015] Preferably, during use, the baffle extends into the top space of the ink tank.

[0016] Preferably, the ink inlet port is positioned above the baffle opening.

[0017] Preferably, the ink can further includes an ink level sensor, wherein the baffle is positioned between the ink level sensor and the ink inlet port.

[0018] Preferably, the ink level sensor includes a float-type level sensor having a rod and one or more floats extending into the ink canister, the one or more floats being movable along the rod.

[0019] Preferably, the vent is connected to a complex channel defined in the top of the ink can.

[0020] In a second aspect, an ink delivery system for an inkjet printer is provided, the ink delivery system comprising: As described above, ink cans; Ink supply storage unit, which is connected to the ink inlet port via an ink supply line; An inkjet printhead having a printhead inlet port connected to the ink outlet port via an ink delivery line; and A control system, which works in conjunction with the ink tank, for controlling the hydrostatic pressure of the ink being delivered to the printhead.

[0021] Preferably, the printhead includes a printhead outlet port that is in fluid communication with the ink tank via an ink return line.

[0022] Preferably, the ink return line is connected to the ink supply line.

[0023] Preferably, the ink delivery system further includes a pump and an air inlet for underfilling the printhead.

[0024] Preferably, air enters the ink tank via the ink inlet port during printhead filling insufficiency and / or printhead filling.

[0025] Preferably, the control system is configured to control the ink level in the ink tank.

[0026] Preferably, the control system controls the supply pump in the ink supply line in response to feedback from one or more ink level sensors in the ink tank.

[0027] As used herein, the term "ink" is considered to refer to any printing fluid that can be printed from an inkjet printhead. Ink may or may not contain colorants. Accordingly, the term "ink" can include conventional dye-based or pigment-based inks, infrared inks, UV inks, fixatives (such as pre-coatings, primers, and finishing agents), 3D printing fluids, bio-fluids, functional printing fluids (such as solar inks, biosensing inks), and so on.

[0028] As used herein, the term "printer" refers to any printing device, such as a conventional desktop printer, label printer, copier, photocopier, digital inkjet printer, 3D printer, etc. For example, a printer can be a sheet-fed or roll-fed printing device. Attached Figure Description

[0029] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 A printer ink delivery system incorporating an ink canister according to the first aspect is schematically illustrated. Figure 2 It is based on the three-dimensional diagram of the ink can in the first aspect; and Figure 3 yes Figure 2 The image shows a cross-sectional view of the ink can. Detailed Implementation

[0030] Gravity-fed ink delivery system The following describes a gravity-fed ink delivery system as an exemplary use of an ink tank according to the first aspect. However, it should be understood that the ink tank according to the first aspect is equally applicable to any circulating ink delivery system incorporating an ink filter.

[0031] Reference Figure 1 The image schematically illustrates a printer 1 having an ink delivery system for supplying ink to a printhead 4. The ink delivery system is a gravity supply system, functioning similarly to those described in US 2011 / 0279566 and US 2011 / 0279562, the contents of which are incorporated herein by reference.

[0032] The ink delivery system includes an ink tank 100 having an ink outlet port 106 connected to a printhead inlet port 8 of a printhead 4 via an ink delivery line 10. The ink inlet port 108 of the ink tank 100 is connected to a printhead outlet port 14 of the printhead 4 via an ink return line 16. Therefore, the ink tank 100, the ink delivery line 10, the printhead 4, and the ink return line 16 together form a closed fluid loop. Typically, the ink delivery line 10 and the ink return line 16 consist of flexible tubes of varying lengths and diameters that may be the same or different. In some embodiments, the diameter of the ink return line 16 is smaller than that of the ink delivery line 10 to effectively remove air bubbles, as described in EP 2844488 B and US2014 / 0015905, the contents of which are incorporated herein by reference.

[0033] Additionally, the ink tank 100 includes: an integrated filter 112 positioned above the ink outlet port 106 to filter the ink delivered to the printhead 4; and a baffle 114 positioned between the ink inlet port 108 and the filter 112. The function of the baffle 114 will be described in more detail below.

[0034] The user can replace the printhead 4 via a first connector 3, which releasably interconnects the printhead inlet port 8 with the ink delivery line 10; and a second connector 5 releasably interconnects the printhead outlet port 14 with the ink return line 16. The printhead 4 is typically a page-width printhead and may be a printhead as described in, for example, US 10399354 or US 10293609, the contents of which are incorporated herein by reference.

[0035] The ink 20 contained in the ink tank 100 is open to the atmosphere via a vent 109 located on the top of the ink tank. Accordingly, during normal printing, the ink is supplied to the print head 4 under gravity with a negative hydrostatic pressure (“back pressure”). In other words, the gravity supply of ink from the ink tank 100 located below the print head 4 provides a pressure regulating system that supplies ink to the print head under a predetermined negative hydrostatic pressure. The magnitude of the back pressure experienced at the nozzle plate 19 of the print head 4 is determined by the height of the nozzle plate above the ink level in the ink tank 100. h To determine.

[0036] Ink is supplied from a bulk ink reservoir to the ink inlet port 108 of the ink tank 100. The bulk ink reservoir includes a collapsible ink pouch 23 contained within an ink cartridge 24. The ink cartridge 24 is open to the atmosphere via an ink cartridge vent 25, allowing the collapsible ink pouch 23 to collapse as the system consumes ink. The collapsible ink pouch 23 is typically an airtight foil pouch containing degassed ink, which is supplied to the ink inlet port 108 via an ink supply line 28 connected to an ink return line 16. The ink cartridge 24 is typically user-replaceable and connected to the ink supply line 28 via a suitable ink supply connector 32. The ink supply line 28 may include an in-line ink filter (not shown) for filtering the ink before it reaches the ink tank 100.

[0037] The control system is used to maintain a substantially constant level of ink in the ink tank 100, and therefore a constant height. h And the corresponding back pressure. For example... Figure 1 As shown, the supply pump 30 is positioned in the ink supply line 28 and controls the flow of ink from the ink cartridge 24 into the ink tank 100. The supply pump 30 operates under the control of a first controller 107, which receives feedback from an ink level sensor 120 having a "high" float sensor 102 and a "low" float sensor 104 (e.g., a magnetic float sensor) positioned in the ink tank 100. When the ink level 20 drops below the "low" sensor 104, the first controller 107 signals the supply pump 30 to pump ink into the ink tank 100, and when the ink level reaches the "high" sensor 102, the first controller signals the supply pump to stop pumping. In this way, the ink level 20 in the ink tank 100 can be maintained at a relatively constant level.

[0038] A closed fluid loop (combining the ink tank 100, ink delivery line 10, printhead 4, and ink return line 16) facilitates filling, underfilling, and other necessary fluid operations. The ink return line 16 includes a reversible peristaltic pump 40 for circulating ink around the fluid loop. However, by convention, the "forward" direction of pump 40 is the same as pumping ink from the ink outlet port 106 to the ink inlet port 108 (i.e., as...). Figure 1 The clockwise direction shown corresponds to the direction in which ink is pumped from the ink inlet port 108 to the ink outlet port 106 (i.e., as shown in the clockwise direction). Figure 1 (The direction shown is counterclockwise) Corresponds to this.

[0039] Pump 40 cooperates with pinch valve arrangement 42 to coordinate various fluid operations. Pinch valve arrangement 42 includes a first pinch valve 46 and a second pinch valve 48, and may take any of the forms of pinch valve arrangements described, for example, in US 2011 / 0279566, US 2011 / 0279562 and US9180676, the contents of which are incorporated herein by reference.

[0040] The first pinch valve 46 controls the flow of air through the air duct 50, which branches off from the ink delivery line 10. The air duct 50 terminates at the air filter 52, which is open to the atmosphere and serves as an inlet for the closed fluid circuit.

[0041] With the aid of the air duct 50, the ink delivery line 10 is divided into a first section 10a located between the ink outlet port 106 and the air duct 50, and a second section 10b located between the printhead inlet port 8 and the air duct 50. The second clamp valve 48 controls the flow of ink through the first section 10a of the ink delivery line 10.

[0042] Pump 40, the first pinch valve 46, and the second pinch valve 48 are all controlled by the second controller 44, which coordinates various fluid operations. Based on the foregoing, it should be understood that... Figure 1 The ink delivery system shown provides a general range of fluid operations. Table 1 describes various clamp valve and pump states for some example fluid operations used in printer 1. Of course, various combinations of these example fluid operations can be employed.

[0043] Table 1. Example fluid operation for printer 1 During normal printing (“PRINT” mode), printhead 4 draws ink from ink tank 100 under gravity with a negative back pressure. In this mode, peristaltic pump 40 can pump ink forward around the fluid loop, or alternatively, it can be disconnected to act as a shut-off valve. First pinch valve 46 is closed and second pinch valve 48 is open to allow ink to flow from ink outlet port 106 to printhead inlet port 8. During printing, ink is supplied to ink inlet port 108 of ink tank 100 under the control of first controller 107 to maintain a relatively constant ink level 20, and thus maintain a relatively constant back pressure for printhead 4.

[0044] During printhead filling or flushing (“PRIME” mode), ink is supplied in the forward direction (i.e., when the supply pump is disconnected) while the printhead is flushing or flushing. Figure 1The fluid circulates around a closed loop (in a clockwise direction as shown). In this mode, the peristaltic pump 40 is actuated in the forward pumping direction, while the first pinch valve 46 is closed and the second pinch valve 48 is opened to allow ink to flow through the printhead 4 from the ink outlet port 106 to the ink inlet port 108. This type of filling can be used to fill ink into a printhead with insufficient filling start, flush out air bubbles in the printhead 4, and / or filter particles in the ink.

[0045] In "STANDBY" mode, pump 40 is disconnected, while the first clamp valve 46 is closed and the second clamp valve 48 is open. Typically, the printhead is covered in standby mode to minimize ink evaporation from the nozzles (see, for example, US2011 / 0279519, the contents of which are incorporated herein by reference).

[0046] To ensure that each nozzle of printhead 4 is fully filled with ink and / or to clear any nozzles that have become clogged, a "Pulse" mode can be used. In "Pulse" mode, the first clamp valve 46 and the second clamp valve 48 are closed, while the pump 40 is actuated in the reverse direction (i.e., as shown in the image). Figure 1 (Indicated by a counter-clockwise direction) to force ink through the nozzles in the nozzle plate 19 of the printhead 4. The supply pump 30 is disconnected during pulse filling, and the ink tank 100 provides a reservoir of ink required for pulse filling. Alternatively, the nozzles can be filled using an external suction at the nozzle plate 19, as described, for example, in U.S. Provisional Application No. 62 / 976,213 (“Method and System for Priming Dry Printheads”), filed February 13, 2020, the contents of which are incorporated herein by reference.

[0047] To replace a depleted printhead 4, it is necessary to deplete the printhead fill before it can be removed from the printer. In "DEPRIME" mode, the first clamp valve 46 is open, the second clamp valve 48 is closed, and the pump 40 is actuated in the forward direction to draw air from the atmosphere via the air duct 50. Depletion causes the ink in the printhead 4 to be replaced by air, and air bubbles are introduced into the ink tank 100 via the ink inlet port 108. Once the printhead 4 has become depleted, the printer is set to "NULL" mode, which isolates the printhead from the ink supply, thereby allowing safe removal of the printhead with minimal ink spillage.

[0048] 100 ink cans In circulating ink delivery systems using degassed ink, introducing air into the system for insufficient printhead filling and printhead replacement can be problematic. Dissolved air is problematic because it can release gas into the printhead, negating the inherent advantages of using degassed ink. Furthermore, undissolved air bubbles behave similarly to particles and can cause blockages in the ink delivery system. Ideally, these undissolved air bubbles should be removed from the system before they cause problems such as nozzle clogging in printhead 4 or ink filter clogging.

[0049] Now for reference Figure 2 and Figure 3 The ink tank 100 is designed to facilitate pressure regulation, ink circulation, filtration, and removal of air bubbles in the ink delivery system. The ink tank 100 includes a housing 200, which is typically formed of molded plastic, defining an upper section 202 and a lower section 204 of the ink tank.

[0050] The lower section 204 includes a truncated cylindrical portion 205 for accommodating a filter 112, which is in the form of a cylindrical filter drum 113. The filter drum 113 is positioned above the ink outlet port 106 at the base of the housing 200 for delivering filtered ink to the printhead 4.

[0051] The ink inlet port 108 is located on the side wall of the lower section 204, so that all ink entering the ink tank 100 through this inlet port is filtered by the filter 112 before leaving the ink tank through the ink outlet port 106. (An additional connection port 207 is provided, which is located in...) Figure 2 and Figure 3 It is covered, and if needed, this additional connection port is used for the option of fluidly connecting multiple ink cans 100 together.

[0052] A cap 206 is fastened to the upper part of the housing 200 to define the top of the ink tank 100. The cap 206 defines a vent 109 communicating with the top space of the ink tank 100 and an intricate passage 208 connected to the vent. A vent port 210 communicating with the atmosphere extends downward from the cap 206 and communicates with the top space of the ink tank 100 via the intricate passage 208 and the vent 109. The intricate passage 208 serves to minimize water evaporation from the ink tank 100 while allowing air to escape through it.

[0053] A baffle 114 extends upward from the base of the ink reservoir 100 toward the cap 206 and is positioned between the ink inlet port 108 and the filter 112. Typically, the baffle 114 is an insert slidably received in the molded housing 200. The baffle 114 effectively divides the ink reservoir 100 into a first side 209 and a second side 210, the first side having the ink inlet port 108 and the second side having the filter 112 and the ink outlet port 106.

[0054] The lower portion of the baffle 114 defines a baffle opening 212 that allows ink to pass through the lower section 204 of the ink tank 100 from the ink inlet port 108 at the first side 209 to the filter 112 at the second side 210. The ink inlet port 108 is positioned above the baffle opening 212 such that any air bubbles entering the ink tank 100 via this inlet port will not pass through the baffle opening into the second side 210 of the ink tank 100. Alternatively, air bubbles carried by the ink pumped into the ink tank via the ink inlet port 108 tend to collide with the baffle 114 above the baffle opening 212 and then float upwards into the top space of the ink tank, where they can be discharged to the atmosphere via the exhaust port 109. Thus, the baffle 114 protects the filter 112 from air bubbles entering the ink tank 100 via the ink inlet port 108. (As far as the minimum number of air bubbles reaching filter 112 are concerned, these air bubbles can float upward toward the exhaust port.) Additionally, baffle 114 protects float-type sensors 102 and 104 from air bubbles, as will be explained further below.

[0055] When degassed fresh ink from the ink reservoir enters the ink tank 100 through the ink inlet port 108, this ink flows through the baffle opening 212 through the lower section 204 of the ink tank to the filter 112. The baffle 114 extends into the top space of the ink tank 100, preventing ink contained in the upper section 202 from flowing from the first side 209 to the second side 210 of the ink tank. Because the air-mixed ink in the upper section 202 is relatively fixed and separated (in height) from the ink in the lower section 204, this air-mixed ink diffuses very slowly only towards the lower section 204. Therefore, during normal printing, the degassed ink in the lower section 204 remains degassed when replenished with degassed fresh ink from the ink reservoir. Therefore, the design of the ink tank 100 provides an effective diffusion barrier between the upper section 202 and the lower section 204, making the ink tank suitable for gravity control of the back pressure at the printhead 4, while also enabling the use of degassed ink.

[0056] The ink level sensor 120 is in the form of a magnetic float sensor with a rod 222, which is secured to the cap 206 and extends into the ink reservoir 100. A "high" float sensor 102 and a "low" float sensor 104 are movable along the rod 222 between corresponding fixed stops 224. Each float sensor contains a magnet that actuates a corresponding reed switch (not shown) in the rod 222 to indicate a "high" or "low" ink level in the ink reservoir 100. As described above, the supply pump 30 is actuated or de-actuated depending on the height of the float sensors 102 and 104 and the corresponding state of the reed switches. The ink level sensor 120 is positioned on a second side of the ink reservoir 100 and is thus protected from air bubbles by a baffle 114. Advantageously, protecting float sensors 102 and 104 from air bubbles is achieved by minimizing erroneous ink level signals from ink level sensor 120 by avoiding interference with the sensitive float sensors.

[0057] Based on the foregoing, it should be understood that the ink tank 100 performs several functions: (1) protecting the filter from air bubbles; (2) protecting the ink level sensor from air bubbles; (3) effectively removing air bubbles from the ink delivery system; and (4) gravity-controlled ink pressure in the ink delivery system supplying degassed ink. These and other advantages will be apparent to those skilled in the art.

[0058] Of course, it should be understood that the invention has been described by way of example only, and modifications to the details may be made within the scope of the invention as defined in the appended claims.

Claims

1. An ink container for an ink delivery system, the ink container comprising: The housing includes an upper section and a lower section, the cross-sectional area of ​​the upper section is larger than the cross-sectional area of ​​the lower section, and the lower section has an ink inlet port and an ink outlet port; An exhaust port, which is connected to the top space of the ink tank; A filter, positioned within the housing, for filtering ink supplied from the ink tank via the ink outlet port; as well as A baffle plate, positioned within the housing between the ink inlet port and the filter, is configured to guide air bubbles entering the ink tank via the ink inlet port toward the top space of the ink tank. The baffle has a baffle opening positioned toward the base of the ink tank, thereby allowing ink to flow from the ink inlet port toward the ink outlet port via the baffle opening.

2. The ink tank of claim 1, wherein, The volume of the upper section is greater than the volume of the lower section.

3. The ink tank of claim 1, wherein, The ink outlet port is located in the base of the housing, and the filter includes a filter drum positioned above the ink outlet port.

4. The ink tank of claim 1, wherein, The baffle plate extends from the base of the housing toward the top of the ink tank.

5. The ink tank of claim 1, wherein, In use, the baffle extends into the top space of the ink tank.

6. The ink tank of claim 1, wherein, The ink inlet port is located above the baffle opening.

7. The ink tank of claim 1, further comprising an ink level sensor, wherein, The baffle plate is positioned between the ink level sensor and the ink inlet port.

8. The ink tank of claim 7, wherein, The ink level sensor includes a float-type level sensor having a rod and one or more floats, the rod extending into the ink tank, and the one or more floats being movable along the rod.

9. The ink tank of claim 1, wherein, The vent is connected to a complex network of channels defined in the top of the ink can.

10. An ink delivery system for an inkjet printer, the ink delivery system comprising: Ink container as claimed in claim 1; An ink supply storage unit is connected to the ink inlet port via an ink supply line; An inkjet printhead having a printhead inlet port connected to the ink outlet port via an ink delivery line; as well as A control system, which works in conjunction with the ink tank, to control the hydrostatic pressure of the ink being delivered to the printhead.

11. The ink delivery system of claim 10, wherein, The printhead includes a printhead outlet port, which is in fluid communication with the ink tank via an ink return line.

12. The ink delivery system according to claim 11, wherein, The ink return line is connected to the ink supply line.

13. The ink delivery system of claim 11, further comprising a pump and an air inlet for underfilling the printhead.

14. The ink delivery system of claim 13, wherein, Air enters the ink tank via the ink inlet port during printhead filling insufficiency and / or printhead filling.

15. The ink delivery system according to claim 10, wherein, The control system is configured to control the ink level in the ink tank.

16. The ink delivery system of claim 15, wherein, The control system controls the supply pump in the ink supply line in response to feedback from one or more ink level sensors in the ink tank.

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