Method and system for priming a dry print head

Abstract

A system for priming a dry inkjet printhead (4). The system includes an inkjet printhead (4) having an inlet port (8) connected to an upstream ink line and an outlet port (14) connected to a downstream ink line; a pump (40) operably connected to the downstream ink line; a capper (200) engaged with the printhead; a vacuum source for applying suction to a capping chamber (202) of the capper (200); and a control system for coordinating actuation of the pump and the vacuum source. In use, the pump (40) and the vacuum source are simultaneously actuated whereby ink is drawn through the printhead (4) from the inlet port to the outlet port and the printhead is primed.

Description

Technical Field

[0001] This invention relates to a method and system for filling a dry printhead. The method and system are primarily developed to facilitate the transport of dry or unfilled page-width printheads that do not contain any transport fluid. Background Technology

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

[0003] Printhead replacements can be shipped 'wet' or 'dry' for user installation in inkjet printers. Typically, printheads are shipped 'wet' to avoid potential problems with filling during installation. Wet-shipped printheads may be filled with ink or a transport fluid, which is usually an ink carrier without any colorant.

[0004] However, wet-shipped printheads are less convenient for users because ink or transport fluids may leak from the printhead during transport and / or spill during installation. Users prefer to receive dry printheads, which are less prone to leakage or spillage during transport or installation.

[0005] However, dry-carrying printheads pose challenges to the ink delivery system used to fill them with ink. Therefore, a method and system for filling dry printheads (such as replacement printheads newly installed in an inkjet printing system) is desired. Summary of the Invention

[0006] 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. Therefore, the term "ink" can encompass conventional dye-based or pigment-based inks, infrared inks, fixatives (such as pre-coatings and finishing agents), 3D printing fluids, and more.

[0007] As used herein, the term "printer" refers to any printing device that leaves a mark on printed media, such as a conventional desktop printer, label printer, copier, photocopying machine, digital inkjet printer, etc. Attached Figure Description

[0008] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0009] Figure 1 The ink delivery system for a printer with a replaceable inkjet printhead is schematically illustrated; and

[0010] Figure 2 A system for filling dry inkjet printheads is illustrated schematically. Detailed Implementation

[0011] Gravity-fed ink delivery system

[0012] refer to Figure 1 The image schematically illustrates a printer having an ink delivery system 1 for supplying ink to a printhead 4. The ink delivery system is a gravity supply system and functions similarly to those described in US 2011 / 0279566 and US 2011 / 0279562, the contents of which are incorporated herein by reference.

[0013] The ink delivery system includes an intermediate ink tank 100 having an ink outlet port 106 connected to a printhead inlet port 8 of a printhead 4 via a first ink line 10. An ink return port 108 of the intermediate ink tank 100 is connected to a printhead outlet port 14 of the printhead 4 via a second ink line 16. Therefore, the intermediate ink tank 100, the first ink line 10, the printhead 4, and the second ink line 16 define a closed fluid loop. Typically, the first ink line 10 and the second ink line 16 are formed by the length of a flexible tube.

[0014] The user can replace the printhead 4 via a first connector 3 and a second connector 5, the first connector releasably interconnecting the printhead inlet port 8 to the first ink line 10, and the second connector releasably interconnecting the printhead outlet port 14 to the second ink line 16. The printhead 4 is typically a page-width printhead and can be as described in, for example, US 2011 / 0279566, US 10,384,461, and US 10,293,609, the contents of each of which are incorporated herein by reference. Such a printhead has one or more ink channels interconnecting the inlet port 8 to the outlet port 14.

[0015] The intermediate ink tank 100 is vented to the atmosphere via a gas port in the form of a vent 109, which is located in the top plate of the tank. Therefore, during normal printing, 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 intermediate ink tank 100 provides a pressure regulating system that supplies ink to the print head, which is located below the print head 4, 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 20 in the intermediate ink tank 100. h To determine.

[0016] Ink is supplied from a bulk ink reservoir to the ink inlet port 110 of an intermediate ink tank 100, the bulk ink reservoir comprising a collapsible ink pouch 23 housed within an ink cartridge 24. The ink cartridge 24 is vented 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 110 via an ink supply line 28. The ink cartridge 24 is typically user-replaceable and connected to the ink supply line 28 via a suitable ink supply connector 32.

[0017] The control system is used to maintain a substantially constant level of ink in the intermediate ink tank 100, and therefore a constant level. h And the corresponding back pressure. For example... Figure 1 As shown, control valve 30 is located in ink supply line 28 and controls the flow of ink from ink cartridge 24 into intermediate ink tank 100. Control valve 30 operates under the control of a first controller 107, which receives feedback from a 'high' sensor 102 and a 'low' sensor 104 (e.g., an optical sensor), both located on the sidewall of intermediate ink tank 100. When the ink level 20 drops below the 'low' sensor 104, the first controller 107 signals valve 30 to open, and when the ink level reaches the 'high' sensor 102, the controller signals valve 30 to close. In this way, the level of ink 20 in intermediate ink tank 100 can be maintained at a relatively constant level. Intermediate ink tank 100 can be, for example, as described in US 10,427,414, the contents of which are incorporated herein by reference.

[0018] The closed fluid loop (combining the intermediate ink tank 100, the first ink line 10, the printhead 4, and the second ink line 16) facilitates filling, de-priming, and other necessary fluid operations. The second ink line 16 includes a peristaltic pump 40 for circulating ink around the fluid loop in a clockwise direction, such as... Figure 1 As shown.

[0019] 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.

[0020] The first pinch valve 46 controls the flow of air through the air duct 50, which branches off from the first ink line 10. The air duct 50 terminates at the air filter 52, which opens to the atmosphere and serves as an inlet for a closed fluid circuit when needed.

[0021] With the aid of the air duct 50, the first ink 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 first ink line 10.

[0022] Pump 40, the first pinch valve 46, and the second pinch valve 48 are all controlled by a 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.

[0023] Table 1. Example fluid operation for printer 1

[0024]

[0025] During normal printing (“Print” mode), printhead 4 draws ink from intermediate ink tank 100 under gravity with a negative back pressure. In this mode, peristaltic pump 40 acts as a shut-off valve, while first clamp valve 46 is closed and second clamp valve 48 is open to allow ink to flow from ink outlet port 106 to first port 8 of printhead 4. During printing, ink is supplied to ink inlet port 110 of intermediate ink tank 100 under the control of first controller 107 to maintain a relatively constant back pressure for printhead 4.

[0026] During printhead filling or flushing (“fill” mode), the ink circulates in the forward direction around a closed fluid loop with control valve 30 closed (i.e., as...). Figure 1(Indicated clockwise direction). In this mode, the peristaltic pump 40 is actuated in the forward pumping direction, while the first clamp valve 46 is closed and the second clamp valve 48 is opened to allow ink to flow from the ink outlet port 106 to the ink return port 108 via the printhead 4. This method of filling can be used to fill the printhead with ink.

[0027] In "standby" mode, pump 40 is disconnected, while the first pinch valve 46 is closed and the second pinch valve 48 is open. The "standby" mode maintains a negative hydrostatic ink pressure on printhead 4, which minimizes color mixing on the nozzle plate 19 when the printer is idle. Typically, the printhead is covered in this mode to minimize ink evaporation from the nozzles (see, for example, US 2011 / 0279519, the contents of which are incorporated herein by reference).

[0028] To replace a depleted printhead 4, the printhead fill start needs to be insufficient before it can be removed from the printer. In "insufficient fill start" mode, the first clamp valve 46 is open, the second clamp valve 48 is closed, and the first pump 40 is actuated in the forward direction to draw air from the atmosphere via the air duct 50. Once the printhead 4 has become insufficiently filled, the printer is set to an "invalid" mode that isolates the printhead from the ink supply, thereby allowing for safe removal of the printhead with minimal ink spillage.

[0029] Based on the foregoing, it should be understood that multiple fluid operations can be combined using the above methods. Figure 1 The ink delivery system described is used to perform this.

[0030] 4-point dry printhead filling

[0031] Combination Figure 1 The described ink delivery system is ideally suited for filling wet printheads (i.e., printheads typically filled with transport fluid). In 'fill' mode, pump 40 is actuated in the forward direction to draw ink into printhead 4 via inlet port 8. In this way, transport fluid is removed from printhead 4 and circulates clockwise back to intermediate tank 100 via second ink line 16 around the ink delivery system. (Any dilution of the ink by the transport fluid is virtually imperceptible to the user, or can be quickly mitigated by ejecting ink from printhead 4).

[0032] However, dry printheads are not well-suited for use with, for example Figure 1The ink delivery system shown is used for filling. This is because the actuating pump 40 in the forward direction tends to draw air into the printhead 4 via the ink jet nozzles, rather than drawing fresh ink into the printhead via the inlet port 8. This problem is particularly severe in longer printheads (e.g., printheads longer than 200 mm or 250 mm). One way to overcome this problem with filling dry printheads is to seal the nozzles to prevent air from being drawn into the printhead 4. Printhead cappers are well known to those skilled in the art and are designed to suppress ink dehydration from the nozzles during idle periods (see, for example, the cappers described in US 10,518,536, the contents of which are incorporated herein by reference). However, cappers rarely provide a perfect airtight seal around the printhead nozzle plate, especially in longer printheads. In practice, many cappers are provided with small vent holes to balance the pressure inside and outside the capping chamber, thereby allowing the capper to be easily opened from the printhead when needed. Therefore, simply covering the printhead 4 usually does not adequately solve the problem of air being drawn into the nozzle when attempting to fill the printhead.

[0033] Figure 2 A system suitable for filling a dry printhead 4 is shown. In this system, during filling, the printhead 4 is covered by a capper 200; furthermore, suction is applied to the capper 200 via a suitable vacuum source (e.g., a vacuum pump) connected to the capping chamber 202.

[0034] Therefore, according to the above-described 'filling' operation, when the pump 40 is actuated in the forward direction, air is not drawn into the printhead 4 through the nozzles. Instead, the capping chamber 202 of the capper 200 maintains a low vacuum pressure, allowing ink to be drawn into the printhead 4 via the inlet port 8 as needed, thereby filling the ink channels(s) in the printhead with ink. The suction amount is controlled to be sufficient to overcome the pressure exerted by the pump at the printhead nozzles. However, the suction amount is controlled to be insufficient to draw ink into the capper 200 through the printhead nozzles. Therefore, the ink channels(s) in the printhead 4 that interconnect the inlet port 8 and the outlet port 14 can be filled with ink.

[0035] The second controller 44 can be used to control the suction volume in the capping chamber 202, in conjunction with the actuation of the pump 40. In this way, the ink delivery system does not rely on forced ink flow through the printhead 4 in a unidirectional manner, and this type of ink delivery system enables the filling of dry printheads.

[0036] Of course, it should be understood that the invention has been described by way of example only, and modifications to the details are possible within the scope of the invention as defined in the appended claims.

Claims

1. A system for filling a dry inkjet printhead, the system comprising: A dry inkjet printhead having an inlet port connected to an upstream ink line and an outlet port connected to a downstream ink line; A pump operably connected to the downstream ink line; A capping device that engages with the dry inkjet printhead; A vacuum source, used to apply suction to the sealing chamber of the capping device; as well as A control system for coordinating the actuation of the pump and the vacuum source. In use, the pump and the vacuum source are simultaneously activated, thereby drawing ink from the inlet port to the outlet port through the dry inkjet printhead and filling the dry inkjet printhead.

2. The system of claim 1, further comprising an ink tank, wherein the upstream ink line and the downstream ink line are connected to the ink tank to form a closed fluid loop with the dry inkjet printhead.

3. The system of claim 2, further comprising a bulk ink supply source for replenishing the ink canister.

4. The system according to claim 3, wherein, The ink reservoir is positioned below the height of the dry inkjet printhead to control the ink pressure in the dry inkjet printhead by gravity.

5. The system according to claim 1, wherein, The pump is a unidirectional pump.

6. The system according to claim 5, wherein, The pump is an online peristaltic pump.

7. The system according to claim 1, wherein, The suction is sufficient to overcome the pressure exerted by the pump at the nozzle of the dry inkjet printhead.

8. The system according to claim 1, wherein, The suction is insufficient to draw ink through the nozzles of the dry inkjet printhead.

9. A method for filling a dry inkjet printhead using a system according to any one of the preceding claims.

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