Ink conditioner for inkjet printers

Abstract

The present invention relates to an ink regulator (14) for an inkjet printer, the ink regulator (14) comprising a body (18) having an ink attenuation cavity (24), the ink regulator (14) further comprising a heat transfer element (26), at least one ink inlet (28), and at least one ink outlet (34), the body (18), the heat transfer element (26), at least one ink inlet (28), and at least one ink outlet (34) being made of the same material and forming a one-piece molded article.

Description

[Technical Field]

[0001] The present invention relates to an ink conditioner for an ink jet printer. [Background technology]

[0002] Inkjet printers are typically used to digitally print on a variety of products, such as labels, textiles, and ceramic tiles, by ejecting small droplets of ink from nozzles in a printhead.

[0003] To achieve consistent, high-quality printing, ink parameters such as ink viscosity, ink flow rate, and ink pressure must be precisely controlled. If the ink viscosity is too high and / or the ink meniscus pressure is too low, the ink may not be able to exit the printhead nozzles. In contrast, if the ink viscosity is too low or the ink meniscus pressure is too high, satellite droplets may form, resulting in an overall reduction in print quality. Furthermore, when inkjet printing is performed on porous substrates, the resulting printed dots are affected by the viscosity-dependent ink spreading and penetration into the substrate.

[0004] Particularly in high-throughput industrial inkjet printing, ink control is often complex, requiring sophisticated ink management systems with manifolds that distribute ink to a single printhead and / or control ink temperature to achieve the desired viscosity.

[0005] Additionally, sophisticated inkjet printers employ ink conditioners that allow for precise control of ink parameters directly at the inlet and / or outlet of the printhead. Such ink conditioners may include means for measuring and regulating ink pressure, means for measuring and regulating ink temperature, means for flushing the printhead, means for circulating ink through the printhead, means for damping ink vibrations, and / or means for equalizing fluctuations in ink flow rate and / or ink pressure that may be caused by ink circulation pumps.

[0006] Previously known ink conditioners typically include several different components, such as hoses, connectors, seals, etc., made from different materials and assembled together. As a result, ink conditioners are prone to errors and / or failures, such as clogging due to seal leaks or ink deposit formation, which can occur if the ink is incompatible with one of the materials that make up the manifold. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide an ink conditioner for an ink jet printer that is less prone to such errors and / or disturbances, thus improving the stability of the printing process. [Means for solving the problem]

[0008] The object of the present invention is solved by an ink regulator for an inkjet printer, the ink regulator comprising a body having an ink damping cavity, the ink regulator further comprising a heat transfer element, at least one ink inlet, and at least one ink outlet, wherein the body, the heat transfer element, the at least one ink inlet, and the at least one ink outlet are made of the same material and form a one-piece molded product.

[0009] In this context, the term "inlet" refers to an opening through which fluid can enter the ink regulator, and the term "outlet" refers to an opening through which fluid can exit the ink regulator.

[0010] The purpose of the ink damping cavity may be to damp vibrations in the ink and / or to even out fluctuations in ink flow rate and / or ink pressure. The heat transfer element may be used to regulate the temperature of the ink.

[0011] The proposed ink regulator structure, with different ink regulator elements formed from the same material in a single piece, reduces the effort required to assemble the ink regulator, and further reduces the total number of separate parts and materials, and therefore potential points of failure, compared to conventional ink regulators.

[0012] In one embodiment, the body, the heat transfer element, the at least one ink inlet, and the at least one ink outlet are manufactured by rapid prototyping, in particular 3D printing, and are composed of metal.

[0013] Rapid prototyping and / or 3D printing techniques allow key elements of an ink regulator to be manufactured in a single, cost-saving process step, even if the ink regulator geometry is complex.

[0014] Preferably, the body, the heat transfer element, the at least one ink inlet, and the at least one ink outlet are made of titanium, a metal with high hardness and excellent corrosion resistance. Furthermore, titanium is antimagnetic and therefore unlikely to interfere with electronic components.

[0015] In a further embodiment, the ink regulator includes a membrane and a spring plate that seals the ink damping cavity, the membrane being disposed between the body and the spring plate. The membrane is elastically deformable. When ink pressure in the ink damping cavity fluctuates, the membrane can deflect inward and / or outward to dampen the pressure fluctuations. The spring plate stabilizes the membrane and limits its maximum deflection.

[0016] The ink damping cavity may be circular in shape, which allows for the application of a circular membrane that seals the ink damping cavity. Due to the circular shape, the membrane deforms symmetrically, which allows for damping in areas of relatively high pressure and generally improves process control.

[0017] To achieve a very compact design, the body can have at least one linear path with an opening into the ink damping cavity, within which a spring plate guide element can be placed. In particular, the spring plate guide element can be a piston with a spring attached thereto that presses against the spring plate to ensure accurate and smooth movement of the spring plate.

[0018] In another variation, the heat transfer element comprises a cavity configured to receive the heating element and an ink passage surrounding the cavity, which allows the ink to be heated without direct contact between the ink and the heating element.

[0019] Preferably, the ink path includes an ink outlet configured to connect directly to the inlet of the print head. Location close to the print head increases the accuracy of printing temperature control. Deviations between the set temperature and the actual printing temperature are prevented or at least minimized by the short flow path between the sensor and the print head.

[0020] In a further embodiment, the ink regulator includes a first pressure sensor configured to measure ink pressure within the ink path over a first pressure range and a second pressure sensor configured to measure ink pressure within the ink path over a second pressure range. Specifically, the first pressure sensor can be configured to accurately measure low ink pressures up to 50 mbar. The second pressure sensor can be configured to measure high ink pressures up to 1 bar. This improves the overall accuracy of ink pressure measurement and / or control across all application-relevant pressure ranges.

[0021] Additionally, the ink regulator can include a mating region configured to receive a screw or bolt that directly couples the ink regulator to the printhead, facilitating assembly. Furthermore, a rigid bond can be formed between the ink regulator and the printhead, reducing the risk of leakage at the interface between the two components.

[0022] In a further variation, the ink regulator includes a valve for flushing the printhead, which allows for quick and easy cleaning of the printhead, for example to restore clogged nozzles, without requiring disassembly of the printer and / or printing unit.

[0023] Further advantages and features will become apparent from the following description of the invention and the accompanying drawings which illustrate non-limiting exemplary embodiments of the invention. [Brief explanation of the drawings]

[0024] [Figure 1] 1 shows a schematic side view of a printing unit for an inkjet printer. [Figure 2] 1 shows a schematic 3D view of an ink regulator according to the present invention. [Figure 3] 3 shows a 3D printing element configured with the ink regulator of FIG. 2. [Figure 4] 3 shows an exploded view of the ink regulator of FIG. 2. [Figure 5] 3 shows a first cross section of the ink regulator of FIG. 2. [Figure 6] 3 shows a second cross section of the ink regulator of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0025] 1 shows a schematic side view of a printing unit 10 of an industrial single-pass inkjet printing press. The inkjet printing press may comprise a plurality of such printing units 10 forming a stack that defines the printing width of the printer.

[0026] Printing unit 10 includes a manifold 12, four ink regulators 14, and four piezoelectric inkjet printheads 16 (e.g., Dimatix Samba printheads having multiple individually addressable nozzles arranged on a trapezoidal nozzle plate). Each ink regulator 14 corresponds to a separate printhead 16.

[0027] In the described embodiment, the manifold 12 comprises means for controlling the ink temperature, such as a body 18 having an ink cavity 20 in thermal contact with a temperature control fluid cavity 22, and means for distributing the ink to individual ink regulators 14, specifically multiple inlets and outlets for the ink.

[0028] 2 shows a schematic 3D view of an ink regulator 14 according to the present invention adapted to receive ink from manifold 12. Ink regulator 14 comprises a body 18 having a circular ink damping cavity 24, specifically for damping ink pressure fluctuations caused by the circulation pump.

[0029] The ink regulator 14 further includes a heat transfer element 26 for fine-tuning the ink temperature, two ink inlets 28 through which ink can enter the ink regulator 14, specifically a main ink inlet 30 and an ink return inlet 32, and two ink outlets 34 through which ink can exit the ink regulator 14, specifically a main ink outlet 36 and a printhead supply outlet 38.

[0030] The ink regulator 14 further includes a coupling area 40 configured to receive a screw or bolt that couples the ink regulator 14 directly to the printhead 16 .

[0031] In the described embodiment, the body 18, heat transfer element 26, ink inlet 28, ink outlet 34, and bonding region 40 form a single piece and are constructed from 3D printed titanium.

[0032] FIG. 3 shows a schematic 3D view of this integrally molded product.

[0033] The single piece may include additional elements such as a fluid inlet, for example, a flushing fluid inlet 42 through which flushing fluid for cleaning the printhead may enter the ink conditioner 14 .

[0034] In an embodiment, the single piece has an opening 46 inside the ink attenuation cavity 24 and further comprises three linear paths 44 for receiving moving parts, in particular guide elements.

[0035] The entire structure including the body 18, heat transfer element 26, ink inlet 28, ink outlet 34, bonding area 40, flushing liquid inlet 42, and three linear paths 44 as shown in FIG. 3 may be 3D printed in a single, cost-saving process step.

[0036] Despite the large number of different elements and complex structure, the one-piece molded part does not include any seals or similar parts made of rubber or similar materials, and is therefore very robust and, due to the inert nature of the titanium surface, very compatible with many different types of inks, in particular inks containing polar and / or non-polar and / or organic solvents.

[0037] In the described embodiment, the ink regulator 14 includes several additional parts attached to a 3D printed titanium structure.

[0038] FIG. 4 shows an exploded view of these ink regulator components, which include a circulation pump 48, a valve 50 that regulates fluid flow through the printhead supply outlet 38, a valve 52 that allows printhead flushing, and specifically a sealed circuit board 54 for controlling the circulation pump 48 and / or the valves 50, 52.

[0039] In the described embodiment, the circulation pump 48 is located between the ink return inlet 32 ​​and the main ink outlet 36. As a result, the circulating ink flows through the printhead 16 before passing through the circulation pump 48.

[0040] It is contemplated that the manifold 12 forms part of an ink circulation system. By way of example, the circulation pump 48 may generate ink flow from the manifold 12 to the ink regulator 14, from the ink regulator 14 to the printhead 16, from the printhead 16 to the ink regulator 14, and from the ink regulator 14 back to the manifold 12.

[0041] The valve 50 can regulate and / or shut off the ink circulation, for example when cleaning and / or flushing of the printhead is intended.

[0042] The ink conditioner 14 further comprises a circular membrane 56 for sealing the ink damping cavity 24 , a spring plate 58 , and a spring plate guide element 60 .

[0043] FIG. 5 shows a first cross section of the assembled ink regulator 14, particularly the ink dampening cavity 24 and corresponding components.

[0044] The membrane 56 is elastically deformable and is disposed between the body 18 and a spring plate 58. When ink pressure within the ink damping cavity 24 fluctuates, the membrane 56 can deform and / or deflect symmetrically toward and / or away from the body 18, thereby changing the cavity volume so that pressure fluctuations are damped. The spring plate 58 stabilizes the membrane 56 as it deflects and limits its maximum travel.

[0045] The spring plate guide element 60 is a spring-mounted piston that is movably fitted within the linear path 44 of the body 18. Due to the spring mounting, the spring plate guide element 60 bears against the membrane 56 and / or the spring plate 58, thereby ensuring accurate and smooth movement of the spring plate. It is believed that the damping characteristics of the ink damping cavity 24 depend on the Young's modulus of the mounting spring and / or the spring plate 58.

[0046] FIG. 6 shows a second cross section of the assembled ink conditioner 14, specifically the heat transfer element 26.

[0047] In an embodiment, the heat transfer element 26 comprises a cavity within which a heating element 64, particularly a resistive heater, is disposed.

[0048] The heat transfer element 26 further comprises an ink passage surrounding the heater cavity.

[0049] The walls forming the heater cavity, as well as the surrounding ink path, are believed to be constructed of 3D printed titanium, which has high thermal conductivity, so that heat from the heating element 64 is efficiently conducted within the ink path towards the ink.

[0050] The ink path includes a printhead supply outlet 38 that is connected directly to an ink outlet, in embodiments to an inlet of the printhead 16. Thus, the temperature of the ink can be regulated just before it enters the printhead 16.

[0051] In the described embodiment, the ink regulator 14 further includes a first pressure sensor 68 configured to measure ink pressure within a first pressure range within the ink path, and a second pressure sensor 70 configured to measure ink pressure within a second pressure range within the ink path.

[0052] The use of multiple different range pressure sensors 68, 70 improves the overall accuracy of ink pressure measurements and therefore process control. [Explanation of symbols]

[0053] 14 Ink regulator 18 Main Unit 24 Ink damping cavity 26 Heat Transfer Elements 28 Ink inlet 34 Ink outlet

Claims

1. 1. An ink conditioner for an ink jet printer, comprising: a body (18) having an ink damping cavity (24), The ink conditioner (14) further comprises a heat transfer element (26), at least one ink inlet (28), and at least one ink outlet (34); The ink conditioner, wherein the body (18), the heat transfer element (26), the at least one ink inlet (28), and the at least one ink outlet (34) are constructed from the same material and form a single unit.

2. 10. The ink regulator of claim 1, wherein the body (18), the heat transfer element (26), the at least one ink inlet (28), and the at least one ink outlet (34) are constructed from 3D printed metal.

3. 3. The ink conditioner of claim 1, wherein the body (18), the heat transfer element (26), the at least one ink inlet (28), and the at least one ink outlet (34) are constructed of titanium.

4. The ink regulator of claim 1 , wherein the ink damping cavity (24) has a circular shape.

5. 2. The ink regulator of claim 1, further comprising a membrane (56) and a spring plate (58) that seal the ink damping cavity (24), the membrane (56) being disposed between the body (18) and the spring plate (58).

6. 2. The ink regulator of claim 1, wherein the body includes at least one linear path having an opening within the ink damping cavity configured to receive the spring plate guide element.

7. The ink regulator of claim 1 , wherein the heat transfer element (26) comprises a cavity configured to receive a heating element (64) and an ink path surrounding the cavity.

8. 8. The ink regulator of claim 7, wherein the ink path comprises an ink outlet (34) configured to connect directly to an inlet of a printhead (16).

9. 9. The ink regulator of claim 7, further comprising a first pressure sensor (68) configured to measure ink pressure within the ink flow path over a first pressure range, and a second pressure sensor (70) configured to measure ink pressure within the ink flow path over a second pressure range.

10. 10. The ink regulator of claim 1, further comprising a coupling area (40) configured to receive a screw or bolt that directly couples the ink regulator (14) to a printhead (16).

11. 10. The ink regulator of claim 1, further comprising a valve (52) for flushing the printhead.

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