Apparatus and system for inkjet printing, and non-transitory computer readable storage medium

Abstract

The present application relates to an apparatus and system for inkjet printing, and a non-transitory computer readable storage medium, the apparatus comprising: a container defining a holding chamber to hold ink, the container comprising: a first portion configured to hold a first amount of ink, and a second portion smaller than the first portion and configured to hold a second amount of ink, the second portion comprising a first thermally conductive surface, and a second thermally conductive surface offset from the first thermally conductive surface by a distance determined according to a melting point of the ink, the second thermally conductive surface defining a barrier between the first portion and the second portion and comprising at least one opening configured to allow flow of the ink from the first portion to the second portion; and at least one heating element configured to heat the container.

Description

Technical Field

[0001] This manual relates to industrial printing systems, including systems and technologies related to drop-on-demand (DOD) inkjet printing systems. Background Technology

[0002] Various industrial printing technologies enable the printing of important information (e.g., sales date) on packaging. DOD inkjet printing systems can be used to print images on commercial products using various types of inks, including hot melt inks. These images can include graphics, company logos, alphanumeric codes, and identification codes. For example, such images can be observed on corrugated cardboard boxes containing consumer goods.

[0003] Hot melt ink (sometimes called phase change ink) may include modified waxes and is typically solid at ambient temperature and liquid at temperatures above ambient. Hot melt ink can be used in, for example, digital printing methods. During printing, the ink is typically heated until it becomes liquid and then ejected through a printhead onto a substrate. The ink can cure on the substrate at ambient temperature. Hot melt ink can be used with DOD inkjet printers that have heating capabilities, which eject ink droplets through tiny nozzles to form small dots, thus creating an image on the substrate. Some DOD inkjet printing systems that use hot melt ink may require at least 60 minutes after startup to reach their printing operating temperature (e.g., DOD inkjet printing systems using large “single-stage” aluminum containers, such as 1.5-liter single-stage reservoirs). Summary of the Invention

[0004] This specification describes technologies related to industrial printing systems, particularly systems and technologies related to drop-on-demand (DOD) inkjet printing systems. A DOD inkjet printing system may include a "holding chamber" comprising a "two-stage" container configured to hold a first amount of ink in a first section and a second amount of ink in a second section, wherein the second section is smaller than the first section (and therefore, the second amount of ink is less than the first amount). The "two-stage" container facilitates a "two-stage heating" technology that ensures the second amount of ink in the second section melts completely after a shorter heating time compared to the first amount of ink in the first section. The geometry of the second section facilitates rapid melting, and the dimensions of the second section can be designed to minimize the thermal mass of the ink to be melted before printing begins, and can be designed to facilitate heat conduction from the surrounding walls.

[0005] Generally, one or more aspects of the subject matter described in this specification may be embodied in one or more devices comprising: a container defining a holding chamber for containing ink, the container including a first portion configured to contain a first amount of ink, and a second portion smaller than the first portion and configured to contain a second amount of ink, the second portion including a first thermally conductive surface and a second thermally conductive surface offset from the first thermally conductive surface by a distance determined according to the melting point of the ink, the second thermally conductive surface defining a barrier between the first and second portions and including at least one opening configured to allow ink to flow from the first portion to the second portion; and at least one heating element configured to heat the container.

[0006] The at least one heating element includes a first heating element and a second heating element. The first heating element has a first rated power, and the second heating element has a second rated power higher than the first rated power. The at least one second heating element is located closer to the second portion than the first portion, and the distance is designed to reduce the thermal mass of the second amount of ink when the heating element heats the container, thereby causing all of the second amount of ink to melt before the first amount of ink.

[0007] The device may include a pressure-reducing valve coupled to the container and configured to activate when the pressure in the container exceeds a threshold pressure. The first portion includes a first chamber and the second portion includes a second chamber, and the obstruction includes a baffle separating the first and second chambers. The at least one opening includes a first opening at a first end of the obstruction and a second opening at a second end of the obstruction opposite the first end. Furthermore, the obstruction includes a plate attached to the bottom surface of the container.

[0008] One or more aspects of the subject matter described in this specification can also be embodied in one or more systems including a first container defining a melting chamber configured to receive ink; a second container in fluid communication with the first container and defining a holding chamber configured to receive the ink from the first container; the second container including: a first portion configured to contain a first amount of the ink; and a second portion smaller than the first portion and configured to contain a second amount of the ink; the second portion including: a first thermally conductive surface; and a second thermally conductive surface offset from the first thermally conductive surface by a distance determined according to the melting point of the ink, the second thermally conductive surface defining a barrier between the first portion and the second portion and including at least one opening configured to... To allow the ink to flow from the first portion to the second portion; at least one first heating element configured to heat the first container; at least one second heating element configured to heat the second container; a printhead including a plurality of nozzles and at least one third heating element configured to heat the printhead, the printhead being configured to eject molten ink through the plurality of nozzles; an ink supply system including an ink line configured to fluidly connect the printhead to the holding chamber and at least one fourth heating element configured to heat the ink line; and a control circuit configured to: cause the at least one first heating element to heat the first container; cause the at least one second heating element to heat the second container; cause the at least one third heating element to heat the printhead; and cause the at least one fourth heating element to heat the ink line.

[0009] The system may include a sensor located within the first portion of the second container, wherein the control circuitry is further configured to: determine the current amount of ink held in the second container based on information captured by the sensor; and, when the current amount of ink does not exceed a threshold amount, cause the at least one first heating element to heat the first container. The control circuitry is further configured to: cause the at least one third heating element to heat the printhead to a threshold temperature; cause the at least one fourth heating element to heat the ink lines to the threshold temperature; and cause the at least one second heating element to heat the holding chamber to the threshold temperature.

[0010] The at least one second heating element may include: a main heating element having a first rated power; and a secondary heating element having a second rated power higher than the first rated power; and the startup procedure includes shutting off the secondary heating element when the second container is heated to the second threshold temperature. The startup procedure includes causing the at least one third heating element to heat the printhead to the second threshold temperature. The system may include a pressure relief valve coupled to the second container and configured to activate when the pressure in the second container exceeds a threshold pressure. The at least one opening includes a first opening at a first end of the barrier and a second opening at a second end of the barrier opposite to the first end. The at least one second heating element is closer to the second portion than the first portion, and when the at least one second heating element heats the second container, the distance is configured such that the second portion of ink melts entirely before the first portion of ink by reducing the thermal mass of the second portion of ink relative to the first portion of ink.

[0011] One or more aspects of the subject matter described in this specification may also be embodied in one or more non-transitory computer-readable storage media, the coded instructions causing the control circuitry of the printing system to perform operations including: adjusting the ink lines of the printing system to a threshold temperature using at least one heating element; adjusting the printhead of the printing system to the threshold temperature using at least one heating element; and heating the holding chamber of the printing system to a second threshold temperature using the at least one heating element.

[0012] The operation may include: determining the current amount of ink held in the holding chamber based on information captured by a sensor within a first portion of the holding chamber; and, when the current amount of ink does not exceed a threshold amount, causing the at least one heating element to heat the melting chamber of the printing system. The at least one heating element includes: a main heating element having a first rated power; and a secondary heating element having a second rated power higher than the first rated power; the main heating element and the secondary heating element are used to heat the holding chamber to a second threshold temperature, and the operation further includes turning off the secondary heating element when the holding chamber is heated to the second threshold temperature. Furthermore, the operation also includes causing the at least one heating element to heat the printhead to the second threshold temperature.

[0013] Compared to conventional technologies, embodiments of this disclosure can provide one or more of the following advantages. By using a container with two ink storage sections (e.g., a 1.5-liter aluminum reservoir), one section being substantially smaller than the other, the printing system can be configured to implement a graded heating technology at startup. The time required for molten ink to be available for printing after a cold start can be reduced. Costs associated with downtime due to startup can be reduced. Potential damage to the printing system due to accelerated heating time can be reduced.

[0014] Details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages of the invention will become apparent from the description, drawings, and claims. Brief description of the attached figures

[0015] Figure 1 An example of a printing system is shown.

[0016] Figure 2 shows an example of a conventional single-stage ink container.

[0017] Figures 3A-3B An example of a two-stage ink container is shown.

[0018] Figure 4 It shows the relationship with Figures 3A-3B The simulation results related to the two-stage ink container.

[0019] Figures 5A-5B It shows in Figures 3A-3B The graph shows the temperature increase over time during the use of a two-stage ink container.

[0020] Figure 6 Another example of a two-stage ink container is shown.

[0021] Figure 7 It shows the relationship with Figure 6 The simulation results related to the two-stage ink container.

[0022] Figures 8A-8B Another example of a two-stage ink container is shown.

[0023] Figures 9A-9C An example of a DOD printing system is shown.

[0024] Figure 9D-9K Details of various embodiments of a pressure-reducing valve for a retaining chamber are shown.

[0025] Figures 10A-10C An example of how to operate a DOD printing system is shown.

[0026] The same reference numerals and names in each figure represent the same elements. Detailed Implementation

[0027] DOD inkjet printing systems may include ink delivery modules (IDMs) configured to supply ink to the system's printhead for printing. Hot melt inks typically comprise modified waxes. At room temperature, they are usually solid. When heated, they may first transform into a "paste" phase (e.g., a phase between solid and liquid), over a wide temperature range of approximately 50°C to 90°C, and then become liquid. The printhead and ink can be designed to eject ink at, for example, 125°C and 10–14 centipoise.

[0028] Implementations of this disclosure can help overcome one or more drawbacks of conventional printing systems caused by the implementation of, for example, large “single-stage” aluminum reservoirs (e.g., 1.5-liter single-stage reservoirs), and the low thermal conductivity (e.g., 0.1756-0.25 W / mK) of some hot melt inks. For example, embodiments of this disclosure can reduce downtime caused by the heating process required to reach the operating temperature for printing, which can be costly for the user (in terms of both time and money). In some embodiments, the printing system is configured to implement a staged heating technique by using a reservoir with two ink reservoir sections (e.g., a 1.5-liter aluminum reservoir) to reduce the thermal mass of the hot melt ink, with one reservoir section being significantly smaller than the others. In some embodiments, this reduction in thermal mass allows heat from the aluminum wall of the smaller section to penetrate the insulating ink via thermal conduction and raise its internal temperature at a faster rate compared to the larger section, thereby reducing the time after a cold start when the molten ink is available for printing. Many hot melt inks expand and contract during heating and cooling. The smaller section prevents some of the hot melt ink from contracting from the aluminum wall during cooling. This ensures that the solid hot melt ink remains in contact with the wall (e.g., an aluminum wall) during cold starts, promoting a smaller portion of heat conduction from the surrounding walls.

[0029] Figure 1 An example of a printing system 100 is shown. The printing system 100 includes a cabinet 102 to house a controller device with a user interface 104 (which includes control circuitry, e.g., as referred to later). Figures 9A-9B (As discussed), and (off-head) ink reservoir (which may include ink containers, e.g., reference) Figures 3A-3BThe ink containers 6 and 8A-8B (one of the two-stage ink containers discussed in this specification) have a door 106 for access thereto. The printing system 100 also includes a print bar 108 configured to receive one, two, three, four, five, or more printheads 110. The printheads 110 can be repositioned and / or reoriented relative to one or more substrates on the print bar 108, such that the printheads 110 eject ink (as guided by a controller device of the printing system 100) to print an image on the substrate as it moves past the printheads 110. In some embodiments, the print bar 108 is a printhead support on its own rollers, wheels, or casters, allowing the printhead support 108 to move independently of the cabinet 102, which includes its own rollers, wheels, or casters. As used herein, the “substrate” for printing is not necessarily a continuous substrate and can include discrete packages and products (e.g., moving past the printheads 110 on a conveyor belt on a production and / or packaging line).

[0030] Printed images may include alphanumeric characters (e.g., date codes or text serial numbers), barcode information (e.g., one-dimensional or two-dimensional barcodes), graphics, logos, etc. Controller devices (e.g., as referenced later) Figures 9A-9B The discussion includes electronic devices (e.g., control circuitry) that may include one or more processors that execute instructions (e.g., stored in the memory of the electronic device) to control the operation of the printing system 100. Suitable processors include, but are not limited to, microprocessors, digital signal processors (DSPs), microcontrollers, integrated circuits, application-specific integrated circuits (ASICs), logic gate arrays, and switch arrays. The electronic device may also include one or more memories for storing instructions executed by one or more processors and / or for storing data developed during the operation of the printing system 100. Suitable memories include, but are not limited to, random access memory (RAM), flash RAM, and electronic read-only memory (e.g., ROM, EPROM, or EEPROM).

[0031] The substrate can be a label added to the product, packaging material for the product (before or after the product is placed in packaging), and / or the surface of the product itself. For example, the substrate can be a corrugated cardboard box containing one or more products. Therefore, the printhead 110 can be repositioned and / or reoriented relative to one or more product lines on the print bar 108, the product lines including conveyors and / or other product movement mechanisms that move products via equipment. This equipment can be product manufacturing equipment, product distribution equipment, and / or other industrial / commercial equipment / buildings, and the product lines can include product packaging systems, product sorting systems, and / or other product handling / management systems. It should be understood that the printing system 100 is merely an example, and many other suitable structures can be used to construct printing systems employing the printhead system and techniques described herein.

[0032] Figure 2 illustrates an example of a conventional single-stage ink container 200. Container 200 defines a chamber 230 configured to contain a quantity of hot melt ink 240. In the illustrated embodiment, the amount of ink has a volume of approximately 1.5 liters. During heating and cooling, much of the hot melt ink expands and contracts relative to the walls of chamber 230 (e.g., aluminum walls). Container 200 also includes a heating element 220, which may have a rated wattage between 400 watts (W) and 800 W (e.g., representing the maximum power at which the device can safely operate continuously). Typically, the single-stage ink container 200 may be located within the ink container of a printing system, as previously referenced. Figure 1 The ink container described.

[0033] Figures 3A-3B An example of a two-stage ink container 300 is shown. The ink container 300 can be used with a DOD printing system, as previously referenced. Figure 1 The printing system 100 described (e.g., located inside the ink container) or referenced later Figure 9A The described printing system 900.

[0034] Container 300 defines a chamber for containing ink, the chamber having a first portion 330a and a second portion 330b. The first portion 330a forms a main container and the second portion 330b forms a secondary container. As shown, the first portion 330a is larger than the second portion 330b. The first portion 330a is designed to contain a first amount of ink 340a, while the second portion 330b is designed to contain a second amount of ink 340b. In the illustrated embodiment, the first amount of ink has a volume of 1.35 liters (L), and the second amount of ink has a volume of 120 milliliters (mL). However, in other embodiments, the dimensions of the first portion 330a and the second portion 330b are designed to contain more or less ink. In some cases, based on printing needs, it may be advantageous for the volume of the second amount of ink to be greater than 120 mL to provide sufficient ink for printing after a short heating time. The dimensions of the first portion 330a and the second portion 330b may be based on factors such as printing needs, ink shrinkage percentage, and the melting point of the ink used.

[0035] The ink container 300 is made of a thermally conductive material, such as aluminum. The container 300 includes a heating element 320 configured to heat the container. In some embodiments, the heating element 320 has a rated power wattage between 200W and 800W. In some embodiments, the heating element 320 includes a 48-volt (V) direct current (DC) heater. Although the illustrated embodiment includes only one heating element 320, in other embodiments, the container 300 includes more than one heating element 320 (e.g., as in reference [reference]). Figure 6(Described implementation). The first part 330a and the second part 330b are separated by a barrier 332.

[0036] refer to Figure 3B As shown, the second portion 330b includes a first thermally conductive surface 331a and a second thermally conductive surface 331b, which are separated by an offset (D). The offset (D) can be based on various factors, such as the desired heat transfer rate, the melting point of the ink, the ink shrinkage percentage, and practical limitations imposed by a particular printing system. In the illustrated embodiment, the barrier 332 includes one or more openings 332b that allow molten ink to flow from the first portion 330a to the second portion 330b. The second portion 330b also includes an inlet port 333, which can be connected via a pump and an ink line (e.g., as referred to later). Figure 9A The barrier 332 is in fluid communication with the printhead of the printing system. Although the illustrated embodiment describes a barrier 332 including an opening 332b, in some embodiments, the barrier 332 does not include any opening. In such embodiments, each of the portions 330a, 330b includes a corresponding inlet in fluid communication with the printhead.

[0037] In printing systems using container 300 (e.g., previously referenced) Figure 1 The described printing system 100 and referenced later Figure 9A During startup of the described printing system 900, heating element 320 begins to heat container 300, thereby heating the ink in the first portion 330a and the second portion 330b. Once the ink in the second portion 330b reaches its peak melting point (~60°C), convection in the liquid phase accelerates the heat conduction process and raises the ink temperature to ~120°C within 3-5 minutes. The molten ink in the second portion 330b exits container 300 through inlet port 333 and flows to the printhead of the printing system (e.g., as referred to later). Figure 9A (as described above). The ink volume, together with the partially melted ink in the first portion 330a, can meet typical printing needs (e.g., up to 3.75 ml / min) for a considerable period of time (e.g., up to 45 minutes). This interval allows unmelted solid ink blocks at the center of the first portion 330a to melt and flow through one or more openings 332b, replenishing the second portion 330b to ensure continuous printing.

[0038] Use container 300 (or other containers discussed in this specification, such as those referred to later). Figure 6 and 8A -8B discussed container) printing system (e.g., the previous reference) Figure 1 The described printing system 100 and subsequent references Figures 9A-9CThe described printing system 900 can support printing at the end of a short heating period (e.g., less than or equal to 15 minutes) because the container 300 is designed to provide sufficient amount of molten ink to continue printing after the short heating period. The second section 330b in the container 300 (or the second sections 630b and 830b in containers 600 and 800) prevents some hot melt ink from shrinking from the aluminum wall during cooling. This ensures that solid hot melt ink remains in contact with the wall of the second section 330b (e.g., the aluminum wall) during cold start, thereby promoting heat conduction from the surrounding walls. Furthermore, unlike conventional technologies, the container 300 is designed to reduce the blockage of inlet port 333 (which is in fluid communication with a pump to pump molten ink to the printhead) and prevent the printing system from running low on ink during the melting period.

[0039] Figure 4 It shows the relationship with Figures 3A-3B Simulation results related to the two-stage ink container: 400. Figure 4 The approximate temperature range of region 401-406 is shown in the table below.

[0040]

[0041]

[0042] As shown in the figure, a heating element with a rated power of 700W can be used to heat container 300 for 900 seconds (15 minutes). At 15 minutes, the entire ink volume within the second section 330b of the two-stage container 300 is comfortably above its peak melting point (60°C) (e.g., region 401). At the end of 15 minutes, the molten ink in the second section 330b can begin to be pumped through inlet port 333 to the print head of the printing system for printing operation. Figure 4 It is also shown that some ink in the first section 330a has already melted (e.g., region 402). As ink begins to leave this section 330b, the melted ink can flow through opening 332b to replenish the amount of ink in the second section 330b. Therefore, continuous printing operations can begin after 15 minutes, while providing sufficient amount of melted ink to allow enough time for the ink inside the first section 330a to fully melt. This reduces the risk of unmelted ink clogging inlet 333 and erroneously causing the printing system to run out of ink during continuous printing operations after the 15-minute heating period.

[0043] Figure 5A It is graph 500a, which shows the use of... Figures 3A-3B The example of a two-stage ink container 300 shows the temperature increasing over time. (Reference) Figure 5AGraph 500a illustrates an experiment in which the inks in the first and second portions 330a and 330b of container 300 were heated using a 400W heater at an ambient temperature of 21°C. Temperature data were collected using thermocouples located at the center of each of the first portion 330a and the second portion 330b. Dashed curve 501a illustrates the transient temperature characteristics of the hot-melt ink at the center of the second portion 330b, while solid curve 502a illustrates the transient temperature characteristics of the hot-melt ink at the center of the first portion 330a. As shown, when using a single 400W heater, substantially all the inks in the second portion 330b reached their peak melting point (60°C) in approximately 22 minutes, while substantially all the inks in the first portion 330a reached their peak melting point in approximately 55 minutes.

[0044] Figure 5B This is graph 500b, illustrating an experiment involving heating the inks in the first and second portions 330a and 330b of container 300 using a 600W heater at an ambient temperature of 24°C. Temperature data were collected using thermocouples located at the center of each of the first and second portions 330a and 330b. The dashed curve 501b illustrates the transient temperature characteristics of the hot-melt ink at the center of the second portion 330b, while the solid curve 502b illustrates the transient temperature characteristics of the hot-melt ink at the center of the first portion 330a. As shown, when using a single 600W heater, substantially all the ink in the second portion 330b reaches its peak melting point (60°C) in approximately 16 minutes.

[0045] The design of ink container 300 also allows for faster start-up times for a variety of different types of inks. For example, ink container 300 can be used with inks that have a higher melting point than with inks that have a relatively low melting point, without a significant impact on start-up time.

[0046] Figure 6 An example of a two-stage ink container 600 is shown. The ink container 600 can be used with a DOD printing system, as previously referenced. Figure 1 The described printing system 100 or later refers to Figure 9A The described printing system 900.

[0047] Container 600 includes a first portion 630a and a second portion 630b, separated by a continuous barrier 650 having one or more openings (not shown) to allow ink to flow from the first portion 630a to the second portion 630b. Container 600 is similar to the previously referenced container. Figures 3A-3B The container 300 described, except for the length (L) of the second part 630b relative to Figures 3A-3BThe second part 330b extends outwards, and the container 600 includes two opposing heating elements 640a, 640b. This extended length may have little (or no) impact on the heat transfer rate, as this rate depends primarily and directly on the width (D), which is related to... Figures 3A-3B The container is the same as 300. When with Figures 3A-3B Compared to container 300 (in the illustrated embodiment, the second portion 630b is capable of holding up to 263 mL of ink), this modification allows for more than doubling the ink volume in the second portion 630b and enables printing after a shorter heating time (e.g., less than or equal to 15 minutes), even when the initial ink level in container 600 is low (e.g., approximately 10 mm from the bottom of container 600), compared to conventional techniques. The second portion 630b in container 600 (or the second portions 330b and 830b in containers 300 and 800) prevents some hot melt ink from shrinking from the walls of the second portion 630b during cooling. This ensures that the solid hot melt ink remains in contact with the walls (e.g., aluminum walls) in the second portion 630b during cold starts, promoting heat conduction from the surrounding walls. Furthermore, using two heating elements 640a and 640b can facilitate a multi-stage heating process, wherein heating elements 640a and 640b are turned on at startup to cause faster heating, and then one of the heating elements 640a and 640b can be turned off after a period of time to promote energy saving and effective thermal regulation at the desired temperature. In some embodiments, the two heating elements 640a and 640b have similar rated wattages (e.g., both can have a 400W rating). In some embodiments, the two heating elements 640a and 640b have different rated power (e.g., one can have a 400W rating and the other can have an 800W rating).

[0048] Figure 7 It shows Figure 6 Simulation results 700 for a two-stage ink container 600. Simulation result 700 shows the temperature distribution of the ink container 600 at the end of 15 minutes using two 400W heating elements 640a and 640b. Figure 7 The approximate temperature range of regions 701-706 shown is shown in the table below:

[0049]

[0050] As shown in the figure, most of the ink in the second part 630b is heated to above its peak melting point (60°C) after 15 minutes (see, for example, areas 701 and 702), so printing can begin even if most of the ink in the first part 630a remains well below its peak melting point temperature (see, for example, areas 703-705).

[0051] Figures 8A-8B An example of a two-stage ink container 800 is shown. The ink container 800 can be used with DOD printing systems, such as those previously referenced. Figure 1 The described printing system 100 or later refers to Figure 9A The described printing system 900.

[0052] Reference Figure 8A The container 800 includes a first part 830a, a second part 830b, a first heating element 820a, and a second heating element 820b. The container 800 is similar to the previously referenced... Figure 6 The described container 600, except that the first portion 830a and the second portion 830b are separated by a baffle barrier 850, which is opposite to the continuous barrier. The baffle barrier 850 may have two openings 852a, 852b at their respective ends to allow ink to flow from the first portion 830a to the second portion 830b. These openings 852a, 852b allow the first portion 830a to be replenished with the second portion 830b immediately after a short heating period (e.g., less than or equal to 15 minutes). This allows for continuous printing even with a low initial ink volume (e.g., approximately 10 mm from the bottom of the container 800). The second portion 830b of the container 800 (or the second portions 630b and 330b in containers 600 and 300) prevents some hot melt ink from shrinking from the aluminum wall during cooling. This ensures that the solid hot melt ink remains in contact with the wall (e.g., the aluminum wall) of the second portion 830b during cold starts, thereby promoting heat conduction from the surrounding walls. Furthermore, the design of container 800 facilitates the use of pigment inks because the openings 852a, 852b at the end of the baffle barrier 850 allow the liquid ink to circulate between the first part 830a and the second part 830b (assisted by stirrer 880) to avoid the sedimentation of heavy pigments.

[0053] Container 800 includes two design dimensions D1 and D2. A first design dimension D1 represents the width of openings 852a and 852b at the ends of the baffle barrier 850. Although dimension D1 is the same for both openings 851a and 852b in the illustrated embodiment, the widths of these openings are different in some embodiments. In some embodiments, the first design dimension D1 is limited (e.g., less than or equal to 15 mm) to ensure complete melting of the ink on the edge of the second portion 830b after a short heating period (e.g., less than or equal to 15 minutes). If the dimension D1 is substantially limited (e.g., less than 10 mm), heat transfer performance can be improved, but this may hinder the recycling of pigment ink from the first portion 830a to the second portion 830b. In some embodiments, the dimension D1 is fixed at 15 mm to optimize heat transfer performance regarding ink recycling between portions 830a and 830b. Although in other embodiments the dimension D1 may be greater than or less than 15 mm, in some embodiments the dimension D1 may be limited to no more than 15 mm to ensure proper melting of the ink in the second part 830b.

[0054] The second design dimension D2 represents the distance between the surface 851 of the baffle barrier 850 facing the second portion 830b and the surface 831 of the container 800 extending along the length of the second portion 830b. The second dimension D2 can directly affect the heat transfer performance of the second portion. A smaller D2 dimension can ensure good heat transfer within the second portion but will limit the amount of molten ink after a short heating time (e.g., less than or equal to 15 minutes) of continuous printing. In some embodiments, this dimension D2 is limited to between 12 and 20 mm to optimize heat transfer performance while taking into account the amount of ink required for continuous printing after a shorter heating time.

[0055] Figures 9A-9C An example of the DOD printing system 900 is shown. (See previous references.) Figure 1 The described printing system 100 may include Figures 9A-9C The printing system 900 shown includes one or more components. The printing system 900 includes a melting chamber 910, a holding chamber 920, an ink supply system 930, an optical sensor 902, an electromagnetic door lock 905, and one or more printheads 950. The system 900 includes a controller circuit 960 configured to control the operation of one or more components of the system 900.

[0056] The melting chamber 910 can be configured to receive and hold ink bottles 901. Ink bottles 901 can be, for example, 1-liter recyclable polypropylene bottles. Bottle 901 can be filled with 900 ml of molten ink at 125°C. The ink can then be cooled to a solid state in bottle 901 and its volume shrinks by approximately 14% during cooling. Access to the melting chamber 910 is controlled by an electromagnetic door lock 905 and an ink door locking switch 906. Ink loading into the system 900 can begin by entering the melting chamber 910 (e.g., by opening the door of chamber 910) and loading bottle 901 into the melting chamber 910. The melting chamber 910 is mechanically designed to prevent the possibility of the access device (e.g., the door) being open. This reduces the risk of burns to the operator when the melting chamber 910 begins to heat up (which can result in an operating temperature of 125°C) and prevents dust contamination from entering the system 910.

[0057] To prevent user access to the heating elements of the melting chamber 910, an electromagnetic lock 905 physically locks the passageway to the melting chamber 910. In some embodiments, the electromagnetic lock 905 is locked by default when power is removed and only opens when energized. In some embodiments, during a melting cycle, when the temperature in the melting chamber 910 rises above 69.9°C, a switch 906 engages the electromagnetic lock 905. In some embodiments, when the melting chamber cools to below 70°C, for user safety, the electromagnetic lock 905 disengages, allowing the empty ink bottle 901 to be removed and a new ink bottle 901 to be added. To cool the melting chamber 910 after melting a bottle of ink 901, a 68 cubic foot / meter (CFM) 24V DC cooling fan 903 with pulse width modulation (PWM) and a tachometer can be used to blow cool air directly onto the melting area. The PWM can operate at 25 kHz with a 99% duty cycle.

[0058] The melting chamber 910 includes one or more heating elements 913 configured to heat the melting chamber 910 to melt the ink in the ink bottle 901 and allow it to flow out of the bottle 901. In some embodiments, the one or more heating elements 913 remain off until ink in a new bottle 901 is melted. In some embodiments, the one or more heating elements 913 include a 48VDC, 200W heater. In some embodiments, the heating elements 913 are provided in the form of a cylindrical heater. The melting chamber 910 includes a first hardwired thermistor 911 and a first redundant hardwired thermistor 912 configured to sense an overheating condition (e.g., due to a runaway heating element) and shut off one or more heating elements 913.

[0059] refer to Figure 9CIn this process, an optical sensor 902 is used in conjunction with a melting chamber 910 to detect the presence of an ink bottle 901. The optical sensor 902 emits an optical signal 902a with a first phase, which is reflected back to the optical sensor 902 by a back-reflecting element 902b (e.g., a reflective strip) in a second phase. If the optical sensor 902 detects the second phase, it can be determined (e.g., via controller circuitry 960) that no ink bottle 901 is present in the melting chamber 910. The ink bottle 901 can be positioned between the optical sensor 902 and the back-reflecting element 902b when inserted into the melting chamber 910, either blocking the reflection of the optical signal 902a or causing the optical signal 902a to be reflected with a phase different from the second phase. In this case, it can be determined that the ink bottle 901 is present in the melting chamber 910.

[0060] Return to reference Figure 9A The holding chamber 920 is in fluid communication with the melting chamber 910 and is configured to receive molten ink flowing from the bottle 901. In some embodiments, the holding chamber 920 includes one of the containers 300, 600, and 800 described earlier in this specification. Therefore, the holding chamber 920 may include a first portion configured to contain a first amount of ink and a second portion smaller than the first portion and configured to contain a second amount of ink smaller than the first amount. The holding chamber 920 also includes one or more heating elements 923, which may include one or more of the heating elements 320, 640a, 640b, 820a, and 820b previously described in this specification. The one or more heating elements 923 are configured to heat the holding chamber 920 to melt the ink in the holding chamber 920. In the illustrated embodiment, the one or more heating elements 923 of the holding chamber 920 include a 48VDC, 400W heater and a 48VDC, 200W heater. When both the 400W and 200W heaters are used during a cold start (e.g., starting system 900 from ambient conditions), the illustrated arrangement can facilitate a 15-minute start-up time. In some embodiments, once the holding chamber 920 has reached a threshold temperature (e.g., 125°C), the 400W heater can be turned off (e.g., via controller circuitry 960, as discussed later) and the 200W heater can be used to maintain the threshold temperature. The holding chamber 920 includes a second hardwired thermistor 921 and a second redundant thermistor 922, which are configured to sense overheating conditions (e.g., due to a runaway heating element) and shut off power to one or more heating elements 923.

[0061] As previously described, in some embodiments, the holding chamber 920 comprises an aluminum sheet metal container designed to divide the holding chamber 920 into a first section and a smaller second section, wherein sufficient ink can be melted within 15 minutes after cold start to facilitate cleaning and printing operations. If a portion of the ink in the holding chamber 920 is liquid, ink pumping may occur. In some embodiments, the second section is sized such that sufficient ink can melt after the 15-minute preheating time to pump ink to the four printheads, equivalent to three 1.5-second cleaning cycles per printhead.

[0062] The holding chamber 920 also includes an ink level sensor 924 configured to sense the amount of ink remaining in the holding chamber 920. In the illustrated embodiment, the ink level sensor 924 includes a floating dual-position level sensor comprising two switches 924a and 924b. In some embodiments, the sensor 924 is made of stainless steel and incorporates two single-pole single-throw reed switches 924a and 924b contained within the shaft of the sensor 924. Position sensing can be activated by a magnet carried by the sensor 924. When the sensor 924 is near one of the switches 924a and 924b, the magnetic field causes the switch to bend and contact to close a normally open switch or to open a normally closed contact. Both the top and bottom reed switches 924a and 924b are normally open. When the sensor 924 contacts the top retaining clip, the top reed switch 924a is activated (closed). When the float contacts the bottom retaining clip, the bottom reed switch 924b is activated (closed). Sensor 924 is configured to sense three conditions: (1) the ink level is full, detected when the top switch 924a is closed and the bottom switch 924b is open; (2) the ink level is OK (this can mean, for example, that the holding chamber 920 contains at least a threshold ink fill amount, such as at least 30% filled with ink), detected when both switches 924a and 924b are open; and (3) the ink level is empty, detected when the top switch 924a is open and the bottom switch 924b is closed. Sensor 924 may be configured to activate alarm module 904 of printing system 900, for example, on an alarm tower, to indicate the ink level in holding chamber 920 to the user of printing system 900. Alarm module 904 may, for example, include one or more colored lights or speakers configured to emit audible sounds.

[0063] Because the ink sensor 924 shown is configured to float in the ink, a drop in the ink level in the holding chamber 920 causes the sensor 924 to move to various switching positions. In some embodiments, the ink level sensor 924 will give a true reading when it is frozen in the ink or when it floats in molten ink. However, the ink level sensor may give an incorrect ink level reading when the ink changes from a frozen state to a molten state. That is, when the ink in the holding chamber 920 melts, the ink around the ink level sensor 924 can remain solid because the sensor's thermal mass can absorb heat from the surrounding ink. A thicker layer of ink suspended from the ink level sensor 924 may cause the sensor 924 to sink into the molten ink. Therefore, the conditions in the table below can be used to read the ink level sensor 924:

[0064]

[0065] The ink supply system 930 includes a first check valve 932, a piston pump 934, a limit switch 933, a second check valve 935, a manifold 936, a filter 931, and an ink line 940. Ink flows from the holder through chamber 920 through filter 931 (which may be a stainless steel filter) before being pumped to printhead 950. In some embodiments, filter 931 is a 10-micron absolute filter with an effective filtration area of ​​20 square inches. In one embodiment, filter 931 is between 5 and 10 microns.

[0066] The piston pump 934 includes a motor for pumping ink from a holding chamber 920 to an ink line 940. In the illustrated embodiment, the motor is a 24V brushed DC motor. It is capable of operating at 3500 rpm and drives a 5-speed gear set with a gear ratio of 190:1. An eccentric wheel can be connected to the motor shaft. Rotation of the eccentric wheel causes the piston of the piston pump 934 to move up and down, thereby drawing ink from the holding chamber 920 into the piston chamber of the pump 934 through a filter 931 and a first check valve 932 (which may be a 2PSI stainless steel check valve). The piston then pushes the ink out of the chamber through a second check valve 935 (which may also be a 2PSI stainless steel check valve) into a manifold 936, which connects to the ink line 940. A limit switch 933 (sometimes referred to as a limit switch 933, original position sensor 933, or pump stroke count switch 933) is configured to indicate when the eccentric wheel connected to the ink pump motor shaft has completed one rotation. In one embodiment, the piston pump includes a 24VDC geared motor.

[0067] The ink line 940 includes one to four ink lines. In some embodiments, the ink lines are manufactured using seamless, fully annealed "316" stainless steel tubing. In some embodiments, the ink line 940 functions as a passive valve allowing ink to flow to the printhead 950. As shown, the ink line 940 includes a heater 941 to ensure that the ink in the ink line 940 does not freeze and clog the ink line 940.

[0068] In some embodiments, printhead 950 includes one or more printheads previously discussed in this specification, such as those previously referenced. Figure 1 The printhead 110 is discussed. The printhead 950 also includes one or more heating elements 951 for heating the ink in the printhead 950 (e.g., ink stored in a reservoir in the printhead 950).

[0069] The holding chamber 920 also includes a pressure relief valve 925 to release the pressure established in the holding chamber 920 by check valves 932, 935 and manifold 936. For example, during a cold start, components of system 900 can be heated in a specific sequence to prevent ink expansion pressure from damaging the components of system 900. The heating element 923 of the holding chamber 920 is only activated after the printhead 950 and ink lines 940 have reached a first threshold temperature (e.g., 80°C). This creates a delay time before the heating element 923 of the holding chamber 920 is activated. To reduce the overall preheating time of system 900 and facilitate printing operations after a shorter heating time (e.g., less than or equal to 15 minutes), the heating element 923 of the holding chamber 920 can be activated initially. To facilitate this, a pressure relief valve 925 can be used to release the ink pressure established from check valves 932, 935 and manifold 936. In the illustrated embodiment, the pressure relief valve 925 is installed in the retaining chamber 920 and is rated for a pressure of 300 PSI, releasing pressure immediately upon reaching approximately 260 PSI. In one embodiment, the pressure relief valve is rated for 20 bar.

[0070] The pressure reducing valve 925 can be implemented in various ways, and in some implementations, the pressure reducing valve is not required. Figure 9D The diagram illustrates, in some implementations, an example of how to address the problem of ink expansion in the holding chamber during startup. Hot-melt ink can expand by 10% from a solid to a fully molten state. The total ink volume after the inlet check valve is approximately 7.7 ml. Therefore, in some cases, this results in a volume expansion of 0.77 ml that needs to be accommodated, allowing the system to begin heating the IDM at t=0 without first heating the printhead reservoir and ink lines. Figure 9DIn this configuration, pump chamber 981 is in fluid communication with vertical axis 982. Four horizontal axes 983 are in fluid communication with vertical axis 982. Volume 984 is not occupied by fittings. In one example, pump chamber 981 is 6 mm high, 19.0 mm in diameter, and has a volume of 1.70 ml. Vertical axis 982 is 122 mm high, 6.35 mm in diameter, and has a volume of 3.86 ml. Horizontal axis 983 is 41.7 mm long and 3.175 mm in diameter, each with a capacity of 1.32 ml. Volume 984 is 1.55 mm long, 13.1 mm in diameter, and has a volume of 0.84 ml.

[0071] Figure 9E Details of an example of a check / pressure reducing valve 985 and its corresponding mounting hole 986 are shown. Note that various sizes and nominal opening pressures can be used, as shown in the table below:

[0072] Component number Nominal burst pressure PCHR5510020S 20 bar (290 psl) PCHR5510040S 40 bar (580 psl) PCHR5510060S 60 bar (870 psl) PCHR5510080S 80 bar (1160 psl) PCHR5510100S 100 bar (1450 psl)

[0073] In some embodiments, the check / pressure relief valve for the retaining chamber is constructed using an internal angle bore 987, such as... Figure 9F As shown. This has the advantage of simplicity because no additional parts are required. However, the disadvantage of this method is that it requires a multi-axis machine tool, which may increase manufacturing costs.

[0074] In some embodiments, the check / pressure relief valve for the retaining chamber is constructed using cross-holes 988, 989, such as... Figure 9G As shown. The cross-drilling method uses a plug with an O-ring seal gland, into which a pressure relief valve is inserted. The threaded plug seals the large hole and secures the pressure relief valve plug assembly. The hole plug seals the cross-drilled hole.

[0075] In some implementations, the check / pressure reducing valve for the retaining chamber uses a bottom-insertion configuration with an external discharge port, such as... Figure 9H As shown. Placing the pressure relief valve 990 at the bottom of the vertical manifold shaft 991 allows for monitoring of the function, as well as ink volume and speed. Note that this method can be used to test newly designed retaining chambers to determine if a pressure relief valve is needed, and if so, what characteristics it should have. After confirming the pressure relief valve, it can be moved to one of the two positions mentioned above, kept in the same position for effective use in the deployed printing system, or eliminated entirely. Furthermore, as... Figure 9H As shown and described, the valve can screw into the pipe fitting boss seal. In some embodiments, the pipe fitting boss seal is as follows: Figure 9I , 9J As shown in Figure 9K. The connector end can conform to AS4395. See the reference figure. Figure 9IAs shown, position P can include a thread runout of 0.015 inches. At chamfer C, the chamfer release of the hexagonal face can be within 15° + / - 5°. The radius R can be between 0.016 and 0.031 inches. Figure 9J As shown, when measured with diameter L, the front surface can be square with the thread PD within 0.010TIR (Total Indicated Runout). Reference Figure 9K The diameter D can be concentric with the thread PD within 0.005TIR. The finished tapered countersunk hole should be free of longitudinal and helical tool marks. Ring tool marks up to 100 microinches are permissible.

[0076] refer to Figure 9B As previously described, the controller circuit 960 can be implemented as hardware or firmware and configured as several components of the operating system 900. In the illustrated embodiment, the controller circuit 960 is communicatively connected via bus 970 to thermistors 911, 912, 921, 922, optical sensor 902, heating elements 913, 923, 941, 951, ink level sensor 924, door lock 905, printhead 950, and pump 934. Therefore, the controller circuit 960 is capable of operating these components. In some embodiments, the controller circuit 960 includes the previously referenced... Figure 1 The control device and control electronics described herein. Controller circuit 960 is configured to initiate a startup sequence for system 900. The startup sequence may be temperature-based and utilize ink properties by measuring the relationship between temperature and time. In some implementations, the startup sequence includes the following:

[0077] 1. At t=0 (e.g., when the user turns on the power to the printing system 900), if the temperature of the holding chamber 920 is <50°C, the controller circuit 960 checks the sensor 924 to see if the system 900 is in a state of ink depletion. This information can be used to determine whether the system 900 will have a 15-minute heating time or whether a new ink bottle 901 must be melted before printing begins.

[0078] 2. At t=0, all printhead heaters 951 are activated, and the two heating elements 923 of the holding chamber 920 (in the illustrated embodiment, these include a 400W heater and a 200W heater) are activated. When the ink in any reservoir of one or more printheads 950 reaches a first threshold temperature (e.g., 80°C, which may be approximately 6 minutes after t=0), the heating elements 941 of the ink line 940 corresponding to those printheads 950 are activated. In some embodiments, 80°C provides a safety margin to allow ink to expand from the ink line 940 into the printhead 950 reservoirs without damaging any components. In some embodiments, the ink does not need to be entirely liquid, as long as it is liquid enough to allow the ink to expand into the printhead 950 reservoirs.

[0079] 3. Once the temperature of the holding chamber 120 reaches the second threshold temperature (e.g., 125°C), the heating element 941 of the ink line 940 is deactivated and the heating element 923 of the holding chamber 120 regulates the temperature of the holding chamber 920 to the desired temperature (e.g., 125°C).

[0080] 4. Once each heating element 951 of the printhead 950 reaches 125°C, adjust the printhead temperature to the desired temperature (e.g., 125°C).

[0081] 5. When all heating elements 923 and 951 of the printhead 950 and the holding chamber 920 are adjusted to the desired temperature, the controller circuit 960 can put the system into an idle state.

[0082] 6. After entering the idle state, the controller circuit 960 can wait for a threshold time (e.g., 30 minutes) before checking the sensor 924 to ensure that all the ink in the holding chamber 920 has melted and that the sensor 924 is floating in the melted ink.

[0083] 7. When entering an idle state, the controller circuit 960 can cause the 200W heater of the heating element 923 in the holding chamber 920 to take over the temperature control of the holding chamber 920. In some embodiments, the temperature of the holding chamber 920 can be maintained within a setpoint range of 125°C + / - 5°C using the 200W heater of the heating element 923. If the temperature drops below a low threshold of the setpoint range, the controller circuit 960 can activate the 400W heater of the heating element 923 to bring the temperature back into the setpoint range.

[0084] The described startup sequence can be used for cold starts and situations where the printer has been shut down for an extended period (e.g., more than an hour) and then restarted, such as for servicing filter 931. The goal of the heating sequence can be to begin printing within 15 minutes while also ensuring that the expansion of frozen ink does not damage any components of system 900. In some embodiments, controller circuitry 960 can initiate an ink melting cycle if sensor 924 indicates that the ink is empty at t=0. In some embodiments, printing cannot begin until sensor 924 indicates that ink is available (e.g., holding chamber 920 contains a threshold amount of ink, e.g., is at least 30% full).

[0085] In some implementations, if sensor 924 is not read upon startup due to ink temperature >50°C, resulting in a potentially erroneous ink-empty reading (as previously described), and sensor 924 indicates an ink-empty state, sensor 924 will not be read until 30 minutes after entering an idle state and will not initiate bottle melting. However, if sensor 924 indicates an ink-available state or an ink-full state, controller circuit 960 can activate pump module 932 and pump ink to printhead 950, equivalent to three 1.5-second flushes per printhead 950.

[0086] In some embodiments, once the 400W heater of the heating element 923 of the holding chamber 920 is deactivated, the heating element 913 of the melting chamber 910 is activated to remain within the predetermined power budget of the system 900 (i.e., in some embodiments, the 400W holding heaters of the heating element 923 of the holding chamber 920 and the heating element 913 of the melting chamber 910 are never energized simultaneously). In some embodiments, the 400W heater of the heating element 923 of the holding chamber 920 takes precedence over the heating element 913 of the melting chamber 910, and if the 400W heater of the heating element 923 of the holding chamber 920 needs to be energized to return the holding chamber 920 to the previously described setpoint range, the heating element 913 of the melting chamber 910 is deactivated for that duration.

[0087] Figures 10A-10C Examples of methods 1000a and 1000b for operating the DOD printing system are shown. In some embodiments, the controller circuitry described herein (e.g., referring to previous...) Figures 9A-9C The described controller circuit 960 is configured to perform operations including one or more parts of methods 1000a and 1000b. (See reference...) Figures 10A-10BMethod 1000a includes: heating the holding chamber of the printing system 1010 to a first threshold temperature; heating the printhead of the printing system 1020 to the first threshold temperature; after determining that the printhead 1022 has been heated to the first threshold temperature, heating the ink lines 1030; after determining that the printhead 1021 has been heated to a second threshold temperature, adjusting 1023 to heat the printhead to a desired adjustment temperature; and after determining that the holding chamber 1011 has been heated to the first threshold temperature, adjusting the heating of the holding chamber 1012 at the adjustment temperature.

[0088] Reference Figure 10A At 1020, the printhead of the printing system is heated to a first threshold temperature using at least one heating element. In some embodiments, the first threshold temperature is 125°C. At 1021, it is determined whether the printhead has reached a second threshold temperature lower than the first threshold temperature. In some embodiments, the second threshold temperature is 80°C. At 1030, after determining that the second threshold temperature has been reached at 1021, the ink lines are heated using at least one heating element. At 1022, it is determined whether the printhead has been heated to the first threshold temperature. At 1023, after the printhead has been heated to the first threshold temperature, and after determining that the printhead has been heated to the first threshold temperature at 1023, the printhead is adjusted to a desired adjustment temperature range using at least one heating element. In some embodiments, the desired adjustment temperature range is 125°C + / - 5°C.

[0089] Reference Figure 10B At 1010, at least one heating element is used to heat the holding chamber of the printing system to a first threshold temperature. In some embodiments, heating 1010 and heating 1020 start simultaneously. In some embodiments, the start times of heating 1010 and heating 1020 are delayed relative to each other. At 1011, it is determined whether the holding chamber has been heated to the first threshold temperature. At 1012, after determining that the holding chamber has been heated to the first threshold temperature, at least one heating element is used to adjust the holding chamber to a desired adjustment temperature range.

[0090] Reference Figure 10C Method 1000b includes determining 1040 the current ink level in the holding chamber of the printing system, determining 1041 whether the ink level exceeds an ink level threshold, and if the ink level exceeds the ink level threshold, performing 1042. Figures 10A-10B Method 1000a, if it is determined that the ink amount does not exceed the ink amount threshold, causes the melting chamber of 1043 to be heated.

[0091] In 1040, once the printing system is powered on but before the heated holding chamber and printhead, a floating sensor is used (e.g., floating sensor 924, see previous reference). Figure 9A(Discussions have been held) to determine the amount of ink to maintain in the room.

[0092] At 1041, it is determined whether the ink level determined at 1040 exceeds an ink level threshold. In some embodiments, determining that the ink level exceeds the ink level threshold includes determining that the float sensor at least indicates a "normal ink level" reading, as previously referenced. Figures 9A-9B The above discussion. In some embodiments, determining that the ink level has not exceeded an ink level threshold includes determining that the float sensor indicates an "ink level empty" reading, as previously referenced. Figures 9A-9B The subject of discussion.

[0093] In step 1042, after determining that the ink quantity in step 1041 exceeds the ink quantity threshold, the following steps are executed: Figures 10A-10B Method 1000A. In 1043, after determining that the ink quantity in 1041 has not exceeded the ink quantity threshold, at least one heating element is used to heat the melting chamber, causing the ink in the bottle contained within the melting chamber to melt and replenish the ink quantity. The ink in the chamber is maintained as previously referenced. Figure 9A As discussed. Once the holding chamber is replenished, method 1000a is executed.

[0094] As used herein, “holding chamber” includes any chamber in which ink can be held. As used herein, “melting chamber” includes any chamber in which ink can be melted.

[0095] Although this specification contains numerous implementation details, these should not be construed as limiting the scope of the invention or the scope that may be claimed, but rather as descriptions of features specific to particular embodiments of the invention. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, while the foregoing features may be described as functioning in certain combinations, or even initially claimed, in some cases one or more features from a claimed combination may be removed from the combination, and a claimed combination may be for a sub-combination or a sub-combination of variations. Therefore, unless explicitly stated otherwise, or unless clearly stated otherwise by knowledge of ordinary skill in the art, any feature of the foregoing embodiments may be combined with any other feature of the foregoing embodiments. Thus, while particular embodiments of the invention have been described, other embodiments are also within the scope of the appended claims. Furthermore, the described systems and methods are applicable beyond printer technology, for example, generally to fluid jetting devices.

Claims

1. An apparatus comprising: A container defining a holding chamber for containing ink, the container comprising: The first part, its configuration is to hold the first amount of ink, and The second part, which is smaller than the first part, and configured to contain a second amount of ink, includes: First thermally conductive surface; and A second thermally conductive surface, offset from the first thermally conductive surface by a distance determined according to the melting point of the ink, defines a barrier between the first and second portions and includes at least one opening configured to allow flow of the ink from the first portion to the second portion; and At least one first heating element configured to heat the container.

2. The apparatus according to claim 1, wherein, The at least one first heating element includes a first heating element and a second heating element.

3. The apparatus according to claim 2, wherein, The first heating element has a first rated power, and the second heating element has a second rated power that is higher than the first rated power.

4. The apparatus according to claim 2, wherein, The second heating element is closer to the second portion than the first portion, and the distance is sized to reduce the thermal mass of the second amount of ink when the second heating element heats the container, thereby causing all of the second amount of ink to melt before the first amount of ink.

5. The apparatus of claim 1 further includes a pressure reducing valve connected to the container and configured to activate when the pressure in the container exceeds a threshold pressure.

6. The apparatus according to claim 1, wherein, The first portion includes a first chamber and the second portion includes a second chamber, wherein the barrier includes a baffle separating the first chamber and the second chamber.

7. The apparatus according to claim 1, wherein, The at least one opening includes a first opening located at a first end of the barrier and a second opening located at a second end of the barrier opposite to the first end.

8. The apparatus according to claim 7, wherein, The barrier includes a plate attached to the bottom surface of the container.

9. A system for inkjet printing, comprising: A first container defines a melting chamber, which is configured as a container for receiving ink; A second container, in fluid communication with the first container and defining a holding chamber, the holding chamber being configured to receive the ink from the container; The second container includes: The first part, configured to contain a first amount of the ink; and The second portion, which is smaller than the first portion and configured to contain a second amount of the ink; the second portion includes: First thermally conductive surface; and A second thermally conductive surface, which is offset from the first thermally conductive surface by a distance determined according to the melting point of the ink, defines a barrier between the first portion and the second portion and includes at least one opening configured to allow the ink to flow from the first portion to the second portion; At least one first heating element configured to heat the first container; At least one second heating element configured to heat the second container; A printhead comprising a plurality of nozzles and at least one third heating element configured to heat the printhead, the printhead being configured to eject molten ink through the plurality of nozzles; An ink supply system comprising an ink line configured to fluidly connect the printhead to the holding chamber and at least one fourth heating element configured to heat the ink line; and The control circuit is configured as follows: This causes the at least one first heating element to heat the first container; This causes the at least one second heating element to heat the second container; This causes the at least one third heating element to heat the print head; and This causes the at least one fourth heating element to heat the ink pipeline.

10. The system of claim 9, further comprising a sensor located within the first portion of the second container, wherein, The control circuit is further configured to: Based on the information captured by the sensor, the current amount of ink held in the second container is determined; and When the current amount of ink does not exceed the threshold amount, the first container is heated by the at least one first heating element.

11. The system according to claim 9, wherein, The control circuit is further configured to: This causes the at least one third heating element to heat the printhead to a first threshold temperature; This causes the at least one fourth heating element to heat the ink pipeline to the first threshold temperature; and This causes the at least one second heating element to heat the holding chamber to the first threshold temperature.

12. The system according to claim 11, wherein: The at least one second heating element includes: The main heating element includes a first rated power; and A secondary heating element, comprising a second rated power exceeding the first rated power; and The startup procedure includes shutting off the auxiliary heating element when the second container is heated to a second threshold temperature.

13. The system according to claim 12, wherein, The startup procedure includes causing the at least one third heating element to heat the printhead to the second threshold temperature.

14. The system of claim 9 further includes a pressure reducing valve connected to the second container and configured to activate when the pressure in the second container exceeds a threshold pressure.

15. The system according to claim 9, wherein, The at least one opening includes a first opening located at a first end of the barrier and a second opening located at a second end of the barrier opposite to the first end.

16. The system according to claim 9, wherein, The at least one second heating element is closer to the second portion than the first portion, and when the at least one second heating element heats the second container, the distance is configured such that the second portion of ink melts entirely before the first portion of ink by reducing the thermal mass of the second portion of ink relative to the first portion of ink.

17. A non-transitory computer-readable storage medium for encoding instructions, said instructions causing control circuitry of a system for inkjet printing according to any one of claims 9-16 to perform operations, comprising: The ink pipeline of the system is adjusted to a first threshold temperature using at least one heating element; The printhead of the system is adjusted to the first threshold temperature using at least one heating element; and The at least one heating element heats the holding chamber of the system to a second threshold temperature.

18. The non-transitory computer-readable storage medium according to claim 17, wherein, The operation also includes: Based on information captured by sensors within the first part of the holding chamber, the current amount of ink held in the holding chamber is determined; and When the current amount of ink does not exceed a threshold amount, the at least one heating element heats the melting chamber of the printing system.

19. The non-transitory computer-readable storage medium according to claim 18, wherein: The at least one heating element includes: The main heating element includes a first rated power; and A secondary heating element, which includes a second rated power higher than the first rated power; The main heating element and the auxiliary heating element are used to heat the holding chamber to the second threshold temperature; and The operation also includes shutting off the auxiliary heating element when the holding chamber is heated to the second threshold temperature.

20. The non-transitory computer-readable storage medium according to claim 17, wherein, The operation also includes causing the at least one heating element to heat the printhead to the second threshold temperature.

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