Flushing system for filter and print head

Abstract

To provide a printing system (10) for applying a coating product.SOLUTION: The printing system (10) includes: a print head (A1) for applying a coating product flowing in a so-called normal flow direction; a single filter (F1) positioned upstream of the print head; and a plurality of valves and conduits for conveying the coating product and at least one flush fluid. The valves and conduits are arranged such that the single filter may be flushed with the flush fluid only in the direction opposite the normal flow direction, and such that the print head may be flushed with the flush fluid in the normal flow direction. The single filter and the print head are flushable independently of each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technical field of the invention is the printing application of coating products to objects to be coated.

[0002] The present invention relates in particular to a system for applying a coating product to an object to be coated, and to several modes of operation of the system, particularly allowing for purging, cleaning, filling and application of the coating product. [Background technology]

[0003] The personalization of decorations and coatings applied to objects is becoming more and more frequent. This is the case, for example, in the automotive industry, when it comes to coating car bodies. This can be done in single, two-tone, or multi-colored versions. Furthermore, the realization of patterns with specific shapes is potentially interesting for certain other markets, especially for visually differentiating two products depending on their purpose or manufacturing method. In this context, the paint industry has recently explored the solution of "printing" paint with a printhead rather than spraying it with a sprayhead.

[0004] The paints used in these print coatings have viscosities in the 50-200 millipascal-second (mPas) range and contain particles in the micron range. Therefore, to apply such coating products using printing techniques, equipment with appropriate dimensions must be used. In particular, printheads use nozzles with small paint outlets on the order of 100-200 μm, which is much smaller than the dimensions of sprayhead outlets, which are typically over 800 μm. Filters with characteristic filtration dimensions on the order of 20 μm are also used. The purpose of such filters is to prevent agglomerates and inhomogeneities in the coating product that could clog the printhead nozzles, ensuring better print quality.

[0005] The demands on the quality of printed coatings mean that printing system components must be regularly cleaned to remove any agglomerates that may be trapped in the filters and any residues that may adhere to the printhead. It is interesting to clean these two components with cleaning products, with the pressure applied depending on the component. In fact, cleaning of filters can be carried out at high pressure using pulsed air. In contrast, printheads are generally cleaned at low pressure. Furthermore, it is preferable not to use air in the printhead cleaning fluid, as its presence risks causing the coating product to dry out and settle, especially in the nozzles. Furthermore, filters gradually become clogged and must be cleaned periodically.

[0006] For reasons of productivity and convenience, the same printhead is commonly used to apply different coating products, typically paints of different colors, and therefore it is necessary to clean the entire printing system, taking into account the specific cleaning requirements of the various components, to avoid improper mixing of the coating products.

[0007] Techniques for cleaning printheads are known from the art, for example a cleaning station consisting of multiple injectors can be used to clean multiple nozzles of a printhead simultaneously.

[0008] Furthermore, in systems that apply coating products, there is a known technique for cleaning a filter installed upstream of the print head, where the filter is cleaned with a cleaning fluid having a bidirectional flow. The drawback of this technique is the long time required to perform this double cleaning, which reduces printing productivity.

[0009] It is also known to use two parallel filters installed upstream of the printhead. The application is performed simultaneously using only one of the two filters, allowing the other filter to be cleaned or replaced without stopping the application of the coating product. This can therefore increase productivity. The drawback is that such a solution requires a more complex and less compact valve assembly to separate the two filters, which imposes a penalty on integration into the printing system.

[0010] Furthermore, these solutions for cleaning the filter and the printhead clean both components with a cleaning fluid whose pressure is adapted depending on the component being cleaned, and do not provide a printing system for cleaning the filter or the printhead without also having to clean other components, or for cleaning the entire printing system.

[0011] Document JP6979546B1 describes a printing system consisting of a set of sections, each containing conduits, valves, and a specific component to be cleaned, such as a filter, print head, and debubbler. The sections of this system (filter, print head, and debubbler sections) are arranged so that they can be cleaned independently of each other. In particular, three-way or four-way valves are installed before and after each component to be cleaned (filter, print head, debubbler) to separate the components and transport the product therein depending on the intended use (printing product, cleaning product, or air).

[0012] The drawback of such systems is that a large number of valves are required to achieve the isolation function of the various components that make them up, which makes the arrangement of the various components of the system (valves, conduits and components) complicated and cumbersome, which is incompatible with the compactness required for such systems.

[0013] Furthermore, such complex assemblies increase the risk of component damage and premature failure, affecting the proper functioning of the system. Therefore, such systems also contradict the business requirements for longevity and reliability of coating printing systems.

[0014] Furthermore, using a special degassing device called a "devabber" adds valves and piping to the assembly, making the system larger and increasing the amount of liquid lost during color changes.

[0015] EP-A-3363640 discloses a printing system including a printhead associated with a filter through which a cleaning agent flows in the same direction as the coating agent. A significant number of fluid flow control valves are provided, making the system complex and bulky.

[0016] Therefore, there is a need for a compact and reliable coating printing system that can clean filters and printheads using cleaning fluid at pressures tailored to the components being cleaned. Summary of the Invention

[0017] The present invention provides a solution to the above problems by enabling independent cleaning of the filters and printheads of a coating printing system, which is also compact and adapted so that cleaning of its components and the entire system can be accomplished in a time that is compatible with productivity constraints for application of the coating product.

[0018] "Productivity constraints" are defined as constraints defined by productivity goals for the coating product application, which may include constraints on print run times for one or more coated objects.

[0019] A first aspect of the present invention relates to a printing system for applying a coating product to an object to be coated, the printing system comprising: a printhead for applying a coating product to the object to be coated, the coating product flowing in the so-called normal flow direction; a single filter positioned upstream of the print head for filtering the coating product; a plurality of valves and conduits adapted to convey coating products, filter cleaning fluids and printhead cleaning fluids, said plurality of valves and conduits comprising: 〇Coating product supply circuit; a filter circuit adapted to convey the coating product through the single filter in the normal flow direction and to convey the filter wash fluid through the single filter only in the direction opposite to the normal flow direction; a head circuit adapted to transport coating product and printhead cleaning fluid through the printhead in a normal flow direction; a plurality of valves and conduits arranged to form a supply filter isolation valve, When closed, the supply circuit is separated from the filter circuit. When open, it connects the supply circuit to the filter circuit. a supply filter isolation valve configured to a printhead-filter separation valve, In the closed position, the filter circuit is separated from the head circuit. In the open position, it connects the filter circuit to the printhead circuit. a print head-filter separation valve configured to Equipped with the filter circuit further comprises a filter cleaning valve disposed opposite the filter head isolation valve and a filter purge valve disposed opposite the supply filter isolation valve; The supply filter isolation valve, the printhead filter isolation valve, the filter cleaning valve, and the filter purge valve are two-way valves; It is a system.

[0020] "Independent operation" means that the filter circuit and the printhead circuit are two independent circuits separated by one or more of the valves. The two circuits can be used independently of each other. In other words, one circuit can be used without the other, and both can be used simultaneously without affecting the other. For example, it is possible to clean the filter circuit without cleaning the printhead circuit, which is isolated during cleaning of the filter circuit. It is also possible to clean the printhead without cleaning the filter. Furthermore, it is possible to clean the printhead circuit and the filter circuit simultaneously without one cleaning interfering with the other.

[0021] Thanks to the present invention, and in particular to the use of a separation valve, the printing system allows the filter circuit containing the filter and the head circuit containing the printhead to be used independently. Therefore, the filter circuit and the head circuit can be flowed separately and decoupled by means of a pair of two-way valves arranged opposite each other. The system according to the present invention therefore allows the use of cleaning fluids with different pressures, adapted to cleaning the various components of the printing system, in particular the filter and the printhead. On the other hand, when the separation valve is open, the different circuits can be connected together to carry out printing of the coating product.

[0022] In fact, the printing system includes several circuits (supply circuit, filter circuit, and printhead circuit) that are separated from each other by isolation valves. These circuits are used for various fluid flows. In this case, the filter circuit is used for a separate flow of filter cleaning fluid, and the printhead circuit is used for a separate flow of printhead cleaning fluid. These three circuits also allow the coating product to flow from the supply inlet through the filter to the printhead. Thanks to the isolation valves and these independent circuits, one circuit can be used separately from the others for a specific purpose. For example, it is possible to separate and clean the filter circuit during the printing process to remove excess agglomerates without emptying the other circuit containing the coating product in preparation for printing.

[0023] Furthermore, since the filter and the printhead belong to independent and separate circuits, the filter can be cleaned with a suitable cleaning fluid without cleaning the printhead. Therefore, it is possible to clean the filter circuit, and in particular the filter alone. This cleaning of the filter alone can be performed, for example, when the filter becomes clogged with agglomerates of the coating product, making it impossible to properly apply the coating product to the product to be coated.

[0024] Additionally, because only one filter is used to filter the coating product, the filter is easy to integrate into the printing system, eliminating the need for complex assemblies that require valves to direct fluid from one side of the filter to the other, facilitating the miniaturization of printing systems.

[0025] Additionally, because the isolation, flush, and purge valves are two-way valves, these types of valves have fewer moving parts, making them not only more compact but also more reliable. They also require fewer controls and actuators to operate. This results in a more compact printing system while still providing the reliability and service life required for your business.

[0026] The printing system is advantageously more compact in that it lacks a return circuit to the supply circuit (from the print head) to return unused coating product (i.e., not ejected by the head) so that it can be reused.

[0027] The arrangement relative to the valves also facilitates compactness of the system by limiting the number and / or length of the conduits, thereby reducing the system's footprint. In particular, the section of the conduit between two facing valves, hereafter referred to as the common conduit section, can be shortened in length to reduce the volume common to the two valves.

[0028] Finally, cleaning of the filter or printhead can be performed in a time that is compatible with the productivity requirements associated with printing activities. In fact, the filter and printhead can be cleaned separately or simultaneously. Therefore, there is no need to wait to clean the filter before cleaning the printhead, or vice versa. Furthermore, because the printing system assembly is compact, the flow of cleaning fluid within the printing system assembly is fast. Because the filter is only cleaned in the direction opposite to the normal flow direction (i.e., the optimal direction for cleaning the filter), there is no need for a second cleaning. Therefore, the filter is cleaned quickly. Similarly, the printhead is only cleaned in the normal flow direction, allowing for quick cleaning of the printhead.

[0029] In one embodiment of the printing system, each of the supply filter isolation valve, the printhead filter isolation valve, the filter cleaning valve, and the filter purge valve comprises a seat and a needle for contacting the seat; the needle of the filter cleaning valve and the needle of the printhead filter isolation valve are aligned and directed in opposite directions toward the first common conduit portion; The needle of the filter purge valve and the needle of the supply filter isolation valve are aligned and pointed in opposite directions towards the second common conduit section.

[0030] According to the detailed description of this embodiment: the first common conduit portion separates the filter cleaning valve seat and the printhead-filter separation valve seat and exhibits a length between 1 mm and 10 mm; The second common conduit section separates the filter purge valve seat and the supply filter separation valve seat and exhibits a length between 1 mm and 10 mm.

[0031] This reduced distance between opposing valves helps limit the amount of coating material needed to prime and refill the printing system, for example, when using the printing system for the first time or when changing coating materials (typically when changing paint colors), and also facilitates the compactness of printing systems.

[0032] In one embodiment, the printing system further comprises a filter wash inlet adapted to supply a filter wash fluid to the filter circuit, the filter wash valve being adapted to: - in the open position, connecting a single filter to the filter cleaning inlet, In the closed state, the single filter is separated from the filter cleaning inlet; It is configured as follows.

[0033] In this way, it is possible to control the supply of filter cleaning fluid from the printing system to the single filter and prevent the flow of coating product towards the filter cleaning inlet along with the flow of coating product through the printing system.

[0034] In one embodiment, the filter circuit further comprises a filter purge outlet adapted to purge the filter circuit with a filter cleaning fluid, and the filter purge valve - in the open state, connecting a single filter to the filter purge outlet, In the closed state, it separates the single filter from the filter purge outlet; It is configured as follows.

[0035] In this way, it is possible to control the discharge of filter cleaning fluid from the printing device after flushing the filter and prevent the coating product flowing through the printing device from entering the filter purge outlet.

[0036] In one embodiment, the supply circuit comprises a supply inlet, a supply purge valve, and a supply purge outlet, the supply inlet adapted to supply the supply circuit with coating product, the supply purge outlet adapted to purge the supply circuit of coating product, and the supply purge valve adapted to: - in the open state, connecting the supply inlet and the supply purge outlet; - in the closed state, separating the feed inlet and the feed purge outlet; It is configured as follows.

[0037] In this way it is possible to control the supply of coating product in the supply circuit and to control the discharge of coating product from the supply circuit.

[0038] In one embodiment, a printing system includes a fill purge circuit and a fill purge isolation valve, the fill purge isolation valve: - in the open state, it connects the head circuit and the fill purge circuit; - In the closed state, the head circuit and the fill purge circuit are separated; It is configured as follows.

[0039] The fill purge circuit allows the coating product to be circulated through a single filter before being expelled from the printing system. It is particularly used to expel air bubbles contained in the filter circuit after cleaning the filter with, for example, pressurized air.

[0040] According to a development of this embodiment, the head circuit further comprises a printhead cleaning valve arranged opposite the fill-purge isolation valve. Advantageously, the printhead cleaning valve and the fill-purge isolation valve are two-way valves.

[0041] Preferably, the printhead cleaning valve and the fill purge isolation valve each include a seat and a needle for contacting the seat, the needle of the printhead cleaning valve and the needle of the fill purge isolation valve being aligned and facing in opposite directions toward the third common conduit portion.

[0042] Advantageously, the third common conduit portion separates the printhead cleaning valve seat and the fill purge separation valve seat and exhibits a length of between 1 mm and 10 mm.

[0043] In one embodiment, the head circuit further comprises a printhead cleaning inlet, the printhead cleaning inlet adapted to supply a printhead cleaning fluid to the printhead circuit, and the printhead cleaning valve - in the open state, connecting the print head to the print head cleaning inlet; - in the closed state, separating the printhead from the printhead cleaning inlet; It is configured as follows.

[0044] In this way, the supply of printhead cleaning fluid towards the printhead can be controlled to prevent the coating product from entering the printhead cleaning inlet as it flows through the printing system.

[0045] In one embodiment, the head circuit further comprises a printhead purge valve and a printhead purge outlet, the printhead purge outlet adapted to purge the head circuit of printhead cleaning fluid and coating product, the printhead purge valve - in the open state, connecting the print head to the print head purge outlet; In the closed state, the printhead is separated from the printhead purge outlet; It is configured as follows.

[0046] In this way, printhead cleaning fluid or coating product can be flushed through the printhead and then exit the printing system through the printhead purge outlet, or the flow of printhead cleaning fluid or coating product to the printhead purge outlet can be blocked, and closing the printhead purge valve will block the flow of product to the printhead if the printhead outlet is closed.

[0047] In one embodiment, the single filter includes a mesh layer configured to filter the coating product, said mesh layer being disposed between two support layers.

[0048] Second, the filter is simple in design and easy to integrate into a printing system.

[0049] In one embodiment, the single filter has a first end and a second end, and is arranged such that the coating product is conveyed along the axis of the filter by entering the first end and exiting the second end, and the cleaning fluid is conveyed along the axis of the filter by entering the second end and exiting the first end.

[0050] Thus, priming of the single filter with the coating product is accomplished completely without trapping air within the single filter, and cleaning of the single filter is accomplished such that the filter cleaning fluid cleans the entire filter space.

[0051] In one embodiment, the system further comprises a monitoring sensor, preferably a pressure sensor located in the printhead or between the printhead and the printhead purge valve.

[0052] Thus, the system is monitored by a monitoring sensor, and the operation of the system is adapted based on data collected by the monitoring sensor. For example, if the sensor measures a pressure in the print head that is lower than the nominal level, it will alert that the coating product is no longer printing under conditions that meet the current printing specifications, and the system will be placed into an operating mode to clean a filter that has become clogged with aggregates that are preventing the proper flow of the coating product.

[0053] In addition to the features just discussed in the previous paragraph, the system according to the first aspect of the invention may present one or more of the following additional features, considered individually or in any technically possible combination: The feed filter isolation valve is arranged upstream of the single filter. The printhead filter isolation valve is located downstream of the single filter.

[0054] A second aspect of the present invention relates to a method for controlling a printing system according to the first aspect of the present invention, said control method comprising: - priming at least a portion of the printing system with the coating product; - printing the coating product onto the object to be coated; - cleaning the print head; - washing a single filter; It includes one or more steps from the above.

[0055] A printing system according to the present invention may be controlled to prime the printing system with a coating product, apply a coating product to an object to be coated, or clean one or more components of the printing system.

[0056] In one embodiment, the steps of cleaning the printhead and cleaning the single filter are performed simultaneously by closing the supply filter isolation valve and the printhead filter isolation valve.

[0057] In this way, it is possible to control the printing system so that the printhead and a single filter are cleaned simultaneously and independently of each other, an implementation that saves time and therefore increases productivity.

[0058] In one embodiment, the control method includes the step of priming the coating product supply circuit, wherein the steps of cleaning the single filter and priming the supply circuit are performed simultaneously by closing the supply filter isolation valve.

[0059] It is therefore possible to control the printing system so that a single filter is cleaned simultaneously and independently of the priming of the supply circuit, this embodiment saving time and therefore increasing productivity.

[0060] In one embodiment, the control method includes priming a coating product supply circuit, and the steps of cleaning the print head and cleaning the supply circuit are performed simultaneously by closing a print head filter isolation valve.

[0061] It is therefore possible to control the printing system so that the printhead is cleaned simultaneously and independently of the priming of the supply circuits, this embodiment saving time and therefore increasing productivity.

[0062] In addition to the features just mentioned in the previous paragraph, the control method according to the second aspect of the invention may present one or more of the following additional features, considered individually or in any technically possible combination: -The pressure of the filter cleaning fluid is strictly higher than the pressure of the printhead cleaning fluid, -The pressure of the filter cleaning fluid is between 4 bar and 8 bar. - the pressure of the printhead cleaning fluid is between 1 bar and 3 bar; the single filter is cleaned by successively conveying air and a cleaning fluid, preferably a solvent; The printhead is cleaned by delivering a cleaning fluid, preferably a solvent.

[0063] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. The figures are shown as representations and are not intended to limit the invention in any way. [Brief explanation of the drawings]

[0064] [Figure 1] FIG. 1 is a fluid diagram of a preferred embodiment of a system according to the present invention. [Figure 2] FIG. 2 is a fluid diagram of the system according to FIG. 1 arranged in a supply circuit priming mode of operation. [Figure 3] FIG. 3 is a fluid diagram of the system according to FIG. 1 arranged in a filter circuit priming mode of operation. [Figure 4] FIG. 4 is a fluid diagram of the system according to FIG. 1 arranged in a head circuit priming mode of operation. [Figure 5] FIG. 5 is a fluid diagram of the system according to FIG. 1 arranged in a coating product printing mode of operation. [Figure 6] FIG. 6 is a fluid diagram of the system according to FIG. 1 arranged in a filter cleaning mode of operation. [Figure 7] FIG. 7 is a fluid diagram of the system according to FIG. 1 placed in a printhead cleaning mode of operation. [Figure 8] FIG. 8 is a fluid diagram of the system according to FIG. 1 arranged in a combined system cleaning mode of operation. [Figure 9] FIG. 9 is a fluid diagram of the system according to FIG. 1 arranged in an operating mode for simultaneous cleaning and priming of the filter circuit 2. [Figure 10] FIG. 10 is a fluid diagram of the system according to FIG. 1 placed in an operating mode for simultaneous cleaning and priming of the head circuit 3. [Figure 11]FIG. 11 is a fluid diagram of the system according to FIG. 1 arranged in a simultaneous cleaning and priming mode of operation of the filter circuit and printhead circuit. [Figure 12] FIG. 12 is a schematic diagram of the assembly for two valves of the system. DETAILED DESCRIPTION OF THE INVENTION

[0065] Unless otherwise specified, identical components appearing in different figures are designated by unique reference.

[0066] In the following text, unless otherwise specified, it is understood as follows: "Coating product" refers to an inorganic or organic compound intended to be applied to the surface of an object to be coated by a printing technique in order to impart a desired functionality. For example, in the automotive industry, this can include coating products for coloring and protecting vehicle chassis. More specifically, the coating product may be a paint, a primer, a varnish, or a more viscous product such as an adhesive or sealant. "Coated object" refers to an object to which it is desired to apply a coating product to provide a desired function. "Printhead" refers to an applicator device for printing a coating product onto an object to be coated. The printhead may also be a continuous jet printhead, i.e., it contains a permanently open circuit and does not contain pressurized coating product. Alternatively, the printhead may be a drop-on-demand (DOD) printhead. To control the application of the coating product, the outlets (also called nozzles) of the DOD head are blocked by a controllable membrane. "Filter" refers to a device for filtering the coating product that prevents agglomerates and irregularities in the coating product from reaching the printhead, thus preventing clogging. The filter can take the form of a screen that is small enough to block agglomerates, but large enough to allow particles of the coating product (typically pigment particles in paint) to pass through. "Valve" refers to a device for regulating the flow of coating products, filters, and printhead cleaning fluids. The valve can be positioned to allow the cleaning fluid or coating product to pass through the valve, or can be blocked from passing through the valve, diverting the flow of the fluid or coating product to another path. - "Conduit" refers to a connection between two components of a system, for example between two valves, that can transport one of the coating products or cleaning fluids from one component to the other. "Component" refers to a component of a system according to the present invention, where a component may refer to a valve, a filter, or a printhead. - A "circuit" is a continuous collection of components and conduits connecting the components, the ends of which are defined by an inlet and an outlet. "Normal flow direction" refers to the direction of flow of the coating product conveyed through the printing system so that the coating product can be applied to the object to be coated by the print head, where normal flow direction is the direction of flow of the coating product from a source of the coating product toward the outlet of the print head that applies the coating product. "Filter cleaning fluid" and "printhead cleaning fluid" are cleaning fluids specifically designed to clean filters and printheads, respectively. They may be the same cleaning fluid, but at different pressures depending on the component being cleaned. The cleaning fluid (filter or printhead) may be a cleaning fluid, preferably a solvent such as water (which can "dissolve" agglomerates of the coating product). The filter cleaning fluid may further contain air. "Feed Inlet" refers to the inlet of the system used to feed the coating product into the system. "Purge Outlet" refers to the outlet used to drain cleaning fluids and coating products from the system and transport them to a collection and processing manifold. "Wash inlet" refers to an inlet in the system that is used to supply wash fluid to the system. - "Isolation valve" means a valve that separates or connects two circuits independently of each other. "System Operating Mode" refers to a particular arrangement in which system valves are opened or closed to enable the system to be used for a particular application. For example, closing or opening a particular valve can isolate a particular portion of the system or a particular circuit to use the circuit for a particular application, such as filter cleaning, print head cleaning, system purging, or coating product printing.

[0067] One aspect of the present invention relates to a printing system for applying a coating product to an object to be coated.

[0068] FIG. 1 shows a fluid diagram of a system 10 according to a preferred embodiment of the present invention.

[0069] System 10 includes printhead A1, a single filter F1, and a plurality of valves and conduits. Preferably, the valves are two-way valves. Each two-way valve includes a seat and a needle, the needle intended to contact the seat to close the valve.

[0070] The printhead is used to print the coating product onto the object to be coated. The coating product is ejected from the printhead A1 by pressurizing the coating product within the system 10.

[0071] The print head contains multiple outlets for printing the coating product onto the object to be coated. These printing outlets are called nozzles A2. The print head can contain multiple nozzles A2 arranged in a row or in a grid pattern (multiple parallel lines).

[0072] In printhead A1, the coating product flows along the normal flow direction, ie, the coating product is conveyed by a portion of the valve and conduit to the inlet of printhead A1 and is discharged through nozzle A2.

[0073] A single filter F1 is used to filter the coating product before it reaches the printhead, preventing agglomerates of the coating product from clogging and blocking the nozzles A2 of the printhead A1. Because the nozzle diameter is, for example, in the range of 100-200 micrometers (μm), the filter advantageously serves to filter out agglomerates or particles of the coating product with a characteristic size, for example, in the range of 20 μm or larger. In the printing system 10, the single filter F1 is then positioned upstream of the printhead A1 in the flow path of the coating product.

[0074] The single filter is a filter used in printing applications such as screen printing. It is preferably a dome-shaped filter containing filter meshes of different characteristic sizes. In this case, the filter is composed of three overlapping meshes. The upper and lower meshes have characteristic mesh sizes (i.e., mesh gap widths) between 100 μm and 900 μm, preferably between 350 μm and 550 μm. These two meshes therefore filter agglomerates larger than their characteristic size and also have the mechanical function of supporting the intermediate mesh. Therefore, the upper and lower meshes have sufficient mechanical properties to prevent deformation of the filter, particularly the intermediate mesh, during normal operation and cleaning. The mesh size of the intermediate mesh is between 1 μm and 100 μm, preferably between 10 μm and 30 μm, and is used to filter agglomerates larger than this characteristic size. This intermediate mesh prevents the coating product from blocking the nozzle A2 of the print head A1 when it reaches the nozzle A2. Therefore, this structure ensures good filtration performance from the intermediate mesh, and by supporting the intermediate mesh between the lower mesh and the upper mesh, it is possible to suppress deformation of the intermediate mesh and maintain the intermediate mesh in a position where deterioration of fluid performance can be significantly suppressed.

[0075] A plurality of valves and conduits are arranged to provide paths for the coating product to flow through the system 10. The coating product is conveyed by some of the valves and conduits in a normal flow direction. The assembly is configured such that the normal flow direction directs the coating product from filter F1 to printhead A1.

[0076] The valves and conduits are also arranged to provide cleaning fluid flow paths for filter F1 and printhead A1. The cleaning fluid for filter F1 is referred to as the "filter cleaning fluid." The cleaning fluid for printhead A1 is referred to as the "printhead cleaning fluid." The filter cleaning fluid is conveyed by some of the valves and conduits in a direction opposite to the normal flow direction. The printhead cleaning fluid is conveyed by all of the valves and conduits in a direction in the normal flow direction. The flow of these two fluids through system 10 is described in more detail below.

[0077] Preferably, the conduits of the printing system 10 are as short as possible. This limits the distance the coating product must travel from one circuit to another. This configuration of the printing system 10 is therefore optimized to limit waste and loss of coating product due to filling the components and conduits of the printing system 10. Furthermore, this configuration improves the compactness of the system 10 and therefore improves its integration into the equipment for printing the object to be coated. Preferably, the conduits are 200 mm or less in length.

[0078] Thus, as illustrated in FIG. 1, the system 10 also includes three separate inlets and four separate outlets.

[0079] The inlets to the system 10 are a supply inlet P1, a filter wash inlet P2, and a printhead wash inlet P3.

[0080] The outlets of the system 10 are a supply purge outlet O1, a filter purge outlet O2, a printhead purge outlet O3, and a fill purge outlet O4.

[0081] The multiple valves and conduits are further arranged to form three different, separable circuits for conveying coating and cleaning products within the system 10 .

[0082] These three circuits are the supply circuit 1, the filter circuit 2 and the head circuit 3.

[0083] The printing system 10 may further include a fourth fill purge circuit 4 .

[0084] These four circuits are connected to each other by so-called isolation valves: Supply circuit 1 is connected to filter circuit 2 by supply filter isolation valve V12. Filter circuit 2 is connected to head circuit 3 by printhead filter isolation valve V23. Head circuit 3 is connected to fill purge circuit 4 by fill purge isolation valve V43.

[0085] The supply circuit 1 includes a supply inlet P1, a supply purge valve V1, a first conduit C1, a second conduit C2, a third conduit C3, and a supply purge outlet O1.

[0086] In the supply circuit 1, a first conduit C1 connects the supply inlet P1 to the supply filter isolation valve V12, a second conduit C2 connects the supply filter isolation valve V12 to the supply purge valve V1, and a third conduit C3 connects the supply purge valve V1 to the supply purge outlet O1.

[0087] Alternatively, the first conduit C1 can connect the supply inlet O1 to the supply purge valve V1, and the second conduit C2 can connect the supply purge valve V1 to the supply filter isolation valve V12 without changing the operation of the printing system 10, as long as the third conduit C3 connects the supply purge valve V1 to the supply purge outlet O1.

[0088] The filter circuit 2 includes a filter cleaning inlet P2, a filter cleaning valve V2, a filter purge valve V3, a single filter F1, a fourth conduit C4, a fifth conduit C5, a sixth conduit C6, a seventh conduit C7, and a filter purge outlet O2.

[0089] In filter circuit 2, a fourth conduit C4 connects filter cleaning inlet P2 to filter cleaning valve V2, a fifth conduit C5 connects filter cleaning valve V2 to single filter F1, a sixth conduit C6 connects filter F1 to filter purge valve V3, and a seventh conduit C7 connects filter purge valve V3 to filter purge outlet O2. Relative to the normal flow direction in filter circuit 2, filter cleaning valve V2 is therefore located downstream of single filter F1 and filter purge valve V3 is located upstream of single filter F1.

[0090] The single filter F1 is arranged in series in the filter circuit 2, i.e. the flow axis of the filter cleaning fluid or coating product in the single filter is parallel to the flow axis of said product in the filter circuit 2. In other words, the single filter comprises two ends for the inlet and outlet of the product therein, and the axis of the filter indicated by its two ends coincides with the flow axis of the coating product or filter cleaning product in the filter circuit 2.

[0091] The head circuit 3 includes a printhead cleaning inlet P3, a printhead cleaning valve V4, a printhead purge valve V5, a printhead A1, an eighth conduit C8, a ninth conduit C9, a tenth conduit C10, an eleventh conduit C11, a twelfth conduit C12, and a printhead purge outlet O3.

[0092] In the head circuit 3, the eighth conduit C8 connects the printhead cleaning inlet P3 to the printhead cleaning valve V4, the ninth conduit C9 connects the printhead cleaning valve V4 to the printhead filter isolation valve V23, the tenth conduit C10 connects the printhead filter isolation valve V23 to the printhead A1, the eleventh conduit C11 connects the printhead A1 to the printhead purge valve V5, and the twelfth conduit C12 connects the printhead purge valve V5 to the printhead purge outlet O3. Relative to the normal flow direction in the head circuit 3, the printhead cleaning valve V4 is therefore located upstream of the printhead A1, and the printhead purge valve V5 is located downstream of the printhead A1.

[0093] The fill purge circuit 4 includes a thirteenth conduit C13 and a fill purge outlet O4.

[0094] In the fill purge circuit 4, a thirteenth conduit C13 connects the fill purge isolation valve V43 to the fill purge outlet O4.

[0095] When the supply purge valve V1 is open, it allows the flow of product between the supply inlet P1 and the supply purge outlet O1. The term "product" includes both coating product and cleaning product. This sequence allows, in particular, the first conduit C1 and the second conduit C2 to be quickly filled with coating product. When the supply purge valve V1 is closed, this flow is not possible. Thus, the supply purge valve V1 allows the supply inlet P1 and the supply purge outlet O1 to be connected or disconnected. In particular, the supply purge valve V1 allows the flow of coating product in the supply circuit 1 to be blocked.

[0096] When the filter wash valve V2 is open, it allows product flow between the filter wash inlet P2 and the single filter F1. When the filter wash valve V2 is closed, this flow is not possible. Thus, the filter wash valve V2 allows the single filter F1 to be connected or disconnected from the filter wash inlet P2. In particular, in the open position, the filter wash valve V2 allows the flow of filter wash fluid from the filter wash inlet P2 to the filter circuit 2, and in the closed position, it blocks the flow of coating product toward the filter wash inlet P2.

[0097] When filter purge valve V3 is open, it allows product flow between single filter F1 and filter purge outlet O2. When filter purge valve V3 is closed, this flow is not possible. Thus, filter purge valve V3 allows single filter F1 to be connected to or disconnected from filter purge outlet O2. In particular, in the open position, filter purge valve V3 allows the flow of filter cleaning fluid toward filter purge outlet O2, and in the closed position, it blocks the flow of coating product to filter purge outlet O2.

[0098] When printhead cleaning valve V4 is open, it allows product flow between printhead cleaning inlet P3 and printhead A1. When printhead cleaning valve V4 is closed, this flow is disabled. Closing printhead cleaning valve V4 also allows for maintaining coating product pressure within printhead A1. Thus, printhead cleaning valve V4 allows for connecting or disconnecting printhead A1 from printhead cleaning inlet P3. In particular, printhead cleaning valve V4, in the open position, allows the flow of printhead cleaning fluid within head circuit 3 from printhead cleaning inlet P3, and, in the closed position, blocks the flow of coating product toward printhead cleaning inlet P3.

[0099] When printhead purge valve V5 is open, it allows product flow between printhead A1 and printhead purge outlet O3. When printhead purge valve V5 is closed, this flow is disabled. Closing printhead purge valve V5 also allows coating product pressure within printhead A1 to be maintained. Thus, printhead purge valve V5 allows printhead A1 to be connected or disconnected from printhead purge outlet O3. Specifically, in the open position, printhead purge valve V5 allows printhead cleaning fluid or coating product within printhead circuit 3 to flow toward printhead purge outlet O3, and in the closed position, printhead purge valve V5 blocks the flow of coating product or printhead cleaning fluid toward printhead purge outlet O3. Furthermore, when printhead purge valve V5 is closed and nozzle A2 of printhead A1 is also closed, the flow of coating product and printhead cleaning fluid to printhead A1 is blocked.

[0100] A supply filter isolation valve V12 is positioned opposite the filter purge valve V3 so that the supply circuit 1 is connected to the filter circuit 2 by a sixth conduit C6.

[0101] "Oppositely disposed" is defined as an assembly of two valves with needles aligned (i.e., oriented in the same direction), preferably with the needles of the two valves pointing in opposite directions toward a common conduit portion.

[0102] The supply filter isolation valve V12 and the filter purge valve V3 are arranged such that their respective seats are separated by a common conduit section (C6). The length of this common conduit section is advantageously between 1 mm and 10 mm. The spacing between the two seats is, for example, equal to 5 mm. In particular, the spacing between the two seats may be equal to the diameter of the seats.

[0103] Relative to the normal flow direction, the supply filter isolation valve V12 is therefore located in the printing system 10 upstream of the single filter F1 and downstream of the supply inlet P1.

[0104] Thus, when the supply filter isolation valve V12 is closed, it allows for the isolation of supply circuit 1 and filter circuit 2, and when the supply purge valve V1 is open, there is product flow only between the first conduit C1 and the second conduit C2. Conversely, when the supply filter isolation valve V12 is open, the two circuits are connected, allowing different products to pass from one to the other. Product flow is then possible between the first conduit C1, the second conduit C2, and the sixth conduit C6. Furthermore, when the supply purge valve V1 is closed, product flow in the second conduit C2 can be stopped.

[0105] More generally, the supply filter isolation valve V12 is positioned as close as possible to the filter purge valve V3.

[0106] The printhead-filter separating valve V23 is arranged opposite the filter cleaning valve V2 so as to connect the printhead circuit 3 to the filter circuit 2 at the level of the fifth conduit C5. Preferably, the seats of these valves are separated by a common conduit section (C5) having a length between 1 mm and 10 mm, for example equal to 5 mm. In particular, the distance between the two seats can be equal to the diameter of the seats. With respect to the normal flow direction, the printhead-filter separating valve V23 is therefore arranged downstream of the single filter F1 and upstream of the printhead A1 in the printing system 10.

[0107] When the printhead-filter isolation valve V23 is closed, it separates the filter circuit 2 from the printhead circuit 3, allowing product flow only within each circuit. Conversely, when the printhead-filter isolation valve V23 is open, it connects the two circuits, allowing different products to pass from one to the other. Product flow is then permitted between the fifth conduit C5, the ninth conduit C9, and the tenth conduit C10. Furthermore, when the printhead cleaning valve V4 is closed, product flow in the ninth conduit C9 can be stopped. Also, when the printhead purge valve V5 is closed and nozzle A2 of printhead A1 is not open, flow can be stopped in the tenth conduit C10.

[0108] More generally, the printhead-filter isolation valve V23 is positioned as close as possible to the filter cleaning valve V2.

[0109] Preferably, printhead-filter isolation valve V23 is open to allow coating product to flow through printing system 10 from supply inlet P1 to head circuit 3.

[0110] In the presence of the fill purge circuit 4, the fill purge isolation valve V43 is advantageously arranged opposite the print head cleaning valve V4, so that the fill purge circuit 4 is connected to the head circuit 3 by a ninth conduit C9. Preferably, the seats of these valves are separated by a common conduit section (C9) of length between 1 mm and 10 mm, for example equal to 5 mm. In particular, the distance between the two seats may be equal to the diameter of the seats.

[0111] When the fill purge isolation valve V43 is closed, it allows the fill purge circuit 4 and the head circuit 3 to be separated. Conversely, when the valve is open, the two circuits are connected, allowing different products to flow from one to the other. In this case, when the fill purge isolation valve V43 is open, products can flow between the ninth conduit C9 and the thirteenth conduit C13. Thus, the fill purge isolation valve V43 connects or disconnects the print head A1 from the fill purge outlet A4.

[0112] More generally, the fill purge isolation valve V43 is further positioned as close as possible to the printhead cleaning valve V4.

[0113] Relative to the normal flow direction, fill purge isolation valve V43 is therefore located in printing system 10 upstream of printhead A1.

[0114] Thus, by opening and closing the various isolation valves, different products can flow through different portions of the system 10 from the inlet to the outlet of the system 10 .

[0115] An advantage of two oppositely positioned valve assemblies is that it reduces the internal volume of the printing system 10. This reduces loss of coating product (and therefore conserves coating product), especially during the cleaning phase before priming the printing system 10 with new coating product.

[0116] Furthermore, the reduction in the internal volume of the printing system 10 makes it possible to have a system 10 that meets the demands of those skilled in the art in terms of compactness. Indeed, the use of opposing valves arranged oppositely makes it possible to reduce the number and / or length of the various conduits of the system 10. In particular, the spacing between two opposing valves formed by a common conduit section is reduced thanks to this particular assembly of the valves.

[0117] Finally, the opposing valve assembly avoids creating dead zones in the system 10. A dead zone can be defined as a zone where the circulating fluid and product have a very low velocity compared to the main flow, and therefore cleaning (by mechanical action of the fluid) is less effective. In particular, the opposing assembly ensures that the common conduit section is not a dead zone.

[0118] Finally, the opposing arrangement allows for easier access to the valves by the operator. Second, it makes installation and maintenance of the valves within the system easier. For example, the opposing arrangement allows the valves to be assembled on only two opposing sides of the system body (or frame).

[0119] An exemplary diagram of an assembly 100 with two opposing valves is shown in Figure 12. A first valve 110 connected to a conduit 113 includes a seat 111 and a needle 112. A second valve 120 connected to a conduit 123 includes a seat 121 and a needle 122. The first valve 110 and the second valve 120 are positioned opposite each other such that the needle 112 of the first valve 110 faces the needle 122 of the second valve 120, and vice versa. Thus, the two needles 112 and 122 face each other. A common conduit 130 is connected to the first valve 110 and the second valve 120. This conduit 130 includes a common conduit portion 131 located between the first valve 110 and the second valve 120.

[0120] Indiscriminately, the assembly 100 of FIG. 12 may correspond to an assembly of a supply filter isolation valve V12 and a filter purge valve V3, an assembly of a printhead-filter isolation valve V23 and a filter wash valve V2, or an assembly of a fill purge isolation valve V43 and a printhead wash valve V4.

[0121] The different configurations in which the valves are actuated, i.e., placed in an open or closed position, allow the system 10 to be positioned in specific modes of operation for predefined purposes, as will be described later in this text.

[0122] 1, the supply circuit 1 is further arranged to circulate the coating product in a normal flow direction. More specifically, the normal flow direction provides that the coating product flows from the supply inlet P1 to the supply filter isolation valve V12 or the supply purge outlet O1.

[0123] Filter circuit 2 is further arranged to allow the coating product to circulate in the normal flow direction, which is from filter purge valve V3 to filter wash valve V2, and is designed to transport filter wash fluid in the opposite direction to the normal flow direction, i.e., from filter wash fluid inlet P2 to filter purge outlet O2.

[0124] The head circuit 3 is further arranged to transport coating product in the normal flow direction from the printhead-filter isolation valve V23 to the print purge outlet O3, and is designed to transport filter cleaning fluid in the direction opposite to the normal flow direction from the printhead cleaning fluid inlet P3 to the print purge outlet O3.

[0125] The fill purge circuit 4 is further positioned to convey the coating product in the normal flow direction, i.e., from the fill purge isolation valve V43 to the fill purge outlet O4. This fourth circuit serves, among other purposes, to enable debubbling of the printing system 10. This debubbling may be performed, for example, before applying the coating product to purge the various circuits of air bubbles that could impair the application of the coating product. Debubbling may also be performed when the various circuits are filled with coating product, for example, after cleaning a single filter or printhead. This fill purge circuit 4 makes it possible to eliminate a bulky, dedicated debubbling module, whose mechanically moving parts would adversely affect the reliability and lifespan of the printing system 10.

[0126] System 10 also includes monitoring sensors (not shown). These sensors are arranged in a circuit to monitor the operating status of system 10. Therefore, these sensors serve to detect abnormalities in the operation of system 10 components. These may include sensors for determining pressure at various locations within the system. Preferably, these are pressure sensors for measuring the pressure of one of the products flowing through filter F1 and the pressure of one of the products flowing through print head A1. Therefore, if an abnormality in the measured pressure is detected, action can be taken to resolve the abnormality. For example, if a sensor detects an abnormality in the coating product pressure at print head A1, this may mean that filter F1 is clogged to the point where print head A1 is unable to ensure the pressure required for printing. Therefore, action would be taken to clean filter F1 to correct this pressure disturbance. To identify filter saturation, a pressure sensor can be placed upstream of the filter and another pressure sensor can be placed downstream of the filter. Additionally, a sensor can be placed upstream of the supply inlet to detect changes in monitored variables in system 10.

[0127] The system 10 further includes an access hatch (not shown) that allows easy access to the single filter and allows replacement of the filter when it becomes unusable or damaged in a time that is consistent with productivity constraints.

[0128] The valves of system 10 are advantageously pneumatic valves. A "pneumatic valve" is a valve controlled by compressed air acting on a piston that pulls on a needle, thereby allowing fluid to pass through. Pneumatic valves are therefore pneumatically controlled to limit the use of electric valves in the environment in which printing system 10 is used, for example, in an explosive atmosphere (ATEX) environment.

[0129] The pneumatic valves can be controlled by a PLC (not shown) during printing, cleaning, and priming operations of the printing system 10. Furthermore, this control can be performed according to instructions in a memory for executing a printing sequence including, for example, printing, cleaning, and priming operations. The PLC can be included in the printing system 10. Preferably, the PLC is external to the printing system 10.

[0130] Each pneumatic valve may be connected to a solenoid valve that ensures electronic control of the pneumatic valve. The solenoid valve may be included in the printing system 10 or may be external to the printing system 10.

[0131] Control of the valves via the solenoid valves is performed by instructions in memory or transmitted by an electronic card or PLC (not shown) that serves to monitor the components of the printing system, thus allowing for autonomous and automated use of the printing system 10. For example, the system 10 can be placed into a desired mode of operation based on data collected by monitoring sensors.

[0132] The electronic card may further enable control of nozzle A2 of print head A1 to eject a coating product through the nozzle. Control of nozzle A2 by the electronic card may be performed depending on the stage of the printing sequence. Control of nozzle A2 may also depend on positional information of the printing system relative to the object being coated.

[0133] The present invention also relates to a method for controlling the printing system 10, which allows for actuation of various valves and placement of various circuits in the printing system 10 in specific configurations to implement operating modes of the printing system 10.

[0134] The control method includes priming at least a portion of the printing system 10 with a coating product. This allows the printing system 10 to be placed in a so-called purge and fill mode of the supply circuit 1, the filter circuit 2, or the head circuit 3. The priming process can be performed to sequentially place the printing system 10 in three so-called purge and fill modes of circuit operation, as described below. During this priming process, it is also possible to place the system 10 in a single operating mode, known as purge and fill, of a single circuit during the priming process. In fact, depending on the previous operating mode in which the printing system 10 was placed and the next operating mode in which the printing system 10 is placed, it may turn out that only one of the so-called purge and fill operating modes is necessary. Similar reasoning applies when combining two of the three so-called purge and fill operating modes.

[0135] This mode of operation can be performed when the printing system 10 is first operated after cleaning a single filter F1 or print head A1, or to perform a coating product change to prime the printing system 10 with a new coating product.

[0136] The method for controlling the system 10 allows, by instruction from an electronic card or a PLC, to place the system 10 in a first operating mode known as purge and fill of the supply circuit 1. This is also called priming of the supply circuit 1. The priming of the supply circuit 1 may further be performed during a first priming of the supply circuit 1 sub-step of the priming step of the control method.

[0137] This first mode of operation, in which the supply circuit 1 is purged and filled with coating product, is illustrated in FIG.

[0138] The purpose of this first operating mode is to first purge the supply circuit 1 of residual coating product from previous applications, unwanted particles, and air contained in the conduits and various components of the supply circuit 1, and then, in a second step, to isolate the supply circuit 1 in order to fill it with coating product.

[0139] In the priming substep of the supply circuit 1, the valves of the system 10 are then actuated such that the supply purge valve V1 is open and the supply filter isolation valve V12 is closed.

[0140] The supply circuit 1 is then separated from the other circuits, so that the coating product circulates only in the supply circuit 1.

[0141] The printing system 10 can then supply coating product to purge and replenish the supply circuit 1. The flow of coating product is in the normal flow direction from supply inlet P1 to supply purge outlet O1.

[0142] In this first operating mode, the first conduit C1, the second conduit C2, the third conduit C3 and the supply purge valve V1 can be filled with coating product. Preferably, the supply circuit 1 is filled with coating product until it passes through the supply purge valve.

[0143] The system 10 is thus placed in an operating mode in which the supply circuit 1 is purged of cleaning fluid and coating product residues that should be discharged from the supply circuit 1. The purging is performed by a coating product supply, which expels unwanted residues through the supply purge outlet O1 as the coating product flows from the supply inlet P1 into the supply circuit 1. This therefore ensures that only the coating product is present in the supply circuit 1, without any impurities that could degrade the quality of the coating product. It also therefore ensures that air bubbles that could degrade print quality are purged from the supply circuit 1. In this operating mode, the coating product flows in its normal flow direction.

[0144] During the priming step of the control method, the printing system 10 is then placed in a second operating mode known as purging and filling the filter circuit 2 with coating product, also referred to as priming the filter circuit 2. Priming of the filter circuit 2 may also be performed during the second step of priming the filter circuit 2 of the priming step of the control method.

[0145] This second mode of operation, in which the filter circuit 2 is purged and filled with coating product, is illustrated in FIG.

[0146] The purpose of this second operating mode is to first purge any residual coating or cleaning product from the previous application of unwanted particles. This second operating mode makes it possible to purge the filter circuit 2 of any air stagnation that may be present due in particular to the previous cleaning of the single filter F1 or the fact that the printing system 10 has not yet been used. In this case, this is called debubbling the printing system 10. In the second step, the purpose is to fill the pipes, valves and single filter F1 of the filter circuit 2 with the coating product.

[0147] In the priming sub-step of filter circuit 2, the valves of system 10 are then actuated such that supply filter isolation valve V12, printhead filter isolation valve V23, and fill purge isolation valve V43 are open, and supply purge valve V1, filter purge valve V3, filter cleaning valve V2, printhead purge valve V5, and printhead cleaning valve V4 are closed.

[0148] The filter circuit 2 is connected to the supply circuit 1, the head circuit 3 and the fill purge circuit 4. In this mode of operation, the print head A1 is kept isolated from the other circuits by closing the print purge valve V5 and closing the nozzle A2.

[0149] The printing system 10 can then dispense coating product to perform a purge and fill the filter circuit 2. The coating product flows in the normal flow direction from the supply inlet P1 to the fill purge outlet O4.

[0150] In this second mode of operation, the first conduit C1, the sixth conduit C6, the fifth conduit C5, the ninth conduit C9, the thirteenth conduit C13, the supply filter isolation valve V12, the single filter F1, the printhead-filter isolation valve V23, and the fill-purge isolation valve V43 may be filled with coating product.

[0151] Next, the system 10 is placed in an operating mode such that residual filter cleaning fluid and coating product to be discharged from the filter circuit 2 are purged. Purging is accomplished by flowing the coating product from the supply inlet O1 of the supply circuit 1 and the filter circuit 2 to the supply purge circuit 4, discharging unwanted residue through the fill purge outlet O4. This ensures that only the coating product is present in the filter circuit 2, free of impurities that could degrade the quality of the coating product. This also ensures that the filter circuit 2 is purged of air bubbles that could degrade print quality. In this operating mode, the coating product flows in the normal flow direction. In particular, the fill purge outlet O4 serves to purge air bubbles that naturally form in the ninth conduit C9. The ninth conduit C9, the fill purge valve V43, and the thirteenth conduit C13 serve the same purpose as the air vent module, but with greater compactness, reliability, and service life.

[0152] Alternatively, the substep of priming filter circuit 2 can include two operations: a first operation of pressurizing printing system 10 from supply inlet P1 to fill purge isolation valve V43, and a second operation of purging ninth conduit C9. Compared to the substep of priming filter circuit 2 described above, this alternative allows for priming filter circuit 2 and purging possible air buildup while minimizing the amount of coating product used for priming. In fact, this alternative requires less coating product to perform debubbling than the substep of priming filter circuit 2 described above.

[0153] In a first pressurization operation of the printing system 10, the valves are operated such that the supply filter isolation valve V12 and the printhead-filter isolation valve V23 are open, and the supply purge valve V1, the filter purge valve V3, the filter cleaning valve V2, the printhead purge valve V5, the printhead cleaning valve V4, and the fill purge isolation valve V43 are closed.

[0154] As a result, the first conduit C1, the sixth conduit C6, the fifth conduit C5, the ninth conduit C9, the supply filter isolation valve V12, the single filter F1, and the printhead-filter isolation valve V23 can be filled with the coating product.

[0155] The filter circuit 2 is then connected to the supply circuit 1 and the head circuit 3, but not to the fill purge circuit 4. In this mode of operation, print head A1 is kept isolated from the other circuits by closing print purge valve V5 and closing nozzle A2.

[0156] The flow of coating product media is then shut off in the head circuit 3 so that the printing system 10 can supply coating product to pressurize the supplied conduits and components. The flow of coating product is in the normal flow direction from supply inlet P1 to fill purge isolation valve V43. Pressurization of the printing system 10 is achieved by increasing the pressure of the coating product entering through supply inlet P1.

[0157] An advantage of this pressurized operation of the printing system 10 is that the coating product conveyed from the feed inlet P1 pushes any trapped air contained in the sixth conduit C6, the single filter, and the fifth conduit C5 toward the ninth conduit C9. Advantageously, as the pressure in the conduits and the single filter increases with the increasing pressure of the coating product conveyed within the printing system 10, the repelled air bubbles are maintained within the ninth conduit C9.

[0158] In a second operation, to purge the ninth conduit C9, the fill purge isolation valve V43 is operated to open and the supply of coating product is shut off, for example, by closing the supply filter isolation valve V12 or the printhead filter isolation valve V23 (or other valves not shown upstream in the system), with the configuration of the other valves remaining unchanged for the first pressurization operation of the printing system 10.

[0159] The coating product that was pressurized in the printing system 10, and in particular in the ninth conduit C9, can then flow towards the fill purge outlet O4, taking the air bubbles with it.

[0160] This blocks the flow of coating product when the printing system 10 is vented, thus reducing the amount of coating product required to prime the filter circuit 2.

[0161] In this alternative, prior to the cleaning operation of the single filter F1, it is also possible to put the print head A1, the tenth conduit C10 and the eleventh conduit C11 under pressure, close the print head purge valve V5, the nozzle A2 and supply the coating product to the head circuit 3. It is thus ensured that air introduced into the filter circuit 2 (during the cleaning operation of the filter F1) is directed only to the ninth conduit C9 during the pressurization operation of the system 10.

[0162] During the priming step of the control method, the printing system 10 is then placed into a third operating mode known as purging and filling the head circuit 3 with coating product, also referred to as priming the head circuit 3. Priming of the head circuit 3 may also be performed during a third sub-step of priming the head circuit 3 of the priming control method.

[0163] This third mode of operation, purging and filling the head circuit 3 with coating product, is illustrated in FIG.

[0164] The purpose of this third operating mode is, first, to purge any coating or cleaning product residue from previous applications, unwanted particles, and air contained in the conduits and various components of the head circuit 3, and second, to fill the conduits, valves, and print head A1 of the head circuit 3 with coating product.

[0165] In the sub-step of priming the head circuit 3, the valves of the system 10 are then actuated such that the supply filter isolation valve V12, the printhead filter isolation valve V23, and the printhead purge valve V5 are open, and the fill purge isolation valve V43, the supply purge valve V1, the filter purge valve V3, the filter cleaning valve V2, and the printhead cleaning valve V4 are closed.

[0166] In this way, the head circuit 3 is connected to the supply circuit 1 and the filter circuit 2. In this mode of operation, the fill purge circuit 4 is kept isolated from the rest of the circuit.

[0167] The printing system 10 can then supply coating product to purge and fill the head circuit 3. The coating product flows in the normal flow direction from the supply inlet P1 to the printhead purge outlet O3.

[0168] In this third mode of operation, the first conduit C1, the sixth conduit C6, the fifth conduit C5, the tenth conduit C10, the eleventh conduit C11, the twelfth conduit C12, the supply filter isolation valve V12, the single filter F1, the printhead-filter isolation valve V23, the printhead purge valve V5, and the printhead A1 can be filled with coating product.

[0169] The system 10 is then placed in an operating mode such that the head circuit 3 is purged of residual printhead cleaning fluid and coating product to be expelled from the head circuit 3. Purging is accomplished by flowing the coating product from the supply inlet O1 of the supply circuit 2 and filter circuit 2 into the head circuit 3, expelling unwanted residue through the printhead purge outlet O3. This ensures that only the coating product is present in the head circuit 3, without any impurities that could degrade the quality of the coating product. The filter circuit therefore also ensures that any air bubbles that could degrade print quality are purged. In this operating mode, the coating product flows in its normal flow direction.

[0170] Once the various circuits of the system 10 have been primed, the system 10 is placed into a fourth mode of operation known as printing a coating product onto the object to be coated with printhead A1. Accordingly, the control method includes printing a coating product onto the object to be coated to place the printing system 10 into the print mode.

[0171] This fourth mode of operation for printing a coating product is illustrated in FIG.

[0172] The purpose of this fourth operating mode is to operate the various valves of the system 10 so that the coating product is conveyed from the supply inlet P1 to the print head A1, where it is ejected by nozzle A2 onto the object to be coated. To perform printing, the valves are actuated to maintain a constant pressure suitable for printing the coating product. In this fourth operating mode, nozzle A2 is open.

[0173] During the printing step of the control method, the valves of system 10 are then actuated such that supply filter isolation valve V12 and printhead-filter isolation valve V23 are open, and supply purge valve V1, filter purge valve V3, filter cleaning valve V2, printhead cleaning valve V4, fill purge isolation valve V43, and printhead purge valve V5 are closed.

[0174] Then, the supply circuit 1, the filter circuit 2 and the head circuit 3 are connected together. In this operating mode, the fill purge circuit 4 is kept isolated from the other circuits.

[0175] The printing system 10 can then supply the coating product to effectively print the coating product, which flows in a normal flow direction from the supply inlet P1 to the printhead A1, where it exits the system 10 through the nozzle A2.

[0176] In this fourth operating mode, the first conduit C1, the sixth conduit C6, the fifth conduit C5, the tenth conduit C10, the eleventh conduit C11, the supply filter isolation valve V12, the single filter F1, the printhead-filter isolation valve V23, and the printhead A1 can be filled with coating product.

[0177] Thus, system 10 is placed in an operating mode in which coating product is supplied from supply inlet O1 to print head A1, where it is printed onto the object to be coated. To do this, the coating product flows through supply circuit 1, then through filter circuit 2, which filters out agglomerates, and finally through head circuit 3. In this operating mode, the coating product flows in the normal flow direction.

[0178] It may be necessary to clean the single filter F1 during printing of a coating product or before changing the coating product. This may be the case, for example, if the filter F1 becomes clogged with agglomerates that prevent the proper flow of the coating product, thus reducing the coating product pressure in the print head A1 and thereby reducing printing performance. This may also be the case when changing the coating material to apply another coating product.

[0179] To clean the single filter F1, the system 10 is placed in a fifth operating mode known as cleaning the filter circuit. Thus, the control method includes cleaning the single filter F1 to place the printing system 10 in filter circuit cleaning mode 2.

[0180] This fifth operating mode for cleaning the filter circuit 2 is illustrated in FIG.

[0181] The purpose of this fifth operating mode is to operate the various valves of the system 10 so that the filter circuit 2 is isolated from the other circuits. The interest is to be able to circulate the filter wash fluid from the filter wash inlet P2 to the filter purge outlet O2 to wash the single filter F1. At this time, the filter wash fluid can flow in the opposite direction to the normal flow direction in the filter circuit 2. This opposite flow direction is optimal for washing the single filter F1 and removing any agglomerates retained in its mesh to the filter purge outlet O2.

[0182] During the process of cleaning a single filter F1, the valves of the system 10 are then operated such that the filter cleaning valve V2 and the filter purge valve V3 are open, and the printhead-filter isolation valve V23 and the supply filter isolation valve V12 are closed.

[0183] The filter circuit 2 is then isolated from the other circuits.

[0184] The printing system 10 can then supply filter cleaning fluid into the filter circuit 2 to cause cleaning of the single filter F1.

[0185] In this fifth mode of operation, the fourth conduit C4, the fifth conduit C5, the sixth conduit C6, the seventh conduit C7, the filter F1, the filter wash valve V2, and the filter purge valve V3 are filled with filter wash fluid.

[0186] Thus, the system 10 is placed in an operating mode in which the single filter F1 is cleaned separately and independently, without interaction with the other circuits of the printing system 10. In particular, the single filter F1 is cleaned without the need to also clean the printhead A1 and / or the supply circuit 1. The single filter F1 is also cleaned only in the direction opposite to the normal flow direction, allowing for short cleaning times that are compatible with the productivity constraints of the printed object being coated. The filter F1 can then be cleaned with a suitable cleaning fluid. This can be a mixture of solvent and water pulsed with air at a predetermined pressure to ensure good removal and evacuation of all agglomerates. The pressure of the filter cleaning fluid is advantageously higher than that of the printhead cleaning fluid, for example, between 1 bar and 20 bar, preferably between 4 bar and 8 bar.

[0187] Preferably, filter cleaning is performed according to an alternative filter cleaning sequence that includes cleaning a single filter F1 with a filter cleaning fluid, e.g., a solvent, followed by a filter purging operation with air, e.g., forced air. In such a case, the filter cleaning fluid and forced air are conveyed from a filter cleaning inlet P2 to a filter purge outlet O2 within the filter circuit 2. This alternative sequence is superior to cleaning with liquid alone in unclogging and / or cleaning the single filter F1 of the coated product.

[0188] The alternative filter cleaning sequence may be repeated one or more times to ensure complete cleaning of the filter circuit 2, particularly to ensure that the single filter F1 is properly unclogged and / or cleaned of any coating product. Preferably, the air used during this alternative filter cleaning sequence is vented from the printing system 10 when the printing system 10 is in the operating mode described in connection with FIG. 3 to purge and fill the filter circuit 2 with coating product.

[0189] Regardless of cleaning the filter circuit 2, it may be necessary to clean the head circuit 3, for example to clean the print head of a previously applied coating.

[0190] In this case, the system 10 is placed in a sixth operating mode known as the head circuit 3 cleaning mode. The control method then includes a print head cleaning step A1 to place the system 10 in the print head cleaning mode A1.

[0191] This sixth operating mode for cleaning the head circuit 3 is illustrated in FIG.

[0192] The purpose of this sixth operating mode is to operate the various valves of the system 10 so that the printhead circuit 3 is isolated from the other circuits. The interest is to allow printhead cleaning fluid to circulate from the printhead cleaning inlet P3 to the printhead purge outlet O3 to clean the printhead A1. The printhead filter cleaning fluid is then allowed to flow in its normal flow direction in the filter circuit 2.

[0193] During the process of cleaning printhead A1, the valves of system 10 are then activated such that printhead purge valve V5 and printhead wash valve V4 are open and printhead-filter isolation valve V23 and fill purge isolation valve V43 are closed. Additionally, printhead A1 can be operated to clean nozzle A2 of printhead A1. In this case, printhead purge valve V5 can be opened and closed. Preferably, printhead purge valve V5 is closed to direct all cleaning fluid pressure to nozzle A2. Cleaning of nozzle A2 is then more efficient.

[0194] Next, the head circuit 3 is isolated from the other circuits.

[0195] The printing system 10 can then supply printhead cleaning fluid into the head circuit 3 to perform printhead cleaning.

[0196] In this sixth mode of operation, the eighth conduit C8, the ninth conduit C9, the tenth conduit C10, the eleventh conduit C11, the twelfth conduit C12, the printhead A1, the printhead purge valve V5, and the printhead cleaning valve V4 are filled with printhead cleaning fluid.

[0197] Thanks to this sixth operating mode, the printheads can be cleaned separately and independently, without interacting with other circuits in the system 10. In particular, printhead A1 can be cleaned without the need to clean the single filter F1 and / or the supply circuit 1. Printhead A2 is also cleaned only in the normal flow direction, allowing for short cleaning times that are compatible with the productivity constraints of the printed object being coated. Furthermore, this sixth operating mode can include opening the A2 nozzles to clean them. The printhead A1 and nozzles A2 can then be cleaned with a suitable printhead cleaning fluid, preferably a liquid. This can be, for example, an air-free solvent-water mixture at a pressure suitable for cleaning without damaging the printhead and / or nozzles A2. Preferably, the printhead cleaning fluid is air-free to avoid the risk of drying out coating product residues on the printhead circuit 3, especially nozzles A2. The pressure of the printhead cleaning fluid is, for example, between 0.1 bar and 10 bar, preferably between 1 bar and 3 bar.

[0198] Furthermore, the ninth conduit C9 is a dead retention zone, in other words, this conduit contains only stagnant and bubble-free coating product. The absence of bubbles in this conduit ensures that air bubbles are not drawn in by the flow of coating product in the tenth conduit C10 during printing. This sixth operating mode makes it possible to ensure that the dead retention zone, i.e., conduit C9 with stagnant coating product, is properly cleaned.

[0199] Through the use of independent, separable circuits, the printing system 10 can be simultaneously placed in a cleaning mode for the filter circuit 2 and a cleaning mode for the head circuit 3. This simultaneous operation is a seventh mode of operation known as combined cleaning. This seventh mode of operation is illustrated in FIG. 8.

[0200] This seventh combined cleaning mode can be implemented by a control method. To this end, the control method includes a first preliminary step to the execution of the steps of cleaning the print head A1 and cleaning the single filter F1, which first preliminary step includes closing the supply filter isolation valve V12 and the print head-filter isolation valve V23. Thus, the head circuit 3 is isolated from the filter circuit 2, and the filter circuit 2 is isolated from the head circuit 3 and the supply circuit 1.

[0201] Once this first preliminary step has been carried out, the step of cleaning printhead A1 can be carried out independently and simultaneously with the step of cleaning single filter F1.

[0202] Thus, thanks to the use of independent, separable circuits, the system 10 can be cleaned in less than 20 seconds, preferably 15 seconds or less.

[0203] Furthermore, thanks to the use of independent, separable circuits, the printing system 10 can be simultaneously placed in a cleaning mode of the filter circuit 2 and priming of the supply circuit 1. This simultaneous mode of operation is an eighth mode of operation called simultaneous cleaning and priming of the filter circuit 2. This eighth mode of operation is illustrated in FIG.

[0204] This eighth mode can be implemented by a control method. To this end, the control method includes a second preliminary step to the execution of the substeps of cleaning the single filter F1 and priming the supply circuit 1, this second preliminary step including closing the supply filter isolation valve V12. Thus, the filter circuit 2 and the supply circuit 1 are isolated from each other. Furthermore, this second preliminary step may include closing the printhead-filter isolation valve V23, thus isolating the filter circuit 2 from the head circuit 3.

[0205] Once this second preliminary step has been carried out, it is possible to carry out the step of cleaning the single filter F1 independently and simultaneously with the sub-step of priming the supply circuit 1.

[0206] Thus, thanks to the use of an independent and separable circuit, a single filter F1 can be washed in less than 20 seconds while the supply circuit 1 is being primed with the coating product, preferably in 15 seconds or less.

[0207] However, thanks to the use of independent separable circuits, the printing system 10 can be simultaneously placed in a cleaning mode of the head circuit 3 and in priming of the supply circuit 1. This simultaneous mode of operation is a ninth mode of operation known as simultaneous cleaning and priming of the head circuit 3. This ninth mode of operation is illustrated in FIG.

[0208] This ninth mode can be implemented by a control method. To this end, the control method includes a third step prior to the execution of the cleaning step of print head A1 and the priming sub-step of supply circuit 1, this second preliminary step including closing print head-filter isolation valve V23, thus isolating head circuit 3 and filter circuit 2 from each other. Furthermore, this second preliminary step may also include closing supply filter isolation valve V12, thus isolating supply circuit 1 from filter circuit 2.

[0209] This second preliminary step makes it possible to carry out the step of cleaning the print head A1 independently of and simultaneously with the sub-step of priming the supply circuit 1.

[0210] Thus, thanks to the use of an independent, separable circuit, the print head A1 can be cleaned in less than 20 seconds while the supply circuit 1 is primed with the coating product, preferably in 15 seconds or less.

[0211] Finally, thanks to the use of independent, separable circuits, the printing system 10 can be simultaneously placed in a cleaning mode of the filter circuit 2, a cleaning mode of the head circuit 3, and a priming of the supply circuit 1. This simultaneous mode of operation is a tenth mode of operation known as simultaneous cleaning and priming of the filter circuit and the printing circuit. This tenth mode of operation is illustrated in FIG. 11.

[0212] This tenth mode can be implemented by the control method. For this purpose, a fourth preliminary step of the control method can be implemented to close the supply filter isolation valve V12 and the printhead-filter isolation valve V23. Thus, the supply circuit 1, the filter circuit 2 and the head circuit 3 are isolated from each other.

[0213] Once this fourth preliminary step has been carried out, the substeps of cleaning the single filter F1, cleaning the print head A1 and priming the supply circuit 1 can be carried out simultaneously and independently of each other.

[0214] Thus, thanks to the use of independent and separable circuits, it is possible to clean a single filter F1 and printhead A1 in less than 20 seconds while priming the supply circuit 1 with coating product, preferably in 15 seconds or less.

[0215] In one embodiment compatible with the preceding embodiment, the fill purge isolation valve V43 and the printhead cleaning valve V4 are assembled into a single three-way valve, i.e., instead of having two separate valves, the system 10 has a single three-way valve that performs the functions of both the fill purge isolation valve V43 and the printhead cleaning valve V4, as described above.

[0216] In an embodiment compatible with the preceding embodiment, the operation of the system 10 is ensured thanks to monitoring sensors that measure indicators representative of the system's operating state. For example, a pressure sensor on the print head or between the print head purge valve and the print head allows monitoring the proper delivery of the coating product to the print head A1 and the proper printing by ejecting the coating product through the nozzle A2.

[0217] In one embodiment compatible with the preceding embodiment, one or more cameras may be incorporated into system 10 to monitor the operation of system 10 and detect operational anomalies. These may include optical cameras or thermal imaging cameras.

[0218] If an abnormality is detected using the monitoring sensors, instructions contained in the electronics board or controller can determine actions to correct such an abnormality. For example, if the sensor detects that filter F1 is clogged with too much agglomerate, the electronics board or controller will automatically execute instructions to place system 10 in filter circuit 2 cleaning mode, as described above. Filter F1 can then be cleaned to remove agglomerate from system 10 through filter purge outlet O2. The electronics board or controller then executes instructions to return system 10 to coating product printing mode.

[0219] Such instructions also exist to place the system 10 into various modes of operation.

[0220] Additionally, additional instructions may be executed for practical purposes or based on current printing activity. For example, these instructions may be used to perform additional control functions.

[0221] Additionally, in one embodiment compatible with the preceding embodiment, the instructions for placing the system 10 in an operational mode are executed in response to control instructions. The control instructions are manually or automatically defined rules that dictate how an electronic board or controller monitors and operates the printing system 10. For example, they may be rules regarding the execution order of instructions for sequentially placing the system 10 in different successive operational modes. Furthermore, the rules may define an instruction execution plan for placing the system 10 in a particular operational mode at a predefined time. This may be the case, for example, for scheduling printing applications in assembly line production of a large number of coated objects.

[0222] In one embodiment compatible with the preceding embodiment, the supply circuit 1, the filter circuit 2, and the head circuit 3 can be cleaned and / or purged with cleaning and / or purging fluid from the purge outlet of the system 10. For this purpose, a purge filter device is installed outside the purge outlet of the system 10 to filter different products for cleaning and / or purging. This embodiment allows the supply circuit 1, the head circuit 3, and the fill-purge circuit 4 to be cleaned and / or purged in a direction opposite to the normal flow direction. This embodiment also allows cleaning of the filter circuit 2 to be performed in the normal flow direction. Thus, this embodiment allows cleaning of the various components and conduits of the system 10 in both directions.

[0223] In particular, in such an embodiment, the supply circuit 1 can be flushed with a dedicated flushing fluid in a direction opposite to the normal flow direction, from the supply purge outlet O1 or the filter purge outlet O2 towards the supply inlet P1.

[0224] When purging the supply circuit 1 from the supply purge outlet O1, the supply purge valve V1 is controlled to be open and the supply filter isolation valve V12 is controlled to be closed.

[0225] When flushing the supply circuit 1 from the filter purge outlet O2, the supply purge valve V1, the printhead filter isolation valve V23 and the filter flushing valve V2 are controlled to close, and the supply filter isolation valve V12 and the filter purge valve V3 are controlled to open.

[0226] Alternatively, the filter cleaning fluid can be directed from the filter cleaning inlet P2 towards the supply inlet P1 in the opposite direction to the normal flow direction through the supply circuit 1. In such a case, the filter cleaning valve V2 and the supply filter isolation valve V12 are controlled to be open, and the supply cleaning valve V1, the printhead-filter isolation valve V23 and the filter cleaning valve V3 are controlled to be closed.

Claims

1. A printing system (10) for applying a coating product to an object to be coated, said printing system (10) comprising: a printhead (A1) for applying the coating product to the object to be coated, the coating product flowing in the so-called normal flow direction; a single filter (F1) placed upstream of the printhead to filter the coating product; a plurality of valves and conduits adapted to convey said coating product, filter cleaning fluid and printhead cleaning fluid, said plurality of valves and conduits comprising: A coating product supply circuit (1), a filter circuit (2) adapted to convey the coating product through the single filter (F1) in the normal flow direction and to convey the filter washing fluid through the single filter (F1) only in the direction opposite to the normal flow direction; a head circuit (3) adapted to transport said coating product and said printhead cleaning fluid through said printhead (A1) in said normal flow direction; a plurality of valves and conduits arranged to form - a supply filter isolation valve (V12), In the closed state, it separates the supply circuit (1) from the filter circuit (2), In the open position, it connects the supply circuit (1) to the filter circuit (2), a supply filter isolation valve (V12) configured as follows: - a printhead-filter separation valve (V23), In the closed state, the filter circuit (2) is separated from the head circuit (3), In the open state, the filter circuit (2) is connected to the head circuit (3); a printhead-filter separation valve (V23) configured as follows: Equipped with the filter circuit (2) further comprises a filter cleaning valve (V2) arranged opposite the print head-filter separation valve (V23), and a filter purge valve (V3) arranged opposite the supply filter separation valve (V12); the supply filter isolation valve (V12), the printhead-filter isolation valve (V23), the filter cleaning valve (V2), and the filter purge valve (V3) are two-way valves; A printing system (10).

2. - the supply filter isolation valve (V12), the printhead-filter isolation valve (V23), the filter cleaning valve (V2) and the filter purge valve (V3) each comprise a seat and a needle for contacting the seat; - the needles of the filter cleaning valve (V2) and the printhead-filter separation valve (V23) are aligned and pointed in opposite directions towards a first common conduit portion; - the needle of the filter purge valve (V3) and the needle of the supply filter isolation valve (V12) are aligned and pointed in opposite directions towards a second common conduit section; The printing system (10) of claim 1.

3. - said first common conduit portion separating said filter cleaning valve (V2) seat and said printhead-filter separation valve (V23) seat presents a length between 1 mm and 10 mm; - said second common conduit portion separating the filter cleaning valve (V3) seat and the supply filter separating valve (V12) seat presents a length between 1 mm and 10 mm; The printing system (10) of claim 2.

4. The filter circuit (2) further comprises a filter cleaning inlet (P2), the filter cleaning inlet (P2) is adapted to supply a filter cleaning fluid to the filter circuit (2), and the filter cleaning valve (V2) - in the open state, connecting said single filter (F1) to said filter washing inlet (P2), - in the closed state, separating the single filter (F1) from the filter cleaning inlet (P2), It is configured as follows: The printing system (10) of claim 1.

5. The filter circuit (2) further comprises a filter purge outlet (O2), the filter purge outlet (O2) being adapted to purge the filter circuit (2) with a filter cleaning fluid, and the filter purge valve (V3) - in the open state, connecting said single filter (F1) with said filter purge outlet (O2), - in the closed state, it separates the single filter (F1) from the filter purge outlet (O2), It is configured as follows: The printing system (10) of claim 1.

6. The supply circuit (1) comprises a supply inlet (P1), a supply purge valve (V1) and a supply purge outlet (O1), the supply inlet being adapted to supply the supply circuit (1) with a coating product, the supply purge outlet (O1) being adapted to purge the supply circuit (1) of coating product, the supply purge valve (V1) - in the open state, connecting the supply inlet (P1) and the supply purge outlet (O1), - in the closed state, it separates the feed inlet (P1) and the feed purge outlet (O1), It is configured as follows: A printing system (10) according to any one of claims 1 to 5.

7. The system further comprises a fill-purge circuit (4) and a fill-purge isolation valve (V43), wherein the fill-purge isolation valve (V43) - in the open state, connecting the head circuit (3) and the fill purge circuit (4); - in the closed state, it separates the head circuit (3) from the fill-purge circuit (4); It is configured as follows: A printing system (10) according to any one of claims 1 to 5.

8. 8. The printing system of claim 7, wherein the head circuit further comprises a printhead cleaning valve arranged opposite the fill-purge isolation valve, and the printhead cleaning valve and the fill-purge isolation valve are two-way valves.

9. The head circuit (3) further comprises a printhead purge valve (V5) and a printhead purge outlet (O3), the printhead purge outlet (O3) is adapted to purge the head circuit (3) of printhead cleaning fluid and coating products, and the printhead purge valve (V5) - in the open state, connecting the printhead (A1) with the printhead purge outlet (O3), - in the closed state, separating the printhead (A1) from the printhead purge outlet (O3), It is configured as follows: A printing system (10) according to any one of claims 1 to 5.

10. 6. The printing system of claim 1, wherein a single filter (F1) has a first end and a second end, the single filter (F1) being arranged such that a coating product is transported along an axis of the filter by entering the first end and exiting the second end, and a cleaning fluid is transported along an axis of the filter by entering the second end and exiting the first end.

11. A method for controlling a printing system (10), the control method comprising: - priming at least a part of said printing system (10) with a coating product, - printing said coating product onto said object to be coated, - cleaning said print head (A1), - washing said single filter (F1), The method includes one or more steps selected from the following: A method for controlling a printing system (10) according to any one of claims 1 to 5.

12. 12. The control method of claim 11, wherein the steps of cleaning the print head (A1) and cleaning the single filter (F1) are performed simultaneously by closing the supply filter isolation valve (V12) and the print head-filter isolation valve (V23).

13. 13. The control method of claim 12, wherein the filter cleaning fluid pressure is strictly greater than the printhead cleaning fluid pressure.

14. 12. A control method according to claim 11, comprising a step of priming the supply circuit (1) with a coating product, wherein the steps of cleaning the single filter (F1) and priming the supply circuit (1) are carried out simultaneously by closing the supply filter isolation valve (V12).

15. 12. A control method according to claim 11, comprising the step of priming the supply circuit (1) with a coating product, wherein the steps of cleaning the print head (A1) and priming the supply circuit (1) are carried out simultaneously by closing the print head-filter separation valve (V23).

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