Patent Description:
It concerns a new cleaning process of CIJ printers.

It also concerns a new architecture (arrangement of the ink circuit) of CIJ printers, in particular the arrangement of the ink circuit, for the purpose of increased flexibility.

Continuous inkjet printers (CIJ) are well known in the field of industrial coding and labelling of various products, for example to mark barcodes or expiry dates on food items directly on the production line and at fast production rate. This type of printer is also found in some fields of design in which use is made of the graphic printing possibilities of the technology.

There is a need for a process to clean an ink circuit of CIJ printers, so that individual components or parts of its ink circuit can be easily disassembled or removed from the ink circuit, for example when they must be repaired or replaced by other components or parts, while minimizing risks of spillage or dropping, in particular of ink. Such process must be able to be carried out by an operator without any particular training.

One particular problem arises when a component or a part of a known printer, for example a valve, must be replaced. Said part is first disassembled from the printer and stoppers are mounted on the hydraulic conduits from which the part was removed and possibly also on the removed part itself, which is time consuming and costly. Alternatively, non-return valves or check valves can be used in the circuit, but they are also costly. Furthermore, the removed part remains dirty and/or is not dry, which causes important ink and/or solvent spills; for this reason, it is sometimes introduced into an airtight bag to be transported, which is not satisfactory since the removed part often remains dirty and retains a lot of residual fluid.

There is also a need, for environmental reasons, to collect the used components or parts of such machines and to recycle or refurbish or evacuate them to waste stations with minimum spillage and dropping. A process must therefore be found to clean an ink circuit of a CIJ printer, so that, after use, clean individual components or parts of said circuit can be easily recycled and/or refurbished and/or transported to a repair station or to a collecting or waste station.

There is also a need for a process to clean an ink circuit of a CIJ printer, so that clean and dry or nearly dry individual components or parts of said circuit can be easily removed and then transported with minimum risks of ink and/or solvent spillage. There is also a need for an ink circuit of a CIJ printer to implement a new cleaning process according to the above requirements.

There is also a need for an ink circuit architecture of such CIJ printers which minimizes the number of components whilst guaranteeing great flexibility and reliability, ease of cleaning and/or maintenance to allow rapid servicing, minimizing risks of spillage and able to be carried out by an operator without any particular training.

There is also a need for components for such an ink circuit which can be easily cleaned and/or removed from said ink circuit for example when they must be repaired or replaced by other components.

There is a further need for an ink circuit architecture of such CIJ printers which can be modulated or tailored depending on the needs and/or on the kind of printing which must be performed; preferably, such an ink circuit architecture has one or more parts or modules which can be adapted or changed, in particular when manufacturing or building the CIJ printer which comprises said ink circuit architecture.

<CIT> discloses a cleaning process for cleaning at least one part of a hydraulic circuit of a continuous inkjet printer, said hydraulic circuit comprising a solvent tank and an ink tank and hydraulic connection means for sending ink and/or solvent to a print head.

The invention concerns a process for cleaning at least part of an ink circuit of a CIJ printer, according to claim <NUM>. For example the invention can apply to an ink circuit as disclosed below; such a circuit may comprise at least one single-block assembly or module.

In an embodiment, said method comprises flushing or cleaning at least said part of the ink or hydraulic circuit of an ink jet printer, or said ink or hydraulic circuit, with a gas, for example with air. Gas is circulated or flowed, in said circuit or in at least part of it, and removes ink from the part in which it is circulated or flowed.

Thus, there is no residual ink in the circuit or in at least part of it. This avoids the risks of spillage or dropping of ink.

Ink is recovered, for example in a recovery cartridge or in a tank or in the main ink tank of the ink circuit. Ink can thus be reused and is not wated.

In an embodiment, said cleaning process comprises circulating or flowing, for example pumping, a gas or a gas and clean solvent, through said circuit or at least one part of said hydraulic circuit and possibly recovering dirty fluid from said circuit or from at least one part of said hydraulic circuit, said dirty fluid comprising a mixture of solvent and ink.

Said process may comprise alternatively or simultaneously circulating or flowing, through said at least one part of said hydraulic circuit or through said circuit, for example by pumping said solvent, for example from said solvent reservoir, and said gas, for example between <NUM>% and <NUM>% of solvent and <NUM>% to <NUM> % of gas.

If said hydraulic circuit comprises a solvent pump for pumping solvent and/or a pressure pump for pumping ink from said ink tank, said circulating or flowing of gas or of gas and solvent can implement pumping of gas and/or solvent and can be performed with one or both of said solvent pump and/or said pressure pump. Gas under pressure (at a pressure higher than the atmospheric pressure) can be directly introduced into the circuit, and in particular into a flow of solvent, without pumping said gas.

Said step of circulating or flowing a gas and solvent in an embodiment of a process according to the invention for example comprises alternatively sending or circulating or flowing several volumes of gas and solvent, forming for example a slug flow, and/or forming a mixture of solvent and gas, forming, or not, a diphasic mixture or an emulsion, said flow or mixture or emulsion comprising for example between <NUM>% and <NUM>% of solvent and <NUM>% to <NUM> % of gas. A slug flow comprises several volumes of solvent, two successive such volumes being separated by one volume of gas.

A cleaning process according to the invention may comprise:.

An embodiment, in which said flushing or cleaning process comprises circulating or flowing a gas and clean solvent through said circuit or at least one part of said hydraulic circuit, can comprise at least one of:.

In a flushing or cleaning process according to the invention, gas, for example compressed gas (at a pressure higher than atmospheric pressure) can be introduced into the ink circuit, for example alternatively or simultaneously to solvent, through a dedicated inlet in the circuit, for example upstream or downstream of one of the pump(s) of the circuit.

Said hydraulic circuit to which the invention applies can comprise a solvent pump for pumping solvent and an ink pump (or a pressure pump) for pumping ink from said ink tank, pumping of gas and solvent according to an embodiment of the invention being performed with one or both of said solvent pump and said ink or pressure pump.

In an embodiment, said hydraulic circuit to which the invention applies comprises at least an ink cartridge and a solvent cartridge, said flushing or cleaning process comprising at least one of:.

In a particular embodiment, a flushing or cleaning process according to the invention may comprise a preliminary step of mounting a device in the circuit for introducing a gas, for example compressed gas, into said circuit, said cleaning process comprising circulating or flowing said gas and solvent.

A flushing or cleaning process according to the invention may comprise or end with a drying step of said at least one part of a hydraulic circuit or of said circuit. Said drying step for example comprises sending or circulating or flowing a flow of gas, which may be heated, through said hydraulic circuit or through said at least one part of said hydraulic circuit.

In a particular embodiment, said hydraulic circuit comprises at least one removable single-block assembly or module or component, said flushing or cleaning process comprising cleaning said at least one removable single-block assembly or module or component. A drying step as mentioned above is particularly useful in this case, for example if said single-block assembly or module or component must be disassembled from said circuit: a clean and dry or nearly dry single-block assembly or module or component can be removed from the circuit with minimum risk of ink or solvent spills and thus with a minimum risk to waste ink or solvent. The drying step of a single-block assembly or module or component may achieve removing at least <NUM>% or <NUM>% of the fluid (mostly solvent) from said assembly or module or component.

The invention also concerns a process for maintaining a hydraulic circuit of a continuous inkjet printer, or at least one part of said hydraulic circuit, which may comprise at least one removable single-block assembly, said process comprising:.

The invention also concerns a continuous inkjet printer, comprising:.

Preferably the controller is controlling, or programmed to control, said hydraulic circuit so as to perform at least one of the following:.

Said CIJ printer can comprise a solvent pump for pumping solvent and/or an ink pump (or a pressure pump) for pumping ink.

Said CIJ printer can comprise at least an ink cartridge receiving portion or connection and/or at least a solvent cartridge receiving portion or connection.

Said ink circuit can comprise an inlet for introducing gas, for example compressed gas, into the ink circuit in order to perform a cleaning step or process according to the invention.

Said ink circuit can comprise at least one removable single-block assembly, as disclosed below, said controller controlling said hydraulic circuit to perform a process according to the invention, for example to circulate or flow at least gas, or to alternatively or simultaneously circulate or flow gas and solvent, through at least said removable single-block assembly.

In a continuous inkjet printer according to the invention, said controller may be programmed to control said hydraulic circuit to perform a drying step by sending or circulating of flowing gas, for example heated gas, through the circuit.

An example of circuit, and of components of such a circuit, to which the invention can be applied is given on <FIG>.

Components for such a circuit are shown on <FIG> and are first described.

An example of a pump module (or ink pressure pump module) <NUM> is illustrated on <FIG>. It comprises a housing or support <NUM>, possibly including a front side or cover <NUM>; said module comprises a fluid inlet <NUM> and a fluid outlet <NUM>; inside the module or its housing, at least the hydraulic part <NUM> of a pump <NUM> is connected to said fluid inlet and said fluid outlet. As illustrated on <FIG>:.

The pump illustrated on <FIG> comprises a hydraulic part <NUM>, a motor <NUM> and an axis <NUM> coupling said hydraulic part <NUM> and said motor <NUM>; the pump can be of the magnetic type. Such a magnetic pump comprises a shell (part of which is referenced <NUM> on <FIG>) containing a hydraulic part, or impeller, coupled to a shaft which bears an inner magnetic ring; outside the shell, an outer magnetic ring is mounted on a drive shaft and is magnetically coupled to the inner magnetic ring through the shell. A motor can drive the drive shaft and the outer magnetic ring in rotation (the motor <NUM> and the outer magnetic ring <NUM> are visible on <FIG>); in turn, the outer magnetic ring drives the inner magnetic ring, and the impeller, in rotation because of the magnetic coupling. In case of a magnetic pump, the axis <NUM> of <FIG> is the drive shaft, the impeller and its shaft being housed in the housing <NUM>.

The ink circuit has a receiving portion or zone or interface to receive the pump module and connect it to the hydraulic circuit of the printer. Said receiving portion or zone or interface has at least one fluid inlet (s) which corresponds to the fluid outlet <NUM> and at least one fluid outlet which corresponds to the fluid inlet <NUM> of said first single-block assembly, so that fluid can flow from said interface outlet into said first single-block assembly and then out of said first single-block assembly to said interface inlet.

An example of said receiving interface is described below.

The pump module can be mounted in or on the ink circuit or on said receiving portion or zone or interface; it can be disassembled from said circuit or from said receiving portion or zone or interface of the ink circuit. For example, one or more screw(s), or nut(s), or bolt(s), or clip(s), or clamp(s) or hook(s) or any other securing means can be used to mount and remove said module.

This pump module, like any other module in this application, can be provided with an identifier, for example an electric identifier or an RFID identifier or a magnetic identifier, to identify which embodiment is implemented, for example which pump is implemented in the module. Electric identifiers, RFID identifiers and magnetic identifiers are described below.

<FIG> show an embodiment of a pump module (or ink pressure pump module) <NUM>, in which the motor <NUM> of the pump <NUM> is located outside the pump module. The hydraulic part <NUM> of the pump is maintained between front cover <NUM> and a back cover <NUM>' which can be demountable as can be seen on <FIG>. The hydraulic part <NUM> of the pump can be easily removed after back cover <NUM>' is demounted. Reference <NUM> is for example the outer magnetic part of the pump, it is located outside of the housing <NUM>.

As seen on <FIG> the back side of the housing of the pump module is not completely closed so that the pump <NUM> (or the part of the pump contained in the housing <NUM>) can be cooled by air of the surrounding atmosphere.

The housing can be provided with slots or openings 22o to facilitate air circulation around the pump.

Any of the embodiments of this module can be provided with one or more member or means <NUM> to allow mounting and disassembling, as described below in connection with <FIG>. Said member or means <NUM> is represented on <FIG>, along axis <NUM> and positioned along a side of the housing <NUM> or of its cover. The remainder (or the other part) of the machine may comprise means (for example holes <NUM>, <NUM>, visible on <FIG>) to cooperate with retractable members or pins <NUM><NUM>, <NUM><NUM> of said means <NUM>.

In another embodiment, it is the remainder or the other part(s) of the machine which may comprise one or more members or pins <NUM><NUM>, <NUM><NUM> (each cooperating with a spring), the module <NUM> being equipped with corresponding holes to cooperate with said members or pins.

In both embodiments the ink circuit has a receiving portion or zone or interface to receive the module, which can be mounted on and disassembled from said receiving portion or zone or interface, for example with one or more screw(s), or nut(s), or bolt(s), or clip(s), or clamp(s) or hook(s) or any other securing means. Hole <NUM><NUM>, <NUM><NUM>, <NUM><NUM> are visible on <FIG> to accommodate screws <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, one screw head <NUM>'<NUM> being visible on <FIG>.

An example of a filter module <NUM> is illustrated on <FIG>. It comprises a housing <NUM>, possibly including a cover <NUM>; said module comprises one or more fluid inlet(s) <NUM>, <NUM>, and one or more fluid outlet(s) <NUM>, <NUM>; inside the module or its housing, one or two filter(s) <NUM> (a so-called "grid filter"), resp. <NUM> (a so-called "main ink filter") is/are connected to a corresponding set of fluid inlet <NUM>, resp. <NUM> and fluid outlet <NUM>, resp. As illustrated on <FIG>:.

Another embodiment of the filter module <NUM>' is illustrated on <FIG>. The reference numbers are the same as on <FIG> and designate the same elements, except for the filter <NUM> which is replaced by a filtering grid <NUM>'at the outlet of the main filter <NUM>.

The ink circuit has a receiving portion or zone or interface to receive the filter module and connect it to the hydraulic circuit of the printer. Said receiving portion or zone or interface has at least two fluid inlets which correspond to the fluid outlets <NUM> and <NUM> and at least two fluid outlets which correspond to the fluid inlets <NUM> and <NUM> of said second single-block assembly, so that fluid can flow from said interface outlet(s) into said second single-block assembly and then out of said second single-block assembly to said interface inlet(s). In a simpler embodiment, said module comprises one fluid inlet, one fluid outlet and one filter; the corresponding receiving portion or zone or interface to receive said filter module and connect it to the hydraulic circuit of the printer has one fluid inlet which corresponds to the fluid outlet of said module and one fluid outlet which corresponds to the fluid inlet of said module.

An example of said receiving interface is described below. The filter module can be mounted in or on the ink circuit or on said receiving portion or zone or interface; it can be disassembled from said circuit or from said receiving portion or zone or interface of the ink circuit. For example, one or more screw(s), or nut(s), or bolt(s), or clip(s), or clamp(s) or hook(s) or any other securing or fastening means can be used to mount and remove said filter module. Holes <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM> are visible on <FIG> to accommodate screws <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM> screw heads <NUM>'<NUM>, <NUM>'<NUM>, <NUM>'<NUM> being shown on <FIG>.

This filter module, like any other module in this application, can be provided with an identifier, for example an electric identifier or an RFID identifier or a magnetic identifier, to identify which embodiment is implemented, for example which filter(s) is/are implemented in the module. Electric identifiers, RFID identifiers and magnetic identifiers are described below.

<FIG> show an example of a filter module <NUM> which can be used in a method according to the invention. The module is preferably able to pivot or is rotatable around an axis (or hinge or pivot pin) <NUM>.

Preferably the module is provided with means <NUM> to allow mounting and dismounting of the module <NUM>. These means may allow the defining of axis (or hinge or pivot pin) about which the module is able to pivot. These means may be in the form of retractable members or pins <NUM><NUM>, <NUM> returned by a spring <NUM><NUM>.

For example, said means <NUM> comprise a cylinder, aligned along axis <NUM> (axis of rotation) and containing said retractable members or pins <NUM><NUM>, <NUM><NUM> said spring <NUM><NUM>. Spring <NUM><NUM> is located between both pins <NUM><NUM> and <NUM>, and is able to be compressed in said cylinder under their action. Each pin can move between an extended position as in <FIG> and a retracted position. At each end of the cylinder there is provided an opening through which the members or pins <NUM><NUM> and <NUM><NUM> can easily enter and exit and thereby be placed in a fixed position along the axis <NUM> (as in <FIG>) and an unlocked position in which the retractable members or pins <NUM><NUM>, <NUM><NUM> are at least partly engaged in the cylinder and in which the module can be removed from the axis.

The members <NUM><NUM> and <NUM><NUM> cooperate with corresponding members (for example holes) on the remainder of the machine.

In another example, it is the remainder of the machine which may comprise one or more members or pins <NUM><NUM>, <NUM><NUM> (each cooperating with a spring), the module <NUM> being equipped with corresponding holes to cooperate with said members or pins. The module can thus be mounted and disassembled from the hydraulic circuit of the printer.

Means <NUM>, <NUM><NUM> - <NUM><NUM> can also be applied to at least one of the other module(s) <NUM>, <NUM> described in connection with <FIG>, <FIG> or to the parts of the circuit or the printer with which said module(s) cooperate. One such member is schematically represented on <FIG>, resp. 3E, positioned along a side of the housing <NUM>, resp. <NUM>, or of its cover. Thus, the module is able to pivot or is rotatable around axis <NUM>, resp. <NUM>, and can be locked in a fixed position along the axis <NUM>, resp. <NUM>, and easily removed from said position.

<NUM> different examples of a recovery module <NUM> are illustrated on <FIG> and variants thereof are illustrated on <FIG>.

In an example, module <NUM> comprises a housing <NUM>, possibly including a cover <NUM>; said module comprises one or more fluid inlet(s) <NUM>, <NUM>, <NUM>, and one or more fluid outlet(s) <NUM>, <NUM>; inside the housing, a recovery device, for example a venturi <NUM> (<FIG>) or a diaphragm pump <NUM>' (<FIG>), is to recover from the printing head ink not used for printing, the recovery device outlet being connected to one of the fluid outlets <NUM>, <NUM>; a filter <NUM> can be connected between the fluid inlet <NUM> and the recovery device in order to filter said ink recovered from the printing head; as illustrated on these figures :.

<FIG>, resp. 3D, are variants of the examples of <FIG>, resp. 3B, showing the same elements as on <FIG>, resp. 3B, positioned differently inside the housing.

This module <NUM>, like any other module in this application, can also be provided with an identifier, for example an electric identifier, or an RFID identifier or a magnetic identifier, to identify which embodiment is implemented, for example an embodiment according to <FIG>, comprising a venturi <NUM> as recovery device, or an embodiment according to <FIG>, comprising a pump <NUM>' as recovery device.

For example, electrodes or contacts of an electric identifier (for example a resistor) can be apparent or accessible through a window of the housing of any module or single block assembly and contact corresponding electrical contacts of the ink circuit or on the interface when the module, for example module <NUM>, is mounted in the circuit or on the interface. Said identifier can be for example a resistance with a first value of resistance for a module according to <FIG> and a second value of resistance, different from the first value, for a module according to <FIG>; a third value of resistance can correspond to another case, for example the absence of a module (an infinite value of resistance is detected if no module is present), or a module according to <FIG>.

Alternatively, any module or module type can have a RFID identifier or tag, storing identification information, the printer having means to read said information stored in said RFID identifier or tag.

Another identifier of any module or module type or single-block assembly in this application, can be of the magnetic type, for example based on an electrical switch, for example a "reed switch", operated by an applied magnetic field.

For example, a module may comprise several possible locations of one or more magnet(s), each location corresponding to a particular module or single-block and/or to at least one technical characteristic of said module or single-block. Several switches are located at different locations in the ink circuit. Depending on the location of the magnet(s) in the module, one or more of the switches is/are activated, which is detected by the printer or its controller. An identification of the module and/or of its technical characteristic(s) is thus obtained. Alternatively, a plurality of magnets can be located in the ink circuit, one or several of them interacting with one or more electrical switch(es) of the module, for example a "reed switch", depending on the location of the switch(es), the location of the switch(es) depending on one or more technical characteristics of the module.

In a particular embodiment, an identifier of a module comprises several (N) magnets disposed at several (N or more than N) possible locations in the module, each combination of magnets locations providing the identification of a particular module or single-block and/or of at least one technical characteristic of said module or single-block; for example, each combination of locations identifies a different type of pump or a different type of filter or a different type of recovery device. Each magnet of the combination interacts with means in the circuit, for example a switch, for example a "reed switch", which interaction is detected by the printer. This multiplies the possible identifications with respect to the identifications with only one magnet.

For example, if a module has <NUM> possible locations for a magnet:.

In this case of <NUM> possible locations, <NUM> identifiers can thus be created, identifying <NUM> different modules or <NUM> variants of a same module.

Another example concerns the case of a module having <NUM> possible and different locations for one or more magnets:.

Of course, more identifications are possible with n ><NUM>.

Each magnet can interact with mans in the circuit, for example a switch, for example a "reed switch", disposed at a particular location in the circuit or in the interface to interact with a magnet disposed at a specific location in the module. For example, for <NUM> locations of <NUM> different magnets in the module, <NUM> switches are provided in the circuit, each one being able to interact with one magnet when it is in one specific position in the module. Any module and the ink circuit, or the corresponding interface of the module in the circuit, can be provided with the means to implement at least one of the above-mentioned identifiers. For example, the characteristics of the main filter <NUM> of the filter module (see <FIG>) can be identified with such an identifier. Or the characteristics of the pump <NUM> of the pump module (see <FIG>) can be identified with such an identifier.

The ink circuit has a receiving portion or zone or interface to receive the recovery module and connect it to the hydraulic circuit of the printer. The recovery module can be mounted in or on the ink circuit or on said receiving portion or zone or interface; it can be disassembled from said circuit or from said receiving portion or zone or interface of the ink circuit. For example, one or more screw(s), or nut(s), or bolt(s), or clip(s), or clamp(s) or hook(s) or any other securing means can be used to mount and disassemble and remove said module (see the examples of <FIG>).

Said receiving portion or zone or interface has at least two fluid outlets which correspond to the fluid inlets <NUM> and <NUM> (<FIG>) or <NUM> and <NUM> (<FIG>) and at least one fluid inlet which corresponds to the fluid outlet <NUM> (<FIG>) or <NUM> (<FIG>) of said third single-block assembly, so that fluid can flow from said interface outlets into said third single-block assembly and then out of said third single-block assembly to said interface inlets.

Preferably, said receiving portion or zone or interface has at least three fluid outlets which correspond to the fluid inlets <NUM>, <NUM> (<FIG>) and <NUM> (<FIG>) and at least two fluid inlets which corresponds to the fluid outlets <NUM> (<FIG>) and <NUM> (<FIG>) of said third single-block assembly; thus, a same receiving portion or zone or interface can connect different types of recovery modules.

Any of the embodiments of this module <NUM> can be provided with one or more means <NUM> as described above in connection with <FIG>. Such means are represented on <FIG>, positioned along a side of the housing <NUM> or of its cover <NUM>. Conversely, it is the remainder of the machine which may comprise one or more means <NUM>, the module <NUM> being equipped with corresponding means (for example holes) to cooperate with said means <NUM>. In both cases the module <NUM> can be mounted along an axis (axis <NUM> on <FIG>) and dismounted and removed from said axis. It is able to pivot or rotate around said axis <NUM> and can be locked and unlocked easily.

<FIG> show an example of a vacuum or recovery module <NUM> which can be used in a method according to the invention. A cover <NUM> contains all fluid inlets/outlets.

Electrical contacts <NUM> of an electric identifier can be seen through an opening in cover <NUM>; as explained above, they can be contacted by corresponding contacts of the circuit for identification of the embodiment of the module, the controller of the printer measuring the value of the resistance value through said contacts. In a variant (not represented on the figures), as explained above, an identifier can comprise means, for example one or more electrical switch(es), for example one or more "reed switch(es)", located in the ink circuit and which can be operated by a magnetic field generated by one or more magnet(s) located in the module.

The ink circuit has a receiving portion or zone or interface to receive the vacuum or recovery module <NUM>, which can be mounted in the ink circuit or disassembled from said receiving portion or zone or interface of the ink circuit, for example with one or more screw(s), or nut(s), or bolt(s), or clip(s), or clamp(s) or hook(s) or any other securing means. Holes <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM>'<NUM>, <NUM>'<NUM>, <NUM>'<NUM>, <NUM>'<NUM> are shown on <FIG> to accommodate screws.

As explained above, each of the modules <NUM>, <NUM>, <NUM> is maintained in the circuit by appropriate securing means so that each module can be mounted on the corresponding receiving zone or portion or interface of the circuit and disassembled or removed from said zone or portion or interface. This possibility to mount or disassemble any of the modules provides an ink-jet printer with a modular feature: the ink-jet printer can be adapted with different pump modules, and/or different filter module(s), and/or different recovery module(s), for example when manufacturing or building it and/or during use of the printer. For example, a recovery module like the one illustrated on <FIG> (resp. 3C) can be replaced by a recovery module according to the example of <FIG> (resp. 3D); more generally, any pump module, resp. filter or recovery module can be replaced by a pump module, resp. filter or recovery module, having different technical characteristics and possibly different inlet(s) and/or outlet(s).

As explained above, this can be achieved by at least one interface portion(s) or zone(s) or surface(s) which has all fluid inlet(s)/outlet(s) to make it compatible with different modules. Furthermore, one or more of said modules can comprise means <NUM> to position it along an axis of rotation and to rotate it around said axis. Such means can be combined with the above-described securing means: after the module is fixed with respect to the rotation axis, it is rotated and brought into contact with the corresponding receiving portion or zone or interface of the hydraulic circuit of the printer. In this position it can be locked with the corresponding securing means and used in combination with the hydraulic circuit. When the module must be removed, for example for being changed or repaired or cleaned, it is unlocked, rotated around the axis and then removed from said axis and from the printer.

<FIG> shows a set of a pump module <NUM>, a filter module <NUM> and a recovery module <NUM> as disclosed above and their fluid interfaces with a fluid circuit and their fluid connections to a print head.

As can be understood from this figure, each module can be removed from the circuit independently from the other modules and can be mounted back (for example after a cleaning step) or replaced with a similar or identical module. For example the a recovery module according to <FIG> can be replaced by a recovery module according to <FIG>, in particular if a different ink is used in the printer. In another example any of the modules is replaced by a technically updated module, with more advanced technical functions.

In particular, a <NUM>-way valve <NUM> can be connected to the inlet <NUM> of the ink pressure pump module <NUM>. Depending on the operation stage of the printer, the fluid to be introduced into the module <NUM> is selected, with help of the valve <NUM>, among a first fluid (ink supplied though a first duct <NUM>) and a second fluid (air and/or solvent supplied though a second duct <NUM>). The first fluid is thus pumped by pump <NUM>, for example when the printer is printing, and is then sent to the print head through the fluid circuit, and in particular through the filter module <NUM>. The second fluid is pumped by pump <NUM>, for example when the circuit is being cleaned. An example of cleaning process implementing air (or gas) and solvent, is given below.

A damper <NUM> can be connected on the fluid path to the inlet <NUM> of the filter module <NUM> (between fluid outlet <NUM> of module <NUM> and fluid inlet <NUM> of module <NUM>), in order to damp the pressures variations or oscillations of the ink before sending it to the print head, such pressures variations or oscillations being generated by the pump and degrading the print quality. The fluid then flows through filter <NUM> and is then sent to the print head through part of the fluid circuit (for example through a fluid manifold as illustrated on <FIG> and <FIG> by arrows), and in particular through the filter <NUM>.

A <NUM>-way valve <NUM> can be connected to the outlet <NUM> of the filter module <NUM>. Depending on the operation stage of the printer, the fluid flowing out of the filter module <NUM> can be sent, through the valve <NUM>, either to the print head <NUM> (possibly through an additional filter <NUM>) or to the main reservoir of the circuit (through the recovery module <NUM>). A sensor <NUM> can be implemented to measure the pressure and/or the temperature of the fluid flowing out of the filter module <NUM>.

In the illustrated example the fluid flowing out of the filter module <NUM> through outlet <NUM> and sent back to the main reservoir of the circuit ink circuit first flows through the recovery module <NUM>, in particular through inlet <NUM>, filter <NUM>, recovery device <NUM> and outlet <NUM>.

Part of the fluid sent to filter module <NUM> can also be sent back to the part of the fluidic circuit, for example to a fluid manifold, as illustrated on <FIG> (see arrow <NUM>); the fluid returning from said part of the circuit (see arrow <NUM>), for example from said fluid manifold, separates between a 1st flow sent to the filter module <NUM> and a <NUM>nd flow sent to the recovery module <NUM>.

<FIG> shows another set of a pump module <NUM>, a filter module <NUM> and a recovery module <NUM> as disclosed above, the vacuum module being of the type disclosed above in connection with <FIG>.

The modules <NUM> and <NUM> are identical to the modules <NUM> and <NUM> of <FIG> and the above description applies to them as well as to the other components bearing identical reference numbers.

Module <NUM> implements a diaphragm pump <NUM>' and comprises a further fluid inlet and a further fluid outlet with respect to <FIG>. Pump <NUM>' pumps either a first fluid through fluid inlet <NUM> (and through filter <NUM>) or a second fluid through second fluid inlet <NUM>.

The fluid flowing out of the filter module <NUM> and sent back to the main reservoir of the circuit ink circuit first flows through the recovery module <NUM>, in particular through inlet <NUM>, filter <NUM> and diaphragm pump <NUM>'.

A <NUM>-way valve <NUM> can be connected to the outlet of filter <NUM>. Depending on the operation stage of the printer, the fluid pumped by pump <NUM>' can be selected, with help of the valve <NUM>, among the first fluid and the second fluid. It then flows through outlet <NUM> and to the main reservoir.

Just like for the embodiment of <FIG>, part of the fluid sent to filter module <NUM> can also be sent back to the part of the fluidic circuit, for example to a manifold, as illustrated on <FIG> ; the fluid returning from said part of the circuit, for example from said manifold, separates between a 1st flow sent to the filter module <NUM> and a <NUM>nd flow sent to the recovery device <NUM>'.

On both <FIG> and <FIG> the hydraulic circuit further comprises fluidic interfaces <NUM>, <NUM>, <NUM>. Examples of such interfaces are shown on <FIG>. Each forms a fluidic interface between one of the modules <NUM>, <NUM>, <NUM> and the rest or the other part(s) of the circuit. Each of said interfaces has fluidic inlet(s)/outlet(s) <NUM>', <NUM>', <NUM>', <NUM>', <NUM>', <NUM>', <NUM>', <NUM>', <NUM>, <NUM>' corresponding to the outlet/inlet(s) of modules <NUM>, <NUM>, <NUM>. It also has inlet(s)/outlet(s) 14a, 16a, 38a, 57a, 63a corresponding to the outlet/inlet(s) of the rest or the other part(s) of the circuit. Each of said interfaces comprises the appropriate ducts to connect its fluid inlet(s) and outlet(s).

<FIG> is an example of interface <NUM> which comprises a substantially flat surface <NUM> and inlet(s)/outlet(s) <NUM>', <NUM>' corresponding to the outlet/inlet(s) of module <NUM>. The other side of interface <NUM>, not visible on this figure, has inlet(s)/outlet(s) corresponding to the outlet/inlet(s) of the part of the circuit connected to said module <NUM> (see <FIG> or <FIG>).

This figure also shows, under the interface <NUM>, the part of a magnetic pump which remains outside housing <NUM> (see <FIG>), including the outer magnetic ring <NUM> and the motor <NUM>; the part <NUM> of the shell (see above and <FIG>) comes into the cylindrical portion surrounded by the outer magnetic ring <NUM>.

The interface <NUM> can comprise means to interact with an identifier of the pump module. For example, the interface <NUM> comprises electrical contacts to contact an electric identifier of the pump module <NUM>, as already explained above. In a variant (not represented on the figures), as explained above, an identifier can comprise means, for example one or more electrical switch(es), for example one or more "reed switch(es)", located in the ink circuit and which can be operated by a magnetic field generated by one or more magnet(s) located in the module.

The holes <NUM>'<NUM>, <NUM>'<NUM>, <NUM>'<NUM> correspond to the holes <NUM><NUM>, <NUM><NUM>, <NUM><NUM> of <FIG>.

<FIG> is an example of interface <NUM> which comprises a substantially flat surface <NUM> and inlet(s)/outlet(s) <NUM>', <NUM>', <NUM>', <NUM>' corresponding to the outlet/inlet(s) of module <NUM>. The other side of interface <NUM>, not visible on this figure, has inlet(s)/outlet(s) corresponding to the outlet/inlet(s) of the part of the circuit connected to said module <NUM> (see <FIG> or <FIG>).

This figure also shows holes <NUM>, <NUM> which cooperate with retractable members or pins <NUM><NUM>, <NUM><NUM> of means <NUM> (<FIG>) as explained above.

The interface <NUM> can comprise means to interact with an identifier of the filter module. For example, the interface <NUM> comprises electrical contacts to contact an electric identifier of the filter module <NUM>, or a plurality of electric switches, like "reed" switches, to cooperate with a magnet which is located in the filter module, at different locations depending on the characteristics of the filter module.

<FIG> is an example of interface <NUM> which comprises a substantially flat surface <NUM> and inlet(s)/outlet(s) <NUM>', <NUM>', <NUM>' corresponding to the outlet/inlet(s) of module <NUM>. The other side of interface <NUM>, not visible on this figure, has inlet(s)/outlet(s) corresponding to the outlet/inlet(s) of the part of the circuit connected to said module <NUM> (see <FIG> or <FIG>).

Each of said interfaces comprises the appropriate duct(s) to connect its fluid inlet(s) and outlet(s). In particular, when several possible alternative modules can be connected on the same interface, said interface comprises the ducts (fluid inlets and/or outlets) and/or electrical contacts to be compatible with the several modules.

For example, interface <NUM> has several inlets/outlets in order to be able to connect either the recovery module of <FIG> or the recovery module of <FIG>. The module of <FIG> has inlets <NUM>, <NUM> which are not used, the fluid entering this module through either inlet <NUM> or inlet <NUM> and leaving the module through outlet <NUM>; the module of <FIG> has <NUM> inlets <NUM>, <NUM>, <NUM> which are all used, the fluid entering this module by any of them, and leaving the module by outlet <NUM> or <NUM>.

The same applies to the other interfaces which are for connecting any of the other single block assemblies: thus, any interface preferably contains all necessary inlets/outlets and/or electrical contact(s) and/or magnetic means, so that any version or technically updated first, resp. second, resp. single block assembly can be connected to interface <NUM>, resp. <NUM>, resp.

<FIG> also shows electric connections <NUM> to connect the electrical contacts <NUM> of an electric identifier (see <FIG>).

In a variant (not represented on the figures), as explained above, an identifier can comprise means, for example one or more electrical switch(es), for example one or more "reed switch(es)", located in the ink circuit, for example in the interface, and which can be operated by a magnetic field generated by one or more magnet(s) located in the module.

One or more of the modules, in particular of the above -described modules, and the part of the circuit or the corresponding interface to which it must be connected can be provided with magnetic means to help positioning the module with respect to the ink circuit or to the corresponding interface. <FIG> shows a module <NUM>, which can be for example any of the above-described first, second or third modules and the corresponding interface <NUM> to which it must be connected. Each of the module and the interface has a magnet <NUM>, <NUM> positioned and oriented such that the two magnets attract each other when the module is correctly positioned with respect to the interface. Alternatively:.

Module <NUM> can be for example any of the above-described modules. Other components or parts can be mounted on the circuit by being guided by magnetic means as described above.

The above-mentioned and described modules can be implemented in a fluid circuit as shown on <FIG>. A cleaning process of this circuit will be explained below.

As illustrated on <FIG>, this circuit comprises a main reservoir <NUM>, an ink cartridge <NUM> and a solvent cartridge <NUM> (both cartridges can be removed from the circuit) and hydraulic module <NUM> (or manifold) and a number of ducts to connect the cartridges <NUM>, <NUM>, the reservoir <NUM> and the different modules <NUM>, <NUM>, <NUM>.

An example of a cartridge <NUM>, <NUM> is shown in <FIG>.

It comprises a portion <NUM> (this portion is the most rigid, but can however be deformed somewhat when the cartridge is empty) and a semi-rigid, or flexible, portion <NUM>. The rigid portion <NUM> is provided with a rigid nipple (or mouth, also called "nose" or "nozzle") <NUM> that allows for a hydraulic connection to the ink circuit. Initially, the nipple is closed by a capsule of a rubber-type material, for example of EPDM, or other (chemically compatible with the fluids in question), being hermetically crimped or sealed. Upon setting up the cartridge, a hollow needle, linked to the ink circuit, hits the capsules and establishes the hydraulic circuit between the cartridge and the ink circuit. The elastic material of the capsule is chosen to ensure the sealing of the needle-capsule junction.

Another example of cartridge has a storage chamber and a distal end portion which has a cylindrical shape and is closed by a lid.

Examples of cartridge holders 82a, 84a are shown on <FIG>. Each comprises means 112c, 114c of fluidic connection, to which the nipple <NUM> of a cartridge is connected when the latter is inserted into the cartridge holder; these means 112c, 114c comprise for example a cannula that fits into the capsule that closes the nipple <NUM>, and are connected to the circuit for supplying the printer, for example, with solvent or ink; alternatively each of these means 112c, 114c comprises a cylindrical portion that fits into the cylindrical shape of the distal end portion of the cartridge. This cannula or the cylinder pierces or penetrates into the nipple <NUM> or the lid of the cartridge in order to put the inside of the cartridge and the supply circuit into fluidic communication. The hydraulic connection nipple or the distal end portion of each cartridge communicates with the ink (or solvent) circuit via the means 112c, 114c.

The hydraulic module <NUM> preferably has an ink portion and a solvent portion, the ink portion comprising ink pump <NUM> for pumping the ink from ink cartridge <NUM> and the solvent portion comprising pump <NUM> for pumping the solvent from solvent cartridge <NUM>. It can also comprise a number of <NUM>-way valves <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM> to send the appropriate fluid to the appropriate module <NUM>, <NUM>, <NUM> and/or to the reservoir <NUM>. Ducts <NUM>-<NUM> connect the ink portion and the solvent portion of the hydraulic module <NUM> with the reservoir <NUM>; ducts <NUM>-<NUM> connect the ink portion and the solvent portion of the hydraulic module <NUM> with the different modules <NUM>-<NUM> as shown on <FIG>.

Each of the modules <NUM>, <NUM>, <NUM> is maintained in the circuit by appropriate fastening or securing means, already described above, so that each module can be mounted on the circuit and disassembled or removed from said circuit.

The main reservoir <NUM> can be of the type comprising two compartments as disclosed in <CIT>, the upper compartment <NUM><NUM> for storing ink and the lower compartment <NUM><NUM> for storing solvent:.

A flushing or cleaning process according to the invention can be implemented to clean the above-described circuit, in particular the <NUM> different modules <NUM>, <NUM>, <NUM>, or to clean only part of it, for example only one of the modules <NUM>, <NUM>, <NUM>, in particular if only one of the modules <NUM>, <NUM>, <NUM> is to be unplugged or detached from the circuit and repaired or replaced. If such a cleaning process is not performed, ink flows out of any of the modules <NUM>, <NUM>, <NUM> when it is unplugged or disassembled from the printer, which results in a loss of ink and solvent and, of course, in dropping on the rest or the other part(s) of the system and out of the printer and of the module.

In an embodiment both solvent and ink cartridges <NUM>, <NUM> are first unplugged from the circuit and ink cartridge <NUM> is replaced with a recovery cartridge for recovering dirty or cleaning fluid from the circuit. The solvent cartridge <NUM> being removed, gas, for example air (at atmospheric pressure) can be pumped from means 114c of fluidic connection by activating the pump(s) <NUM>, <NUM> and the valves of the circuit, in particular valves <NUM><NUM>, <NUM><NUM>, <NUM>, as if the solvent cartridge was connected to the ink circuit and solvent had to be pumped.

Pump <NUM> is started, thus pumping air as explained above throughout the whole circuit or through part of it, and in particular through one or more of the modules <NUM>, <NUM>, <NUM>. Ink present in the circuit is thus sent back to the ink tank <NUM>, through appropriate position of each of the valves <NUM>, <NUM>, <NUM>, <NUM>.

In the following steps, ink present in the circuit is sent to the recovery cartridge, through appropriate position of each of the valves <NUM>, <NUM>, <NUM>, <NUM>.

The valves <NUM> (<FIG>) or <NUM> (<FIG>, commented below) are then controlled so that alternative or simultaneous steps of cleaning one or more of the modules <NUM>, <NUM>, <NUM> with gas (for example air) and solvent (in this order or in the reversed order) are performed a number of times, for example between <NUM> and <NUM> times. Clean solvent can be pumped by pump <NUM> from the lower part <NUM><NUM> of tank <NUM> (or from tank <NUM> on <FIG>).

A solvent rinsing step can be performed to eliminate any residual ink which could remain in the circuit, or in part of it, for example in one or more of the <NUM> modules <NUM>, <NUM>, <NUM>. In a preferred embodiment, a drying step can be performed after cleaning by circulating gas in all or part of the circuit, ensuring elimination of substantially all the residual solvent, for example at least <NUM>% or <NUM> % of the residual solvent, present in the circuit. Thus, one or more of the modules <NUM>, <NUM>, <NUM> can be disassembled from the circuit with reduced risks of ink or solvent spillage.

In the above-described process, solvent thus flows through the same path as the gas.

The above flushing or cleaning steps can be performed for only a part of the circuit, for example for only one of the modules <NUM>, <NUM>, <NUM>. Only cleaning the part or the component of the circuit which must be removed from the circuit saves solvent.

After a flushing or cleaning process as described above has been performed, one or more of the cleaned modules <NUM>, <NUM>, <NUM> can be disassembled and removed from the printer, and repaired or replaced.

The above process can also be implemented if:.

<FIG> shows steps of an embodiment of a flushing or cleaning process according to the invention:.

In a variant, the order of gas and solvent can be reversed and steps S5-S7 are replaced by following steps S'<NUM>-S'<NUM>:.

In an example, gas and solvent are alternatively pumped according to steps S5-S7 or S'<NUM>-S'<NUM> through only one of the modules <NUM>, <NUM>, <NUM> because only one module, for example the pump module <NUM>, must be disassembled from the circuit. More generally, gas and solvent can be alternatively pumped according to steps S5-S7 or S'<NUM>-S'<NUM> through at least one component or part, for example a valve or a filter or a pump, because said component or part must be replaced. An alternative pumping can be performed by activating one or more valves.

In a preferred embodiment, an initial step of circulating gas in at least part of the circuit allows recovering ink which can be sent to the main tank (ref <NUM> on <FIG>).

The further steps of the flushing or cleaning process comprise circulating gas and solvent in at least part of the circuit, dirty fluid being recovered in the cartridge for recovering dirty fluid through adapted control of the valves of the circuit.

This creates a gas-solvent mixture, for example a circulation of alternating volumes <NUM> of gas and of volumes <NUM> of solvent in a duct <NUM> (<FIG>, or "slug flow"), each of said volumes being for example less than <NUM><NUM>, possibly forming a diphasic or biphasic mixture of said gas and said solvent (for example between <NUM>% and <NUM>% of solvent and <NUM>% to <NUM> % of gas) which is efficient to clean the circuit; alternatively, it can be a mixture of gas in solvent like for example on <FIG> (bubbles of gas <NUM> being in suspension in a solvent flow <NUM> or "emulsion").

In a variant of the process illustrated on <FIG>, compressed gas is introduced into the circuit, in which case there is no need to pump it, the volume of gas introduced being for example controlled by a valve.

As indicated above, a drying step can be performed at the end of the cleaning process, for example by circulating gas in all or part of the circuit, for example compressed gas and/or heated gas. Gas can be heated by circulating it over heating means, for example one or more resistors, for example before being injected into the circuit. A drying step allows disassembling one or more of the modules <NUM>, <NUM>, <NUM> with a reduced risk of ink or solvent spillage.

In another embodiment, a circuit may comprise removable cartridges but the process may not involve removing said cartridges, steps S1 and S2 not being performed (see example below).

In another embodiment, if a circuit does not comprise removable cartridges (see example below), steps S1 and S2 are also not performed.

<FIG> shows another example of fluid circuit to which another flushing or cleaning process according to the invention can be applied. This circuit does not contain any removable module or block, except the cartridges and some fluidic components like one or more valve(s) and/or one or more pump(s) and/or one or more filter(s) or damper(s) which can possibly be disassembled or removed from the circuit.

This fluid circuit is described in detail in <CIT>.

A flushing or cleaning process as explained above, in particular in connection with <FIG> (but not step S10), or one of its above-mentioned variants, can be applied to the circuit of <FIG>.

In particular, cartridges <NUM> and <NUM> can be unplugged, cartridge <NUM> being replaced with a recovery cartridge.

<NUM>-way valve <NUM> can be controlled so that gas, for example air (at atmospheric pressure) and solvent can be alternatively pumped by pumps <NUM> and <NUM> and sent to at least part of the circuit, dirty solvent being recovered in the recovery cartridge by controlling <NUM>-way valves <NUM> and <NUM> (the valves of the printing head, not illustrated on this figure, being closed, so that no solvent flows towards the printing head).

Thus a gas-solvent mixture is formed, for example a circulation of alternating volumes <NUM> of gas and of volumes <NUM> of solvent in a duct <NUM> (<FIG>, or "slug flow"), each of said volumes being for example less than <NUM><NUM>, possibly forming a diphasic or biphasic mixture of said gas and said solvent (for example between <NUM>% and <NUM>% of solvent and <NUM>% to <NUM> % of gas) which is efficient to clean the circuit; alternatively, it can be a mixture of gas in solvent like for example on <FIG> (bubbles of gas <NUM> being in suspension in a solvent flow <NUM> or "emulsion").

In a preferred embodiment, an initial step of circulating gas, for example air, in at least part of the circuit allows recovering ink which is sent to the main tank. The further steps of the cleaning process comprise circulating air and solvent in at least part of the circuit, dirty fluid being recovered in the recovery cartridge, through adapted control of the valves of the circuit.

As indicated above, a drying step can be performed at the end of the cleaning process, for example by circulating air in all or in part of the circuit, for example compressed air and/or heated air. Air can be heated by circulating it over heating means, for example one or more resistors, for example before being injected into the circuit. A drying step allows disassembling one or more of fluidic components like one or more valve(s) and/or one or more pump(s) and/or one or more filter(s) or damper(s) with reduced risk of ink or solvent spillage.

It has to be noted that some residual amount of solvent may remain in at least part of the circuit after cleaning and drying but this amount is minor (less than <NUM> % or <NUM>% of the initial volume, this value can even be significantly reduced with compressed air and/or heated air) and does not prevent from disassembling one or more of the above-mentioned fluidic components in good conditions, with a minimum risk of spillage or dropping.

Another cleaning process can be applied to the circuit of <FIG>, without removing cartridges <NUM>, <NUM>.

Air, or, more generally, a gas, can be introduced into the ink circuit at specific locations, for example:.

Gas can be introduced into the circuit at any of the above locations for example through a side duct laterally connected to the main ducts (or the main duct has a "T" shape). <FIG>, which are commented below, give examples of a tool for introducing gas directly into the circuit, in particular without removing the solvent cartridge.

Gas can be introduced under a pressure higher than the atmospheric pressure into the flow of cleaning solvent circulating in the ink circuit.

In all the above discussed cases, a gas-solvent mixture is formed, for example a circulation of alternating volumes <NUM> of gas and of volumes <NUM> of solvent in a duct <NUM> (<FIG>, or "slug flow"), each of said volumes being less than <NUM><NUM>, possibly forming a diphasic or biphasic mixture of said gas and said solvent (for example <NUM>% of solvent and <NUM>% gas, or between <NUM>% and <NUM>% of solvent and between <NUM>% and <NUM>% of gas) which is efficient to clean the circuit; alternatively, it can be a mixture of gas in solvent like for example on <FIG> (bubbles of gas <NUM> being in suspension in a solvent flow <NUM> or "emulsion").

The alternative pumping of solvent and air generates pressure surges or pulses or bumps of the pump(s) which contribute to an efficient cleaning of the ducts of the circuit.

Dirty solvent can be recovered in a separate tank <NUM> through an extra valve <NUM>. This dirty solvent can be reused in the main tank <NUM> when there is a need to dilute ink contained therein, for example by pumping part of said solvent by pump <NUM>, through an extra duct <NUM> and an extra valve <NUM>.

This other cleaning process, without removing cartridges <NUM>, <NUM> can be applied to a circuit like illustrated on <FIG>, in which reference numbers identical to those of <FIG> designate the same technical means.

Gas is for example introduced upstream of pump <NUM> through a lateral duct <NUM>. Alternatively, compressed gas can be introduced downstream of a pump, for example with a device as explained in connection with <FIG> (described below).

Dirty solvent can be recovered in a separate tank <NUM>. With respect to <FIG>, the circuit of <FIG> contains additional valves 393a and 397a in order to recover dirty fluid in tank <NUM> and to be able to pump said dirty fluid therefrom and reuse it in the main tank <NUM> (in case there a need to dilute the ink contained therein).

Preferred embodiments of cleaning processes of the circuits of <FIG> and <FIG>, without removing cartridges <NUM>, <NUM>, can comprise at least one of:.

<FIG> shows a device <NUM> which can be used to perform an embodiment of a cleaning process according to the invention, without removing solvent cartridge <NUM>.

It comprises a valve <NUM> and a non-return valve <NUM> in series, both being mounted in parallel to a non-return valve <NUM>.

A gas, for example from a compressor (not represented on the figure) can be introduced through end <NUM> and then through valves <NUM> and <NUM>; the other end <NUM> of the device, upstream of non-return valve <NUM> can be connected to the outlet of a pump, for example pump <NUM> or pump <NUM> of <FIG>.

Thus gas, for example compressed gas, can be introduced into the circuit, alternatively with solvent or simultaneously to a solvent flow, forming an alternation of gas and solvent or a flow of a mixture, possibly a diphasic mixture, of solvent and gas. The gas can be air.

The device <NUM> can be permanently in the circuit, for example downstream or at the outlet of a pump <NUM> (as illustrated on <FIG>), the end <NUM> being closed by a removable plug <NUM>, the ends <NUM> and <NUM> being connected to the circuit.

Alternatively, as illustrated on <FIG>, the device <NUM> can be temporarily mounted in the circuit for cleaning purposes and removed from the circuit after cleaning; for example, it replaces a removable duct section <NUM> of the circuit. The removable section is coupled by coupling flanges <NUM> and <NUM>, which can be disassembled and replaced by the device <NUM> which has similar coupling flanges <NUM>' and <NUM>'. A compressor <NUM> can be connected to the free end <NUM> of the device <NUM> to inject compressed gas, for example compressed air. After cleaning, the device <NUM> can be disassembled and removed from the circuit and replaced by section <NUM>.

This other cleaning method and/or the device of <FIG> can be applied to the circuit of <FIG> or <FIG> or <FIG> or <FIG> (described below), allowing the introduction of gas, for example compressed gas, at various locations of the circuit, preferably downstream or at the outlet of one or more pump(s), alternatively to solvent or into a flow of solvent to form a solvent - gas mixture. Thus, a cleaning process of the circuit of any of the above-mentioned figures can be performed, in particular for the circuit of <FIG>, <FIG> and <FIG> without removing solvent cartridge <NUM>.

Any of the above cleaning methods can be applied to the preparation of a new ink jet printer just after manufacturing or building of a new printer. Indeed, the ink circuit of a new printer may contain residual solid particles which can be eliminated by a cleaning process as described above. Solvent containing solid particles is then sent in a waste tank or filtered before being reused in the ink circuit.

Any of the above cleaning methods can also be applied to a circuit not comprising removable cartridges <NUM>, <NUM>, for example a circuit as illustrated on <FIG> in which the solvent and ink tanks <NUM>, <NUM> are replenished by an operator.

An example of such circuit is illustrated on <FIG>, on which the reference numbers are the same as on <FIG>; this circuit further comprises <NUM>-way valves <NUM>, <NUM> to send solvent downstream of the reservoir, said solvent being pumped by pump <NUM>; gas, for example air, can be pumped from a lateral duct (or the main duct may have "T" shape) , for example at <NUM> or <NUM> or <NUM> (or upstream of pump <NUM>) on <FIG> or gas under pressure (higher than the atmospheric pressure) can be introduced into the circuit) at <NUM> or <NUM> or <NUM> on <FIG>; solvent is pumped from solvent tank or reservoir <NUM> and the dirty solvent which was used to clean the circuit can be collected in an extra tank <NUM> after opening a <NUM>-way valve <NUM>. The dirty solvent can be reused by injecting part of it into the main ink tank <NUM>, when there is a need to dilute ink contained therein.

Air, or, more generally, a gas, can be introduced into the ink circuit of <FIG> at specific locations, upstream (from lateral duct <NUM>) of one or more pumps <NUM>, <NUM> or at the outlet or downstream of one or more of said pumps as indicated on <FIG> by arrow <NUM>, resp. <NUM>, in particular if gas is introduced under pressure. Compressed gas can be provided by a compressor. The device <NUM> of <FIG> can be used in combination with the circuit of <FIG>, for example downstream of any of pumps <NUM>, <NUM>.

The introduction of gas creates a gas-solvent mixture, for example a circulation of alternating volumes <NUM> of gas and of volumes <NUM> of solvent in a duct <NUM> (<FIG>, or "slug flow"), each of said volumes being for example less than <NUM><NUM>, possibly forming a diphasic or biphasic mixture of said gas and said solvent (for example between <NUM>% and <NUM>% of solvent and <NUM>% to <NUM> % of gas) which is efficient to clean the circuit; alternatively, it can be a mixture of gas in solvent like for example on <FIG> (bubbles of gas <NUM> being in suspension in a solvent flow <NUM> or "emulsion"). The alternative pumping of solvent and air creates pressure surges or pulses or bumps of the pump(s) which contribute to an efficient cleaning of the ducts of the circuit.

It is preferable to avoid any interference of the gas with the pump <NUM> or <NUM>; for this reason, a non-return valve can be mounted at the outlet of said pump(s). Thus, a gas can be introduced under a pressure higher than the atmospheric pressure into the flow of cleaning solvent circulating in the ink circuit. This creates a gas-solvent mixture, possibly a diphasic mixture of said gas and said solvent (for example <NUM>% of solvent and <NUM> % gas or between <NUM>% and <NUM>% of solvent and between <NUM>% and <NUM>% of gas) which is efficient to clean the circuit.

The device <NUM> of <FIG> can be used in combination with the circuit of <FIG>, for example downstream of any of pumps <NUM>, <NUM>.

In preferred embodiments of a cleaning process of the circuit of <FIG>:.

A circuit like illustrated on <FIG>, without removable cartridges, may contain removable single-block assemblies or modules, like modules <NUM>, <NUM>, <NUM> described above, in which case the already mentioned advantages (in particular in terms of clean disassembling of said modules) apply and step S10 (<FIG>) can be implemented.

Another embodiment of a flushing or cleaning process according to the invention can be applied to an ink circuit of a CIJ printer, for example an ink circuit according to the invention, in particular according to any of the above-described circuits (<FIG>, <FIG>, <FIG>, <FIG>).

It comprises a step of circulating or flowing gas in at least part of the circuit or in the whole circuit; ink is thus flushed and removed from said part of the circuit or from said circuit and can be recovered, for example in the main tank <NUM>.

Gas can be introduced into the circuit at any of the above locations for example through a side duct laterally connected to the main duct (or the main duct has a "T" shape) and possibly an additional valve (not represented). <FIG> give examples of a tool for introducing gas directly into the circuit, in particular without removing a cartridge.

Ink is thus eliminated from the part(s) of the circuit which have been cleaned.

The process can be followed by disassembling or removing from the circuit at least one part which was cleaned according to said above process, for example:.

Preferably a flushing or cleaning process to the invention ends with a drying step of the part of the hydraulic orfluid circuit which has been cleaned. For example, the cleaning process can include a final step of pumping gas and sweeping that part of said circuit with said gas.

In particular, if a module, for example like any of the above-described first, second or third module, must be disassembled and removed from the circuit, a cleaning process of the fluid path inside of said module can be performed according to the invention, ending with a drying step of said fluid path. The dry module can then be removed without any fluid dropping from the device.

A "dry" module or a component of a fluid circuit as mentioned in this application or according to the invention also includes any module or a component which has been cleaned and contains less than a maximum volume of fluid.

Indeed, some residual amount of solvent may remain in any of the removable modules <NUM>, <NUM>, <NUM> after cleaning and drying but this amount is minor and can be trapped in the filter(s) of the module <NUM>, <NUM> (in particular if the filter comprises absorbent materials) or does not prevent from disassembling the module in good conditions, with a minimum spillage or dripping.

For example, the modules may have an internal fluid volume comprised between <NUM><NUM> and <NUM><NUM>. Tests were made with the circuit of <FIG>, comprising a cleaning process of the whole circuit according to the invention, followed by a drying step.

A remaining volume of liquid (solvent) of:.

Thus, after cleaning and drying, more than <NUM>% or <NUM>% of the initial volume of solvent has been eliminated and less than about <NUM>% or <NUM>% of the initial volume remains in the module or the component. Most of the liquid which remains in module <NUM> or <NUM> is trapped in the filter(s) of this module.

A cabinet (also called console or body of the printer) for an ink jet printer comprising a fluid circuit as described in this application is illustrated on <FIG> (front side).

The cabinet can contain three sub-assemblies:.

In other words, the body <NUM> can comprises <NUM> sub-assemblies: at the top part the electronics, electrical supply and operator interface; and in the lower part an ink circuit supplying the head with ink under pressure and providing a negative pressure for recovery of the ink not used by the head.

As can be seen on <FIG>, the lower part of the cabinet can comprise the appropriate ink cartridge receiving portion 82a and solvent cartridge receiving portion 84a (on <FIG>, both cartridges are unplugged); it also comprises at least part of the ink circuit <NUM>, including the pump module <NUM>, the filter module <NUM> and the recovery module <NUM>. The other parts of the circuit of <FIG> and <FIG> are located in the back of the cabinet and cannot be seen on <FIG>.

As can be seen on <FIG>, the filter module <NUM> is preferably inclined with respect to a horizontal plane, so that pigments from a pigment ink cannot sediment.

The <NUM> modules are accessible from the front side of the printer, so that they can be easily disassembled from the circuit by an operator, independently of each other.

A rear view of the cabinet is illustrated on <FIG>, showing the main reservoir <NUM> and a portion of the pump module <NUM>.

The ducts, valves and the other pumps of the circuit are not shown on <FIG>, but are also included in the hydraulic circuit.

The console is hydraulically and electrically connected to a print head (not represented on the figure) by an umbilical.

A gantry, not represented, makes it possible to install the print head facing a printing support <NUM> (see <FIG>), which moves along a direction. This direction is perpendicular for example to an axis of alignment of the nozzles of the print head or to an axis of deviation of the drops (see deviated jet <NUM> on <FIG>). The support moves along direction X. The position of the support with respect to the print head can be detected by a detector.

Such a printer can be integrated into a packaging machine.

<FIG> illustrates in particular a printing head which can be implemented in a CIJ printer according to the invention, for example of the multi-deflected type. It comprises:.

In the drop generator <NUM> a cavity is supplied with an electrically conductive ink. This ink, held under pressure, by an ink circuit <NUM> external to the head, escapes from the cavity through at least one nozzle <NUM> thus forming at least one ink jet.

A periodical stimulation device <NUM> is associated with the cavity in contact with the ink upstream of the nozzle <NUM>; it transmits to the ink a (pressure) periodical modulation which causes a modulation of velocity and jet radius from the nozzle. When the dimensioning of the elements is suitable, this modulation is amplified in the jet under the effect of surface tension forces responsible for the capillary instability of the jet, up to the jet rupture. This rupture is periodical and is produced at an accurate distance from the nozzle at a so-called «break» point <NUM> from the jet, which distance depends on the stimulation energy.

In the case where a stimulation device, called an actuator, comprises a piezoelectric ceramic in contact with the ink of the cavity upstream of the nozzle, the stimulation energy is directly related to the amplitude of the electrical signal for driving the ceramics. Other jet stimulation means (thermal, electro-hydrodynamic, acoustic,. ), can also be implemented in the frame of this invention. The stimulation using piezoelectric ceramics remains the preferred embodiment due to its efficiency and relative workability.

At its breaking point <NUM>, the jet, which was continuous from the nozzle, is transformed into a train <NUM> of identical and evenly spaced apart ink drops. The drops are formed at a time frequency identical to the frequency of the stimulation signal; for a giving stimulation energy, any other parameter being otherwise stabilized (in particular ink viscosity), there is an accurate (constant) phase relationship between the periodical stimulation signal and the breaking instant, itself periodical and with a same frequency as the stimulation signal. In other words, to an accurate instant of the period of the stimulation signal corresponds an accurate instant in the separation dynamic of the jet drop.

Without further action (this is the case where drops are not used for printing), the drop train travels along a trajectory <NUM> collinear to the drop ejection axis (nominal trajectory of the jet) which joins, by a geometric construction of the printing head, the recovery gutter <NUM>. This gutter <NUM> for recovering non-printed drops uptakes the ink not used which comes back to the ink circuit <NUM> to be recycled.

For printing, the drops are deflected and deviated from the nominal trajectory <NUM> of the jet. Consequently, they follow oblique trajectories <NUM> which meet the support to be printed <NUM> at different desired impact points. All these trajectories are in a same plane. The placement of the drops on the matrix of impacts of drops to be printed on the support, to form characters, for example, is achieved by combining an individual deflection of drops in the head deflection plane with the relative movement between the head and the support to be printed (generally perpendicular to the deflection plane). In the deviated continuous jet printing technology, the deflection is achieved by electrically charging drops and by passing them into an electric field. In practice, the means for deflecting drops comprise at least one charging electrode <NUM> for each jet, located in the vicinity of the break point <NUM> of the jet. It is intended to selectively charge each drop formed at a predetermined electrical charge value which is generally different from one drop to the other. To do this, the ink being held at a fixed potential in the drop generator <NUM>, a voltage slot with a determined value, driven by the control signal, is applied to the charging electrode <NUM>, this value being different at each drop period.

In the control signal of the charging electrode, the voltage application instant is shortly before the jet fractionation to take advantage of the jet electrical continuity and attract a given charge amount, which is a function of the voltage value, at the jet tip. This variable charge voltage affording the deflection is typically between <NUM> and <NUM> Volts. The voltage is then held during the fractionation to stabilize the charge until the detached drop is electrically insulated. The voltage remains applied for a certain time after the drop is detached to take break instant issues into account.

The drop deflecting means usually comprise a set of <NUM> deflection plates <NUM>, located on either side of the drop trajectory upstream of the charging electrode. Both these plates are put to a high fixed relative potential producing an electrical field Ed substantially perpendicular to the drop trajectory, capable of deflecting the electrically charged drops which are engaged between the plates. The deflection amplitude is a function of the charge, the mass and the velocity of these drops.

A CIJ printhead may also comprise several ink-jet cavities for generating several ink jets, each cavity having its own nozzle and activation means or a same cavity may comprise several nozzles to produce several ink-jets. Charging electrodes and deviation electrodes can be associated with each jet as explained above.

The instructions for activating the means <NUM>, <NUM> for producing ink jets and/or for activating the pumping means, for example of modules <NUM> or <NUM>, and/or for opening and closing of valves in the path of the different fluids (ink, solvent, gas) and/or for applying the voltage(s) to the charge and/or the deviation electrode(s) can be sent by control means (also called "controller"). It is also these instructions that can make it possible to circulate ink under pressure in the direction of the means <NUM>, <NUM> then to generate jets as a function of the patterns to be printed on a support <NUM>.

These control means or controller are for example realised in the form of a processor or a microprocessor, or of an electrical or electronic circuit, adequately programmed, for example to implement a cleaning method according to the invention. In particular these control means can be programmed to control one or more pump and/or valve to circulate gas or gas and solvent in the circuit or in at least part of the circuit.

The control means may also be programmed to assure the memorisation of data, for example measurement data of ink levels in one or more reservoirs, and their potential processing.

These control means or controller can also be programmed to read one or more identifier(s) of one or more module(s) or single- block assembl(y)ies according to the invention and to identify said module(s) or single- block assembl(y)ies, which information can be displayed or processed.

Embodiments of a process according to the invention or of a CIJ printer according to the invention can implement at least one removable single-block assembly or removable module. Such single-block assembly may comprise at least one fluid component like for example at least one pump and/or at least one filter and/or at least one damper and/or at least one valve.

Said at least one removable single-block assembly can further comprise means, such as securing or fastening means, for mounting and disassembling said single-block assembly to and from an ink circuit of a CIJ printer.

Said at least one removable single-block assembly may comprise a housing having at least one fluid inlet and at least one fluid outlet, and fluid connection means, for example ducts, to allow fluid to flow from said at least one fluid inlet to said at least one fluid component, and then to said at least one fluid outlet.

Several examples of said removable single-block assembly are a "first single-block assembly" (or "first block or module"), a "second single-block assembly" (or "second block or module"), a "third single-block assembly" (or "third block or module") which are described below. The adjectives "first", "second", "third" do not indicate a preferred order or any order of importance, but are merely used for the sake of clarity. Said single-block assemblies can be used independently from each other in a printer.

A first single-block assembly comprises:.

In one embodiment said first single-block assembly comprises a hydraulic part of a pump, and coupling means for coupling said hydraulic part and a motor for driving said hydraulic part, said motor being in an ink circuit, outside said first single-block assembly. For example, said coupling means of said first single-block assembly comprises an axis of said pump, said axis traversing said housing.

A second single-block assembly comprises:.

A third single-block assembly comprises:.

Said third single-block assembly may further comprise at least one filter, said fluid connection means allowing a fluid to flow from said fluid inlet or from one of said at least two fluid inlets to said filter, then to said recovery device, and to said fluid outlet or to one of said at least two fluid outlets.

Said recovery device of said third single-block assembly may comprise at least a second pump or a venturi.

Said third single-block assembly may further comprise at least a <NUM>-way valve.

Any of said removable single-block assemblies or removable modules, for example any of said first, second, or third single-block assemblies, can comprise an identifier, for example of the electrical or of the magnetic type.

An electrical identifier can have for example an electrical characteristic having one of at least two or three values; it can have more values, for example if there are:.

A magnetic identifier can comprise at least one magnet disposed at one or more specific location(s) or position(s) in the single-block assembly, said specific location(s) or position(s) depending on at least one technical characteristic of the single-block. A magnetic identifier comprising one magnet can have for example at least two or three different positions in the device, each position identifying for example a different type of pump or a different type of filter or a different type of recovery device. It can have more possible positions, for example if there are:.

A magnetic identifier can cooperate with means in the circuit, for example a switch, for example a "reed switch", to identify the removable single-block assembly or the removable module. Several switches can be located at different locations in the ink circuit. Depending on the location of the magnet in the module, which itself depends on one or more technical characteristics of the module, one or the other of the switches is activated when the module is connected to the circuit, which is detected by the printer or its controller. An identification of the module is thus obtained.

An identifier of a module can comprise several magnets disposed at several locations in the module or single-block, each combination of locations depending on at least one technical characteristic of the module or single-block; for example, each combination of locations provides the identification of a different type of pump or a different type of filter or a different type of recovery device and each magnet interacting with means in the circuit, for example a switch, for example a "reed switch". This multiplies the possible identifications with respect to the identifications with only one magnet.

Any of said removable single-block assemblies or removable modules, for example any of said first, second, or third single-block assemblies can comprise means, preferably magnetic means, for guiding its positioning in a printer or with respect to an ink circuit or to a corresponding interface in the printer. Any removable component or part of the circuit can also be provided with such magnetic guiding means.

In an embodiment, at least one of said removable single-block assemblies or removable modules, for example any of said first, second, or third single-block assemblies, as well as the corresponding part of the printer to which it must be connected, have magnetic means that cooperate to attract each other when said single-block assembly or module approaches the location in the printer where it must be connected so that it is easier for an operator to mount said assembly or module.

For example, each of said at least one single-block assembly and the corresponding connecting part or surface of the printer to which it must be connected has a magnet, both magnets attracting each other. Or one of them has a magnet and the other part has a material having magnetic properties such that both the assembly and the corresponding connecting part of the printer attract each other when the module approaches said connecting part. Other components or parts of the circuit can be mounted on or in the circuit, the mounting being assisted or guided by magnetic means as described above.

Further aspects and embodiments of the above described single-block assemblies or modules or blocks are disclosed in the following parts and in the drawings of this application.

In an embodiment, of a process according to the invention or of a CIJ printer according to the invention, an ink circuit of said continuous inkjet printer comprises one or more of the above described removable single-block assemblies or removable modules, for example one or more of said first, second, or third single-block assemblies. Any of said removable single-block assemblies or removable modules, for example any of said first, second, or third single-block assemblies can be mounted in or on the ink circuit or disassembled or removed from the ink circuit, for example after a flushing or cleaning process according to the invention, independently from the others.

An ink circuit of a continuous inkjet printer to which the invention can apply or an ink circuit of a continuous inkjet printer according to the invention, can comprise:.

Said circuit may further comprise means for mounting and disassembling said at least one single-block assembly or module to and from the first part of said ink circuit, for example to and from at least one corresponding receiving interface. A receiving interface may have at least one fluid inlet and/or at least one fluid outlet which correspond(s) to the at least one fluid outlet(s) and/or to the at least one fluid inlet(s) of the single-block assembly or module which must be mounted or assembled with said interface.

If the ink circuit has several single-block assemblies or modules, each of them can be disassembled or removed from said ink circuit, for example after a flushing or cleaning process according to the invention, independently from the other(s) and can be mounted back (for example after a cleaning or repairing step) or replaced with a different or similar or identical module. For example, a recovery module can be replaced by a recovery module having a different structure and/or one or more different component(s), in particular if a different ink is used in the printer. Another example can be the replacement of a module by a technically updated module, with more advanced technical function(s) or updated component(s).

A different or updated component(s) can be for example a different or more advanced filter (having a different, for example a smaller, mesh size than the previous one) and/or a different pump (having a different, for example a larger, flow rate or power, than the previous one) and/or pumps differing by their technology (a gear pump or a peristaltic pump or a diaphragm pump, which can be adapted to different types of inks) and/or a different pump or venturi (having a different, for example larger, geometry than the previous one).

An ink circuit to which the invention applies, or an ink circuit of a continuous inkjet printer according to the invention, may be compatible with a plurality of the above-described modules, for example with two different third single block assemblies; at least two of said modules, although they may differ from each other by one or more technical features, for example different filters, may be alternatively mounted on said circuit or printer, or on the same corresponding interface of said circuit. Said circuit or interface has connections (at least one fluid inlet and/or at least one fluid outlet) so that said at least two different modules (different modules having different structure(s) and/or one or more different component(s) as explained above) can be alternatively connected to said circuit or printer or to said corresponding interface, the exchange of module occurring for example after a flushing or cleaning process according to the invention.

The invention applies in particular to an ink circuit of a continuous inkjet printer or to a continuous inkjet printer, or a continuous inkjet printer which can comprise, or a continuous inkjet printer according to the invention can comprise:.

Such an ink circuit may further comprise a third single-block assembly or module as disclosed above.

As already explained above, any single-block assembly of an ink circuit to which the invention may apply, in particular any of the first, second or third single-block assembly or module, may comprise at least one identifier, for example of the electrical or of the magnetic type. Said identifier may cooperate with corresponding means in the ink circuit to read said identifier.

As already explained, said first single-block assembly may comprise a pump or at least a hydraulic part of a pump, and coupling means for coupling said hydraulic part of a pump and a motor for driving said hydraulic part. Said motor of said first single-block assembly may be in the ink circuit, outside said first single-block assembly, said coupling means coupling said motor and said pump.

Said coupling means of said first single-block assembly may comprise an axis of said pump, said axis traversing said housing.

The means for mounting and disassembling any of said single-block assemblies or any single block assembly of an ink circuit to which the invention applies:.

The invention also concerns a process for maintaining a hydraulic circuit of a continuous inkjet printer, comprising a solvent tank or reservoir and a main tank for ink, and at least one removable single-block assembly among:.

Claim 1:
A cleaning process for cleaning at least one part of a hydraulic circuit of a continuous inkjet printer, said hydraulic circuit comprising a solvent tank (<NUM><NUM>, <NUM>) and an ink tank (<NUM>, <NUM><NUM>) and hydraulic connection means for sending ink and/or solvent to a print head, said cleaning process comprising:
- removing a cartridge (<NUM>) from a cartridge connection and pumping gas from said cartridge connection or mounting a device (<NUM>) in the circuit for introducing a gas, for example compressed gas, into said circuit;
- circulating said gas, through at least one part of said hydraulic circuit and recovering ink from said at least one part of said hydraulic circuit in a recovery cartridge or in said ink tank (<NUM>, <NUM><NUM>) or in a tank (<NUM>).