Continuous ink jet printer

Abstract

A continuous inkjet printer for printing on an outer substrate moving past the printer is provided. The printer includes a printhead. The printhead includes: a nozzle for generating and ejecting a stream of ink droplets for printing; at least one electrode for guiding a stream of ink droplets; and a tank for receiving ink droplets not used for printing. The printer includes an ink system for storing and supplying ink to the printhead, the ink system including a tank pump in fluid communication with the tank. The printhead is fluidly coupled to the ink system via a plurality of fluid conduits, the plurality of conduits including a main return line; the length of the portion of the main return line extending between the tank and the tank pump is not more than 1 meter.

Description

Technical Field

[0001] The present invention relates to a continuous inkjet (CIJ) printer, and related methods of using and controlling the same. Background Art

[0002] In an inkjet printing system, printing is constituted by individual ink droplets generated at a nozzle and propelled towards a substrate. There are two main systems: drop-on-demand, where ink droplets for printing are generated as needed and when needed; and continuous inkjet (CIJ) printing, where droplets are continuously generated and only selected droplets are directed towards the substrate, with the other droplets being recycled back to the ink system.

[0003] A CIJ printer supplies pressurized ink to a printhead droplet generator, in which a continuous stream of ink issuing from a nozzle is broken up into individual regular droplets, for example by an oscillating piezoelectric element. The droplets are directed through a charging electrode, where they are selectively and individually given a predetermined charge, and then through a transverse electric field provided across a pair of deflection plates, the pair of deflection plates comprising a high voltage (or extra-high tension (EHT)) plate and a zero or negative voltage plate ("ground" plate). Each charged droplet is deflected by the field by an amount depending on its charge quantity before hitting the substrate, while uncharged droplets proceed without deflection and are collected at a gutter, from where they are recycled back to the ink system. The charged droplets bypass the gutter and hit the substrate at a position determined by the charge on the droplet and the position of the substrate relative to the printhead. Typically, the substrate moves relative to the printhead in one direction and the droplets are deflected in a direction substantially perpendicular thereto, although the deflection plates can be oriented obliquely relative to the vertical to compensate for the speed of the substrate (the movement of the substrate relative to the printhead between droplet arrivals means that a row of droplets would otherwise not extend completely perpendicular to the direction of movement of the substrate). The various components of the printhead are typically contained within a cover tube or a printhead housing.

[0004] In continuous inkjet (CIJ) printing, characters are printed by a dot matrix consisting of regularly arranged potential ink droplet positions. Each dot matrix contains a plurality of columns (i.e., strokes), each column being constituted by a row of a plurality of potential ink droplet positions (e.g., 7), which positions are determined by the charge applied to the ink droplets. Thus, each actually used ink droplet is charged according to its target position in the stroke. If a particular ink droplet is not used, the droplet is not charged and is captured by the recovery gutter for recycling. This process is cyclically repeated for all strokes of the dot matrix, and then the processing of the next character dot matrix is started.

[0005] Ink is delivered to the print head under pressure through an ink system, which is typically housed in a sealed compartment of the cabinet that includes a separate compartment for the control circuitry and the user interface panel. The ink system includes a main pump that draws ink from a reservoir or tank (commonly referred to as a mixing tank) via a filter and delivers it to the print head under pressure. When the ink is consumed, the reservoir is refilled as needed from a replaceable ink cartridge that is releasably connected to the reservoir via a supply conduit. The ink is supplied from the reservoir to the print head via a flexible delivery conduit. Unused ink drops captured by the gutter are recycled to the reservoir via a pump through a return conduit. The ink flow in each conduit is typically controlled by solenoid valves and / or other similar components.

[0006] As the ink circulates through the system, there is a tendency for the ink to thicken due to solvent evaporation, particularly in relation to the recycled ink that has been exposed to air in the channels between the nozzles and the gutter. To compensate for this, "make-up" solvent is added to the ink as needed from a replaceable solvent cartridge to maintain the ink viscosity within a desired limit. The ink cartridge and the solvent cartridge are filled with a predetermined amount of fluid and are typically releasably connected to the reservoir or mixing tank of the ink supply system such that the reservoir can be intermittently topped up as needed by drawing ink and / or solvent from the cartridges.

[0007] CIJ printers typically operate in high-throughput environments for which the printer and the ink need to be able to keep up with high production line speeds, fast drying time requirements, and nearly continuous production. This typically requires larger containers to store and hold the ink and the solvent (such as ink cartridges and mixing tanks), which occupy space within the system and result in a large amount of ink circulating through the printer. For example, the main pump of the ink supply system can typically circulate about 0.5 liters of ink per minute, of which only about 2 - 3 milliliters of ink are ejected from the print head per minute for printing during that time. Thus, the main pump is typically quite large and space-consuming, and the operation of the pump typically results in the generation of a large amount of heat. To manage this, the printer typically requires a fan to prevent the printer and / or the ink supply system from overheating, so the fan also occupies space within the printer. Thus, the printer, particularly the printer cabinet, tends to be quite large.

[0008] As described above, the ink supply system is typically housed within the cabinet, so the cabinet needs to be large enough to accommodate the ink supply system and any associated components. The print head is typically disposed outside the cabinet. Ink is delivered from the ink supply system to the print head and is recycled back to the ink supply system via a flexible tube that is bundled with other fluid tubes and electrical wires to form what is (described in the art as) an umbilical cable. Thus, the ink supply system and the cabinet are connected to the print head via the umbilical cable, which is typically about 2 to 8 meters long.

[0009] As described above, unused ink droplets captured in the slots of the print head are recycled via a pump through a return conduit to a mixing tank in the ink supply system. The pump can draw air, ink, and / or solvent into the slots and return it to the ink supply system via the return conduit. Given the length of the umbilical cord and thus the length of the return path including the return conduit, this typically results in a significant airflow through the system. This significant airflow can result in solvent vapor loss, meaning that additional "make-up" solvent may be required to keep the ink viscosity within the desired limits to account for this loss.

[0010] Connecting the print head to the cabinet via an umbilical cord means that the printer is typically provided with two mounts for printing: one for supporting the cabinet and one for supporting the print head. This arrangement is desirable for at least two reasons. The first is that the print head needs to be supported near the production line for printing onto a substrate. Thus, keeping the relatively compact print head slightly separate from the cabinet avoids the need to provide sufficient space on the production line for a larger and bulkier cabinet. The print head can be positioned adjacent to the production line, and the cabinet can be spaced apart from the production line. The second is that the ink supply system and thus the cabinet may need to be placed in a specific orientation so that the printer can print. Thus, keeping the print head slightly separate from the cabinet via an umbilical cord means that the print head can be positioned in different positions and orientations (i.e., the position of the print head is at least partially separate from the position of the cabinet) to allow for greater flexibility in printer operation and printing orientation.

[0011] There is a need to provide an alternative continuous inkjet (CIJ) printer that overcomes one or more disadvantages of known systems, whether mentioned herein or otherwise. SUMMARY OF THE INVENTION

[0012] According to a first aspect, there is provided a continuous inkjet printer for printing on an external substrate that moves past the printer, the printer comprising: a print head including: nozzles for generating and ejecting a stream of ink droplets for printing; at least one electrode for guiding the stream of ink droplets; and slots for receiving ink droplets not used for printing; and an ink system for storing ink and supplying ink to the print head, the ink system comprising: a slot pump in fluid communication with the slots; wherein: the print head is fluidly coupled to the ink system via a plurality of fluid conduits, the plurality of conduits including a main return line; and the portion of the main return line extending between the slots and the slot pump has a length of no more than 1 meter.

[0013] The external substrate can form part of an article (e.g., a fast-moving consumer good) on which printing occurs. The external substrate can move past the printer by being disposed on a printing line.

[0014] The nozzle can also be referred to as the orifice or the jewel orifice of the droplet generator. During operation, at least some of the ink droplets in the ink droplet stream can be deflected to apply a printed pattern onto an external substrate. The ink droplet stream generated by the nozzle can be formed by fragmenting a continuous ink droplet stream by means of a device such as an oscillating piezoelectric element. The droplets can then be guided past a charging electrode where they are given an electric charge and are subsequently guided by another electrode to direct the now charged droplets as required. At least one electrode for guiding the ink droplet stream can include a zero voltage plate or a negative voltage plate (such as a ground plate) and a high voltage (extra-high tension (EHT)) plate. An (lateral) electric field is generated on the plates, and the charged droplets are deflected by an amount depending on the charge and the electric field.

[0015] The ink system can include a plurality of components, including but not limited to a mixing tank, a plurality of pumps (a sump pump can be one of them), ink cartridges, a plurality of filters, a plurality of valves, and optionally one or more quick-disconnect connectors (e.g., an array of quick-disconnect connectors). The ink system can be described as a closed system where ink and solvents are received through the ink cartridges and an appropriate mixture is prepared in the mixing tank in preparation for printing. The ink is supplied from the mixing tank to the print head.

[0016] The plurality of fluid conduits through which the print head is fluidly coupled to the ink system can include a main supply line and a main return line. The main supply line can be described as extending at least from the ink pump to the nozzle. More specifically, the main supply line can extend from the mixing tank to the nozzle. The main return line extends at least from the sump to the sump pump and more preferably from the sump to the mixing tank. The print head can thus be described as being fluidly coupled to the mixing tank, the ink pump, and the sump pump. A plurality of electrical wires can extend between the ink system and the print head.

[0017] The portion of the main return line that extends between the sump and the sump pump can alternatively be described as a conduit extending from the sump to the sump pump. The portion of the main return line that extends between the sump and the sump pump can be described as the first portion of the main return line. The main return line can extend beyond the sump pump to put the sump pump in fluid communication with the mixing tank. That is, the main return line can extend from the sump to the mixing tank. The extension can be referred to as the second portion of the main return line. The portion of the main return line that extends between the sump pump and the sump and has a length of no more than 1 meter can be described as the sump and the sump pump being fluidly connected to each other by a conduit having a length of 1 meter or less. One or more valves, quick-disconnect connectors, or other components can be provided along this portion of the conduit. The sump pump is preferably located within the printer body.

[0018] The portion of the main return line that extends between the sump pump and the sump and has a length of no more than 1 meter offers a number of advantages: reduced sump flow due to the relatively short length of the fluid conduit; lower solvent consumption; and fewer conduits to be flushed during the flushing cycle.

[0019] The length of the entire main return line extending between the sump and the mixing tank can be at most 1 meter.

[0020] The length of each of the plurality of fluid conduits extending between the ink system and the print head can be at most 1 meter.

[0021] By limiting the length of the fluid conduits to a length not exceeding approximately 1 meter, the fluid conduits fluidly connect the print head to the ink system: i) the volume of ink contained in the main supply line is reduced, thereby reducing the volume of ink that needs to be flushed during a flushing cycle (e.g., priming the printer at startup can occur more quickly); ii) the pumping work required by the pump(s) is reduced, resulting in less heat generation in the system, a reduction in the size of various components in the system (e.g., the pump(s) and the entire printer itself), and a reduction in power consumption; iii) less air is drawn into the ink system, reducing the amount of degassing required, which reduces the amount of solvent vapor discharged from the system (thereby reducing emissions and odors), and thus reduces the consumption of make-up solvent; and iv) the ink life in the ink system is improved. The ink life in the ink system is improved at least by reducing the air flow and temperature in the ink system (by reducing the pumping power). This reduces the risk of the ink being oxidized, which otherwise could occur in the presence of air and heat. It also mitigates the potential loss of the electrical conductivity of the ink and the chemical degradation of the ink.

[0022] The portion of the main return line extending between the sump and the sump pump can have a length of no more than 500 millimeters. The portion of the main return line extending between the sump and the sump pump can have a length of at least 100 millimeters.

[0023] The flushing volume of the printer can be no more than 4 ml.

[0024] The flushing volume is defined by the combined volume of the conduits and the portion of the nozzle extending between the feed valve and the nozzle, and the side ports and the purge valve. The flushing volume is the volume of the line that needs to be flushed with solvent when printing stops (e.g., when the injection of the ink / solvent mixture through the main supply line stops). The flushing volume refers to the volume of the conduits and does not include, for example, any ink pumps, pressure transducers, dampers, filters, valves, and any quick-disconnect connectors (if applicable).

[0025] By limiting the flushing volume, flushing uses a lower volume of solvent. Thus, flushing can be carried out more quickly and with less solvent compared to other cases.

[0026] The printer can include a printer body that houses ink system components, and the ink system components include an ink tank and an ink pump.

[0027] The printer body may alternatively be described as a printer cabinet. The printer body is a housing that contains most of the components of the printer. In particular, the printer body may be described as housing the various components of a fluid circuit, many of which form part of the printer's ink system. In addition to the ink tank and ink pump, the ink system may also include ink and solvent refill pumps, ink and solvent supply lines, sump pumps, mixing tanks, and various other valves and filters. The ink system may be configured to control the consistency of the ink and solvent mixture in the mixing tank for printing.

[0028] The printer body may include a graphical user interface, such as a screen, that receives signals from an operator to control the printer.

[0029] The printer may also include an umbilical cable that couples the print head to the printer body and houses a plurality of fluid conduits, where the length of the umbilical cable may not exceed 1 meter.

[0030] The length of the umbilical cable may not exceed 500 millimeters.

[0031] The length of the umbilical cable may be at least 100 millimeters.

[0032] The umbilical cable may be described as a flexible conduit that houses a plurality of other lines and / or conduits. The umbilical cable may house a plurality of fluid conduits that couple the print head to the ink system. A plurality of electrical wires may also extend through the umbilical cable.

[0033] Advantageously, the umbilical cable means that the print head can be correctly manipulated and aligned at a convenient distance from the printer body relative to an external substrate to be printed. In the case where the length of the umbilical cable does not exceed 1 meter, the print head position can still be adjusted without incurring the disadvantages associated with long umbilical cables known in the prior art. These disadvantages include increased pumping requirements, increased heat generation, and increased requirements for refilling solvents, among others.

[0034] The print head may be pivotally connected to the printer body and may rotate about a print head rotation axis.

[0035] The print head can be directly connected to the printer body. Alternatively, the print head can be indirectly connected to the printer body via one or more insertion members, such as a print head support arm (e.g., a tiltable or non-tiltable portion of the print head support arm). The print head can be pivotally connected to the printer body by a rotatable coupler. The rotatable coupler can be configured to allow the print head to rotate relative to the printer body about a print head rotation axis. The print head rotation axis can be substantially perpendicular to an ink jet axis defined by ink jet holes of the print head. In other words, the print head that can rotate about the print head rotation axis adjusts the orientation of the print head (e.g., the ink jet axis) relative to the printer body, rather than rotating the print head about a fixed mount to simply change the orientation of the ink pattern.

[0036] The print head can be connected to the printer body by an umbilical cable and a rotatable coupler.

[0037] The rotatable coupler can be interposed between the printer body and the umbilical cable. The print head can be directly coupled to the umbilical cable. The rotatable coupler can facilitate the adjustment of the orientation of the umbilical cable relative to the printer body.

[0038] The print head can be supported by the printer body during operation.

[0039] In other words, the printer body supports the print head (directly or indirectly). This eliminates the need for additional print head fixtures or support structures that might otherwise be required. The printer body can support the print head and does not require an umbilical cable.

[0040] Advantageously, by directly supporting the print head from the printer body, a person can easily move the entire printer because the total mass can be reduced and there is no trailing umbilical cable and print head. This allows for easier movement from one production line to another or replacement due to a malfunction. Additionally, the umbilical cable further includes various fluid conduits and wires passing through it, as well as surrounding shielding, which can resist manipulation / bending.

[0041] During the printing operation, the print head rotation axis can be substantially horizontal.

[0042] The print head can have an extended configuration for printing and a retracted configuration for storage.

[0043] The printer body can include a print head recess for receiving the print head in the retracted configuration.

[0044] The print head can be connected to a print head support arm that is pivotally coupled to the printer body.

[0045] The print head can be removable from the print head support arm.

[0046] A continuous inkjet printer may also include a position detector. The position detector may be an accelerometer.

[0047] According to a second aspect, there is provided a continuous inkjet printer for printing on an external substrate that moves past the printer, the printer comprising: a print head including: nozzles for generating and ejecting a stream of ink droplets for printing; at least one electrode for guiding the stream of ink droplets; and a gutter for receiving ink droplets not used for printing; and an ink system for storing ink and supplying the ink to the print head; and a printer body that houses the ink system; wherein the print head is pivotally connected to the printer body by a rotatable coupler configured to allow the print head to rotate relative to the printer body about a print head axis of rotation.

[0048] The external substrate may form part of an article (e.g., a fast-moving consumer good) on which printing takes place. The external substrate may move past the printer by being disposed on a print line.

[0049] The nozzles may alternatively be described as holes or orifice jewels of a droplet generator. At least some of the ink droplets in the stream of ink droplets may be deflected during operation to apply a printed pattern to the external substrate. The stream of ink droplets generated by the nozzles may be produced by breaking up a continuous stream of ink using, for example, an oscillating piezoelectric element. The droplets may then be guided past a charging electrode where they are given an electric charge and subsequently guided by another electrode to direct the now charged droplets as required. At least one electrode for guiding the stream of ink droplets may include a zero voltage plate or a negative voltage plate (e.g., a ground plate) and a high voltage (extra-high tension (EHT)) plate. An (lateral) electric field is generated on the plates, and the charged droplets are deflected by the field depending on the amount of charge and the electric field.

[0050] The ink system may include a plurality of components including, but not limited to, a mixing tank, a plurality of pumps (a sump pump may be one of them), ink cartridges, a plurality of filters, a plurality of valves, and optionally one or more quick-disconnect connectors (e.g., an array of quick-disconnect connectors). The ink system may be described as a closed system where ink and solvent are received through the ink cartridges and an appropriate mixture is prepared in the mixing tank in preparation for printing. Ink is supplied from the mixing tank to the print head.

[0051] The print head may be directly connected to the printer body. Alternatively, the print head may be indirectly connected to the printer body via one or more intervening components, such as a print head support arm (e.g., a tiltable or non-tiltable portion of a print head support arm).

[0052] By providing a rotatable coupling between the printhead and the printer, the printhead can be rotated relative to the printer body to ensure that printing occurs at the correct location on the substrate. Additionally, the rotatable coupling eliminates the need for a separate printhead support while still allowing for convenient adjustment of the printhead position (by rotating the printhead).

[0053] Another advantage of pivotally connecting the printhead to the printer body is that the fluid conduits that couple the printhead to the ink system can be made relatively short (e.g., no more than 1 meter in length). Thus, various advantages associated with these relatively short fluid conduit lengths can be obtained.

[0054] A higher flush printhead is also provided, which has: reduced channel flow; lower solvent consumption; and fewer conduits to be flushed during the flush cycle.

[0055] The printhead can have a deployed configuration for printing and a retracted configuration for storage.

[0056] The printer can have multiple different deployed configurations. For example, when in the deployed configuration, the printhead can be positioned to face either the first major surface or the second major surface of the printer body, or in a different orientation.

[0057] The deployed configuration can alternatively be described as a ready-to-print configuration. The retracted configuration refers to a configuration where the printer is not ready to print, but rather is used when the printer is in transit (e.g., to protect the printhead).

[0058] Advantageously, the ability to transition the printhead between configurations provides improved flexibility in aligning the printhead with an external substrate on which to print, and also provides a function where the printhead can be well protected during transit. Thus, the risk of damage to the printhead can be reduced when the printer is not actively required to print.

[0059] The printhead can include inkjet orifices through which ink droplets that are not captured by the channels are ejected.

[0060] The inkjet orifices can be described as openings through which the stream of ink droplets to be used for printing is directed. The ink droplets can be described as charged and deflected ink droplets. The ink droplets captured by the channels can be described as droplets not used for printing.

[0061] In the retracted configuration, the printhead can be orientable such that the inkjet orifices face the printer body.

[0062] The inkjet orifices can face the printer body such that if ink is to be ejected, the risk of the ink being ejected onto a substrate (e.g., an article) or onto a production line is low. By having the inkjet orifices face the printer body, the printhead (especially its inkjet orifices) is well protected against debris entry.

[0063] In the retracted configuration, the print head can be sealed by engaging with the face of the printer body. That is, the sealing surface of the groove in the printer body can interfere with / contact the outer surface of the print head to seal the ink jet holes.

[0064] In the deployed configuration, the print head can be orientable such that the ink jet holes face away from the printer body.

[0065] The ink jet holes can face away from the printer body by pointing in the same direction as the first main surface or the second main surface of the printer body or in a different direction (e.g., pointing away from the base of the printer body). The deployed configuration can be described as a configuration in which the ink jet holes are directed such that the ejected ink does not strike the printer body.

[0066] The printer body can include a print head recess for receiving the print head in the retracted configuration.

[0067] It can be said that the print head recess allows the print head to rotate between the retracted configuration and the deployed configuration. The print head can be nested within the print head recess. The print head recess can be described as a cutout in the entire main covering area of the printer body.

[0068] Advantageously, in the retracted configuration, the print head support arm can be received in the print head recess to reduce the risk of damaging the print head when the printer is in transit.

[0069] The print head can be connected to a print head support arm that is pivotally coupled to the printer body.

[0070] The print head can be directly connected to the print head support arm (e.g., its tiltable portion). The print head support arm (e.g., its non-tiltable portion) can be directly (pivotally) connected to the printer body.

[0071] The print head can be removable from the print head support arm.

[0072] The print head can be removed from the print head support arm by snap fit coupling or other detachable coupling. The print head can be described as removably engaging with the print head support arm.

[0073] Advantageously, the removable print head from the print head support arm facilitates the replacement of the print head when maintenance or repair is needed.

[0074] The continuous inkjet printer can also include a position detector.

[0075] The position detector can be a rotational position detector. The position detector can be an accelerometer. The print head and / or the print head support arm can include a position detector.

[0076] The printer may include a plurality of position detectors. One or more position detectors may be configured to detect one or more of the following: the rotational position of the print head relative to the printer body, the orientation of the printer body in use, and the tilt angle of the print head relative to the printer body. One or more position detectors may be operably connected to a controller.

[0077] Advantageously, the combination of position detectors provides useful information about the status and position of the printer or one or more of its sub-components (e.g., the print head). One or more position detectors may also be configured to detect whether the printer is in a deployed configuration or a stowed configuration, and furthermore to detect which of a plurality of different deployed configurations the printer is in.

[0078] The rotatable coupler may include a position detector.

[0079] The position detector may be a rotary encoder.

[0080] The print head may rotate about a print head rotation axis by approximately 270 degrees.

[0081] The position detector may be an accelerometer.

[0082] The accelerometer may be incorporated in one or more of the print head, the print head support arm (e.g., the tiltable portion and / or the non-tiltable portion, where applicable), the printer body, and the rotatable coupler. The accelerometer may be operably connected to a controller.

[0083] Advantageously, the accelerometer may be configured to detect the orientation of the entire printer. For example, the accelerometer may be configured to detect whether the printer is supported on either the first major surface or the second major surface of the printer body, or on another surface.

[0084] The print head may tilt about a print head tilt axis, which may be substantially orthogonal to the print head rotation axis.

[0085] The print head may be specifically tiltable relative to the non-tiltable portion of the print head support arm. The print head may be coupled (e.g., removably engaged) to the tiltable portion of the print head support arm such that both the print head and the tiltable portion of the print head support arm tilt (e.g., are tiltable) relative to the non-tiltable portion of the print head support arm.

[0086] Advantageously, the ability to tilt the print head relative to the printer body can compensate for the tilt of the print pattern, which may be caused by an external substrate moving past the print head at a certain speed. Thus, the tiltable nature of the print head facilitates printing onto a printing line at a higher speed or onto a tilted line where the characters may otherwise be deformed.

[0087] The printhead tilt axis can be parallel to the inkjet axis.

[0088] Advantageously, tilting the printhead in this way allows the printing angle on the substrate to be changed.

[0089] The printhead can be tilted by approximately + / - 20 degrees.

[0090] The tiltable printhead facilitates printing onto high-speed lines (to avoid skewed characters) or tilted lines.

[0091] During the printing operation, the printhead rotation axis can be substantially horizontal.

[0092] The printhead can be fluidly coupled to the ink system via a plurality of fluid conduits, the plurality of conduits can include a main return line; and the portion of the main return line extending between the sump and the sump pump can have a length of no more than 1 meter.

[0093] The plurality of fluid conduits through which the printhead is fluidly coupled to the ink system can include a main supply line and a main return line. The main supply line can be described as extending at least from the ink pump to the nozzles. More specifically, the main supply line can extend from the mixing tank to the nozzles. The main return line extends at least from the sump to the sump pump, and more preferably from the sump to the mixing tank. The printhead can thus be described as being fluidly coupled to the mixing tank, the ink pump, and the sump pump.

[0094] The ink system can include a sump pump. The sump pump is in fluid communication with the sump

[0095] The portion of the main return line extending between the sump and the sump pump can alternatively be described as the conduit extending from the sump to the sump pump. The portion of the main return line extending between the sump and the sump pump can be described as the first portion of the main return line. The main return line can extend beyond the sump pump to put the sump pump in fluid communication with the mixing tank. That is, the main return line can extend from the sump to the mixing tank. This extension can be referred to as the second portion of the main return line. The portion of the main return line extending between the sump pump and the sump having a length of no more than 1 meter can be described as the sump and the sump pump being fluidly connected to each other by a conduit having a length of 1 meter or less. One or more valves, quick-disconnect connectors, or other components can be provided along this portion of the conduit.

[0096] The portion of the main return line extending between the sump pump and the sump having a length of no more than 1 meter offers several advantages: reduced sump flow due to the relatively short length of the fluid conduit; lower solvent consumption; and fewer conduits to be flushed during the flushing cycle.

[0097] The length of each of a plurality of fluid conduits (e.g., a main supply line and a main return line) extending between an ink system and a print head can be at most 1 meter. A plurality of electrical wires can extend between the ink system and the print head.

[0098] The flushing volume of the printer can be no more than 4 ml.

[0099] The flushing volume is defined by the combined volume of the conduits and the portions of the nozzles that extend between the feed valve and the nozzles, as well as the side ports and the purge valve. The flushing volume is the volume of the pipeline that needs to be flushed with solvent when printing stops (e.g., when the injection of the ink / solvent mixture through the main supply line stops). The flushing volume refers to the volume of the conduits and does not include, for example, any ink pumps, pressure transducers, dampers, filters, valves, and any quick-disconnect connectors (if applicable).

[0100] By restricting the flushing volume, flushing uses a lower volume of solvent. Thus, compared to other cases, flushing can be carried out faster and with less solvent.

[0101] It should be understood that the features of the first aspect can be combined with the features of the second aspect, and the features of the second aspect can be combined with the features of the first aspect.

[0102] According to a third aspect, a method of using a continuous inkjet printer is provided, including: positioning a printer body relative to a target printing position; rotating a print head relative to the printer body about a print head rotation axis to align an inkjet orifice of the print head with the target printing position.

[0103] The target printing position can be an external substrate.

[0104] Advantageously, rotating the print head relative to the printer body can eliminate the need for a separate print head support.

[0105] Rotating the print head relative to the printer body can convert the printer from a retracted configuration, in which the print head can be received in a print head recess, to an extended configuration, in which the inkjet orifices can face away from the printer body.

[0106] After printing, the print head can be rotated relative to the printer body to convert the printer to a retracted configuration in which the print head can be received in the print head recess.

[0107] According to a fourth aspect, a method of controlling a continuous inkjet printer is provided, including: using a position detector to generate data indicating the position of a print head; comparing the data indicating the position of the print head with reference data indicating a reference position of the print head; and generating an output indicating a difference between the position and the reference position.

[0108] The method can be described as a method of returning a printer to a pre - cleaning configuration.

[0109] The method is advantageous because after the printer has been cleaned (and thus the print head has been adjusted relative to the printer body), the printer can effectively recall a previous print configuration, so that the operator can easily return the printer to the print configuration.

[0110] The method according to the claim may further include: adjusting the position of the print head based on the output; and using the position detector to generate new data indicating the adjusted position of the print head; comparing the data indicating the adjusted position of the print head with reference data indicating a reference position of the print head; and generating an output indicating the difference between the position and the reference position.

[0111] The features of the first aspect may be combined with the features of the second to fourth aspects. The features of the second aspect may be combined with the features of the first, third or fourth aspects. The features of the third aspect may be combined with the features of the first, second or fourth aspects. The features of the fourth aspect may be combined with the features of the first to third aspects. Brief Description of the Drawings

[0112] The features of one aspect or embodiment or example as described and / or illustrated herein may be combined with the features of any other aspect or embodiment or example or its features as described and / or illustrated herein, where appropriate and applicable. Specific embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0113] Figure 1 is a schematic diagram of a continuous inkjet (CIJ) printer according to an embodiment of the present invention;

[0114] Figure 2 is a schematic diagram of a fluid circuit of a CIJ printer according to an embodiment of the present invention;

[0115] Figure 3 is a perspective view of a CIJ printer in an unfolded configuration according to an embodiment of the present invention;

[0116] Figure 4 is Figure 3 a perspective view of the CIJ printer shown in a retracted configuration;

[0117] Figures 5 to 7 is Figure 3 and Figure 4 perspective views of the CIJ printer in three different deployment configurations;

[0118] Figure 8 is Figures 3 to 7Exploded view of components forming a rotatably coupled part of a CIJ printer;

[0119] Figure 9 when assembled Figure 8 perspective view of the components;

[0120] Figure 10 is Figures 3 to 7 exploded view of components providing a tilting function of a CIJ printer;

[0121] Figure 11 shows separately Figure 10 the alignment plate;

[0122] Figure 12 shows from a first side Figure 10 a sub - assembly of the assembled components;

[0123] Figure 13 shows from the opposite side Figure 12 the sub - assembly;

[0124] Figure 14 is Figure 12 and Figure 13 a perspective cross - sectional view of the sub - assembly, where the tiltable part is aligned with the non - tiltable part about the tilt axis;

[0125] Figure 15 is Figure 15 a perspective cross - sectional view of the sub - assembly, where the tiltable part is tilted relative to the non - tiltable part about the tilt axis;

[0126] Figure 16 is Figures 12 to 15 an end cross - sectional view of the sub - assembly, where the tiltable part is tilted relative to the non - tiltable part about the tilt axis;

[0127] Figure 17 is a schematic diagram of a method for controlling a CIJ printer according to an embodiment of the present invention; and

[0128] Figure 18 is a schematic diagram of a CIJ printer according to an embodiment of the present invention. Detailed Description

[0129] Figure 1 Schematically shows a continuous inkjet (CIJ) printer 1 according to an embodiment of the present invention. The printer 1 includes a printer body 2 and a print head 3. The print head 3 is pivotally connected to the printer body 2 by a rotatable coupler 4. The printer body 2 houses an ink system 5 and a printer controller 6. The printer body 2 also has an interface 7 (e.g., a display, a keypad, and / or a touch screen) for use by an operator.

[0130] The print head 3 is arranged to print on a substrate disposed adjacent to the print head 3. The printer 1 includes two connectors (e.g., male connectors) for engaging corresponding fluid compartments of one or more ink cartridges, optionally via corresponding connectors (e.g., female connectors) of the compartments or ink cartridges. In particular, the printer 1 includes a connector for engaging the ink compartment 8 and a connector for engaging the solvent compartment 10. The connectors generally each include a fluid port that is arranged to be connected to a fluid path within the printer 1 to allow fluid to flow between the compartments 8, 10 and other parts of the inkjet printer 1, such as the ink system 5 and the print head 3.

[0131] In operation, ink from the ink compartment 8 and solvent from the solvent compartment 10 can be mixed within the ink system 5 to produce print ink having a desired viscosity suitable for printing. The ink is supplied to the print head 3, and unused ink returns from the print head 3 to the ink system 5. When unused ink returns from the print head 3 to the ink system 5, air can be drawn in with the ink from the slots of the print head 3. The air can then become saturated with the solvent in the slot tubing.

[0132] In operation, ink is conveyed from the ink system 5 to the print head 3 under pressure and recirculated back via a flexible tube bundled together with other fluid tubes and wires (not shown). To maintain the correct consistency of the ink, the ink system 5 is operable to mix the ink removed from the ink compartment 8 with the solvent removed from the solvent compartment 10 and combine them to obtain ink having the correct viscosity and / or density for a particular printing application.

[0133] The printer 1 also includes a first position detector 11. The first position detector 11 is disposed within the printer body 2. The first position detector 11 is configured to detect the position (e.g., orientation) (e.g., vertical, horizontal, etc.) of the printer body 2. The printer 1 also includes a second position detector 12. The second position detector 12 is disposed within the print head 3. The second position detector 12 is configured to detect the position (e.g., orientation) (e.g., its rotational position) of the print head 3.

[0134] Each of the first position detector 11 and the second position detector 12 is connected to the printer controller 6. The printer controller 6 is also connected to the interface 7.

[0135] Figure 2 is a schematic diagram of a fluid circuit 100. The fluid circuit 100 forms part of a CIJ printer according to an embodiment of the present invention.

[0136] Figure 2 uses dashed lines to indicate the boundaries of the various components shown in the fluid circuit 100 that make up a CIJ printer according to an embodiment of the present invention (e.g.,Figure 1 a part of the printer 1). The first box 102 indicates the components housed within the printer body (e.g., Figure 1 the components within the printer body 2). The second box 104 indicates the components installed in the print head support arm. The third box 106 indicates the components installed within the print head (e.g., Figure 1 the print head 3). The combination of the second box 104 and the third box 106 can be referred to as defining the print arm. The components defined by at least the first box 102 can be described as the ink system.

[0137] In some embodiments, and as will be described in detail below, the print head support arm (e.g., the component defined by 104) can be rotatably connected to the printer body (e.g., the component defined by 102). The print head (e.g., the component defined by 106) can be removably connected to the print head support arm. The print head can be tilted relative to the print head support arm. In other embodiments, the print head support arm can be omitted, and the print head is coupled to the printer body via an umbilical cable.

[0138] In the illustrated embodiment, the fluid circuit 100 includes a single replaceable ink cartridge 108. The ink cartridge 108 contains both the solvent and the ink used during the printing process. Different from the prior art arrangements, the fluid circuit 100 includes a single ink cartridge 108 instead of separate ink cartridges for the solvent and the ink respectively. The ink cartridge 108 is divided into a plurality of different compartments (e.g., it can have only two compartments). The ink cartridge 108 in the illustrated embodiment is divided into a pair of compartments: a solvent compartment 110 and an ink compartment 112. As the names indicate, each compartment contains (only) the solvent and (only) the ink respectively. The compartments 110, 112 can also be referred to as tanks. The single ink cartridge 108 is an optional feature of the present invention, and in other embodiments, multiple ink cartridges can be incorporated in other ways. However, for reasons of reducing waste and reducing maintenance requirements, incorporating a single ink cartridge is beneficial.

[0139] Downstream of the ink cartridge 108, a solvent supply line 114 and an ink supply line 116 are provided. The solvent and ink supply lines 114, 116 are separate conduits that can be selectively placed in fluid communication with each other if needed. Each of the solvent and ink supply lines 114, 116 connects the ink cartridge 108 (specifically, its solvent and ink compartments 110, 112) to a solvent refill pump 118 and an ink refill pump 120. Each of the solvent refill pump 118 and the ink refill pump 120 can be used to selectively pump the solvent and the ink from the solvent compartment 110 and the ink compartment 112 of the ink cartridge 108 respectively. In the illustrated embodiment, the solvent refill pump 118 and the ink refill pump 120 are diaphragm pumps, but other types of pumps can be used in other ways.

[0140] Each of the solvent compartment 110 and the ink compartment 112 of the ink cartridge 108 is removably connected to a respective solvent supply line 114 and ink supply line 116. This allows for the regular replacement of the ink cartridge 108 when the level of ink and solvent in either or both of the compartments 110, 112 drops below a threshold level (e.g., when completely emptied). Each of the solvent supply line 114 and the ink supply line 116 may include a probe (e.g., a male connector) configured to engage a corresponding port (e.g., a female connector) in fluid communication with the respective solvent compartment 110 and ink compartment 112. The ports on the ink cartridge 108 may be sealed prior to being introduced into the ink system. When introduced or inserted into the ink system, the seal may be pierced by the respective probe, thereby placing the compartments 110, 112 in fluid communication with the solvent and ink supply lines 114, 116, respectively. It should be understood that there are many alternative options (e.g., switching valves, etc.) for placing the compartments 110, 112 in fluid communication with the solvent and ink supply lines 114, 116.

[0141] The solvent filter 122 is inserted along the solvent supply line 114 between the ink cartridge 108 and the solvent refill pump 118. Similarly, the ink filter 124 is inserted along the ink supply line 116 between the ink cartridge 108 and the ink refill pump 120. The purpose of the filters 122, 124 is to remove any small particles from the solvent and ink before the solvent and ink pass downstream of the solvent and ink refill pumps 118, 120. Examples of such particles include debris (e.g., rubber debris) from seals (e.g., needle diaphragm seals) generated by the introduction / insertion of the ink cartridge 108. The filters 122, 124 may be filters of approximately 8 microns (e.g., mesh size).

[0142] The mixing valve 126 is disposed between the solvent and ink supply lines 114, 116. The mixing valve 126 selectively places the solvent supply line 114 and the ink supply line 116 in fluid communication with each other. This is mainly used to directly supply the solvent from the solvent compartment 110 to the mixing tank 128 (which may be referred to as the mixing tank). When it is desired to add the solvent from the solvent compartment 110 to the mixing tank 128 (e.g., "fill up" the mixing tank 128 with the solvent), the flushing valve 144 (disposed along the flushing line 170) is closed, the mixing valve 126 is opened, and the solvent refill pump 118 is activated. The closing of the flushing valve 144 prevents the solvent from flowing through the flushing valve 144. The ink refill pump 120 acts as a valve when not pumping (e.g., as in the case when the solvent is added to the mixing tank 128), and substantially prevents the solvent from traveling along the ink supply line 116 towards the ink compartment 112 beyond the ink refill pump 120. Under the action of the solvent refill pump 118, the solvent is thus added to the mixing tank 128. For completeness, when it is desired to add ink from the ink compartment 112 to the mixing tank 128, the mixing valve 126 is closed and the ink refill pump 120 is activated. Under the action of the ink refill pump 120, the ink is thus added to the mixing tank 128 (along the ink supply line 116).

[0143] The ink and the solvent are mixed together in the mixing tank 128, which may be referred to as a storage tank or reservoir. For example, when needed, more solvent can be added to reduce the viscosity of the solvent-ink mixture in the mixing tank 128. From Figure 2 the fluid circuit 100 shown, it should be understood that the solvent refill pump 118 and the ink refill pump 120 can be used to pump or drive the solvent and the ink respectively from the solvent compartment 110 and the ink compartment 112 of the ink cartridge 108 to the mixing tank 128.

[0144] Now turning to describe the main circuit of the fluid circuit 100, an ink pump 130 is provided downstream of the mixing tank 128. The ink pump 130 is disposed along the main supply line 132, and the main supply line 132 extends from the mixing tank 128 to the nozzle 134. The nozzle 134 can alternatively be described as the orifice of a droplet generator. The ink pump 130 is used to pump the mixture of ink and solvent from the mixing tank 128 to the nozzle 134. Downstream of the ink pump 130 is the filter module 136. The filter module 136 is replaceable when needed. In the illustrated embodiment, the filter module 136 has a filtration size of about 15 microns, but it should be understood that this can vary in other arrangements. The main supply line 132 is an example of one of a plurality of fluid conduits, which can have a length of no more than 1 meter and fluidly connects the print head to the ink system.

[0145] Downstream of the filter module 136, along the main supply line 132, a pressure transducer 138 and a damper 140 are also provided. Continuing downstream, a feed valve 142 is provided. The feed valve 142 selectively places the mixing tank 128 in fluid communication with the nozzle 134. The feed valve 142 is one of the valves in the valve array 141. Other valves in the array 141 include a flush valve 144, a purge valve 146, and a reflux valve 148. Each of these valves will be described in detail where appropriate.

[0146] An array 150 of quick-disconnect connectors also forms part of the fluid circuit 100. The array 150 of quick-disconnect connectors is incorporated to provide a leak-free connection (and, more precisely, disconnection) of the print head (e.g., the housing component in the third block 106) during operation. The array 150 of quick-disconnect connectors includes first through fourth connectors 152, 154, 156, 158. In some embodiments, the array 150 of quick-disconnect connectors may be omitted.

[0147] Downstream of the first of the quick-disconnect connectors 152 is a nozzle filter 160, which may be referred to as a last-chance filter. The nozzle filter 160 is disposed immediately upstream of the nozzle 134. The nozzle filter 160 is introduced to reduce the risk of any particles clogging the nozzle 134. When ejected by the nozzle 134, the ink flow 162 of non-printing ink is shown as entering the sump 164. This indicates that the ink will not be applied to the substrate as part of the printing process but will instead be recycled back to the mixing tank 128. While the above components form part of the print head, the print head also includes Figure 2 a number of other components not shown. For example, the print head includes at least one electrode, such as a charging electrode 161 and deflection plates 163 (also referred to as deflection electrodes). The deflection plates 163 may be held at a potential of approximately 8 kV relative to a reference electrode (e.g., a ground plane). The deflection plates 163 and the reference electrode may be referred to as a pair of deflection electrodes.

[0148] Continuing with the description of the main circuit, the sump 164 is connected to the main return line 166. The main return line 166 passes through the third quick-disconnect connector 154 in the quick-disconnect connectors to the reflux valve 148. Further downstream of the main return line 166 is a sump pump 168. The sump pump 168 applies a constant suction during use to effectively pump a mixture of air, ink, and solvent from the flow 162 back into the mixing tank 128 via the sump 164. As will be apparent from Figure 2It is understood that the sump pump 168 is arranged outside the print head (e.g., outside the frame 106). The operation of the main circuit thus ends at this stage. The main return line 166, together with the ink main supply line 132, is an example of another of the plurality of fluid conduits that fluidly connect the print head to the ink system. The main return line 166 includes: a first portion 166a and a second portion 166b. The first portion 166a extends from the sump 164 to the sump pump 168. The second portion extends from the sump pump 168 to the mixing tank 128. The first portion 166a may be referred to as the upstream portion of the main return line 166, and the second portion 166b may be referred to as the downstream portion of the main return line 166.

[0149] An aspect of particular importance in the present application is the length of the first portion 166a of the main return line 166. The length of the first portion 166a of the main return line 166 is at most 1 meter, which gives advantages such as reduced pumping work and heat generation. In an embodiment where the first portion 166a of the main return line 166 is at most 1 meter, the restriction between the sump 164 and the sump pump 168 is relatively low (e.g., compared to known arrangements), so less flow is required to flush the sump 164 and the first portion 166a of the main return line 166. As a result, the use of solvent is reduced. In a preferred embodiment, the length of the first portion 166a of the main return line 166 is preferably less than about 750 mm, more preferably less than about 500 mm. In some embodiments, the length of the first portion 166a of the main return line 166 is at least about 100 mm. The length of the first portion 166a is preferably between about 100 mm and about 500 mm. Another aspect of particular importance in the present application is that the print head is pivotally connected to the printer body by a rotatable connector. These aspects may be combined with each other, or used independently of each other.

[0150] The function of the flushing valve 144 will now be described. From Figure 2It can be understood that when the mixing valve 126 is closed, the solvent supply line 114 and the ink supply line 116 are not directly connected to each other, and the flushing line 170 provides a direct flow path for the solvent downstream of the solvent refill pump 118 to the flushing valve 144 (and the nozzle 134). During startup and shutdown processes, it is particularly desirable for the flushing solvent to pass through the nozzle 134 to reduce the risk of the nozzle 134 becoming blocked. When the nozzle flushing process occurs, the purge valve 146 opens, and the sump pump 168 applies suction through the purge line 172 to suck the solvent from the nozzle 134 to the mixing tank 128. The purge line 172 is connected to the nozzle 134 via a side port 173. The sump 164 can also be flushed with solvent in a similar manner. When the sump flushing process occurs, the mixing valve 126 is closed, the solvent refill pump 118 is activated, the flushing valve 144 is opened, and the sump pump 168 applies suction through the main return line 166 (and the open return valve 148) to suck the solvent from the sump 164 to the mixing tank 128. The nozzle flushing process can utilize a higher solvent flow rate because the solvent is withdrawn from the side port 173 rather than from the sump 164 (the sump 164 has a smaller cross-sectional area and thus limits the flow rate of the fluid passing through it). The nozzle flushing process utilizes a solvent jet ejected from the nozzle 134, which is cleared by the sump 164 and the sump pump 168. Advantageously, providing the printhead with multiple fluid lines (e.g., the purge line 172 and the main return line 166) means that different cleaning processes can be performed as required. It should be understood that considering the passage of the solvent through the nozzle 134, the sump flushing process can also clean the nozzle 134 to some extent.

[0151] Another line connected to the mixing tank 128 is the exhaust line 174. The exhaust line 174 is connected to the mixing tank 128 via an exhaust filter 176. The exhaust line 174 passes through the fourth quick disconnect connector 158 of the array 150 of quick disconnect connectors. The exhaust line 174 leads into the printhead to provide pressure relief for the air sucked into the mixing tank 128 via the sump pump 168. By discharging into the printhead, the loss of solvent from within the mixing tank 128 is relatively lower than the case where the exhaust line 174 discharges to the atmosphere. This is because the printhead defines a substantially enclosed volume in which the air is saturated with solvent vapor.

[0152] The fluid circuit 100 offers many advantages over known fluid circuits of CIJ printers. First, there is no incorporated ink heater, which reduces the heat generated within the printer body. This is particularly advantageous considering the relatively compact and small volume nature of the printer according to embodiments of the present invention (as will be described in detail below). The solvent refill pump 118 and the ink refill pump 120 are small and precise diaphragm pumps that respectively pump and measure the solvent and the ink. Thus, the pumps 118, 120 can respectively provide feedback (e.g., passive feedback) regarding the levels of solvent and ink usage. That is, the number of actuations of the pumps 118, 120 indicates the volume of fluid pumped across the pumps 118, 120. The presence of the "separate" sump pump 168 in combination with the ink pump 130 means that there is no need for a venturi tube to draw the ink / air / solvent mixture from the sump 164 back into the mixing tank 128 (as is typically the case in prior art fluid circuits). This results in a significant reduction in the heat generated within the printer body, at least because the ink pump 130 would otherwise have to pump up to approximately 100 times the volume of ink actually required for printing in order to generate the necessary sump suction with the help of the venturi tube.

[0153] Although not shown in Figure 2 , the various components of the fluid circuit 100 and more generally other components of the printer are controlled by a controller (labeled 6 in Figure 1 ). The controller receives signals from various sensors within the printer and is operable to provide appropriate control signals to the components of the fluid circuit 100 (e.g., the solvent refill pump 118 and the ink refill pump 120, the ink pump 130, the sump pump 168, an array of valves 141) to control the flow of ink and solvent through the printer. The controller can be any suitable device known in the art and generally includes at least a processor and a memory.

[0154] Turning to Figure 3 , a perspective view of a printer 200 according to an embodiment of the present invention is provided. The printer 200 includes a printer body 202 and a print arm 204. Figure 3 The printer 200 shown in Figure 1 generally corresponds to the schematic diagram of the printer 1 shown in

[0155] The printer body 202 houses an ink system, the components of which are generally bounded by the Figure 2 frame 102. For example, the printer body 202 houses (referring to Figure 2 ) the ink cartridge 108, pumps (e.g., the ink pump 130), the mixing tank 128, and various fluid conduits (e.g., the main supply line 132 and the main return line 166) extending therebetween. Although not shown in Figure 3shown, but the printer body 202 also houses a controller. The controller receives signals from various sensors within the printer 200 and is operable to provide appropriate control signals to components of the printer 200 to control the flow of ink and solvent through the printer 200.

[0156] The print arm 204 includes a print head support arm 206 and a print head 208. The print head support arm 206 is pivotally connected to the printer body 202 about a rotatable coupler ( Figure 3 not visible in). Accordingly, the print head support arm 206 and the print arm 204 can more generally rotate relative to the printer body 202 about a print head rotation axis 210. The arrow 212 indicates the direction of rotation in which the print arm 204 can rotate.

[0157] Advantageously, the print head 208 is pivotally connected to the printer body 202, meaning that the rotational position of the print head 208 can be adjusted relative to the printer body 202 to a plurality of different rotational configurations. This provides greater flexibility in the position of the print head 208 relative to the external substrate on which printing occurs. The print head 208 is preferably rotatable about the print head rotation axis 210 through a range of approximately 270°. The degree of rotation of the print head 208 can be limited to approximately 270° about the print head rotation axis 210 to avoid damage to the electrical / fluid conduits extending between the printer body 202 and the print head 208. However, in other embodiments, the print head 208 can rotate about the print head rotation axis 210 by more than approximately 270°.

[0158] During a printing operation, the print head rotation axis 210 is preferably horizontal. The vertical position at which printing occurs on the external substrate can be adjusted by adjusting the rotational position of the print head 208. The horizontal position at which printing occurs can be controlled by adjusting the printing timing on the associated print line.

[0159] The print head 208 can be removed from the print head support arm 206. Specifically, the print head 208 can be described as removably engaging the print head support arm 206. The print head 208 can be removed by snap-fit connection or other detachable connection. Specifically, as Figure 3 shown, the print head 208 can be removed from the tiltable portion 214 of the print head support arm 206.

[0160] The tiltable portion 214 of the support arm can be tilted about a tilt axis 216. Due to the connection of the print head 208 to the tiltable portion 214, the print head 208 can also be tilted about the tilt axis 216. The tilt axis 216 can be described as a print head tilt axis. The tilt axis 216 is parallel to the inkjet holes of the print head 208 ( Figure 3An inkjet axis 218 defined (not shown in [the figure]) is provided. Arrow 220 indicates the relative direction of rotation (i.e., tilting) of the printhead 208 and the tiltable portion 214 of the printhead support arm 206 relative to the non-tiltable portion 220 of the printhead support arm 206. The printhead 208 and the tiltable portion 214 of the support arm 204 can tilt up to approximately ±20° relative to the non-tiltable portion 220 of the printhead support arm 206 (and the printer body 202) about the tilt axis 216. The tilt axis 216 is preferably substantially orthogonal to the printhead rotation axis 210. The printhead rotation axis 210 is generally orthogonal to the inkjet axis 218.

[0161] Advantageously, being able to tilt the printhead 208 relative to the printer body 202 can compensate for any tilt of the printed pattern that might otherwise result from the external substrate moving past the printhead 208 at a certain speed. The tiltable nature of the printhead 208 thus facilitates printing onto high-speed printing lines or onto tilted lines, where otherwise the printed characters might be distorted. However, in other embodiments, the printhead 208 may not tilt relative to the printer body 202.

[0162] Figure 3 The printer body 202 is also shown to include a printhead recess 222. The printer 200 can be placed in a stowed configuration where the print arm 204 is rotated such that the printhead 208, and more generally the print arm 204, is received in the printhead recess 222. Advantageously, this means that when the printer 200 is in the stowed configuration, the overall footprint of the printer 200 is reduced. Additionally, when the printer 200 is in the stowed configuration (which is desirable, for example, when the printer 200 is in transit), the printhead 208 is better protected. For completeness, as Figure 3 shown, the printer 200 is in the deployed (i.e., print-ready) configuration where the printhead 208 is not received within the printhead recess 222. In the deployed configuration (where there can be multiple different examples of the deployed configuration), the printhead 208 generally faces away from the printer body 202 such that the inkjet axis 218 can be angled towards the external substrate on which printing is to be performed.

[0163] Moving on to Figure 4 a perspective view of the printer 200 in an alternative configuration is provided. In Figure 4 it, the printer 200 is shown in the stowed configuration where the printhead 208 and more generally the print arm 204 are received within the printhead recess 222 of the printer body 202. The print arm 204, as well as the printhead 208, are nested within Figure 4Within the printhead recess 222 of the printer body 202. Thus, the printhead 208 and the print arm 204 can be described as nestable within the printhead recess 222. The print arm 204 nested within the printhead recess 222 can alternatively be described as the print arm 204 being fully contained within the main coverage area defined by the printer body 202 (i.e., the volume defined by the printer body 202 in the absence of the printhead recess 222).

[0164] In the stowed configuration (i.e., as Figure 4 shown), the printer 200 can be substantially box-shaped or cubic. The approximate dimensions of the printer 200 in the stowed configuration and the approximate dimensions of the box shape can be in the range of 0.35 m × 0.2 m × 0.085 m. The volume of the printer 200 can be less than approximately 0.01 m 2 , and more preferably less than approximately 0.006 m 2 . Thus, the printer 200 is significantly more compact than existing CIJ printers.

[0165] In Figure 4 the stowed configuration shown, the printhead 208 can be substantially sealed for ease of cleaning or other maintenance. In some embodiments, the outer end face of the printhead 208 can contact (e.g., interfere with) the sealing surface 223 of the recess 222 to provide a seal. It is desirable to be able to clean / maintain the printhead 208 when the printhead 208 is in the stowed configuration, and more generally, to be able to clean / maintain the printer 200, at least because initial splashing of the printhead 208 (e.g., due to pressure differences within the ink system) can be avoided at startup. That is, undesirable ink / solvent ejection from the printhead 208 can be avoided, which otherwise risks contaminating the associated print line. It should also be understood that the printer 200 can be powered on, and any pre-print cycle (e.g., cleaning cycle) can be run with the printhead 208 in the stowed configuration. Briefly returning to Figure 2 , the vent line 174 facilitates a "sealed" startup of the printer 200, through which air carrying solvent can be drawn from the mixing tank 128 into the printhead 208. This is because the mixing tank 128, the reflux line 166, the exhaust line 174, and the printhead form various closed loops, allowing pressure equilibrium within the system without using "fresh" external air (which would otherwise result in increased solvent use due to not being loaded with solvent).

[0166] Moving on to Figures 5 to 7 , perspective views of the print arm 204 and the printhead 208 in three different rotational positions are provided.

[0167] From Figure 5Beginning, although not described in conjunction with any drawings so far, the print head 208 includes an ink jet orifice 224. As the name indicates, this is an opening through which ink droplets to be printed on an external substrate are ejected. The ink jet orifice 224 also defines an ink jet axis 218. In the Figure 5 shown rotary configuration which is a first example of an extended configuration, the ink jet orifice 224 faces in the same direction as the first major face 226 of the printer body 202. In contrast, in Figure 7 , the ink jet orifice (although not visible in Figure 7 ) faces in the same direction as the second major face 228 of the printer body 202. Figure 5 The configuration of the print arm 204 shown in Figure 4 can alternatively be described as being rotated approximately 90° from the retracted configuration shown in Figure 7 , while the configuration of

[0168] can be described as an alternative and opposite 90° rotation from the retracted configuration. Figure 6 , in this further extended configuration, the ink jet orifice 224 directly faces away from the print head recess 222 of the printer body 202. The ink jet axis 218 is also marked in Figure 6 and is shown as being generally parallel to the first major surface 226 and the second major surface 228 of the printer body 202.

[0169] To avoid doubt, printing can occur when the printer 200 is in any of the extended configurations shown in Figures 5 to 7 . Additionally, printing can occur when the printer 200 (specifically its printer body 202) is positioned such that either the first major surface 226 or the second major surface 228 is substantially horizontal, or substantially vertical, or at any position between them (e.g., inclined). For example, the first major surface 226 or the second major surface 228 can be placed on a support surface. Alternatively, the face 230 of the printer 200 that is away from the print arm 204 (which can be referred to as the base) can be placed on a support surface (e.g., as shown in Figure 3 ). Regardless of the orientation of the printer body 202, the print head rotation axis 210 is preferably substantially horizontal during the printing operation.

[0170] Figure 8 is an exploded view of the components of the printer 200 that form a rotatable coupling (e.g., between the printer body 202 and the print head Figure 8 not shown in Figure 8 shows a part of the printer body 200, the print head support arm 206, the disk 236, and the collar 238. The print head rotation axis 210 is also schematically shown. In the illustrated embodiment, the rotatable coupling can be described as a ratchet rotary joint.

[0171] When assembled, the disk 236 is coupled to the printhead support arm 206 such that the printhead support arm 206 and the disk 236 are rotationally fixed relative to each other. The disk 236 can be received by the aperture 240 of the printer body 202. Then the collar 238 is coupled to the disk 236. The disk 236 and the collar 238 (and the printhead support arm 206) are thus axially constrained within the aperture 240 about the printhead rotation axis 210. The teeth of the collar 238 (not visible in Figure 8 but labeled 242 in Figure 9 ) engage the ratchet profile 244 (e.g., a groove) of the aperture 240. Thus, the disk 236 and the collar 238 and the printhead support arm 206 can be incrementally rotated relative to the printer body 202 about the printhead rotation axis 210.

[0172] Turning to Figure 9 , a perspective view of the components of Figure 8 when assembled is provided. Thus, Figure 9 shows the rotatable coupler 248. Figure 9 Shows the teeth 242 of the collar 238 engaging the ratchet profile 244 of the aperture 240 of the printer body 202. As described above, this provides incremental rotation of the printhead support arm 206 about the printer body 202, as indicated by the arrow 212.

[0173] Finally, three ducts 250, 252, 254 are also shown extending through the disk 236 (and thus more generally through the rotatable coupler 248). These ducts extend between the printer body 202 and the printhead (when the printhead is mounted on the printhead support arm 206). An additional fourth duct also extends between the printer body 202 and the printhead but is not shown in Figure 9 . The fourth duct is for air / vapor.

[0174] Figure 10 is an exploded view of the components of the printer 200 that provides a tilting function (e.g., between the tiltable portion 214 and the non-tiltable portion 220 of the printhead support arm 206). Figure 10 Shows the tiltable portion 214 of the printhead support arm 206, the non-tiltable portion 220 of the printhead support arm 206, the indexer 256, and the alignment plate 258. The tilt axis 216 is also shown schematically.

[0175] When assembled, the indexer 256 is coupled to the non-tilting portion 220. In the illustrated embodiment, this is accomplished by three alignment holes (through which fasteners can be received) for each of the indexer 256 and the non-tilting portion 220, one marked 264 on the indexer 256 and 266 on the non-tilting portion 220. When assembled, the alignment plate 258 is coupled to the tiltable portion 214. The indexer 256 is held between the alignment plate 258 and the tiltable portion 214. The alignment plate 258 is held between the indexer 256 and the non-tilting portion 220. Relative rotation between the indexer 256 and the alignment plate 258 provides the tilting function about the tilt axis 216. Engagement of the protrusions 260 (e.g., teeth) of the indexer 256 with the ratchet profile 262 (e.g., grooves) on the alignment plate 258 provides incremental tilting of the alignment plate 258 relative to the indexer 256, and thus incremental tilting of the tiltable portion 214 relative to the non-tilting portion 220. Tilting can occur in increments of approximately 2° or approximately 2.5°.

[0176] Figure 11 The alignment plate 258 is shown isolated from the side thereof adjacent to the non-tilting portion 220. The first and second tracks 272, 274 are visible, which receive corresponding lugs of the indexer 256 to limit rotation or tilting of the alignment plate 258 relative to the indexer 256. The third track 276 receives a boss in which a hole 266 is defined therethrough. The tilt axis 216 is also schematically shown. The tilt axis 216 is defined by the first through third tracks 272, 274, 276. One of four holes is also marked, which is configured to receive a fastener therethrough to couple the alignment plate 258 to the tiltable portion 214.

[0177] Figure 12 An exploded view of a subassembly including the indexer 256, the alignment plate 258, and the non-tilting portion 220 is shown. Figure 12 The subassembly is shown from the perspective of the tiltable portion 214. Figure 12 The protrusions 260 of the indexer 258 engaging the ratchet profile 262 of the alignment plate 258 are also shown.

[0178] Figure 13 The subassembly is shown from the opposite side. The first and second lugs 278, 280 of the indexer 258 are shown received in the first and second tracks 272, 274, respectively. The boss 282 forming part of the non-tilting portion 220 is shown received in the third track 276.

[0179] Figure 14 is a perspective cross-sectional view of the subassembly, where the tiltable portion 214 is aligned with the non-tilting portion 220 about the tilt axis 216. The protrusions 260 of the indexer 256 engage the central portion of the ratchet profile 262.Figure 15 is a perspective cross-sectional view of a sub-component, in which the tiltable portion 214 is tilted relative to the non-tiltable portion 220 about the tilt axis 216. The protrusion 260 of the indexer 256 engages a non-central portion of the ratchet profile 262.

[0180] Figure 16 is an end cross-sectional view of a sub-component, in which the tiltable portion 214 is tilted relative to the non-tiltable portion 220 about the tilt axis 216.

[0181] A method of using the printer 200 may include positioning the printer body 202 relative to a target printing location (such as an external substrate). The method may also include rotating the print head 208 about the print head rotation axis 210 (e.g., optionally by rotating the print arm 204) to align the inkjet orifice 224 with the target printing location.

[0182] Rotating the print head 208 relative to the printer body 202 may cause the printer 200 to transition from a stowed configuration (e.g., as Figure 4 shown) to a deployed configuration (e.g., Figure 3 and Figures 5 to 7 ), in which, in the stowed configuration, the print head 208 is received in the print head recess 222, and in the deployed configuration, the inkjet orifice 224 faces away from the printer body 202. After printing, the print head 208 may be rotated relative to the printer body 202 to transition the printer 200 to the stowed configuration (e.g., Figure 4 ), in which the print head 208 is received in the print head recess 222.

[0183] The printer 200 may include one or more position detectors (e.g., the first position detector 11 and the second position detector 12 shown in Figure 1 ). One or more position detectors may be configured, for example, to detect the relative orientation (e.g., rotational position and / or tilt angle) between two components of the printer 200. For example, the relative orientation of the print arm 204 (optionally, its print head 208) relative to the printer body 202. One or more position detectors may be configured, for example, to detect the absolute orientation of one or more components in space (e.g., which orientation the printer body 202 is in), rather than the relative orientation between two components. The printer body 202 and / or the print arm 204 or its sub-components (e.g., the print head 208 and / or the print head support arm 206) may include one or more position detectors. For example, the rotatable coupling between the printer body 202 and the print arm 204 may include a position detector.

[0184] The position detector can be a rotary encoder or a sensor capable of detecting a rotational position and transmitting a signal indicative of the (relative) rotational position. The position detector can be an accelerometer. One or more position detectors can be configured to detect, for example, whether the printer 200 is in a stowed configuration or a deployed configuration. Optionally, one or more position detectors can be configured to detect which of a plurality of different deployed configurations the printer 200 is in. A position detector configured to detect a rotational position can be referred to as a rotational position detector.

[0185] The position detector can be incorporated in one or more of the print head 208, the tiltable portion 214 of the print head support arm 206, the non-tiltable portion 220 of the support arm 206, the printer body 202, and the rotatable coupler. The position detector can be configured to detect the relative tilt angle of the print head 208 with respect to the non-tiltable portion 220 of the print head support arm 206. The position detector can be referred to as a tilt position detector.

[0186] One or more position detectors incorporated in the printer 200 can alternatively or in combination be configured to detect the orientation of the printer body 202 and thus, more generally, the orientation of the printer 200. Such a position detector can be referred to as a printer orientation detector. For example, referring to Figure 6 , one or more position detectors can be configured to detect whether the printer 200 is supported by the first major surface 226, the second major surface 228, or the face 230. Thus, one or more position detectors can indicate whether the printer 200 is in a horizontal configuration (e.g., as Figures 5 to 7 illustrated) or in a vertical configuration (e.g., as Figure 3 illustrated). One or more printer orientation detectors can be accelerometers. In combination with a rotational position detector, which indicates the rotational position of the print arm 204 and thus the print head 208 with respect to the printer body 202, a combination of position detectors (e.g., at least one rotational position detector and at least one printer orientation detector) can thus be configured to indicate which deployed configuration the printer 200 is in (e.g., capable of directly distinguishing between the deployed configurations shown in Figures 5 to 7 ).

[0187] An accelerometer can be incorporated to provide a global baseline of the position of the printer 200 in space. For example, a rotary encoder can be used to detect the relative positions of the print arm 204 and the print head 208 with respect to the printer body 202 (or any other component that can rotate about an axis relative to another component). Thus, the combination of the accelerometer and the rotary encoder can be used to determine the position of the print arm 204 and, thus, the position of the print head 208. Alternatively, the accelerometer can be incorporated in any component that senses a position of interest (e.g., one or more of the print head 208, the tiltable portion 214 of the print head support arm 206, the non-tiltable portion 220 of the support arm 206, the printer body 202, and the rotatable coupler).

[0188] One or more of the above-mentioned position detectors can form part of a method 300 for controlling the printer 200, as schematically indicated by Figure 17 In a first step 302 of the method, data indicating the position of the print head 208 is generated. The data in step 302 relates to the current position of the print head 208. The position of the print head 208 can be indicated by a signal output by a position sensor (such as a rotary encoder or an accelerometer). As described above, the position can be the relative position of the print head 208 with respect to the printer body 202 (e.g., using a rotary encoder), or can be the absolute position of the print head 208 in space (e.g., using an accelerometer).

[0189] Then, at step 304, the data indicating the position of the print head 208 is compared with reference data indicating a reference position of the print head 208. The reference position of step 304 can be the rotational position of the print head 208 in the last or a preset print configuration. Thus, the reference data can indicate the position of the print head when it was last used for printing, or the position of the print head for printing on a given external substrate. The reference data can indicate the position of the print head 208 before the printer 200 is placed in a stowed configuration so that the print head 208 can be cleaned.

[0190] At step 306, the data indicating the position of the print head 208 is compared with the reference data indicating the reference position of the print head 208. In other words, a comparison is made as to whether the print head 208 is in the correct position (the correct position is determined based on the reference data).

[0191] If the printhead 208 is in the correct position, as shown by line 308, then a signal is output at step 310 to indicate that the printhead is in the correct position. The output can be communicated to the operator via a user interface (e.g., a graphical user interface). Printing can be started when the printhead 208 is in the correct position. In other words, step 310 can correspond to the printer being in a print-ready configuration. Step 310 can indicate that the printhead 208 has returned to its previous correct position before the printhead 208 is cleaned.

[0192] If the printhead 208 is not in the correct position, as shown by line 312, then a signal is output at step 314 to indicate that the printhead 208 is not in the correct position. In other words, the output signal indicates the difference between the position of the printhead 208 and the reference position. Examples of the printhead 208 not being in the correct configuration include the printhead 208 being in a retracted configuration instead of an extended configuration, and being in an incorrect extended configuration (e.g., having Figure 5 the configuration shown, as opposed to Figure 6 the configuration shown). Step 314 can correspond to the printer not being in a print-ready configuration. Step 314 also preferably indicates to the user the adjustments required to place the printhead 208 in the correct position. For example, at step 314, the operator can be notified via the user interface (e.g.) that the printhead 208 needs to be rotated in a specific direction to transition the printhead 208 towards the print-ready configuration.

[0193] At step 316, the operator adjusts the printhead 208 in response to the signal output at step 314 indicating that the printhead 208 is not in the correct position. For example, the operator can rotate the printhead 208 in a first rotational direction relative to the printer body 202. The adjustment made at step 316 is preferably notified by the signal output at step 314. For example, step 314 can indicate to the operator that the printhead 208 should be rotated in the first rotational direction towards the correct position. Accordingly, the operator manually rotates the printhead 208 in the suggested first rotational direction. Thus, step 314 can be described as guiding the operator to adjust the printhead 208 as needed.

[0194] After step 316, the method returns to step 302, where data indicating the position of the printhead 208 is generated. Method 300 thus loops in an iterative manner until the printhead 208 is placed in the correct position and the printer 200 is thus in a print-ready configuration.

[0195] Method 300 can be described as a method of returning printer 200 to a pre-clean configuration. Method 300 is advantageous because after printer 200 has been cleaned (and thus the print head 208 has been adjusted relative to the printer body 202), printer 200 can effectively recall the previous print configuration, so that the operator can easily return printer 200 to the print configuration.

[0196] It should be understood that the reference data of step 304 can be adjusted by the operator during use. For example, the operator can manually set the correct printing position of the print head, thereby generating corresponding reference data.

[0197] For a variety of reasons, it is advantageous for print head 208 to be rotatably connected to printer body 202. First, print head 208 and the associated inkjet orifices and inkjet axes can be adjusted relative to printer body 202 such that printing occurs at the correct location on the external substrate. In addition, a print head support (e.g., a bracket) that is separate from the corresponding support for the printer body can be eliminated while still providing convenient adjustment of print head 208 relative to printer body 202.

[0198] Another advantage of pivotally connecting print head 208 to printer body 202 is that the fluid conduits (e.g., main supply line 132 and main return line 166, as Figure 2 shown) that fluidly couple print head 208 to the ink system can be made relatively shorter than prior art arrangements.

[0199] As previously mentioned, in prior art arrangements, the print head is typically connected to the printer body via an umbilical cable that is at least about 2 m in length and can be up to about 8 m in length to allow the printer body to be spaced apart from the print head. However, a disadvantage of these known arrangements is that the long umbilical cable and thus the fluid conduits that extend through the umbilical cable place significant strain on the pump in driving ink and / or solvent to the print head and returning unprinted ink via the return line (e.g., sucking / siphoning a mixture of unprinted ink, air, and solvent from the sump back into the mixing tank). Due to the length of the conduits, a relatively high air flow is required through the fluid conduits to ensure that all of the ink returns from the sump and no ink remains in the fluid conduits from the sump. In addition, at any given time, a relatively high volume of ink is contained within the ink supply line, and thus during a flushing process (e.g., at printer startup or priming after printing), a relatively high volume of ink must be flushed through the ink supply line.

[0200] In a preferred embodiment, (refer to Figure 2) The length of the first portion 166a of the main return line 166 is at most 1 meter. The pressure drop between the sump 164 and the sump pump 168 is relatively low (e.g., compared to the pressure drop in known arrangements), so less flow is required to purge the sump 164 and the first portion 166a of the main return line 166. As a result, the use of solvent is reduced.

[0201] In a preferred embodiment, by limiting the length of the fluid conduit that fluidly connects the print head to the ink system to no more than about 1 meter: i) the volume of ink contained in the main supply line is reduced, thus reducing the volume of ink that needs to be flushed during a flushing cycle (e.g., when priming the printer at startup); and ii) the pumping work required by the pump is reduced, resulting in less heat generated in the system and a reduction in the size of various components in the system (e.g., the pump and the printer as a whole).

[0202] In a preferred embodiment, the combined volume of the various portions of the line (including the nozzle 134, which extends between the feed valve 142 and the nozzle 134) and the side port 173 and the purge valve 146 is no greater than about 4 ml. The total volume of these portions of the line can be referred to as the flush volume, since when printing stops (e.g., when the ejection of the ink / solvent mixture through the main supply line 132 stops), this volume of the line needs to be flushed with solvent. By limiting the flush volume, the flushing uses a lower volume of solvent. Thus, compared to other cases, the flushing can be done more quickly and with less solvent.

[0203] Turning to Figure 18 , a schematic view of a printer 500 according to another embodiment is provided. The printer 500 includes a printer body 502 that houses an ink system that shares many common features with the features shown in Figure 2 . The printer 500 also includes a print head 504 that is coupled to the printer body 502 via an umbilical cable 506.

[0204] Although not visible in Figure 18 , a plurality of fluid conduits fluidly couple the print head 504 to the ink system housed within the printer body 502. The fluid conduits include a main supply line 132 and a main return line 166, as shown in Figure 2 . These fluid conduits (i.e., at least the main supply line 132 and the main return line 166) extend along the entire extent of the umbilical 506 and preferably extend beyond the entire extent of the umbilical cable 506 (i.e., in order to reach components within the print head 504 and within the printer body 502 or to extend between components within the print head 504 and within the printer body 502).

[0205] Of particular importance (with reference to Figure 2), the length of the first portion 166a of the main return line 166. The length of the first portion 166a of the main return line 166 is at most 1 meter, which results in advantages such as reduced pumping work and heat generation and reduced air flow, which reduces solvent loss from the ink system. The pressure drop between the sump 164 and the sump pump 168 is relatively low (e.g., compared to known arrangements with relatively long umbilical cables for example), and thus less flow is required to purge the sump 164 and the first portion 166a of the main return line 166. As a result, the use of solvent is reduced. In a preferred embodiment, the length of the first portion 166a of the main return line 166 is preferably less than about 750 mm, more preferably less than about 500 mm. In some embodiments, the length of the first portion 166a of the main return line 166 is at least about 100 mm. The length of the first portion 166a is preferably between about 100 mm and about 500 mm.

[0206] In a preferred embodiment, the length of the plurality of fluid conduits that fluidly couple the printhead 504 to the ink system does not exceed 1 meter. This provides a number of advantages, some of which were elaborated above in connection with the printer 200, including: i) a reduced volume of ink contained in the main supply line, thereby reducing the volume of ink that needs to be flushed during a flushing cycle (e.g., priming the printer at startup); and ii) reduced pumping work required by the pump, resulting in less heat generated in the system and reduced sizing of various components in the system (e.g., the pump and the printer as a whole). The overall size of the printer 500 is also reduced compared to prior art arrangements where the length of the umbilical cable can be, for example, up to about 8 m.

[0207] As described above, the printer body 502 houses an ink system that includes Figure 2 many of the features shown in. However, some differences are provided below. First, assuming the printhead 504 is fluidly coupled to the printer body 502 only via the umbilical cable 506, an array 150 of quick disconnect connectors as shown in Figure 2 is omitted from the fluid circuit. Additionally, although the components defined by the box 104 in Figure 2 represent components that would be disposed within the printhead support arm 206 for the embodiment shown in Figure 3 , in this embodiment, there is no such printhead support arm. Thus, all components defined by the boxes 104 and 106 can be disposed within the printhead 504 in practice, except for the array 150 as described above. Aside from these differences, all of the descriptions provided in connection with the fluid circuit 100 shown in Figure 2 also apply to this embodiment. Additionally, although the printer 500 shown in Figure 18 includes a printhead 504 that is fluidly coupled to the printer body 502 only via the umbilical cable 506, in other embodiments, a rotatable coupling (such asFigure 1 The rotatable coupling shown in ) can be combined with the umbilical cable 506.

[0208] In a preferred embodiment, the length (i.e., range) 508 of the umbilical cable 506 is at most 1 meter. In a preferred embodiment, the flushing volume of the printer 500 does not exceed 4 ml.

[0209] In a preferred embodiment, the length of the umbilical cable 506 is at least about 100 mm. Advantageously, this means that the printer body 502 can be away from the print head 504, where the print head 504 is located near the print line. In other words, in most cases, it has been found that an umbilical cable at least about 100 mm long provides sufficient adjustability of the print head 504 relative to the printer body 502.

Claims

1. A continuous inkjet printer for printing on an external substrate moving past the printer, the printer comprising: A print head, the print head comprising: Nozzles for generating and ejecting a stream of ink droplets for printing; At least one electrode for guiding the stream of ink droplets; and A gutter for receiving ink droplets not used for printing; and An ink system for storing ink and supplying ink to the print head, the ink system including a gutter pump in fluid communication with the gutter; Wherein: The print head is fluidly coupled to the ink system via a plurality of fluid conduits, the plurality of conduits including a main return line; and The portion of the main return line extending between the gutter and the gutter pump has a length of no more than 1 meter.

2. The continuous inkjet printer according to claim 1, wherein, The length of the entire main return line extending between the gutter and the mixing tank is at most 1 meter.

3. The continuous inkjet printer according to claim 1 or 2, wherein, The length of each of the plurality of fluid conduits extending between the ink system and the print head is at most 1 meter.

4. The continuous inkjet printer according to any one of claims 1 to 3, wherein, The portion of the main return line extending between the gutter and the gutter pump has a length of no more than 500 millimeters.

5. The continuous inkjet printer according to any one of claims 1 to 4, wherein, The portion of the main return line extending between the gutter and the gutter pump has a length of at least 100 millimeters.

6. The continuous inkjet printer according to any one of the preceding claims, wherein, The flushing volume of the printer does not exceed 4 ml.

7. The continuous inkjet printer according to any one of the preceding claims, wherein, The printer includes a printer body that houses ink system components including an ink tank and an ink pump.

8. The continuous inkjet printer according to claim 7, wherein, The printer further includes an umbilical cable that couples the print head to the printer body and houses the plurality of fluid conduits.

9. The continuous inkjet printer according to claim 8, wherein, The length of the umbilical cable does not exceed 1 meter.

10. The continuous inkjet printer according to claim 9, wherein, The length of the umbilical cable does not exceed 500 millimeters.

11. The continuous inkjet printer according to claim 9 or 10, wherein, The length of the umbilical cable is at least 100 millimeters.

12. The continuous inkjet printer according to any one of claims 7 to 11, wherein, The print head is pivotally connected to the printer body and is rotatable about a print head rotation axis.

13. The continuous inkjet printer according to at least claims 12 and 8, wherein, The print head is connected to the printer body by the umbilical cable and a rotatable coupler.

14. The continuous inkjet printer according to claim 12, wherein, The print head is supported by the printer body during operation.

15. The continuous inkjet printer according to any one of claims 12 to 14, wherein, The print head rotation axis is substantially horizontal during the printing operation.

16. A continuous inkjet printer according to claim 12 or any preceding claim dependent thereon, wherein, The print head has a deployed configuration for printing and a retracted configuration for storage.

17. The continuous inkjet printer according to claim 16, wherein, The printer body includes a print head recess for receiving the print head in the retracted configuration.

18. A continuous inkjet printer according to claim 7 or any preceding claim dependent thereon, wherein, The print head is connected to a print head support arm that is pivotally coupled to the printer body.

19. The continuous inkjet printer according to claim 18, wherein, The print head is removable from the print head support arm.

20. The continuous inkjet printer according to any one of the preceding claims, further comprising a position detector.

21. The continuous inkjet printer according to claim 20, wherein, The position detector is an accelerometer.

22. A continuous inkjet printer for printing on an external substrate moving past the printer, the printer comprising: A print head, the print head comprising: Nozzles for generating and ejecting a stream of ink droplets for printing; At least one electrode for guiding the stream of ink droplets; and A gutter for receiving ink droplets not used for printing; and An ink system for storing ink and supplying ink to the print head; and A printer body that houses the ink system; Wherein, the print head is pivotally connected to the printer body through a rotatable connector, and the rotatable connector is configured to allow the print head to rotate relative to the printer body about a print head rotation axis.

23. The continuous inkjet printer according to claim 22, wherein, The print head has a deployed configuration for printing and a retracted configuration for storage.

24. The continuous inkjet printer according to claim 22 or 23, wherein, The print head includes ink ejection holes, and ink droplets not captured by the grooves are ejected through the ink ejection holes.

25. The continuous inkjet printer according to claims 23 and 24, wherein, In the retracted configuration, the print head can be oriented such that the ink ejection holes face the printer body.

26. The continuous inkjet printer according to claim 23 and 24 or 25, wherein, In the deployed configuration, the print head can be oriented such that the ink ejection holes face away from the printer body.

27. The continuous inkjet printer according to claim 23 or any one of the dependent claims thereof, wherein, The printer body includes a print head recess for receiving the print head in the retracted configuration.

28. The continuous inkjet printer according to any one of claims 22 to 27, wherein, The print head is connected to a print head support arm, and the print head support arm is pivotally coupled to the printer body.

29. The continuous inkjet printer according to claim 28, wherein, The print head can be removed from the print head support arm.

30. The continuous inkjet printer according to any one of claims 22 to 29, further comprising a position detector.

31. The continuous inkjet printer according to claim 30, wherein, The rotatable connector includes the position detector.

32. The continuous inkjet printer according to any one of claims 22 to 31, wherein, The print head can rotate about the print head rotation axis by approximately 270 degrees.

33. The continuous inkjet printer according to any one of claims 30 and 31, wherein, The position detector is an accelerometer.

34. The continuous inkjet printer according to any one of claims 22 to 33, wherein, The print head can tilt about a print head tilt axis that is substantially orthogonal to the print head rotation axis.

35. The continuous inkjet printer according to claim 34, wherein, The print head tilt axis is parallel to the ink ejection axis.

36. The continuous inkjet printer according to claim 34 or 35, wherein, The print head can tilt by approximately + / - 20 degrees.

37. The continuous inkjet printer according to any one of claims 22 to 36, wherein, The print head rotation axis is substantially horizontal during a printing operation.

38. The continuous inkjet printer according to any one of claims 36 and 37, wherein, The print head is fluidly coupled to the ink system via a plurality of fluid conduits, and the plurality of conduits includes a main return line; and The portion of the main return line that extends between the groove and the groove pump has a length of no more than 1 meter.

39. The continuous inkjet printer according to claim 38, wherein, The flushing volume of the printer does not exceed 4 ml.

40. A method of using a continuous inkjet printer, comprising: Positioning the printer body relative to a target printing position; Rotating the print head relative to the printer body about a print head rotation axis to align the ink ejection holes of the print head with the target printing position.

41. The method of using a continuous inkjet printer according to claim 40, wherein, Rotating the print head relative to the printer body to transition the printer from a retracted configuration, in which the print head is received in a print head recess, to a deployed configuration, in which the ink ejection holes face away from the printer body.

42. The method of using a continuous inkjet printer according to claim 41, wherein, After printing, rotating the print head relative to the printer body to transition the printer to the retracted configuration in which the print head is received in the print head recess.

43. A method of controlling a continuous inkjet printer, comprising: Generating data indicating the position of the print head using a position detector; Comparing the data indicating the position of the print head with reference data indicating a reference position of the print head; and Generating an output indicating the difference between the position and the reference position.

44. The method according to claim 43, further comprising: Adjusting the position of the print head based on the output; and Generating new data indicating the adjusted position of the print head using the position detector; Compare data indicating an adjustment position of the print head with reference data indicating a reference position of the print head; and Generate an output indicating a difference between the position and the reference position.

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