Printhead

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 droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to divert the stream of ink droplets; and a tank configured to receive ink droplets that are not used for printing. The printer also includes an ink system configured to store ink and supply ink to the printhead. The printing head is releasably connected to the ink system through a printing head connecting interface, and the printing head connecting interface comprises a plurality of fluid connectors and a plurality of electric connectors; and the printer is configured to allow the printhead to be removed from the printer, connect the replacement printhead to the printer, and initiate the printing operation for a period of approximately 2 minutes.

Description

Technical Field

[0001] The present invention relates to a continuous inkjet (CIJ) printer and related methods for 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, in which ink droplets for printing are generated as required and when needed; and continuous inkjet (CIJ) printing, in which droplets are generated continuously and only selected droplets are directed towards the substrate, with the other droplets being recycled to the ink system.

[0003] A CIJ printer supplies pressurized ink to a printhead droplet generator, in which a continuous stream of ink emerging from the nozzle is broken up into individual regular droplets by, for example, 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 voltage (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 amount before hitting the substrate, while uncharged droplets proceed without deflection and are collected at a trough from where they are recycled to the ink system. The charged droplets bypass the trough 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 may 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 exactly 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 are determined by the charge applied to the 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 a recovery trough for recycling. This process is cyclically repeated for all strokes of the dot matrix, and subsequently the next character dot matrix is processed.

[0005] Ink is delivered to the printhead under pressure through an ink system, which is typically housed in a sealed compartment of a cabinet that includes a separate compartment for the control circuitry and 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 printhead 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. Ink is supplied from the reservoir to the printhead via a flexible delivery conduit. Unused ink droplets captured by the gutter are recycled to the reservoir via a pump through a return conduit. The flow of ink in each conduit is typically controlled by solenoids 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 by drawing ink and / or solvent from the cartridges as needed.

[0007] CIJ printers are typically operated 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 solvent (such as ink cartridges and mixing tanks), which occupy space within the system and result in a large amount of ink being circulated through the printer. For example, the main pump of an ink supply system can typically circulate approximately 0.5 liters per minute of ink, of which only approximately 2 - 3 milliliters per minute are ejected from the printhead for printing during that time. As a result, the main pump is typically quite large and space-consuming, and the operation of the pump typically generates a significant 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. Consequently, printers, particularly the printer cabinet, tend to be rather large.

[0008] The printhead is typically disposed outside the cabinet. Ink is delivered from the ink supply system to the printhead and is recycled back to the ink supply system via a flexible tube that is bundled together with other fluid tubes and electrical wires to form what is described in the art as an umbilical cable. The printhead must be directly or indirectly coupled to the umbilical cable, and the coupling includes a plurality of fluid connectors and electrical connectors. The printhead can also be fixed to the umbilical cable via a plurality of fasteners. This can result in a large print system that is difficult to maneuver and reposition.

[0009] All non-consumable components of a continuous inkjet printer do have a service time and / or product life where they need to be repaired, maintained, serviced or replaced. Replacement and maintenance of components can lead to undesirable downtime of the printer. Further, if components need to be replaced frequently, a service engineer or technician is required to replace the components of the printer, leading to further downtime of the printer.

[0010] There is a need to provide an alternative continuous inkjet (CIJ) printer that overcomes one or more drawbacks of known systems, whether mentioned herein or otherwise. Summary of the Invention

[0011] According to a first aspect, there is provided a continuous inkjet printer for printing on a moving external substrate passing by the printer, the printer comprising: a print head including: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; and a gutter configured to receive ink droplets not used for printing; and an ink system configured to store ink and supply ink to the print head; wherein: the print head is releasably connected to the ink system via a print head connection interface, the print head connection interface including a plurality of fluid connectors, a plurality of electrical connectors and a self-coupling mechanical interlock.

[0012] The droplet generator may alternatively be described as a nozzle, an orifice of the droplet generator or a jewel. At least some of the ink droplets in the stream of ink droplets may be deflected in operation to apply a printed pattern to the external substrate. That is, the ink droplets may be conductive. The droplet generator may include a nozzle. The stream of ink droplets produced by the nozzle may be produced by shattering a continuous stream of ink using, for example, an oscillating piezoelectric element. The ink droplets may then be directed past a charging electrode where they are given an electric charge and are subsequently directed by another electrode to direct the now charged ink droplets as required. The at least one electrode for directing 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. The at least one electrode may surround a pair of deflection plates. An (lateral) electric field is generated on the plates and the charged ink droplets are deflected by the field by an amount depending on the charge and the electric field.

[0013] The print head connection interface includes the interface between the print head and the printer body, which may include, but is not limited to, the printer body, a print head support arm and an umbilical cable. The print head connection interface may include all features connected to or connected with the printer body, or it may include only some features.

[0014] The ink system may include a plurality of components, including but not limited to a mixing tank, a plurality of pumps, 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.

[0015] The plurality of fluid connectors may include a main supply line connector and a main return line connector. The main supply line connector may be configured to connect to a main supply fluid conduit, which may be described as extending at least from an ink pump to a nozzle. More specifically, the main supply line may extend from the mixing tank to the nozzle. The main return line connector may be configured to connect to a main return line fluid conduit, which may extend at least from the sump to a sump pump, and more preferably from the sump to the mixing tank. Thus, the print head may be described as being fluidly coupled to the mixing tank, the ink pump, and the sump pump when connected to the ink system.

[0016] The plurality of fluid connectors may be non-drip connectors.

[0017] The plurality of electrical connectors may include at least one low voltage connector and at least one high voltage connector. At least one high voltage connector may be an extra high voltage (EHV) connector or an extra high tension (EHT) connector, where the voltage range is 6 - 10 kilovolts. The low voltage connector may comprise a printed circuit board (PCB) connector. Other low voltage connectors may be used, but the PCB connector has the advantages of being rugged and adaptable to changes in connection distance. The PCB connector may include a plurality of independently mounted surface mount technology (SMT) contacts. The low voltage connector may provide a connection with a voltage of about 24V, up to 300V alternating current or up to 300V switched direct current.

[0018] The plurality of electrical connectors may be vertically separated from the plurality of fluid connectors. That is, the plurality of electrical connectors may be vertically above or below the plurality of fluid connectors. It should be understood that the terms vertically above and vertically below do not require directly vertically above or below, and there may be an axial separation in addition to the vertical separation.

[0019] The electrical connection between the connection interface and the ink system can include an early disconnection so that other electrical signals can be powered off in preparation for separating the printhead from the ink system. That is, the electrical connectors can be arranged such that they disconnect before the fluid connectors. In some embodiments, the EHT connectors can be arranged to disconnect first. The disconnection of the electrical connectors can be achieved by the physical arrangement of the connectors (e.g., the electrical connectors can protrude more or less than other connectors). Disconnecting the EHT connectors first can cause other wires and connections to be shut off. For example, the printhead can be arranged such that disconnecting the EHT connectors prevents power from being supplied to other electrical components. In other embodiments, the controller can be arranged to prevent power from being supplied to other wires and connectors if it recognizes that the EHT connectors have been disconnected.

[0020] The term "connection interface" encompasses the area of the printhead that includes fluid connectors and electrical connectors and is arranged for coupling the connectors to complementary connectors of the ink system. The connectors of the connection interface can all be provided on a single face of the printhead. The connectors of the connection interface can be provided on two or more faces of the printhead. The connectors of the connection interface can be provided on parallel but axially spaced faces of the printhead. The fluid connectors and electrical connectors of the connector interface can be "male" connectors that are configured to be received in corresponding "female" connectors; or the fluid connectors and electrical connectors of the connector interface can be "female" connectors that are configured to be received in corresponding "male" connectors. The fluid connectors can include at least one male connector and at least one female connector, and the electrical connectors can include at least one male connector and at least one female connector.

[0021] In some embodiments, the printhead and / or the printhead support arm can include a printhead controller, such as a touchscreen. The printhead controller can be arranged to control the actuation of the components of the printhead and / or the power supply to the components of the printhead. The printhead controller can be in electrical communication with the controller of the continuous inkjet printer.

[0022] The term "self - coupling mechanical interlock" encompasses self - locking mechanical coupling assemblies that can be integrally formed with the printhead. A self - coupling mechanical interlock differs from other mechanical fasteners such as screws and bolts in that it does not require fixing or tightening to secure the locking assembly. The self - coupling mechanical interlock can include a latch and a body mechanism, and the body can be a protruding barb or a clamping arm and a clamping rod. As an example, the latch can be coupled to the wall of the printhead or the wall of the printer, and the corresponding barb can be coupled to the wall of the printer or the printhead respectively. The latch can include a keyhole that is configured to receive and engage the barb. The latch and / or the barb can be biased. Any other suitable type of interlock can be provided. These types of mechanical interlocks are simple and have a high tolerance for low - creep engagement, thus facilitating the quick engagement and release of the interlock.

[0023] By providing a mechanical interlock, the printhead can be quickly and mechanically fixed to the ink system and can equally be quickly released from the ink system. In addition, the provision of the mechanical interlock reduces the likelihood of multiple fluid and / or electrical connectors becoming displaced or disconnected during use. This is particularly important for electrical connectors, where at least one of the electrical connectors can be a high-voltage electrical connector and / or where one of the fluid connectors can be a high-voltage fluid connector. Providing a quick mechanical release mechanism in the form of a mechanical interlock is advantageous as it reduces the downtime in printing when removing and replacing the printhead. The printhead can be removed from the ink system in a single movement.

[0024] The printhead may further include a removable cover, and wherein the removable cover can only be removed from the printhead when the printhead is not connected to the ink system.

[0025] According to a second aspect, there is provided a continuous inkjet printer for printing on an external substrate moving past a printer, the printer comprising: a printhead including: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; a gutter configured to receive ink droplets not used for printing; and a removable cover; and an ink system configured to store ink and supply ink to the printhead; wherein: the printhead is releasably connected to the ink system via a printhead connection interface including a plurality of fluid connectors and a plurality of electrical connectors; and wherein the removable cover can only be removed from the printhead when the printhead is not connected to the ink system.

[0026] The droplet generator may alternatively be described as a nozzle, an orifice of the droplet generator, or a jewel. At least some of the ink droplets in the stream of ink droplets can be deflected in operation to apply a printed pattern to the external substrate. That is, the ink droplets can be conductive. The droplet generator may include a nozzle. The stream of ink droplets produced by the nozzle can be generated by breaking up a continuous stream of ink using, for example, an oscillating piezoelectric element. The ink droplets can then be directed past a charging electrode where they are given an electric charge and are subsequently directed by another electrode to direct the now charged ink droplets as required. At least one electrode for directing the stream of ink droplets can include a zero voltage plate or a negative voltage plate (e.g., a ground plate) and a high voltage (extra-high tension (EHT)) plate. The at least one electrode can surround a pair of deflection plates. An (lateral) electric field is generated on the plates and the charged ink droplets are deflected by the field by an amount depending on the charge and the electric field.

[0027] The ink system can include multiple components, including but not limited to a mixing tank, multiple pumps, ink cartridges, multiple filters, multiple 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 solvent are received through the ink cartridges, and an appropriate mixture is prepared in the mixing tank to prepare for printing. Ink is supplied from the mixing tank to the printhead.

[0028] The multiple fluid connectors can include a main supply line connector and a main return line connector. The main supply line connector can be configured to connect to a main supply fluid conduit, which can be described as extending at least from an ink pump to a nozzle. More specifically, the main supply line can extend from the mixing tank to the nozzle. The main return line connector can be configured to connect to a main return line fluid conduit, which can extend from at least the sump to a sump pump, and more preferably from the sump to the mixing tank. Thus, the printhead can be described as being fluidly coupled to the mixing tank, the ink pump, and the sump pump when connected to the ink system.

[0029] The multiple fluid connectors can be non-drip connectors.

[0030] The multiple electrical connectors can include at least one low voltage connector and at least one high voltage connector. At least one high voltage connector can be an extra high voltage (EHV) connector or an extra high tension (EHT) connector, where the voltage is in the range of 6 - 10 kilovolts. The low voltage connector can include a printed circuit board (PCB) connector. Other low voltage connectors can be used, but the PCB connector has the advantages of being robust and adaptable to changes in connection distance. The PCB connector can include multiple independently mounted surface mount technology (SMT) contacts. The low voltage connector can provide a connection with a voltage of about 24V, up to 300V alternating current or up to 300V switched direct current.

[0031] The multiple electrical connectors can be vertically separated from the multiple fluid connectors. That is, the multiple electrical connectors can be vertically above or below the multiple fluid connectors. It should be understood that the terms vertically above and vertically below do not require directly above or directly below vertically, and there can be an axial separation in addition to the vertical separation.

[0032] The electrical connection between the connection interface and the ink system may include an early disconnection so that other electrical signals can be powered off in preparation for separating the printhead from the ink system. That is, the electrical connectors can be arranged such that they disconnect before the fluid connectors. In some embodiments, the EHT connectors can be arranged to disconnect first. The disconnection of the electrical connectors can be achieved by the physical arrangement of the connectors (e.g., the electrical connectors can protrude more or less than other connectors). Disconnecting the EHT connectors first can cause other wires and connections to be shut off. For example, the printhead can be arranged such that disconnecting the EHT connectors prevents power from being supplied to other electrical components. In other embodiments, if the controller recognizes that the EHT connectors have been disconnected, the controller can be arranged to prevent power from being supplied to other wires and connectors.

[0033] The term "connection interface" encompasses the area of the printhead that includes fluid connectors and electrical connectors and is arranged for coupling the connectors to complementary connectors of the ink system. The connectors of the connection interface can all be provided on a single face of the printhead. The connectors of the connection interface can be provided on two or more faces of the printhead. The connectors of the connection interface can be provided on parallel but axially spaced faces of the printhead. The fluid connectors and electrical connectors of the connector interface can be "male" connectors that are configured to be received in corresponding "female" connectors; or the fluid connectors and electrical connectors of the connector interface can be "female" connectors that are configured to be received in corresponding "male" connectors. The fluid connectors can include at least one male connector and at least one female connector, and the electrical connectors can include at least one male connector and at least one female connector.

[0034] In some embodiments, the printhead and / or the printhead support arm can include a printhead controller, such as a touchscreen. The printhead controller can be arranged to control the actuation of the components of the printhead and / or the power supply to the components of the printhead. The printhead controller can communicate electrically with the controller of the continuous inkjet printer.

[0035] The removable cover can include an orifice, particularly an elongated orifice for ejecting a stream of ink droplets.

[0036] The removable cover prevents access to the components of the printhead during operation, which has the advantage of protecting the features of the printhead from external factors and environmental conditions such as moisture, dust, foreign particles, and extreme temperatures; and also has the advantage of protecting the operator or a third person from contacting the components of the printhead that may have a high voltage (i.e., a voltage that can cause serious injury or death to a person) during operation.

[0037] By being able to remove the cover only when the printhead is not connected to the system, the user or operator is prevented from contacting the high-voltage components during the printing operation, thereby increasing the safety of the printer.

[0038] The safety of the printhead is promoted by making the cover removable only when the printhead is not connected to the ink system, i.e., when there is no fluid or electrical connection between the printhead and the ink system, since the high-voltage parts of the printhead cannot be touched during operation. Additionally, this allows for the quick and safe removal and replacement of individual printheads without the need to remove the removable cover to access, for example, the printhead release screw and then remove the printhead.

[0039] The printhead connection interface may also include a self-coupling mechanical interlock device.

[0040] The mechanical interlock device may be configured to prevent the removal of the printhead unless a safety condition is met.

[0041] That is, the mechanical interlock cannot be released until the safety condition is met. By not allowing the mechanical interlock to be released until the safety condition is met, removal or disconnection of the printhead from the ink system is prevented.

[0042] This can prevent the printhead from being accidentally disassembled from the second support member during printing, in which case printer fluid may inadvertently come into contact with the electrical connectors on the printhead or the second support member.

[0043] The safety condition to be met may include at least one of the following:

[0044] - There is no power transfer between the plurality of electrical connectors;

[0045] - There is no voltage drop across the plurality of electrical connectors;

[0046] - There is no fluid passage between the fluid connectors.

[0047] The printhead connection interface may include a release trigger configured to initiate a release sequence.

[0048] The release sequence may include determining whether the safety condition is met and releasing the mechanical interlock only if the safety condition is met.

[0049] The term release trigger encompasses a release button, a touch screen, or may be implemented by a feature of the printhead such as a button. By providing a release trigger to initiate the release sequence, safe removal of the printhead can occur. For example, actuation of the release trigger may cause all power supply to the electrical components of the printhead to be terminated before the printhead can be disconnected from the printhead support arm.

[0050] In other embodiments, the release trigger may not form part of the printhead connection interface.

[0051] The first step of the release sequence can be to turn off the inkjet. In particular, stop the ink from being ejected from the nozzles of the printhead. Turning off the inkjet can be initiated by the user. For example, the user can engage a release trigger that initiates the release sequence. Activation of the release trigger can cause the inkjet to be turned off. However, for example, if one of the electrical components of the printhead or the printer trips, it can cause the inkjet to be turned off. For example, if the extra-high voltage electrical connector trips. If the inkjet is stopped due to a component or electrical failure, the printer can warn the user. Turning off the inkjet can initiate the release sequence.

[0052] Subsequently, turn off the inkjet. One or more safety checks can be completed. Once the safety checks are completed and thus the safety conditions are met, removal of the printhead can be permitted. Possible safety checks include but are not limited to:

[0053] - Check if the EHT is turned off. This can be achieved by the controller checking that no power is being supplied to the printhead via the EHT connector.

[0054] - Check if the power to the electrical components of the printhead is turned off (except for the solenoid, if there is a solenoid).

[0055] - Check if the ink pump of the printer is turned off.

[0056] - Check if the solvent pump of the printer is turned off.

[0057] - Check if the sump pump of the printer is turned off.

[0058] - Check that the pressure transducer is less than a predetermined pressure. In particular, the pressure can be less than about 0.1 bar.

[0059] - Check if the fluid control valve is closed.

[0060] In embodiments including an electric lock (such as a solenoid), unlocking of the electric lock can be prohibited until the safety conditions are met.

[0061] The continuous inkjet printer can also include an electric lock configured to electrically lock a self-coupling mechanical interlock.

[0062] The term electric lock includes a solenoid, in particular a solenoid release actuator. The printhead can include an electric lock. The electric lock can be arranged to prevent the mechanical interlock device from disconnecting during operation of the printer. As an example, the solenoid release actuator can be actuated to engage with the mechanical interlock device to prevent disengagement of the mechanical interlock device, and when the solenoid release actuator is not engaged with the mechanical interlock device, the mechanical interlock device can only be disengaged and thus permit removal of the printhead.

[0063] The self-coupling mechanical interlock device can include a latch for engaging with a corresponding locking body of the continuous inkjet printer.

[0064] The self - coupling mechanical interlock device can be arranged to provide a quick and secure release of the printhead from the ink system.

[0065] As an example, a latch can be coupled to a wall of the printhead or a wall of the printer, and a corresponding locking body (such as a barb) can be coupled to a wall of the printer or the printhead respectively. The latch can include a keyhole configured to receive and engage the barb. The latch and / or the barb can be biased. Any other suitable type of interlock device can be provided. These types of self - coupling mechanical interlock devices are simple and have a high tolerance for low - creep engagement, thus facilitating the quick engagement and release of the interlock device.

[0066] That is, the printhead can be quickly disconnected from the printer. In particular, the printhead can be quickly disconnected from the umbilical cable or from the printhead support arm. An arrangement allowing for quick disconnection can include that the user or operator only needs to release the mechanical interlock, for example, by actuating a mechanical button and / or an electronic switch, and then allows the user to disconnect the printhead in a single motion (e.g., pulling the printhead away from the printer). The self - coupling mechanical interlock can provide a secure release of the printhead because the self - coupling mechanical interlock can be arranged such that it cannot be disengaged from the ink system without user input (such as the user actuating a button). This is advantageous because it reduces the downtime during printing when removing and replacing the printhead. The printhead can be removed from the ink system in a single motion.

[0067] A continuous inkjet printer can include a controller, and at least one of the plurality of fluid connectors and / or at least one of the plurality of electrical connectors can include a sensor, and the controller can be operable to receive signals from the sensor.

[0068] The signals received by the controller can indicate the status of the connector associated with the sensor. For example, the sensor can be capable of sending a signal indicating whether the valve of the fluid connector is open or closed. Similarly, the sensor can be capable of sending a signal indicating whether power is passing through the electrical connector. The continuous inkjet printer can include a plurality of sensors. Based on the signals received by the controller, the controller can be configured to determine whether a safety condition is met. The controller can be configured to allow the disconnection of the printhead when the safety condition is met. In particular, the controller can be capable of allowing the disengagement of the self - coupling mechanical interlock when the safety condition is met; or when the controller receives a predetermined signal or set of signals. By not being able to release the mechanical interlock and thus disengage the plurality of fluid connectors and electrical connectors until the safety condition is met, it reduces the risk that a user who may be attempting to remove the printhead comes into contact with a live voltage source or connector.

[0069] The self - coupling mechanical interlock can be engaged and released without the use of tools.

[0070] The self - coupling mechanical interlock device can be configured to engage only when a plurality of fluid connectors and a plurality of electrical connectors are engaged with their corresponding connectors of the ink system.

[0071] That is, a user can be able to engage and disengage the self - coupling mechanical interlock using only their hands, without the need to use tools such as screwdrivers, wrenches, etc. In particular, a user can be able to engage and disengage the self - coupling mechanical interlock without using any rotational movement (i.e., without the user having to twist or untwist any mechanical fastening features).

[0072] Without tools, the detachment and engagement of the mechanical interlock device further reduces print downtime when removing and replacing the print head and can reduce the need for a professional maintenance technician to remove and replace the print head.

[0073] This is advantageous because the self - coupling mechanical interlock ensures the engagement of the plurality of fluid connectors and the plurality of electrical connectors with their corresponding connectors of the ink system.

[0074] The distal ends of the plurality of fluid connectors can be offset from the distal ends of the plurality of electrical connectors.

[0075] That is, the distal ends of the plurality of fluid connectors are not in the same plane as the distal ends of the plurality of electrical connectors. This reduces the likelihood of fluid (especially ink or solvent) from the fluid connectors dripping onto the electrical connectors and damaging them.

[0076] Furthermore, arranging the fluid connectors and the electrical connectors on a connection interface, preferably on a single face of the connection interface, or on parallel but axially spaced faces of the connection interface, improves the formation of a secure connection with the complementary connectors of the ink system.

[0077] At least one of the plurality of fluid connectors can include a self - sealing fluid valve for preventing print fluid leakage when the print head is removed.

[0078] The printer can be configured to allow the print head to be removed from the printer and connected to the printer without using any tools.

[0079] The print head can be configured such that ink (or other fluid) does not leak when the print head is disconnected from the ink system. At least one of the plurality of fluid connectors can include a self - sealing valve.

[0080] A continuous inkjet printer may include a self-sealing valve assembly for connecting to a complementary connector of a fluid connector. Positioning the assembly outside the printhead allows for a smaller printhead size. However, the assembly may be otherwise disposed within the printhead. The assembly may be configured to automatically open when the printhead is connected to a second ink system and automatically seal shut when the printhead is disconnected from the ink system. Opening may mean that fluid can flow along a fluid flow path between the ink system and the printhead. Closing may mean preventing fluid from flowing out of the ink system and thus disrupting the fluid path. The assembly may minimize or eliminate fluid leakage when the printhead is removed or disconnected from the ink system.

[0081] In other words, a user or operator of the printer may be able to connect the printhead to the printer using only their hands and, similarly, may be able to remove the printhead from the printer using only their hands. Since no tools are required to, for example, release fasteners, the printhead can be quickly connected to and removed from the printer. Thus, printer downtime is reduced when replacing the printhead.

[0082] The printer may include a printhead support coupled to the ink system, and a printhead connection interface may be supported by components of the printhead support and the printhead.

[0083] The printhead support may be rotatably coupled to the printer.

[0084] The printhead support may be referred to as a printhead support member or as a printhead support arm. That is, the printhead may be indirectly connected to the ink system via one or more insertion components, such as a printhead support arm (e.g., a tiltable or non-tiltable portion of the printhead support arm). The printhead support arm may be pivotally connected to the printer body by a rotatable coupler. The rotatable coupler may be configured to allow the printhead to rotate relative to the printer body about a printhead rotation axis. Alternatively, the printhead support arm may be rigidly fixed to the printer or may be mounted in a printing position. When the printhead support arm is mounted in the printing position, the printhead support arm may be connected to an umbilical cable.

[0085] The printhead support may be pivotally connected to the printer body by a rotatable coupler. The rotatable coupler may be configured to allow the printhead support and thus the printhead to rotate relative to the ink system about a printhead rotation axis.

[0086] A continuous inkjet printer may include a product detection sensor to sense the position of an external substrate.

[0087] The printhead support may include a product detection sensor.

[0088] The product detection sensor may include a sensor beam. The product detection sensor may include one or more lenses. The product detection sensor may be arranged to detect the product / substrate onto which the ink droplets will be printed and may be able to sense the direction and speed of the product. The sensor may be a standard sensor, such as a proximity sensor. The product detection sensor may include a photo sensor (also known as a photocell pair sensor), which may use infrared radiation, or may include a pinhole sensor.

[0089] The product detection sensor placed on the print head support member provides the possibility of a more compact print head. In addition, since the print head does not need to include the product detection sensor, the cost of manufacturing the print head can be reduced.

[0090] The product detection sensor may include a plurality of detection sensors. The product detection sensor may include two sensors. In an embodiment where the product detection sensor includes two sensors, one sensor may be provided on either side of the position where the ink droplets are ejected from the print head.

[0091] The product detection sensor may be provided behind the position or orifice from which the ink droplets are ejected from the print head. This reduces the splashing of ink droplets on the sensor.

[0092] The product detection sensor may be positioned less than about 5 millimeters from the slot. Preferably, the detection area, i.e., the area covered by the product detection sensor 1305, should be 5 mm below the slot. This is so that the product detection sensor 1305 can sense in the area where printing is required.

[0093] When covering the print head, the removable cover can prevent access to the droplet generator, at least one electrode, and the slot.

[0094] The removable cover can be removed from the print head without tools.

[0095] In other words, when the removable cover is removed, access can be obtained to at least one of the droplet generator, at least one electrode, and the slot.

[0096] Providing a removable cover allows easy access to the components of the print head, particularly access to at least one of the droplet generator, at least one electrode, and the slot. This allows easy access to the print head components for repair, maintenance, and replacement, as well as replacement of parts. However, the removable cover protects the components of the print head from external factors and environmental conditions (such as moisture, dust, foreign particles, and extreme temperatures), particularly during the printing operation.

[0097] When the print head cover is removed, the droplet generator, at least one electrode, and the slot are all accessible to the user.

[0098] That is, the user can remove the removable part using only their hands, without the need to use tools such as screwdrivers, wrenches, etc.

[0099] The removable cover may include clips that cooperate with grooves in the printhead in a "clamp and retract" type mechanism. The clips may each have protrusions that mate with and / or abut against steps or step portions within their respective grooves such that when the clips are fully inserted into the grooves, the clips cannot be pulled out of the grooves in a purely linear motion. The user may need to bias (e.g., "clamp") the clips such that the protrusions can overcome the step portions and then can be pulled out of the grooves in a purely linear motion. Thus, the removable cover can be removed from the printhead using a "clamp and retract" type mechanism.

[0100] In other embodiments, the removable cover may be removed only by using a tool. For example, the removable cover may be removed only when an unlocking "key" is inserted into the locking mechanism of the removable cover. The advantage of requiring a tool to remove the cover is that it reduces unauthorized users from removing the cover and thereby reduces unauthorized users from damaging the components of the printhead.

[0101] The printhead connection interface may include mating guide features configured to guide the printhead from a disconnected configuration to a connected configuration.

[0102] The term "mating guide features" includes alignment features or alignment devices. The mating guide features help to provide a quick and easy connection or disconnection of the printhead with the ink system. Corresponding mating guide devices may be provided on the printer, or on a second member, or on a printhead support member, without any difficult alignment.

[0103] The guide features may form part of the printhead connection interface. The advantage of providing the guide features is that it reduces misalignment between the fluid connectors and electrical connectors of the printhead and the corresponding connectors of the ink system. Thereby reducing damage to the fluid connectors and electrical connectors.

[0104] A first guide feature may be provided on the printer, and a second guide feature may be provided on the printhead.

[0105] In particular, the first guide feature may be provided on the printhead support, particularly on the printhead support arm.

[0106] Advantageously, it reduces misalignment between the fluid connectors and electrical connectors of the printhead and the corresponding connectors of the ink system. Thereby reducing damage to the fluid connectors and electrical connectors. Additionally, by providing the guide features on the printer and the second guide features on the printhead, the printhead must be correctly oriented, thereby again reducing misalignment of the corresponding connectors.

[0107] The guiding features can include guide rails or guiding grooves. The term "guide rail" encompasses one or more guide pins or rails for mating with one or more guiding runners or grooves on the printhead surface. The printer can include two guide rails, and the printhead can include two mating guiding grooves. In particular, the printhead support member can include two guide rails. The one or more guide pins or rails and the one or more guiding runners or grooves can be linear. The one or more guide pins or rails can be easily inserted into the one or more guiding runners or grooves and are configured to have a sliding relationship. In this way, the one or more guide pins or rails can slide through the one or more guiding runners or grooves to provide easy connection / disconnection and alignment of the printhead and the second support member. One or more suitable stoppers can be provided in the one or more guiding runners or grooves such that when various electrical connectors and fluid connectors are connected to complementary connectors, the printhead is forced to stop sliding.

[0108] Alternatively, the printhead can include one or more guide pins or rails, and the second support member can include one or more guiding runners or grooves. Alternatively, the alignment means can include any other suitable mechanism that can also have other types of mechanical relationships, for example, the printhead can be rolled into place on the second support member.

[0109] The continuous inkjet printer can further include a printhead support for supporting the printhead, wherein the mating guiding features can be configured to allow only a substantially linear movement of the printhead relative to the printhead support.

[0110] The printhead support can be a printhead support arm. The printhead support arm can include a plurality of fluid connectors and electrical connectors for connection to corresponding connectors of the printhead. The printhead support arm can be rigidly attached to the continuous inkjet printer, or can be provided at the end of an umbilical cable, or can partially define a rotatable and / or tiltable support arm as defined herein. That is, when connecting and disconnecting the printhead, in particular, the electrical connectors and fluid connectors are disconnected from the corresponding connectors of the ink system. The guide rails are configured to allow only linear movement of the printhead. In doing so, lateral and orthogonal movements of the printhead are generally prohibited. This is particularly advantageous at the connection and disconnection points of the printhead because any non-linear connection or disconnection of the fluid connectors and electrical connectors can cause damage to the connectors. Additionally, it also allows for quick connection and disconnection of the printhead because at the connection point, the corresponding electrical connectors and fluid connectors are aligned. Thus, the torque required by the user is limited to one-dimensional movement.

[0111] The guiding features can extend along 75% of the length of the printhead. The guiding features can extend between 75% and 95% of the printhead.

[0112] The length of the printhead should be understood as the length of the printhead on which the guiding features are provided. Since the guiding features extend beyond 75% of the length of the printhead, this further reduces any lateral or orthogonal movement that may occur at the point where the corresponding electrical and fluid connectors are joined.

[0113] The guiding features can include a first guiding region configured to provide coarse guidance, a second guiding region configured to provide fine guidance, and a tapered region between the first and second guiding regions.

[0114] Providing the first coarse guidance facilitates the quick connection of the printhead to the ink system. This is because the user connecting the printhead to the ink system does not need to spend time precisely aligning the guiding features provided on the printhead with the corresponding guiding features on the printer. Instead, the user can roughly align the guiding features of the printhead with the corresponding guiding features of the printer, and as the user moves the multiple fluid and electrical connectors towards the corresponding connectors, the first guiding region allows the user to guide the printhead towards the second guiding region, where the second guiding region ensures that the fluid and electrical connectors of the printhead will be aligned with the corresponding connectors of the printer.

[0115] In addition to providing alignment of the corresponding connectors between the printhead and the printer, the guiding features can also mitigate damage to the connectors by ensuring that the printhead is always provided in the correct orientation, and if in an incorrect orientation, the guiding features cause an offset between the connectors on the printhead and the corresponding connectors of the ink system, such that the user does not inadvertently attempt to connect two non - corresponding connectors.

[0116] The printer can be configured to allow the printhead to be removed from the printer, a replacement printhead to be connected to the printer, and the printing operation to start within a period of approximately 2 minutes.

[0117] The replacement printhead can be the printhead removed from the printer.

[0118] The printing operation can start within a period of approximately 3 minutes. The printing operation can start within a period between approximately 2 minutes and approximately 3 minutes. The printing operation can start within a period between approximately 1 minute and approximately 3 minutes. The printing operation can start within a period between approximately 1 minute and approximately 2 minutes.

[0119] The printer can be configured to allow the print head to be removed from the printer in about 10 seconds or less. That is, within about 10 seconds or less, a user can initiate removal of the print head, and the print head disconnects from the print head support arm. In other words, within about 10 seconds or less, the print head can be removed such that it is not mechanically, electrically, and fluidly connected to the print head support arm. In particular, the print head can be removed within about 10 seconds or less while meeting one or more safety conditions.

[0120] Before removing the print head from the print head support arm, the user can (i) deactivate the electrical locking mechanism in embodiments including an electrical locking mechanism, i.e., move the solenoid from the extended position to the retracted position; and / or (ii) stop supplying power to the components of the print head.

[0121] After removing the print head from the print head support arm, the user can (i) provide a replacement print head, connect the print head connection interface of the replacement print head to the print head support arm, and optionally electrically lock the replacement print head to the print head support arm. Then power can be supplied to the components of the replacement print head, and the printing operation can begin. The printing operation can include ink being ejected from the print head to print on a substrate. The time taken to start the printing operation with the replacement print head can be about 50 seconds.

[0122] A continuous inkjet printer can include a controller; the controller can be arranged to check that no current is supplied to the components of the print head before the print head is disconnected.

[0123] This facilitates safe removal of the print head by relieving the user from removing the print head during the printing operation.

[0124] That is, before allowing the print head to be disconnected, the controller is arranged to check that no current passes through the components of the print head, such as to the charging electrode and / or the deflection plate. It should be understood that if the print head includes an electrical locking device, such as a solenoid, current can still be applied to the solenoid in order to allow actuation of the solenoid.

[0125] It should be understood that the features of the second aspect can be combined with the first aspect, and the features of the first aspect can be combined with the features of the second aspect.

[0126] According to a third aspect, there is provided a print head for a continuous inkjet printer, the print head comprising: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; and a gutter configured to receive ink droplets not used for printing; and wherein the print head is releasably connected to an ink system of a continuous inkjet system via a print head connection interface, the print head connection interface including a plurality of electrical connectors, a plurality of fluid connectors, and a self - coupling mechanical interlock device.

[0127] The print head may include a removable cover, and wherein the removable cover can be removed from the print head only when the print head is not connected to the ink system.

[0128] According to a fourth aspect, there is provided a print head for a continuous inkjet printer, the print head comprising: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; and a gutter and a removable cover, the gutter being configured to receive ink droplets not used for printing; and wherein the print head is releasably connected to an ink system of a continuous inkjet system via a print head connection interface, the print head connection interface including a plurality of electrical connectors and a plurality of fluid connectors, and wherein the removable cover can be removed from the print head only when the print head is not connected to the ink system.

[0129] The print head connection interface may further include a self - coupling mechanical interlock device.

[0130] The self - coupling mechanical interlock device may be configured to prevent removal of the print head unless a safety condition is met.

[0131] The print head connection interface may include a release trigger configured to initiate a release sequence.

[0132] The release sequence may include determining whether the safety condition is met and releasing the mechanical interlock device when the safety condition is met.

[0133] The mechanical interlock device may include a solenoid release actuator.

[0134] When the removable cover covers the print head, the removable cover can prevent access to the droplet generator, at least one electrode, and the gutter.

[0135] The removable cover can be removed from the print head without tools.

[0136] The print head connection interface may include mating guide features configured to guide the print head from a disconnected configuration to a connected configuration.

[0137] The printer may be configured to allow the print head to be removed from the printer, connect a replacement print head to the printer, and initiate a printing operation within a period of about 2 minutes.

[0138] The features of the third aspect may be combined with the first, second, or fourth aspect. The features of the fourth aspect may be combined with the features of the first, second, or third aspect.

[0139] According to a fifth aspect, there is provided a method of operating a continuous inkjet printer for printing on an external substrate moving past the printer, the printer including a printhead and an ink system for storing ink and supplying ink to the printhead, wherein the printhead is removably connected to the ink system; the printhead includes: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; and a gutter configured to receive ink droplets not used for printing; wherein the printhead is removably connected to the ink system by a printhead connection interface, the printhead connection interface including a plurality of fluid connectors, a plurality of electrical connectors, and a self-latching mechanical interlock; the method includes: connecting the plurality of fluid connectors to corresponding connection means of the printer; connecting the plurality of electrical connectors to corresponding connection means of the printer; and engaging the self-latching mechanical interlock to prevent removal of the printhead.

[0140] The printhead may further include a removable cover, and the method may include removing the removable cover when the printhead is not connected to the ink system.

[0141] According to a sixth aspect, there is provided a method of operating a continuous inkjet printer for printing on an external substrate moving past the printer, the printer including a printhead and an ink system for storing ink and supplying ink to the printhead, wherein the printhead is removably connected to the ink system; the printhead includes: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; a removable cover; and a gutter configured to receive ink droplets not used for printing; wherein the printhead is removably connected to the ink system by a printhead connection interface, the printhead connection interface including a plurality of fluid connectors, a plurality of electrical connectors; the method includes: disconnecting the plurality of fluid connectors from corresponding connectors of the printer; disconnecting the plurality of electrical connectors from corresponding connectors of the printer; and removing the removable cover when the printhead is not connected to the plurality of electrical connectors and the plurality of fluid connectors.

[0142] When the printhead connection interface may include a self-latching mechanical interlock, the method may include engaging the self-latching mechanical interlock to prevent removal of the printhead before disconnecting the fluid connectors and the electrical connectors.

[0143] The method may include satisfying a safety condition; releasing the mechanical interlock to allow removal of the printhead.

[0144] A controller may be used to determine that the safety condition is satisfied.

[0145] The printhead connection interface may include a release trigger, and the method may include: actuating the release trigger; initiating a printhead release sequence.

[0146] The printhead release sequence may include:

[0147] - Shut off the inkjet;

[0148] - Check that at least one or more safety conditions are met;

[0149] - Disengage the solenoid;

[0150] - Remove the printhead.

[0151] In some embodiments, the step of checking that at least one safety condition is met may be omitted or may be manually overridden by the user.

[0152] In embodiments that do not include a solenoid, the step of disengaging the solenoid may not be present.

[0153] Removing the removable cover may include clamping and withdrawing the removable cover.

[0154] The method may further include meeting at least one safety condition and removing the removable cover after the safety condition is met.

[0155] A controller may be used to determine that a safety condition is met.

[0156] The printhead connection interface may include mating guide features configured to guide the printhead from a disconnected configuration to a connected configuration, and the method may include: aligning the mating guide features; connecting the plurality of fluid connectors to corresponding connection devices of the printer; connecting the plurality of electrical connectors to corresponding connection devices of the printer.

[0157] The method may further include sliding the printhead toward the printhead support member.

[0158] The method may include: within a period of approximately 2 minutes: removing the printhead from the printer; providing a replacement printhead; connecting the plurality of fluid connectors of the replacement printhead to corresponding connection devices of the printer; connecting the plurality of electrical connectors of the replacement printhead to corresponding connection devices of the printer; resuming the printing operation.

[0159] The printhead may be configured to allow removal from the printer within a period of approximately 10 seconds or less from when one or more safety conditions are met.

[0160] The printhead can be removed in about 10 seconds. The removal of the printhead involves moving the printhead so that multiple fluid connectors and multiple electrical connectors are not engaged with corresponding connectors of the printhead support arm, umbilical cord, etc. The safety checks that are satisfied include checking whether the EHT connector is disconnected and no power is supplied to the printhead, etc., which may be printer-specific. In some embodiments, safety checks may not be required, and a period of 10 seconds or less can start when the inkjet of the printhead stops.

[0161] The features of the fifth aspect can be combined with the features of the first to fourth aspects and the sixth aspect. The features of the sixth aspect can be combined with the features of the first to fifth aspects.

[0162] According to a seventh aspect, there is provided a continuous inkjet printer for printing on an external substrate that moves past the printer, the printer comprising: a printhead including: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; and a gutter configured to receive ink droplets not used for printing; and an ink system configured to store ink and supply the ink to the printhead; wherein: the printhead is releasably connected to the ink system via a printhead connection interface, the printhead connection interface including multiple fluid connectors, multiple electrical connectors; and the printer is configured to allow the printhead to be removed from the printer, a replacement printhead to be connected to the printer, and a printing operation to start within a period of about 2 minutes.

[0163] The droplet generator may alternatively be described as a nozzle, an orifice of the droplet generator, or a jewel. At least some of the ink droplets in the stream of ink droplets can be deflected during operation to apply a printed pattern to the external substrate. That is, the ink droplets can be conductive. The droplet generator can include a nozzle. The stream of ink droplets generated by the nozzle can be produced by breaking a continuous stream of ink using, for example, an oscillating piezoelectric element. The ink droplets can then be directed past a charging electrode where they are given a charge and subsequently directed by another electrode to direct the now charged ink droplets as required. The at least one electrode for directing the stream of ink droplets can include a zero voltage plate or a negative voltage plate (e.g., a ground plate) and a high voltage (extra-high voltage (EHT)) plate. The at least one electrode can surround a pair of deflection plates. An (lateral) electric field is generated on the plates, and the charged ink droplets are deflected by the field depending on the amount of charge and the electric field.

[0164] The ink system can include multiple components, including but not limited to a mixing tank, multiple pumps, cartridges, multiple filters, multiple 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 solvent are received through a cartridge, and an appropriate mixture is prepared in the mixing tank in preparation for printing. Ink is supplied from the mixing tank to the printhead.

[0165] The plurality of fluid connectors may include a main supply line connector and a main return line connector. The main supply line connector may be configured to connect to a main supply fluid conduit, which may be described as extending at least from an ink pump to a nozzle. More specifically, the main supply line may extend from a mixing tank to a nozzle. The main return line connector may be configured to connect to a main return line fluid conduit, which may extend at least from the sump to a sump pump and more preferably from the sump to the mixing tank. Thus, the printhead may be described as being fluidly coupled to the mixing tank, ink pump, and sump pump when connected to an ink system.

[0166] The plurality of fluid connectors may be non-drip connectors.

[0167] The plurality of electrical connectors may include at least one low-voltage connector and at least one high-voltage connector. At least one high-voltage connector may be an extra-high voltage (EHV) connector or an extra-high tension (EHT) connector, where the voltage is in the range of 6 - 10 kV. The low-voltage connector may comprise a printed circuit board (PCB) connector. Other low-voltage connectors may be used, but the PCB connector has the advantages of being rugged and adaptable to variations in connection distance. The PCB connector may include a plurality of independently mounted surface mount technology (SMT) contacts. The low-voltage connector may provide a connection with a voltage of approximately 24V, up to 300V alternating current or up to 300V switched direct current.

[0168] The plurality of electrical connectors may be vertically separated from the plurality of fluid connectors. That is, the plurality of electrical connectors may be vertically above or below the plurality of fluid connectors. It should be understood that the terms vertically above and vertically below do not require directly vertically above or below, and there may be an axial separation in addition to the vertical separation.

[0169] The electrical connection between the connection interface and the ink system may include an early disconnection such that other electrical signals may be powered off to prepare for separating the printhead from the ink system. That is, the electrical connectors may be arranged such that they disconnect before the fluid connectors. In some embodiments, the EHT connector may be arranged to disconnect first. The disconnection of the electrical connectors may be achieved by the physical arrangement of the connectors (e.g., the electrical connectors may protrude more or less than other connectors). Disconnecting the EHT connector first may cause other electrical lines and connections to be shut off. For example, the printhead may be arranged such that disconnecting the EHT connector prevents power from being supplied to other electrical components. In other embodiments, the controller may be arranged to prevent power from being supplied to other wires and connectors if it identifies that the EHT connector has been disconnected.

[0170] The term "connection interface" encompasses the area of the printhead that includes fluid connectors and electrical connectors and is arranged to couple the connectors to complementary connectors of the ink system. The connectors of the connection interface can all be provided on a single face of the printhead. The connectors of the connection interface can be provided on two or more faces of the printhead. The connectors of the connection interface can be provided on parallel but axially spaced faces of the printhead. The fluid connectors and electrical connectors of the connector interface can be "male" connectors configured to be received in corresponding "female" connectors; or the fluid connectors and electrical connectors of the connector interface can be "female" connectors configured to receive in corresponding "male" connectors. The fluid connectors can include at least one male connector and at least one female connector, and the electrical connectors can include at least one male connector and at least one female connector.

[0171] In some embodiments, the printhead and / or the printhead support arm can include a printhead controller, such as a touchscreen. The printhead controller can be arranged to control the actuation of the components of the printhead and / or the power supply to the components of the printhead. The printhead controller can communicate electrically with the controller of the continuous inkjet printer.

[0172] The replacement printhead can be a printhead removed from the printer.

[0173] The printing operation can start within a period of about 3 minutes. The printing operation can start within a period between about 2 minutes and about 3 minutes. The printing operation can start within a period between about 1 minute and about 3 minutes. The printing operation can start within a period between about 1 minute and about 2 minutes.

[0174] The printhead connection interface can include mating guiding features configured to guide the printhead from a disconnected configuration to a connected configuration.

[0175] The term "mating guiding features" encompasses alignment features or alignment devices. The mating guiding features help to provide a quick and easy connection or disconnection of the printhead with the ink system. Corresponding mating guiding devices can be provided on the printer, or on a second member, or on the printhead support member, without any difficult alignment.

[0176] The guiding features can form part of the printhead connection interface. The advantage of providing the guiding features is that it reduces the misalignment of the fluid connectors and electrical connectors of the printhead with the corresponding connectors of the ink system. Thereby reducing damage to the fluid connectors and electrical connectors.

[0177] According to an eighth aspect, there is provided a continuous inkjet printer for printing on an external substrate moving past a printer, the printer comprising: a print head including: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; and a gutter configured to receive ink droplets not used for printing; and an ink system configured to store ink and supply the ink to the print head; wherein: the print head is releasably connected to the ink system via a print head connection interface, the print head connection interface including a plurality of fluid connectors, a plurality of electrical connectors, and mating guide features configured to guide the print head from a disconnected configuration to a connected configuration.

[0178] The droplet generator may alternatively be described as a nozzle, an orifice of the droplet generator, or a gemstone. 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. That is, the ink droplets may be conductive. The droplet generator may include a nozzle. The stream of ink droplets produced by the nozzle may be generated by breaking up a continuous stream of ink using, for example, an oscillating piezoelectric element. The ink droplets may then be directed past a charging electrode where they are given an electric charge and are subsequently directed by another electrode to direct the now charged ink droplets as required. The 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. The at least one electrode may surround a pair of deflection plates. An (lateral) electric field is generated on the plates, and the charged ink droplets are deflected by the field depending on the amount of charge and the electric field.

[0179] The ink system may include a plurality of components, including but not limited to a mixing tank, a plurality of pumps, 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.

[0180] The plurality of fluid connectors may include a main supply line connector and a main return line connector. The main supply line connector may be configured to connect to a main supply fluid conduit which may be described as extending at least from an ink pump to the nozzle. More specifically, the main supply line may extend from the mixing tank to the nozzle. The main return line connector may be configured to connect to a main return line fluid conduit which may extend from at least the gutter to a gutter pump and more preferably from the gutter to the mixing tank. Thus, the print head may be described as being fluidly coupled to the mixing tank, an ink pump, and a gutter pump when connected to the ink system.

[0181] The plurality of fluid connectors may be non-drip connectors.

[0182] Multiple electrical connectors may include at least one low-voltage connector and at least one high-voltage connector. At least one high-voltage connector may be an extra-high voltage (EHV) connector or an extra-high tension (EHT) connector, where the voltage range is 6 - 10 kV. The low-voltage connector may include a printed circuit board (PCB) connector. Other low-voltage connectors may be used, but the PCB connector has the advantages of being robust and adaptable to changes in connection distance. The PCB connector may include a plurality of separately mounted surface mount technology (SMT) contacts. The low-voltage connector may provide a connection with a voltage of about 24V, up to 300V alternating current or up to 300V switched direct current.

[0183] The multiple electrical connectors may be vertically separated from the multiple fluid connectors. That is, the multiple electrical connectors may be vertically above or below the multiple fluid connectors. It should be understood that the terms vertically above and vertically below do not require directly above or directly below vertically, and there may be an axial spacing in addition to the vertical spacing.

[0184] The electrical connection between the connection interface and the ink system may include an early disconnection such that other electrical signals can be powered off to prepare for separating the printhead from the ink system. That is, the electrical connectors may be arranged such that they disconnect before the fluid connectors. In some embodiments, the EHT connector may be arranged to disconnect first. The disconnection of the electrical connectors may be achieved by the physical arrangement of the connectors (e.g., the electrical connectors may protrude more or less than other connectors). Disconnecting the EHT connector first may cause other wires and connections to be closed. For example, the printhead may be arranged such that disconnecting the EHT connector prevents power from being supplied to other electrical components. In other embodiments, the controller may be arranged to prevent power from being supplied to other wires and connectors if it recognizes that the EHT connector has been disconnected.

[0185] The term "connection interface" encompasses the area of the printhead that includes the fluid connectors and the electrical connectors and is arranged to couple the connectors with complementary connectors of the ink system. The connectors of the connection interface may all be provided on a single face of the printhead. The connectors of the connection interface may be provided on two or more faces of the printhead. The connectors of the connection interface may be provided on parallel but axially spaced faces of the printhead. The fluid connectors and the electrical connectors of the connector interface may be "male" connectors that are configured to be received in corresponding "female" connectors; or the fluid connectors and the electrical connectors of the connector interface may be "female" connectors that are configured to be received in corresponding "male" connectors. The fluid connectors may include at least one male connector and at least one female connector, and the electrical connectors may include at least one male connector and at least one female connector.

[0186] In some embodiments, the printhead and / or the printhead support arm may include a printhead controller, such as a touchscreen. The printhead controller may be arranged to control the actuation of the components of the printhead and / or the power supply to the components of the printhead. The printhead controller may be in electrical communication with the controller of the continuous inkjet printer.

[0187] The term "mating guide feature" includes alignment features or alignment means. The mating guide features help to provide a quick and easy connection or disconnection of the printhead to the ink system. Corresponding mating guide means may be provided on the printer, or on a second member, or on the printhead support member, without any difficult alignment.

[0188] The guide features may form part of the printhead connection interface. The advantage of providing the guide features is that it reduces the misalignment of the fluid connectors and electrical connectors of the printhead with the corresponding connectors of the ink system. Thereby reducing damage to the fluid connectors and electrical connectors.

[0189] The printer may be configured to allow the printhead to be removed from the printer, and to connect a replacement printhead to the printer, and for the printing operation to start within a period of about 2 minutes.

[0190] The replacement printhead may be a printhead removed from the printer.

[0191] The printing operation may start within a period of about 3 minutes. The printing operation may start within a period between about 2 minutes and about 3 minutes. The printing operation may start within a period between about 1 minute and about 3 minutes. The printing operation may start within a period between about 1 minute and about 2 minutes.

[0192] The printer may be configured to allow the printhead to be removed from the printer within about 10 seconds or less from when one or more safety conditions are met.

[0193] The removal of the printhead may be performed within about 10 seconds. The removal of the printhead involves moving the printhead such that the multiple fluid connectors and multiple electrical connectors are not engaged with the corresponding connectors of the printhead support arm connection interface, umbilical cable, etc. The safety checks that are met include checking whether the EHT connector is disconnected, no power is supplied to the printhead, etc., which may be printer specific. In some embodiments, safety checks may not be required, and the 10 - second or less period may start when the inkjet of the printhead stops.

[0194] That is, within about 10 seconds or less, the user can initiate removal of the printhead, and the printhead disconnects from the printhead support arm. In other words, within about 10 seconds, the printhead can be removed such that it is not in mechanical, electrical, and fluid communication with the printhead support arm. Within 10 seconds, the solenoid can move from the engaged configuration to the disengaged configuration, and the user can remove the printhead such that it is not in electrical or fluid communication with the corresponding connectors.

[0195] The user can (i) in embodiments including an electrical locking mechanism, disable the electrical locking mechanism, i.e., move the solenoid from the extended position to the retracted position; and / or (ii) stop supplying power to the components of the printhead.

[0196] After removing the printhead from the printhead support arm, the user can (i) provide a replacement printhead, connect the printhead connection interface of the replacement printhead to the printhead support arm, and optionally electrically lock the replacement printhead to the printhead support arm. Power can then be supplied to the components of the replacement printhead, and the printing operation can be started. The printing operation can include ink being ejected from the printhead to print on a substrate. The time taken to provide the replacement printhead and start the printing operation can be about 50 seconds.

[0197] The continuous inkjet printer can include a controller. The controller can be arranged to check that no current is supplied to the components of the printhead before the printhead is disconnected.

[0198] This facilitates safe removal of the printhead by relieving the user of removing the printhead during the printing operation.

[0199] That is, before allowing the printhead to be disconnected, the controller is arranged to check that no current passes through the components of the printhead, such as to the charging electrode and / or the deflection plate. It should be understood that if the printhead includes an electrical locking device, such as a solenoid, current can still be applied to the solenoid to allow actuation of the solenoid.

[0200] A first guiding feature can be provided on the printer, and a second guiding feature can be provided on the printhead.

[0201] In particular, the first guiding feature can be provided on the printhead support, particularly on the printhead support arm.

[0202] Advantageously, misalignment of the fluid connector and the electrical connector of the printhead with the corresponding connectors of the ink system is reduced. Thereby reducing damage to the fluid connector and the electrical connector. In addition, by providing the guiding feature of the printer and the second guiding feature on the printhead, the printhead must be correctly oriented, thereby again reducing misalignment of the corresponding connectors.

[0203] The guiding feature can include a rail or a guiding groove.

[0204] The term "guide rail" encompasses one or more guide pins or rails adapted to cooperate with one or more guide chutes or grooves on the surface of the printhead. The printer may include two guide rails, and the printhead may include two mating guide grooves. In particular, the printhead support member may include two guide rails. The one or more guide pins or rails and the one or more guide chutes or grooves may be linear. The one or more guide pins or rails may be easily inserted into the one or more guide chutes or grooves and are configured to have a sliding relationship. In this way, one or more guide pins or rails can slide through one or more guide chutes or grooves to provide easy connection / disconnection and alignment of the printhead and the second support member. One or more suitable stoppers may be provided in the one or more guide chutes or grooves such that when various electrical connectors and fluid connectors are connected to complementary connectors, the printhead is forced to stop sliding.

[0205] Alternatively, the printhead may include one or more guide pins or rails, and the second support member may include one or more guide chutes or grooves. Alternatively, the alignment means may include any other suitable mechanism that may also have other types of mechanical relationships, for example, the printhead may roll into place on the second support member.

[0206] The continuous inkjet printer may also include a printhead support for supporting the printhead, wherein the mating guide features are configured to allow only a substantially linear movement of the printhead relative to the printhead support.

[0207] The printhead support may be a printhead support arm. The printhead support arm may include a plurality of fluid connectors and electrical connectors for connection to corresponding connectors of the printhead. The printhead support arm may be rigidly attached to the continuous inkjet printer, or may be provided at the end of an umbilical cable, or may partially define a rotatable and / or tiltable support arm as defined herein. That is, when connecting and disconnecting the printhead, in particular the electrical connectors and fluid connectors are disconnected from the corresponding connectors of the ink system. The guide rails are configured to allow only linear movement of the printhead. In doing so, lateral and orthogonal movement of the printhead is generally prohibited. This is particularly advantageous at the connection and disconnection points of the printhead because any non-linear connection or disconnection of the fluid connectors and electrical connectors may cause damage to the connectors. Additionally, it also allows for quick connection and disconnection of the printhead because at the connection point, the corresponding electrical connectors and fluid connectors are aligned. Thus, the torque required by the user is limited to one-dimensional movement.

[0208] The guide features may extend along 75% of the length of the printhead.

[0209] The guide features may extend between 75% and 95% of the printhead.

[0210] The length of the printhead should be understood as the length of the printhead on which the guiding features are provided. Since the guiding features extend beyond 75% of the length of the printhead, this further reduces any lateral or orthogonal movement that may occur at the point of joining the corresponding electrical and fluid connectors.

[0211] The guiding features can include a first guiding region configured to provide coarse guidance, a second guiding region configured to provide fine guidance, and a tapered region between the first and second guiding regions.

[0212] Providing the first coarse guidance helps with the quick connection of the printhead to the ink system. This is because the user connecting the printhead to the ink system does not need to spend time precisely aligning the guiding features provided on the printhead with the corresponding guiding features on the printer. Instead, the user can roughly align the guiding features of the printhead with the corresponding guiding features of the printer, and as the user moves the plurality of fluid and electrical connectors towards the corresponding connectors, the first guiding region allows the user to direct the printhead towards the second guiding region, where the second guiding region ensures that the fluid and electrical connectors of the printhead will be aligned with the corresponding connectors of the printer.

[0213] In addition to providing alignment of the corresponding connectors between the printhead and the printer, the guiding features can also mitigate damage to the connectors by ensuring that the printhead is always provided in the correct orientation, and if in an incorrect orientation, the guiding features cause an offset between the connectors on the printhead and the corresponding connectors of the ink system, such that the user will not inadvertently attempt to connect two non-corresponding connectors.

[0214] The printhead connection interface can include a self - coupling mechanical interlock device.

[0215] The term "self - coupling mechanical interlock" encompasses self - locking mechanical coupling assemblies that can be formed integrally with the printhead. Self - coupling mechanical interlocks differ from other mechanical fasteners such as screws and bolts in that they do not require fixing or tightening to secure the locking assembly. The self - coupling mechanical interlock can include a latch and a body mechanism, where the body can be a protruding barb, or a clamping arm and a clamping rod. As an example, the latch can be coupled to the wall of the printhead or the wall of the printer, and the corresponding barb can be coupled to the wall of the printer or the printhead, respectively. The latch can include a keyhole configured to receive and engage the barb. The latch and / or the barb can be biased. Any other suitable type of interlock can be provided. These types of mechanical interlocks are simple and have a high tolerance for low - creep engagement, thus facilitating the quick engagement and release of the interlock.

[0216] By providing a mechanical interlock, the printhead can be quickly and mechanically fixed to the ink system and can equally be quickly released from the ink system. Additionally, the provision of the mechanical interlock reduces the likelihood of multiple fluid and / or electrical connectors becoming displaced or disconnected during use. This is particularly important for electrical connectors, where at least one of the electrical connectors can be a high-voltage electrical connector and / or one of the fluid connectors can be a high-voltage fluid connector. Providing a quick mechanical release mechanism in the form of a mechanical interlock is advantageous as it reduces the downtime in printing when removing and replacing the printhead. The printhead can be removed from the ink system in a single motion.

[0217] The mechanical interlock device can be configured to prevent removal of the printhead unless a safety condition is met.

[0218] That is, the mechanical interlock cannot be released until the safety condition is met. By not being able to release the mechanical interlock until the safety condition is met, removal or disconnection of the printhead from the ink system is prevented.

[0219] This can prevent the printhead from being inadvertently disassembled from the second support member during printing, in which case printer fluids may inadvertently come into contact with electrical connectors on the printhead or the second support member.

[0220] The safety condition to be met can include at least one of the following:

[0221] - There is no power transfer between the plurality of electrical connectors;

[0222] - There is no voltage drop across the plurality of electrical connectors;

[0223] - There is no fluid passage between the fluid connectors.

[0224] The printhead connection interface can include a release trigger configured to initiate a release sequence.

[0225] The term release trigger encompasses a release button, a touchscreen, or can be implemented by a feature of the printhead such as a button. By providing a release trigger to initiate the release sequence, safe removal of the printhead can occur. For example, actuation of the release trigger can cause all power supply to the electrical components of the printhead to be terminated before the printhead can be disconnected from the printhead support arm.

[0226] In other embodiments, the release trigger may not form part of the printhead connection interface.

[0227] The release sequence can include determining whether the safety condition is met and releasing the mechanical interlock only if the safety condition is met.

[0228] The first step of the release sequence can be to turn off the inkjet. In particular, stop the ejection of ink from the nozzles of the printhead. Turning off the inkjet can be initiated by the user. For example, the user can engage a release trigger that initiates the release sequence. Activation of the release trigger can cause the inkjet to turn off. However, for example, if one of the electrical components of the printhead or the printer trips, it can cause the inkjet to turn off. For example, if the extra-high voltage electrical connector trips. If the inkjet is stopped due to a component or electrical failure, the printer can warn the user. Turning off the inkjet can initiate the release sequence.

[0229] Subsequently, turn off the inkjet. One or more safety checks can be performed. Once the safety checks are completed and thus the safety conditions are met, removal of the printhead can be permitted. Possible safety checks include, but are not limited to:

[0230] - Check if the EHT is turned off. This can be achieved by the controller checking that no power is being supplied to the printhead via the EHT connector.

[0231] - Check if the power to the electrical components of the printhead is turned off (except for the solenoid, if there is a solenoid).

[0232] - Check if the ink pump of the printer is turned off.

[0233] - Check if the solvent pump of the printer is turned off.

[0234] - Check if the sump pump of the printer is turned off.

[0235] - Check that the pressure transducer is less than a predetermined pressure. In particular, the pressure can be less than about 0.1 bar.

[0236] - Check if the fluid control valve is closed.

[0237] In embodiments including an electric lock (such as a solenoid), unlocking of the electric lock can be prohibited until the safety conditions are met.

[0238] The continuous inkjet printer can also include an electric lock that is configured to electrically lock a self-coupling mechanical interlock. The term electric lock includes solenoids, in particular solenoid release actuators. The printhead can include an electric lock. The electric lock can be arranged to prevent the mechanical interlock device from disconnecting during the operation of the printer. As an example, the solenoid release actuator can be actuated to engage with the mechanical interlock device to prevent disengagement of the mechanical interlock device, and when the solenoid release actuator is not engaged with the mechanical interlock device, the mechanical interlock device can only be disengaged and thus allow removal of the printhead.

[0239] The self - coupling mechanical interlock device may include a latch for engaging a corresponding locking body of a continuous inkjet printer. As an example, the latch may be coupled to a wall of the printhead or a wall of the printer, and the corresponding locking body (such as a barb) may be respectively coupled to a wall of the printer or the printhead. The latch may include a keyhole configured to receive and engage the barb. The latch and / or the barb may be biased. Any other suitable type of interlock device may be provided. These types of self - coupling mechanical interlocks are simple and have a high tolerance for low creep engagement, thus facilitating the quick engagement and release of the interlock.

[0240] The self - coupling mechanical interlock may be arranged to provide a quick and secure release of the printhead from the ink system.

[0241] That is, the printhead can be quickly disconnected from the printer. In particular, the printhead can be quickly disconnected from the umbilical cable or from the printhead support arm. An arrangement allowing quick disconnection may include that the user or operator only needs to release the mechanical interlock, for example by actuating a mechanical button and / or an electronic switch, and then allows the user to disconnect the printhead in a single motion (e.g., pull the printhead away from the printer). The self - coupling mechanical interlock can provide a secure release of the printhead because the self - coupling mechanical interlock can be arranged such that it cannot be disengaged from the ink system without user input (e.g., user actuating a button). This is advantageous because it reduces the downtime during printing when removing and replacing the printhead. The printhead can be removed from the ink system in a single motion.

[0242] The self - coupling mechanical interlock can be engaged and released without using tools. That is, the user can be able to engage and release the self - coupling mechanical interlock using only their hands, without the need to use tools such as screwdrivers, wrenches, etc. In particular, the user can be able to engage and release the self - coupling mechanical interlock without using any rotational movement (i.e., without the user having to turn or unfasten any mechanical fixing features).

[0243] Without tools, the disengagement and engagement of the mechanical interlock device further reduce the printing downtime when removing and replacing the printhead and can reduce the need for professional maintenance technicians to remove and replace the printhead.

[0244] The self - coupling mechanical interlock device may be configured to engage only when a plurality of fluid connectors and a plurality of electrical connectors are engaged with their corresponding connectors of the ink system. This is advantageous because the self - coupling mechanical interlock ensures the engagement of the plurality of fluid connectors and the plurality of electrical connectors with the corresponding connectors of the ink system.

[0245] The continuous inkjet printer may further include a controller, and at least one of the plurality of fluid connectors and / or at least one of the plurality of electrical connectors may include a sensor, and the controller may be operable to receive signals from the sensor.

[0246] The signals received by the controller may indicate the status of the connectors associated with the sensors. For example, the sensor may be capable of sending a signal indicating whether the valve of the fluid connector is open or closed. Similarly, the sensor may be capable of sending a signal indicating whether power is passing through the electrical connector. The continuous inkjet printer may include a plurality of sensors. Based on the signals received by the controller, the controller may be configured to determine whether a safety condition is met. The controller may be configured to allow the printhead to be disconnected when the safety condition is met. In particular, the controller may be capable of allowing the release of a self-latching mechanical interlock when the safety condition is met; or when the controller receives a predetermined signal or set of signals. By not being able to release the mechanical interlock and thus disconnect the plurality of fluid connectors and electrical connectors until the safety condition is met, a user who may attempt to remove the printhead is protected from contact with a live voltage source or connectors.

[0247] The distal ends of the plurality of fluid connectors may be offset from the distal ends of the plurality of electrical connectors.

[0248] That is, the distal ends of the plurality of fluid connectors are not located in the same plane as the distal ends of the plurality of electrical connectors. This reduces the likelihood of fluid (especially ink or solvent) from the fluid connectors dripping onto the electrical connectors and damaging them.

[0249] In addition, arranging the fluid connectors and the electrical connectors on a connection interface, preferably on a single face of the connection interface, or on parallel but axially spaced faces of the connection interface, improves the formation of a secure connection with complementary connectors of the ink system.

[0250] At least one of the plurality of fluid connectors may include a self-sealing fluid valve for preventing leakage of the printing fluid when the printhead is removed.

[0251] The printhead may be configured such that ink (or other fluid) does not leak when the printhead is disconnected from the ink system. At least one of the plurality of fluid connectors may include a self-sealing valve.

[0252] A continuous inkjet printer may include a self-sealing valve assembly for connecting to a complementary connector of a fluid connector. Positioning the assembly outside the printhead may allow for a smaller printhead size. However, the assembly may be otherwise disposed within the printhead. The assembly may be configured to automatically open when the printhead is connected to a second ink system and automatically seal closed when the printhead is disconnected from the ink system. Opening may mean that fluid can flow along a fluid flow path between the ink system and the printhead. Closing may mean preventing fluid from flowing out of the ink system and thus breaking the fluid path. The assembly may minimize or eliminate fluid leakage when the printhead is removed or disconnected from the ink system.

[0253] The printer may be configured to allow the printhead to be removed from the printer and connected to the printer without using any tools.

[0254] In other words, a user or operator of the printer may be able to connect the printhead to the printer using only their hands and, similarly, may be able to remove the printhead from the printer using only their hands. Since no tools are required to, for example, release fasteners, the printhead can be quickly connected to and removed from the printer. Thus, printer downtime is reduced when removing and replacing the printhead.

[0255] The printer may include a printhead support coupled to an ink system, and a printhead connection interface may be supported by components of the printhead support and the printhead.

[0256] The printhead support may be referred to as a printhead support member or as a printhead support arm. That is, the printhead may be indirectly connected to the ink system via one or more insertion components, such as a printhead support arm (e.g., a tiltable or non-tiltable portion of the printhead support arm). The printhead support arm may be pivotally connected to the printer body via a rotatable coupler. The rotatable coupler may be configured to allow the printhead to rotate relative to the printer body about a printhead rotation axis. Alternatively, the printhead support arm may be rigidly fixed to the printer or may be mounted in a printing position. When the printhead support arm is mounted in the printing position, the printhead support arm may be connected to an umbilical cable.

[0257] The printhead support may be rotatably coupled to the printer.

[0258] The printhead support may be pivotally connected to the printer body via a rotatable coupler. The rotatable coupler may be configured to allow the printhead support and thus the printhead to rotate relative to the ink system about a printhead rotation axis.

[0259] A continuous inkjet printer may include a product detection sensor to sense the position of an external substrate.

[0260] The product detection sensor may include a sensor beam. The product detection sensor may include one or more lenses. The product detection sensor may be arranged to detect the product / substrate onto which the ink droplets will be printed and may be capable of sensing the orientation and speed of the product. The sensor may be a standard sensor such as a proximity sensor. The product detection sensor may include a photoelectric sensor (also referred to as a photocell pair sensor) which may use infrared radiation, or may include a pinhole sensor.

[0261] The printhead support may include a product detection sensor. The product detection sensor may include a plurality of detection sensors. The product detection sensor may include two sensors. In an embodiment where the product detection sensor includes two sensors, one sensor may be disposed on either side of the position where the ink droplets are ejected from the printhead.

[0262] The product detection sensor may be disposed behind the position or orifice from which the ink droplets are ejected from the printhead. This reduces ink droplet splashing on the sensor.

[0263] The product detection sensor may be positioned less than about 5 millimeters from the slot. Preferably, the detection area, i.e., the area covered by the product detection sensor 1305, should be less than 5 mm below the slot. This is so that the product detection sensor 1305 can sense in the area where printing is required.

[0264] The printhead may include a removable cover.

[0265] The removable cover may be removed from the printhead only when the printhead is not connected to the ink system.

[0266] The removable cover prevents access to components near the printhead during operation, which has the advantage of protecting the features of the printhead from external factors and environmental conditions such as moisture, dust, foreign particles, and extreme temperatures; and also has the advantage of protecting the operator or a third person from contacting components of the printhead that may have high voltage (i.e., a voltage that can cause serious injury or death to a person) during operation.

[0267] By being able to remove the cover only when the printhead is not connected to the system, it prevents the user or operator from contacting high voltage components during the printing operation, thereby increasing the safety of the printer.

[0268] By making the cover removable only when the printhead is not connected to the ink system, i.e., when there is no fluid or electrical connection between the printhead and the ink system, it promotes the safe use of the printhead because the high voltage parts of the printhead cannot be accessed during operation. Additionally, this allows for the quick and safe removal and replacement of an individual printhead, rather than requiring the removal of the removable cover in order to access, for example, a printhead release screw to then remove the printhead.

[0269] When covering the printhead, the removable cover can prevent access to the droplet generator, at least one electrode, and the trough.

[0270] In other words, when the removable cover is removed, access can be gained to at least one of the droplet generator, at least one electrode, and the trough.

[0271] Providing a removable cover allows easy access to the components of the printhead, particularly to at least one of the droplet generator, at least one electrode, and the trough. This allows easy access to the printhead components for repair, maintenance, and replacement, as well as for replacing parts. However, the removable cover protects the components of the printhead from external factors and environmental conditions, such as moisture, dust, foreign particles, and extreme temperatures, particularly during the printing operation.

[0272] When the printhead cover is removed, the droplet generator, at least one electrode, and the trough are all accessible to the user.

[0273] The removable cover can be removed from the printhead without tools. That is, the user can be able to remove the removable part using only their hands, without the need to use tools such as screwdrivers, wrenches, etc.

[0274] The removable cover can include clips that cooperate with grooves in the printhead in a "clamp and retract" type mechanism. The clips can each have protrusions that mate with and / or abut against steps or step portions within their respective grooves such that when the clips are fully inserted into the grooves, the clips cannot be pulled out of the grooves in a purely linear motion. The user may need to bias (e.g., "clamp") the clips such that the protrusions can overcome the step portions and then can be pulled out of the grooves in a purely linear motion. Thus, the removable cover can be removed from the printhead using a "clamp and retract" type mechanism.

[0275] In other embodiments, the removable cover can be removed only by using tools. For example, the removable cover can be removed only when an unlocking "key" is inserted into the locking mechanism of the removable cover. The advantage of requiring a tool to remove the cover is that it discourages unauthorized users from removing the cover and thereby damaging the components of the printhead.

[0276] The features of the seventh aspect can be combined with the features of the eighth aspect. The features of the eighth aspect can be combined with the features of the seventh aspect.

[0277] According to a ninth aspect, there is provided a print head for a continuous inkjet printer, the print head comprising: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; and a gutter configured to receive ink droplets not used for printing, wherein the print head is removably connectable to an ink system of a continuous inkjet system via a print head connection interface, the print head connection interface comprising a plurality of electrical connectors and a plurality of fluid connectors, and the print head is configured to be removed from the printer, a replacement print head is connected to the printer, and printing operation is started within a period of about 2 minutes.

[0278] The replacement print head can be a print head removed from the printer.

[0279] Printing operation can be started within a period of about 3 minutes. Printing operation can be started within a period between about 2 minutes and about 3 minutes. Printing operation can be started within a period between about 1 minute and about 3 minutes. Printing operation can be started within a period between about 1 minute and about 2 minutes.

[0280] The print head connection interface can include mating guiding features configured to guide the print head from a disconnected configuration to a connected configuration.

[0281] According to a tenth aspect, there is provided a print head for a continuous inkjet printer, the print head comprising: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; and a gutter configured to receive ink droplets not used for printing; and wherein the print head is releasably connected to an ink system of a continuous inkjet system via a print head connection interface, the print head connection interface comprising a plurality of electrical connectors, a plurality of fluid connectors and mating guiding features configured to guide the print head from a disconnected configuration to a connected configuration.

[0282] The print head can be configured to be removed from the printer, a replacement print head is connected to the printer, and printing operation is started within a period of about 2 minutes.

[0283] The print head can be configured to be removed from the printer within about 10 seconds.

[0284] The print head can include a first guiding feature which can be complementary to a guiding feature of the printer.

[0285] The guiding feature can include a guide rail or a guiding groove.

[0286] The guiding feature can extend along 75% of the length of the print head.

[0287] The length of the printhead should be understood as the length of the printhead on which guiding features are provided. Since the guiding features extend over 75% of the length of the printhead, this further reduces any lateral or orthogonal movement that may occur at the point of engaging the corresponding electrical and fluid connectors.

[0288] The guiding features can include a first guiding region configured to provide coarse guidance, a second guiding region configured to provide fine guidance, and a tapered region between the first and second guiding regions.

[0289] The printhead connection interface can include a self - coupling mechanical interlock device.

[0290] The printhead can include a removable cover, and wherein the removable cover can be removed from the printhead only when the printhead is not connected to the ink system.

[0291] The features of the ninth aspect can be combined with the features of the seventh, eighth, or tenth aspect. The features of the tenth aspect can be combined with the features of the seventh, eighth, or ninth aspect.

[0292] According to the eleventh aspect, there is provided a method of operating a continuous inkjet printer for printing on an external substrate moving past the printer, the printer including a printhead and an ink system for storing ink and supplying ink to the printhead, wherein the printhead is releasably connected to the ink system; the printhead includes: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; a gutter configured to receive ink droplets not used for printing; wherein the printhead is releasably connected to the ink system through a printhead connection interface, the printhead connection interface including a plurality of fluid connectors and a plurality of electrical connectors; the method includes, within a period of about 2 minutes: removing the printhead from the printer; providing a replacement printhead; connecting the plurality of fluid connectors of the replacement printhead to the corresponding connection means of the printer; connecting the plurality of electrical connectors of the replacement printhead to the corresponding connection means of the printer; resuming the printing operation.

[0293] The printhead connection interface can include mating guiding features configured to guide the printhead from a disconnected configuration to a connected configuration, and the method can include: aligning the mating guiding features; connecting the plurality of fluid connectors to the corresponding connection means of the printer; connecting the plurality of electrical connectors to the corresponding connection means of the printer.

[0294] According to a twelfth aspect, there is provided a method of operating a continuous inkjet printer for printing on an external substrate moving past the printer, the printer including a print head and an ink system for storing ink and supplying ink to the print head, wherein the print head is releasably connected to the ink system; the print head includes: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; a gutter configured to receive ink droplets not used for printing; wherein the print head is releasably connected to the ink system through a print head connection interface, the print head connection interface including a plurality of fluid connectors, a plurality of electrical connectors, and mating guiding features configured to guide the print head from a disconnected configuration to a connected configuration; the method includes: aligning the mating guiding features; connecting the plurality of fluid connectors to corresponding connection means of the printer; connecting the plurality of electrical connectors to corresponding connection means of the printer.

[0295] The method may include, within a period of about 2 minutes: removing the print head from the printer; providing a replacement print head; connecting the plurality of fluid connectors of the replacement print head to corresponding connection means of the printer; connecting the plurality of electrical connectors of the replacement print head to corresponding connection means of the printer; resuming the printing operation.

[0296] The removal of the print head may occur within a period of about 10 seconds or less starting from when one or more safety conditions are met.

[0297] The removal of the print head may be performed within about 10 seconds. The removal of the print head involves moving the print head such that the plurality of fluid connectors and the plurality of electrical connectors are disengaged from corresponding connectors of a print head support arm connection interface, an umbilical cable, etc. The safety checks performed include checking whether the EHT connector is disconnected and no power is supplied to the print head, etc., which may be printer-specific. In some embodiments, safety checks may not be required, and the period of 10 seconds or less may start when the inkjet of the print head stops.

[0298] Before removing the print head, the method may include using a controller to check that no current is supplied to components of the print head.

[0299] Removing the print head may include sliding the print head away from a print head support member.

[0300] Providing a replacement print head may include sliding the replacement print head towards the print head support member.

[0301] The print head connection interface may include a release trigger, and the method may include: actuating the release trigger; initiating a print head release sequence.

[0302] The printhead release sequence may include:

[0303] - Closing the inkjet

[0304] - Checking that at least one safety condition is met

[0305] - Disengaging the solenoid

[0306] - Removing the printhead.

[0307] In some embodiments, the step of checking that at least one safety condition is met may be omitted or may be manually overridden by the user.

[0308] In embodiments that do not include a solenoid, the step of disengaging the solenoid may be absent.

[0309] The printhead connection interface may include a self - coupling mechanical interlock device, and the method may include engaging the self - coupling mechanical interlock device to prevent removal of the printhead.

[0310] The method may include meeting a safety condition; releasing the mechanical interlock to allow removal of the printhead.

[0311] A controller may be used to determine that a safety condition is met.

[0312] The printhead may further include a removable cover, and the method may include removing the removable cover when the printhead is not connected to the ink system.

[0313] Removing the removable cover may include clamping and withdrawing the removable cover.

[0314] The method may further include: meeting a safety condition; removing the removable cover after the safety condition is met.

[0315] A controller may be used to determine that a safety condition is met.

[0316] The features of the eleventh aspect may be combined with the features of the seventh to tenth aspects and the twelfth aspect. The features of the twelfth aspect may be combined with the features of the seventh to eleventh aspects.

[0317] The features of the first aspect can be combined with the features of the second to twelfth aspects. The features of the second aspect can be combined with the features of the first aspect and the third to twelfth aspects. The features of the third aspect can be combined with the features of the first aspect, the second aspect, and the fourth to twelfth aspects. The features of the fourth aspect can be combined with the features of the first to third aspects and the fifth to twelfth aspects. The features of the fifth aspect can be combined with the features of the first to fourth aspects and the sixth to twelfth aspects. The features of the sixth aspect can be combined with the features of the first to fifth aspects and the seventh to twelfth aspects. The features of the seventh aspect can be combined with the features of the first to sixth aspects and the eighth to twelfth aspects. The features of the eighth aspect can be combined with the features of the first to seventh aspects and the ninth to twelfth aspects. The features of the ninth aspect can be combined with the features of the first to eighth aspects and the tenth to twelfth aspects. The features of the tenth aspect can be combined with the features of the first to ninth aspects and the eleventh and twelfth aspects. The features of the eleventh aspect can be combined with the features of the first to tenth aspects and the twelfth aspect. The features of the twelfth aspect can be combined with the features of the first to eleventh aspects.

[0318] The optional and / or preferred features of each aspect of the invention described herein are also applicable to any other aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0319] Specific embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0320] Figure 1 is a schematic view of a continuous inkjet (CIJ) printer according to an embodiment of the invention;

[0321] Figure 2 is a schematic view of a fluid circuit of a CIJ printer according to an embodiment of the invention;

[0322] Figure 3 is a perspective view of a CIJ printer in an extended configuration according to an embodiment of the invention;

[0323] Figure 4 is Figure 3 a perspective view of the CIJ printer shown in a retracted configuration;

[0324] Figure 5 is a perspective view of a print head of a continuous inkjet printer according to an embodiment of the invention;

[0325] Figure 6 is Figure 5 an exploded view of the print head shown;

[0326] Figure 7 is Figure 5 and Figure 6 a perspective end view of the print head, showing the connection interface;

[0327] Figure 8 is Figure 5 and Figure 6 a side view of the print arm as shown in, with a partial cutaway to show the internal components of the print head;

[0328] Figure 9 is a perspective cutaway view of the print head and the print head support arm according to Figures 5 to 8 , including a self - coupling mechanical interlock device in an unlocked state;

[0329] Figure 10 is Figure 9 a perspective cutaway view of the print head and the print head support arm, wherein the self - coupling mechanical interlock device is in a latched state;

[0330] Figure 11 is a perspective end view of a model of the print head support arm according to an embodiment of the present invention;

[0331] Figure 12 is a perspective end view of a model of the print head support arm according to an embodiment of the present invention;

[0332] Figure 13 is Figure 11 an end view of the print head support arm;

[0333] Figure 14 is a perspective end view of a model of the print head support arm according to an embodiment of the present invention;

[0334] Figure 15 is a schematic diagram of a method for removing and replacing a print head according to an embodiment of the present invention after a release sequence.

[0335] Figure 16 is a flowchart showing steps that may occur when shutting off the inkjet before removing the print head.

[0336] Figure 17 is a flowchart showing steps for checking whether safety conditions are met. Detailed Description of the Invention

[0337] 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 connector 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.

[0338] 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.

[0339] 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.

[0340] In operation, ink is delivered from the ink system 5 to the print head 3 under pressure and recirculated via a flexible tube bundled 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.

[0341] 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.

[0342] 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.

[0343] 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.

[0344] 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 Part of the printer 1). The first box 102 indicates the components housed within the printer body (e.g., Figure 1 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 Components within 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.

[0345] 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.

[0346] 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.

[0347] 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.

[0348] 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 periodic 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.

[0349] A solvent filter 122 is inserted along the solvent supply line 114 between the ink cartridge 108 and the solvent refill pump 118. Similarly, an 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).

[0350] 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 is 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 the 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).

[0351] 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 from the solvent compartment 110 and the ink compartment 112 of the ink cartridge 108, respectively, to the mixing tank 128.

[0352] 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 that fluidly couple the print head to the ink system.

[0353] 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 enables fluid communication between the mixing tank 128 and 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 flushing valve 144, a purging valve 146, and a reflux valve 148. Each of these valves will be described in detail where appropriate.

[0354] An array 150 of quick-disconnect connectors also forms part of the fluid circuit 100. The array 150 of quick-disconnect connectors is coupled 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. Additional quick-disconnect connectors may be provided in other embodiments. Fewer quick-disconnect connectors may be provided in other embodiments.

[0355] 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 blocking the nozzle 134. When ejected by the nozzle 134, an ink stream 162 of non-printing ink is shown 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 a deflection plate 163 (also referred to as a deflection electrode). The deflection plate 163 may be maintained at a potential of approximately 8 kV relative to a reference electrode (e.g., a ground plate). The deflection plate 163 and the reference electrode may be referred to as a pair of deflection electrodes.

[0356] 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. 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 stream 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 provided 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 one of the plurality of fluid conduits that fluidly couple 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.

[0357] The length of the first portion 166a of the main return line 166 can be at most 1 meter, which results in advantages such as reduced pumping work and heat generation. In embodiments 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 rate is required to clean the sump 164 and the first portion 166a of the main return line 166. As a result, the use of solvent is reduced. In some embodiments, the length of the first portion 166a of the main return line 166 can be less than about 750 mm, can be less than about 500 mm. In some embodiments, the length of the first portion 166a of the main return line 166 can be at least about 100 mm. The length of the first portion 166a can be between about 100 mm and about 500 mm.

[0358] 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 start-up and shut-down 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 into 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 into the mixing tank 128. The nozzle flushing process can utilize a higher solvent flow rate as 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 restricts the flow rate of the fluid passing through it). The nozzle flushing process utilizes a jet of solvent ejected from the nozzle 134 which is cleared by the sump 164 and the sump pump 168. Advantageously, providing the print head 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, given the passage of solvent through the nozzle 134, the sump flushing process can also clean the nozzle 134 to some extent.

[0359] 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 print head to provide pressure relief for the air sucked into the mixing tank 128 via the sump pump 168. By discharging into the print head, 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 print head defines a substantially enclosed volume in which the air is saturated with solvent vapour.

[0360] 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). Solvent refill pump 118 and ink refill pump 120 are small and precise diaphragm pumps that respectively pump and measure solvent and ink. Thus, 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 pumps 118, 120 indicates the volume of fluid pumped across pumps 118, 120. The presence of "separate" sump pump 168 combined with ink pump 130 means that a venturi tube is not required to draw the ink / air / solvent mixture from sump 164 back into 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 by means of the venturi tube.

[0361] Although not shown in Figure 2 various components of 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 fluid circuit 100 (e.g., solvent refill pump 118 and ink refill pump 120, ink pump 130, sump pump 168, 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.

[0362] Turning to Figure 3 a perspective view of a printer 200 according to an embodiment of the present invention is provided. 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 of printer 1 shown in

[0363] Printer body 202 houses an ink system, and the components of the ink system are generally bounded by the Figure 2 frame 102. For example, printer body 202 houses (referring to Figure 2 ) ink cartridge 108, pumps (e.g., ink pump 130), mixing tank 128, and various fluid conduits extending therebetween (e.g., main supply line 132 and main return line 166). 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.

[0364] 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). Thus, the print head support arm 206 and the print arm 204 are more generally rotatable relative to the printer body 202 about a print head rotation axis 210. Arrow 212 indicates the direction of rotation in which the print arm 204 is rotatable.

[0365] 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 extent 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°.

[0366] 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.

[0367] The print head 208 is removable 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.

[0368] The tiltable portion 214 of the support arm is tiltable about a tilt axis 216. Due to the connection of the print head 208 to the tiltable portion 214, the print head 208 is also tiltable 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 ink jet 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 print head 208 and the tiltable portion 214 of the print head support arm 206 relative to the non-tiltable portion 220 of the print head support arm 206. The print head 208 and the tiltable portion 214 of the support arm 204 can tilt relative to the non-tiltable portion 220 of the print head support arm 206 (and the printer body 202) about the tilt axis 216 by up to approximately ±20°. The tilt axis 216 is preferably substantially orthogonal to the print head rotation axis 210. The print head rotation axis 210 is substantially orthogonal to the inkjet axis 218.

[0369] Advantageously, being able to tilt the print head 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 print head 208 at a certain speed. The tiltable nature of the print head 208 thus facilitates printing onto a high-speed printing line or onto an inclined line, where otherwise the printed characters might be distorted. However, in other embodiments, the print head 208 may not tilt relative to the printer body 202.

[0370] Figure 3 Also shown is that the printer body 202 includes a print head recess 222. The printer 200 can be placed in a retracted configuration, in which the print arm 204 is rotated such that the print head 208, and more generally the print arm 204, is received in the print head recess 222. Advantageously, this means that when the printer 200 is in the retracted configuration, the overall footprint of the printer 200 is reduced. Additionally, when the printer 200 is in the retracted configuration (which is desirable, for example, when the printer 200 is in transit), the print head 208 is better protected. For completeness, as Figure 3 shown, the printer 200 is in an extended (i.e., print-ready) configuration, in which the print head 208 is not received within the print head recess 222. In the extended configuration (where there can be multiple different examples of the extended configuration), the print head 208 typically 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.

[0371] Moving on to Figure 4 a perspective view of the printer 200 in an alternative configuration is provided. In Figure 4 this figure, the printer 200 is shown in a retracted configuration, in which the print head 208 and more generally the print arm 204 are received within the print head recess 222 of the printer body 202. The print arm 204, as well as the print head 208, are nested within Figure 4within the printhead recess 222 of the printer body 202. Accordingly, 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).

[0372] 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 . Accordingly, the printer 200 is significantly more compact than existing CIJ printers.

[0373] 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 differentials 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 "sealed" startup of the printer 200 is facilitated in conjunction with the exhaust pipeline 174, 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 pipeline 166, the exhaust pipeline 174, and the printhead form various closed loops, allowing for pressure equilibration within the system without using "fresh" external air (which, due to not being loaded with solvent, would otherwise result in increased solvent usage).

[0374] Figure 5 is a perspective view of a print arm 1204 of a continuous inkjet printer according to an embodiment of the present invention.

[0375] The print arm 1204 includes a printhead support arm 1206, a removable printhead 1208, and a removable cover 1301. The printhead 1208 and the printhead cover 1301 may be collectively referred to as a printhead magazine, and the printhead cover 1301 may be interchangeably referred to as a printhead magazine cover.

[0376] As will be more clearly described below Figure 6 when, the printhead 1208 is removable from the printhead support arm 1206. That is, the printhead 1208 can be disconnected from the printhead support arm 1206 such that a different printhead can be connected (or the same printhead 1208 reconnected) to the printhead support arm 1206. Although in this embodiment and the subsequent embodiments described below, the printhead 1208 is shown as connected to the printhead support arm 1206, the printhead support arm 1206 can be replaced, for example, by an umbilical cable such that the printhead 1208 can be connected to the umbilical cable, or the printhead 1208 can be directly connected to the printer housing and removable from the printer housing.

[0377] The printhead support arm 1206 includes a rotatable coupler 1303 for coupling to a rotating mechanism of the printer. The rotatable coupling allows rotation of the print arm 1204. The printhead support arm 1206 also includes a product detection sensor 1305. The product detection sensor is configured to sense the position of an external substrate moving past the print arm 1204 to be printed thereon. The product detection sensor 1305 is disposed in an end of the printhead support arm 1206 remote from the rotatable coupler 1303. Regarding Figure 6 and Figure 8 further details of the product detection sensor are described.

[0378] The removable printhead cover 1301 includes three side walls 1307 (although only two are visible in Figure 5 ) and an end face 1309, and an elongated hole 1311 is provided in the end face 1309. The removable printhead cover 1301 protects the components of the printhead 1208 from external factors and environmental conditions, such as moisture, dust, foreign particles, and extreme temperatures. The removable cover 1301 also provides the advantage of protecting the operator or user from contact with high-voltage (i.e., voltages that can cause serious injury or death to a person) components of the printhead. The elongated hole 1311 provides an opening for charged ink droplets to leave the printhead 1208 and be printed onto an external substrate. In other embodiments, the cover 1301 may not be removable, but rather the cover 1301 may be permanently fixed (e.g., welded or glued) to the printhead 1208. Permanently fixing the cover 1301 has the advantage that the user cannot contact the components of the printhead 1208, particularly the high-voltage components that can cause death or serious injury to a person.

[0379] Refer to Figure 6 .Figure 6 is Figure 5 an exploded view of the print arm 1204 shown in

[0380] The print arm 1204 includes a print head support arm 1206, a removable print head 1208, and a removable cover 1301.

[0381] As described with respect to Figure 5 the print head support arm 1206 includes a rotatable coupler 1303, which may also be referred to as a rotatable joint for coupling to a rotatable mechanism of a printer. The rotatable coupler 1303 allows the print arm 1204 to rotate about a rotation axis 1210.

[0382] The print head support arm 1206 further includes a tiltable portion 1313, which allows the print head support arm 1208 to tilt about a tilt axis 1211.

[0383] The print arm 1204 includes a print head support arm connection interface 1315. The print head support arm connection interface 1315 includes a plurality of connectors for connection to corresponding connectors of the print head 1208 (mostly not visible in Figure 6 but shown in Figure 7 ). The plurality of connectors may include Figure 2 quick disconnect connectors for the circuitry shown in

[0384] The connectors of the print head support arm connection interface 1315, in addition to being configured to connect to corresponding connectors of the print head 1208, are also connected in use to a continuous inkjet printer, including connection to an ink system.

[0385] The sump line connector 1317 and the exhaust line connector 1319 are vertically disposed above the other connectors of the print head support arm connection interface 1315 in the orientation shown in Figure 6 The term vertically above does not limit to directly vertically above, but means that the sump line connector 1317 and the exhaust line connector 1319 are located above the other connectors, but they are not necessarily in the same plane. The sump line connector 1317 is a fluid connector and provides a connection between the sump in the print head 1208 and a mixing tank in the ink system. In use, based on Figure 2In the schematic diagram shown, the sump line connector 1317 will be in fluid communication with the return line 166. The return line 166 may also be referred to as the sump line. The return line 166 allows ink to be cleared from the printhead and also draws in air in order to return air and ink to the ink system. The exhaust line connector 1319 is also a fluid connector. The exhaust line connector 1319 provides a connection for the exhaust line to lead to the printhead 1208, thereby providing a pressure release for the air drawn into the mixing tank in the ink system of the printer, especially when ink and / or solvent is cleared from the sump of the printhead. By discharging into the printhead 1208, the solvent loss from within the mixing tank is relatively lower than the case where the discharge line discharges directly to the atmosphere in the main body of the printer's ink system. This is because the printhead 1208 defines a substantially enclosed volume in which the air is saturated with solvent vapor (or at least has an elevated solvent vapor concentration relative to ambient air). Most of the exhausted air (which may be saturated with solvent vapor) will be drawn back into the sump and recycled, thereby reducing the amount of fresh (i.e., not saturated with solvent vapor) air drawn into the system and thus also reducing the amount of solvent vapor discharged.

[0386] When the print arm 1204 is in the stowed configuration (see Figure 5 ), the exhaust line connector 1319 can be further utilized. This is because when in the stowed configuration (i.e., during post-print or pre-print operations), the exhaust line can provide an air source to the sump and the sump line 166. For example, if the print holes of the printhead are sealed, the sump draws in air saturated with solvent vapor, which in turn reduces solvent consumption.

[0387] The drive (feed) line connector 1321 and the return line connector 1323 are both fluid connectors. The drive (feed) line connector 1321 and the return line connector 1323 are vertically arranged below the sump line connector 1317 and the exhaust line connector 1319 along the Figure 6 orientation shown. The drive (feed) line connector 1321 and the return line connector 1323 can both be self-sealing connectors. The return line connector 1323 may also be referred to as the main return line connector 1323. Thus, the return line connector 1323 provides a connection between the main return line 166 and the return valve of the main loop shown in Figure 2 . The drive line connector 1321 and the return line connector 1323 are non-dripping connectors, that is, they include self-sealing valves and provide a leak-free connection (especially when disconnecting). Although in other embodiments, the connectors 1321 and 1323 may not be self-sealing (non-dripping).

[0388] The EHT connector 1327 and the low voltage interface 1329 are provided at the lowest region of the printhead support connection interface 1315. In other embodiments, the electrical connectors 1327, 1329 may be provided above the fluid connector. If the printhead 1208 and the printhead support arm 1206 are connected and disconnected in a predetermined orientation, providing the electrical connectors above the fluid connector can reduce the flow of fluid, particularly ink and / or solvent, onto the electrical connectors and damage the electrical connectors. The EHT connector 1315 allows a high voltage connection to the printhead 1208. In particular, it is used to apply a high voltage to the droplet generator in the printhead 1208 for generating a stream of charged ink droplets; and / or to apply a high voltage to the electrode plate to deflect the charged ink droplets. The low voltage interface 1329 is in the form of a printed circuit board (PCB) including a plurality of individually mounted SMT (surface mount technology) contacts, but other suitable low voltage connectors may be used. The EHT connector 1327 and the low voltage interface 1329 may be configured for early disconnection so that other signals can be powered down in preparation for removing the printhead 1208. That is, the EHT connector 1327 is arranged such that it disconnects first. Disconnecting the EHT connector 1327 can then cause other wires and connections to be shut off.

[0389] The printhead 1208 may include a resistor positioned close to the electrode plate (which may also be referred to as a deflection electrode). Regarding Figure 8 The components of the printhead 1208 including the electrode plate are shown and described. Providing a resistor in series with and close to the electrode plate can improve the safety of the printhead and reduce the need to provide an additional internal housing around the electrode plate. When the printhead 1208 is disconnected from the printhead support arm 1206, the electrode plate may still be charged. Providing a resistor close to the electrode charging plate reduces the total capacitance of the resistor, the electrode plate, and the corresponding wiring (due to shorter wires), and thus reduces the total amount of stored energy. When the printhead is in operation and when it is disconnected, there may be solvent ingress and it can be easily ignited. Therefore, by limiting the stored energy, the likelihood of solvent ignition is reduced. In some embodiments, resistors may be provided in the printhead 1208 and the printhead support arm 1206, and each resistor is provided as close as possible to the connection interface of the printhead 1208 and the printhead support arm 1206 to limit the energy stored in each component.

[0390] The EHT connector 1327 may be configured such that when the printhead 1208 is removed, the user cannot touch the EHT connector 1327 of the printhead support arm 1206 or the corresponding EHT connector of the printhead 1208 (described below).

[0391] The washer 1331 surrounds the EHT connector 1327, the low voltage interface 1329, and the solenoid 1326. In use, the washer 1331 seals against the wall of the printhead 1208, particularly the wall of the printhead connection interface (described below). Since the washer 1331 seals against the wall of the printhead 1208, any fluid that might leak or drip from the fluid connectors 1317, 1319, 1321, 1323 is prevented from contacting the electrical connectors 1327, 1329. If any ink or solvent contacts the electrical connectors 1327, 1329, the electrical connectors 1327, 1329 may be damaged and need to be replaced. This is advantageous because the EHT connector 1327 and the low voltage interface 1329, and possibly the solenoid, can be adversely affected by the ingress of water, dust, or ink. As described above, the fluid connectors are non-dripping connectors. Thus, when the printhead 1208 is removed from the printhead support arm 1206, the fluid in the conduits connected to the fluid connectors 1317, 1319, 1321, 1323 does not drip onto the electrical connectors 1327, 1329, thereby reducing damage to the electrical connectors caused by the fluid (especially liquid).

[0392] The washer 1331 can be formed from a synthetic elastomer, particularly from ethylene propylene diene monomer (EPDM) rubber. The EPDM rubber can be Parker grade E515 or 3540. Since the washer 1331 can come into contact with ink and / or solvent, forming the washer from a material resistant to corrosion by ink and solvent (such as EPDM rubber) increases the lifespan of the washer 1331 and thus increases the lifespan of other components (such as the electrical connectors of the printhead 1208 and the printhead support arm 1206).

[0393] As described above, the printhead support arm connection interface 1315 includes a mechanical latch barb 1323 that is used to engage with a self - coupling mechanical interlock device, particularly with a latch in the printhead 1208, for mechanically connecting the printhead 1208 to the printhead support arm 1206. The solenoid 1326 is used to electrically lock the mechanical latch barb 1325 to the latch of the printhead 1208. When described Figure 9 and Figure 10 the use of the latch barb 1323, the solenoid 1326, and the latch of the printhead 1208 is described in more detail below. Although the mechanical latch barb 1323 and the corresponding latch of the printhead 1208 have several advantages described below, they are not essential for the removable printhead 1208. It should be understood that the connectors of the printhead support interface 1315 can be connected to the corresponding connectors of the printhead 1208 without the need for mechanical fastening.

[0394] In other embodiments, the latch of the printhead 1208 can be a solenoid. When the latch of the printhead is a solenoid, the solenoid 1326 may not be provided. In embodiments where the latch is a solenoid, the latch can be electrically locked to prevent detachment between the latch barb 1325 and the latch.

[0395] The printhead support arm 1206 further includes an elongate strut 1333. The elongate strut 1333 extends in a direction away from the electrical connectors 1327, 1329 and fluid connectors 1317, 1319, 1321, 1323 of the printhead support arm 1206. The elongate strut 1333 is generally orthogonal to the mating surface 1318 of the printhead connection interface 1339, on which the electrical connectors 1327, 1329 and fluid connectors 1317, 1319, 1321, 1323 are disposed. The printhead connection interface 1339 includes the interface between the printhead and the printer body, which may include, but is not limited to, the printer body, the printhead support arm, and the umbilical cable. The printhead connection interface can include all features connected to or connected with the printer body, or it can include only some features. The printhead connection interface 1339 can be interchangeably referred to as the connection interface 1339.

[0396] The printhead 1208 has a generally cubic shape, so the elongate strut 1333 has an upper surface with a generally rectangular shape to support the printhead 1208. The elongate strut 1333 includes two guide rails 1335 that extend parallel to each other. The guide rails 1335 serve as alignment means. The printhead 1208 includes two mating guide channels 1337 ( Figure 6 only one is visible in). The guide channels 1337 of the printhead 1208 and the removable cover 1301 together define two mating guide slots 1338 (shown more clearly in Figure 7 ). The guide rails 1335 are received in the guide slots 1338 to provide a sliding relationship between the printhead 1208 and the printhead support arm 1206. That is, in order to connect the printhead 1208 to the printhead support arm 1206, the guide rails 1335 of the printhead support arm 1206 must be received in the guide slots 1338 of the printhead 1208, and then the user can slide the printhead 1208 towards the printhead support arm connection interface 1315. The presence of the guide rails 1335 and the corresponding guide slots 1338 provides easy connection and disconnection and alignment of the printhead 1208 and the printhead support arm connection interface 1315.

[0397] The guide rails 1335 extend along the elongate strut 1333 in a direction parallel to the tilt axis 1211. That is, the guide rails use Figure 6The axis shown extends in the x direction. In other words, the guide rail 1335 extends in the longitudinal direction of the print head, extending in a direction substantially parallel to the inclined axis 1211. The guide rail 1355 extends from the distal end of the elongated strut 1333 to the location where the electrical connectors 1327, 1329 and the fluid connectors 1317, 1319, 1321, 1323 are provided, such that the guide rail 1335 meets the mating surface 1318. Since the guide rail 1335 is long and abuts against the electrical connectors 1327, 1329 and the fluid connectors 1317, 1319, 1321, 1323, they provide safe guidance for the print head before the corresponding connectors of the print head 1208 engage with the electrical connectors 1327, 1329 and the fluid connectors 1317, 1319, 1321, 1323 of the print head support arm 1206. In other embodiments, the guide rail 1335 may extend close to the electrical connectors 1327, 1329 and the fluid connectors 1317, 1319, 1321, 1323, but does not abut against the electrical connectors 1327, 1329 and the fluid connectors 1317, 1319, 1321, 1323.

[0398] The guide rail 1335 thus allows linear movement of the print head in the x direction, but restricts movement of the print head 1208 in the y direction. In addition, the guide rail 1335 is an L-shaped track. The advantage of having an L-shaped track is that movement of the print head 1208 in the z direction is restricted. Thereby, correct alignment of the electrical connectors 1327, 1329 and the fluid connectors 1317, 1319, 1321, 1323 with the corresponding connectors of the print head 1208 is further ensured.

[0399] Turning to the print head 1208. The print head 1208 includes a connection interface 1339 (not visible in Figure 6 but visible in Figure 7shown), a shield 1341, and a print module 1343. In some embodiments, the printhead 1208 and / or the printhead support arm 1206 may include a printhead controller, such as a touchscreen. The printhead controller may be arranged to control the actuation of solenoids and / or control the power supply to the components of the printhead 1208. The print module 1343 includes a droplet generator (which may be referred to as a nozzle) for generating and ejecting a stream of ink droplets for printing; at least one electrode for manipulating the stream of ink droplets; and a gutter for receiving ink droplets not used for printing. The droplet generator (inkjet nozzle) may be a 60-micron droplet generator. The droplet generator (inkjet nozzle) may be a 70-micron droplet generator. In some embodiments, the inkjet nozzle may be 42 microns. In some embodiments, the inkjet nozzle may be 50 microns. In some embodiments, the inkjet nozzle may be 65 microns. In some embodiments, the inkjet nozzle may be 75 microns. In some embodiments, the inkjet nozzle may be between about 30 microns and about 80 microns. In some embodiments, the inkjet nozzle may be between about 30 microns and about 90 microns. The above dimensions of the droplet generator (inkjet nozzle) are related to the diameter of the orifice. The ink droplets produced may have a diameter that is approximately twice the diameter of the orifice opening.

[0400] Regarding Figure 8 Describe the components of the printhead 1208 in more detail.

[0401] In some embodiments, the droplet generator and the gutter of the printhead 1208 may be replaceable. This helps to quickly solve nozzle clogging problems that cannot be solved by normal cleaning.

[0402] The removable cover 1301 is configured to be received above the printhead 1208 to cover the print module 1343. The removable cover 1301 may include clips that cooperate with grooves in the printhead 1208 in a "clamp and retract" type mechanism. The clips may each have a protrusion that mates with and / or abuts a step or step portion within their respective grooves such that when the clips are fully inserted into the grooves, the clips cannot be pulled out of the grooves by pure linear motion. The user may need to bias (e.g., "clamp") the clips such that the protrusions can overcome the step portions and then can be pulled out of the grooves by pure linear motion.

[0403] The printhead 1208, particularly the shield 1341 and / or the removable cover 1206, may be formed of polypropylene because this material resists corrosion by the inks and solvents that the printhead may come into contact with.

[0404] In some embodiments, the removable cover 1301 can be removed only when the printhead 1208 is disconnected from the printhead support arm connection interface 1315 and / or completely removed from the printhead support arm 1206 (i.e., where the guide rail 1335 of the printhead support arm 1206 is not engaged with the corresponding guide slot 1338 of the printhead 1208). In particular, the printhead 1208 can be disconnected from the printhead support arm 1206 only by removing both the printhead 1208 and the removable cover 1301 simultaneously, and then the removable cover 1301 can be removed from the printhead 1208 once disconnected. This is advantageous because it prevents the user from contacting the components of the printhead during use and allows the user to remove the printhead 1028 and the removable cover 1301 in a single step.

[0405] In other embodiments, the removable cover 1301 can be removed without disconnecting the printhead 1208 from the print arm 1206. In such embodiments, the printhead can include an additional internal housing / casing to reduce user contact with the components of the printhead 1208.

[0406] In Figure 6 it can be seen more clearly that the end face 1309 of the removable cover does not cover the lowermost portion of the printhead support arm 1206 where the production detection sensor 1305 is provided. In an embodiment, in the case where the product detection sensor 1305 is not provided in the printhead support arm 1305, the removable cover can cover the lowermost portion of the printhead support arm 1206.

[0407] Figure 7 A perspective end view of the printhead 1208 is shown, particularly showing the connection interface 1339 of the printhead 1208, which is not visible in Figure 5 or Figure 6 .

[0408] The connection interface 1339 includes a plurality of fluid connectors and a plurality of electrical connectors for connection to the corresponding connectors of the printhead support arm connection interface 1315. In particular, the connection interface 1339 of the printhead 1208 includes a slot line connector 1345 for connection to the slot line connector 1317 of the printhead support arm connection interface 1315.

[0409] The connection interface 1339 further includes an exhaust line connector 1347 for connection to the exhaust line connector 1319 of the printhead support arm connection interface 1315. The connection interface 1339 also includes a drive line connector 1349 and a return line connector 1351 for connection to the drive line connector 1321 and the return line connector 1323 of the printhead support arm connection interface 1315, respectively.

[0410] The fluid connectors 1345, 1347, 1349, 1351 are quick-disconnect connectors. Quick-disconnect connectors allow for quick disconnection between corresponding connectors. As an example, in the present embodiment, by simply pulling and sliding the printhead 1208 in a direction away from the printhead support arm 1206 and parallel to the elongate strut 1333, the fluid connectors 1345, 1347, 1349, 1351 can be quickly disconnected from the corresponding connectors of the printhead support arm interface 1315 without having to perform any other manual operations (such as rotating a part of the connector) in order to disconnect the connectors.

[0411] The connection interface 1339 of the printhead 1208 also includes an extra-high voltage (EHT) connector 1353 and a low-voltage interface 1355 for connection to the EHT connector 1327 and the low-voltage interface 1329 of the printhead support arm connection interface 1315. Both the EHT connector 1353 and the low-voltage interface 1355 are quick-disconnect connectors. Quick-disconnect connectors allow for quick disconnection between corresponding connectors. As an example, in the present embodiment, the EHT connector 1353 and the low-voltage interface 1355 can be quickly disconnected from the corresponding connectors of the printhead support arm interface 1315 by simply pulling and sliding the printhead 1208 in a direction away from the printhead support arm 1206 and parallel to the elongate strut 1333 without having to perform any other manual operations (such as rotating a part of the connector) in order to disconnect the connectors.

[0412] The connection interface 1339 of the printhead 1208 also includes a first hole 1357 for receiving the mechanical latch barb 1326 and a first hole 1357 of the printhead support arm connection interface 1315, and a second hole 1359 for receiving a solenoid of the printhead support arm connection interface 1315. The first hole 1357 and the second hole 1359 at least partially define a coupling mechanical interlock for mechanically connecting the printhead 1208 to the printhead support arm 1206.

[0413] As Figure 6 and Figure 7 shown, except for the EHT connector 1353, all of the connectors of the printhead 1208 are female connectors, and the corresponding connectors on the printhead support arm 1206 are male connectors. It should be understood that in other embodiments, different combinations of male and female connectors can be provided.

[0414] The printhead connection interface 1339 includes an end face 1361, fluid connectors, and electrical connectors (1345, 1347, 1349, 1351, 1353, 1355), and bores 1357, 1359 extend from the end face 1361, and the printhead connection interface 1339 is configured to mate with a mating surface 1318 of the printhead support arm 1206. However, the end face 1361 is not a flat surface and includes a stepped region 1363 such that a lower region 1361a of the face 1361 is offset from an upper region 1361b of the face 1361 in the Figure 7 orientation shown. The fluid connectors 1345, 1347, 1349, 1351 all extend from the upper region 1361b, and the electrical connectors 1353, 1355 extend from the lower region 1361a. Thus, the upper region 1361b overhangs the lower region 1361a, which is advantageous because it reduces the exposure of the electrical connectors 1353, 1355 to fluid (particularly ink and / or solvent), thereby preventing damage to the electrical connectors 1353, 1355.

[0415] It should be understood that in other embodiments, the connectors shown on the connection interface 1339 of the printhead 1208 may be provided on the printhead support arm connection interface 1315. Similarly, the connectors shown on the printhead support arm connection interface 1339 may be provided on the connection interface 1339 of the printhead 1208, and / or any other combination, provided that there are corresponding connections on the connection interface 1339 of the printhead 1208 and the printhead support arm connection interface 1315.

[0416] Furthermore, although the printhead 1208 is described and shown as being connected to the printhead support arm connection interface 1315, it should be understood that in other embodiments, the printhead 1208 may be directly connected to an umbilical cable or a printer.

[0417] Figure 8 is Figure 5 and Figure 6 a side view of the print arm 1204 shown in, with a portion cut away to show internal components of the printhead 1208 and the printhead support arm 1206.

[0418] As briefly described with respect to Figure 6 the printhead support arm 1206 includes a product detection sensor 1305. The product detection sensor 1305 is configured to sense the position of an external substrate moving past the print arm 1204 to be printed upon.

[0419] The product detection sensor 1305 is disposed in the end portion of the printhead support arm 1206 that is remote from the rotatable coupler 1303. In particular, it is disposed within the housing of the elongate strut 1333. The product detection sensor 1305 is integrated into the printhead support arm 1206. In other embodiments, the product detection sensor 1305 may be disposed within the printhead 1208. The production detection sensor 1305 includes a sensor 1365 and a lens 1369, the sensor 1365 being configured to generate a sensor beam 1367 (shown as a dashed line), and the lens 1369 being for focusing the sensor beam 1367. In other embodiments, the product detection sensor may include multiple sensor beams and / or multiple lenses. In an embodiment where the product detection sensor 1305 includes two sensors 1365, the sensors 1365 may be disposed on either side of the position where ink droplets are ejected from the printhead 1208 (i.e., on either side of the elongate aperture 1311 of the removable cover 1301). The product detection sensor 1305 is arranged to detect the product / substrate onto which the ink droplets are to be printed, and in some embodiments is capable of sensing the direction and speed of the product. The product detection sensor 1305 may be a standard sensor. For example, the product detection sensor 1305 may include a VL6180X proximity detector (manufactured by STMicroelectronics), or the product detection sensor 1305 may include a photo sensor (also known as a photocell pair sensor), which may use infrared radiation. The product detection sensor 1305 located within the printhead support member 1206 allows for a more compact printhead 1208. Additionally, since the printhead 1208 does not need to include the product detection sensor 1305, the cost of manufacturing the removable printhead 1208 can be reduced.

[0420] The product detection sensor 1305 is retracted from the elongate aperture 1311 of the removable cover 1301, where the ink droplets are ejected from the printhead 1208. This reduces the splashing of ink droplets onto the product detection sensor 1305.

[0421] Preferably, the detection area, i.e., the area covered by the product detection sensor 1305, should be less than 5 mm below the slot. This is so that the product detection sensor 1305 can sense within the area where printing is required.

[0422] The printhead 1208 further includes a droplet generator 1501 having nozzles 1503 and slots 1505. During a printing operation, an ink jet is ejected from the nozzles 1503 of the droplet generator 1501 towards the slots 1505 along a print axis A. The droplet generator 1501 also includes a piezoelectric element ( Figure 8 not shown in the drawings) that allows for modulation of the ink jet such that droplets are formed within the jet in a predictable manner.

[0423] The charging electrode 1507 is disposed near the droplet generator 1501 and, as is known in the art, the charging electrode 1507 is configured to induce a charge on the droplets as the droplets detach from the inkjet ejected from the droplet generator 1501. A voltage of about 300 V can be applied to the charging electrode 1507. The first deflection electrode 1509 and the second deflection electrode 1511 are arranged on either side of the printing axis A and are configured to deflect the charged droplets away from the printing axis A and thus miss the entrance of the slot 1505. A voltage of about 6000 volts to 8000 volts can be applied between the first deflection electrode 1509 and the second deflection electrode 1511 to deflect the droplets.

[0424] By varying the magnitude of the charging voltage applied to the charging electrode 1507, the amount of charge induced on each droplet can be changed and, in this way, the amount of deflection in the electrostatic field established between the deflection electrodes 1509, 1511 can be changed for each droplet.

[0425] The droplet generator 1501, the slot 1505, the charging electrode 1507 and the deflection electrodes 1509, 1511 are all mounted within the print head, which means that there is a fixed positional relationship between each of these components.

[0426] Figure 9 is a perspective cross-sectional view of the print head 1208 and the print head support arm 1206, the print head support arm 1206 including a self-coupling mechanical interlock 1371 in an unlocked (i.e., decoupled) state; Figure 10 shows the self-coupling mechanical interlock in a latched (i.e., coupled) state. The self-coupling mechanical interlock can be considered to form part of the print head connection interface 1339.

[0427] The self-coupling mechanical interlock 1371 may be referred to interchangeably as the self-locking mechanical coupling assembly 1371 or the mechanical interlock. The print head 1208 includes a biasing latch 1373. The latch 1373 includes an arm 1375 that extends in a direction generally orthogonal to the direction in which the mechanical latch barb 1325 extends. The arm 1375 of the latch 1373 includes an aperture 1381 sized to receive the mechanical latch barb 1325.

[0428] The latch 1373 includes a button 1377 when in the latched state ( Figure 10) When the button 1377 is flush with the side wall 1307 of the removable cover 1206. The button 1377 being flush with the side wall 1307 reduces the risk of the user accidentally pressing the button 1377 or the button being caught or contacted by an external object, which could lead to an unwanted release of the printer. The latch 1373 includes a biasing spring (not shown) that is arranged to push the button 1377 towards the side wall 1307 and thus push the arm 1375 to which the button 1377 is connected. In other words, the biasing spring pushes the latch 1373 in the direction of the arrow 1379 shown in Figure 10 That is to say, unless the solenoid 1326 is in the retracted position, the biasing spring prevents the button 1377 from being pressed.

[0429] As can be seen more clearly in Figure 6 , the mechanical latch barb 1325 includes a locking region 1325a and a distal end having a frustoconical head 1325b. The diameter of the locking region 1325a is smaller than the diameter of the base of the frustoconical head 1325b. In other words, the diameter of the locking region 1325a of the latch barb 1325 is smaller than the diameter of the distal end of the latch barb 1325 adjacent to the locking region 1325a.

[0430] Returning to Figure 9 and Figure 10 . When in the latched state ( Figure 10 ), the connectors of the print head 1208 (i.e., the fluid connector and the electrical connector) are connected to the corresponding connectors of the print head support arm 1208. The washer 1331 of the print head support arm 1206 abuts the surface of the print head 1208. In particular, the washer 1331 abuts the surface 1361a of the print head 1208. The mechanical latch barb 1325 is received in the orifice 1381 of the arm 1373. The orifice 1381 is a circular orifice because the mechanical latch barb 1325 has a circular cross-section. In other embodiments, the mechanical latch barb 1325 may have any suitable cross-sectional shape, such as a square cross-section, and other suitable shapes of the mechanical latch barb cross-section and the orifice 1381 may also be used.

[0431] The size of the orifice 1381 is designed such that when the center of the orifice (i.e., the centroid of the orifice) is aligned with the central axis 1383 of the latch barb 1325 (in Figure 6 and Figure 10As shown, the latch barb 1325 extends freely through the aperture 1381, and the aperture 1381 can slide freely over the mechanical latch barb 1325. The length of the latch barb 1325 is such that when the electrical and fluid connectors of the printhead 1208 are connected to the corresponding connectors of the printhead support arm 1206, the locking region 1325a of the latch barb is aligned with the arm 1377 of the latch 1373 and extends through the aperture 1381. Thus, the inner wall of the latch 1373 that defines the aperture 1381 lies in the same plane and is able to contact the locking region 1325a.

[0432] In this embodiment, in order to align the axis 1383 of the latch barb 1325 with the centroid of the aperture 1381, the latch 1373 must be actuated by the user away from the side wall 1307 of the removable cover 1206. The user can actuate the latch 1373 in this manner by pressing the button 1377 to provide a force opposite to the biasing spring force. As Figure 9 shown, the user can press the button 1377 to actuate the latch 1373, as shown by the arrow 1385, which aligns the centroid of the aperture 1381 with the axis 1383 of the latch barb 1325. Then, the user can slide the printhead 1208 away from the printhead support arm 1206 as shown by the arrow 1387. Thus, quick disconnect of the printhead 1208 from the printhead support arm 1206 can be achieved. However, if the button 1377 is not pressed, the user will not be able to remove the printhead 1208. This is because when in the latched state, as Figure 10 shown, the centroid of the aperture 1381 is not aligned with the central axis 1383 of the mechanical latch barb. This misalignment causes the latch barb 1325 not to pass through the aperture 1381, and thus in the latched state, the printhead 1208 and the printhead support arm 1206 are mechanically locked. This mechanical interlock is advantageous because it prevents the printhead 1208 from disconnecting from the printhead support arm 1206 during a printing operation. This is particularly important when the printhead 1208 is used in a printer as shown in Figure 3 and Figure 4 shown, where the printhead 1208 can be manipulated (rotated, tilted, and translated) to multiple positions during use. The mechanical interlock also prevents removal of the printhead 1028 when the valve of the fluid connector is open. Additionally, because the use of the latch 1377 relieves the user from having to use any fasteners (such as screws) to achieve a secure mechanical coupling between the printhead 1208 and the printhead support arm 1206, providing the mechanical interlock substantially does not increase the downtime of the printer when removing and replacing the printhead 1208.

[0433] For additional security during printing, the mechanical interlock 1371 is electrically locked. This electrical locking is achieved by the solenoid 1326. The solenoid 1326 is controlled by the printer's controller to be actuated to an extended position to engage the arm 1375 of the latch 1373.

[0434] When the printhead 1208 is connected to the printhead support arm 1206, the solenoid 1326 is in a retracted position, and current is applied to the solenoid 1326 by the controller 6 (see Figure 1 ), such that the solenoid 1326 does not contact the arm 1375 of the latch 1373. Once the printhead 1208 is connected to the printhead support arm 1206 and the latch 1371 is in the latched state, as Figure 10 shown, the current can be removed from the solenoid 1326, causing the solenoid 1326 to move to the normal position (i.e., the non-retracted position or the extended position). When the solenoid 1326 is in the normal position, it is received in the second orifice 1389 (or a recess in some embodiments) of the arm 1375. The solenoid 1326 received in the second orifice 1389 prevents lateral (in the y-direction) movement of the arm 1375 and thus prevents the user from being able to actuate the arm 1375 by pressing the button 1385. The lateral movement of the arm 135 is indicated by the arrow 1385 in Figure 9 and 1379 in Figure 10 . The solenoid 1326 is referred to as being electrically locked to the mechanical interlock device 1373 because the solenoid 1326 can only retract to allow the arm 1375 to move when current is applied to the solenoid 1326 to move the solenoid 1326 to the retracted position. The electrically locked mechanical interlock device 1373 further increases user security. This is because the printhead 1208 cannot be removed until current is applied to the solenoid 1326. This further prevents the user from removing the printhead 1208 during a printing operation where high voltage may be present in the printhead.

[0435] Another advantage of the solenoid 1326 being arranged such that it moves to the retracted position when current is applied is that if there is any power failure, the solenoid will remain in the normal position (and prevent movement of the arm 1375). This is because no current and thus no power is required to hold the solenoid 1326 in the normal position to be electrically locked to the latch 1373. In other words, if there is no power supply, the printhead 1208 is locked. In some embodiments, the print arm can be configured such that the printhead 1208 can be removed in the event of a power failure. The configuration can be arranged such that the user can manually retract the solenoid.

[0436] It should be understood that in other embodiments, the solenoid 1326 may be arranged such that when no current is applied, the solenoid 1326 is in a retracted position (i.e., not engaged with the arm 1375), and when current is applied, the solenoid 1326 is actuated to engage the arm 1327 and prevent movement of the arm.

[0437] More specifically, when the printhead 1208 is connected to the printhead support arm 1206, the solenoid 1326 is in a retracted position because the controller is configured not to apply current to the solenoid 1326. That is, when in a non-excited or OFF state, the solenoid 1326 is in a retracted position. This results in the solenoid 1326 not contacting the arm 1375 of the latch 1373.

[0438] Once the printhead 1208 is connected to the printhead support arm 1206 and the latch 1371 is in the latched state, as Figure 10 shown, current can be applied to the solenoid 1326 such that the solenoid 1326 is in an excited or ON state, thereby causing the solenoid 1326 to move to a normal position (i.e., a non-retracted position or an extended position). When the solenoid 1326 is in the normal position, it is received in the second aperture 1389 (or in some embodiments, a recess) of the arm 1375. The solenoid 1326 received in the second aperture 1389 prevents lateral movement (in the y-direction) of the arm 1375, and thus prevents the user from being able to actuate the arm 1375 by pressing the button 1385. The lateral movement (in the y-direction) of the arm 1375 is indicated by the arrow 1385 in Figure 9 and 1379 in Figure 10 The solenoid 1326 is referred to as being electrically locked to the mechanical interlock device 1373 because when the current is removed to cause the solenoid 1326 to move to the retracted position, the solenoid 1326 can only retract to allow movement of the arm 1375. The electrically locked mechanical interlock device 1373 further increases user safety. This is because the printhead 1208 cannot be removed before current is applied to the solenoid 1326. This further prevents the user from removing the printhead 1208 during a printing operation where high voltages may be present in the printhead.

[0439] In addition, it should be understood that the solenoid 1326 is not necessary for the use of the mechanical interlock device 1371, but it provides additional safety for the printhead 1208. The solenoid 1326 may be omitted from other embodiments. In other embodiments, the printhead 1206 may include the solenoid 1326.

[0440] Figure 11 A perspective end view of another printhead support arm 2206 for connection to a printhead (not shown) is illustrated.

[0441] For the sake of brevity, only the differences between printhead support arm 1206 and printhead support arm 2206 will be described.

[0442] Similar to printhead support arm 1206, printhead support arm 2206 includes a plurality of electrical connectors and a plurality of fluid connectors. In particular, the plurality of fluid connectors and the plurality of electrical connectors are provided on the printhead support arm connection interface 2315. Printhead 2206 includes a high-voltage connector 2327 and a low-voltage connector 2329. The high-voltage connector 2327 and the low-voltage connector 2329 can be the same type of connectors as described with respect to Figures 6 to 10 the same.

[0443] The printhead support arm connection interface 2315 further includes a slot line connector 2317, an exhaust line connector 2319, a drive line connector 2321, and a return line connector 2323, which together define the fluid connectors. The fluid connectors 2317, 2319, 2321, and 2323 can be the same type of connectors as described with respect to Figures 6 to 10 the description.

[0444] The printhead support arm connection interface 2315 further includes a mechanical latch barb 2325. Figure 11 The mechanical latch barb 2325 of Figures 6 to 10 is different from the mechanical latch barb in Figures 6 to 10 in that it includes a first region 2325a that extends from the face 2328 of the printhead support arm connection interface 2315 and has a first diameter. The latch barb 2325 includes an end region 2325b that is remote from the face 2328 of the printhead support arm connection interface 2315. The end region 2325b has a frustoconical end with a base diameter equal to the first diameter of the first region 2325a. The latch barb 2325 further includes a locking region 2325c that is disposed between the first region 2325a and the end region 2325c and has a diameter smaller than the first diameter. Similar to the latch barb 2325 in Figures 6 to 10 the description, the locking region 2325c of the latch barb 2325 is configured to engage with the latch of the printhead in the same manner as described with respect to

[0445] The printhead support arm connection interface 2315 further includes a solenoid 2326. The solenoid 2326 functions in the same manner as the solenoid 1236.

[0446] The arrangement (layout) of the connectors on the printhead support arm connection interface 2315 is different from the arrangement of the printhead support arm connection interface 1315. In Figure 11In the orientation shown, the high-voltage connector 2327 and the low-voltage connector 2329 are disposed on the left hand side of the interface 2315. Additionally, the high-voltage connector 2327, the low-voltage connector 2329, and the solenoid 2326 are disposed on a protruding structure 2330 extending from the face 2326. The sump line connector 2317 and the exhaust line connector 2319 are disposed below the protruding structure 2330. That is, the protruding structure 2330 overhangs the sump line connector 2317 and the exhaust line connector 2319. An advantage of this arrangement is that when the printhead support arm 2206 and the printhead 2208 (not shown) are in the orientation shown, fluid that might drip from the sump line connector 2317 and the exhaust line connector 2319 will not drip onto the electrical connectors. Figure 11 The orientation shown in may be the orientation in which the printhead support arm 2206 needs to be in order to connect and disconnect the printhead. Additionally, the drive line connector 2321 and the return line connector 2323 are disposed on the right hand side of the protruding structure 2330 (in Figure 11 the orientation shown). Similarly, the drive line connector 2321 and the return line connector 2323 are positioned to mitigate any fluid that might drip from these connectors contacting the electrical connectors 2327, 2330.

[0447] The printhead support arm 2206 or the corresponding printhead may include an orientation sensor to determine the orientation of the printhead support arm 2206; or in some embodiments, a stepper motor may be used to effect rotation of the print arm, and the number of steps taken by the stepper motor may be extrapolated to determine the orientation of the printhead support arm 2206. Disconnection of the printhead from the printhead support arm 2206 may be prohibited unless the printhead support arm 2206 is in a predetermined orientation, such as a horizontal orientation.

[0448] The printhead support arm 2206 includes an elongate strut 2333. The elongate strut 2333 extends in a direction away from the printhead support arm connection interface 2315 and provides support for the printhead (not shown). The printhead for connection to the printhead support arm 2206 may have a shape similar to the Figures 6 to 10 printhead 1208 in, but it should be understood that the connectors on the printhead for connection to the printhead support arm 2206 will be arranged to be complementary to the connectors of the printhead support arm connection interface 2315.

[0449] The elongate strut 2333 includes two guide rails 2335 that extend parallel to each other. The guide rails 2335 serve as an alignment means for the printhead, and the alignment means will include mating guide slots of the type described with respect to Figures 6 to 10 the.

[0450] The guide rails 2335 mate with Figures 6 to 10The guide rails 1335 are different in that the guide rails 2335 are not parallel along their entire length. Instead, the guide rails 2335 include divergent tapered ends 2335a. That is, the vertical distance between the guide rails 2335 at the divergent tapered ends 2335a, indicated by the dashed arrow 2401, is greater than the vertical distance between the guide rails 2335 where the guide rails 2335 are parallel (i.e., closer to the surface 2328), indicated by the dashed arrow 2403.

[0451] The divergent tapered end region 2335a provides a first rough guidance to help quickly connect the print head to the print head support arm 2206 and thus quickly connect to the ink system. The tapered end region 2335a allows the user to achieve a lower degree of precision by aligning the slot (guidance feature) of the corresponding print head with the guide rail 2335. This is because the user can generally align the slot of the print head with the corresponding guide rail 2335 of the print head support arm 2206, and when the user slides the print head and thus slides the multiple fluid connectors and electrical connectors towards the corresponding connectors of the print head support arm connection interface 2315. The divergent tapered end 2335a allows the user to guide the print head towards the surface 2328 where the guide rails 2335 are parallel, thus ensuring the alignment of the connectors of the print head connection interface with the corresponding connectors of the print head support arm connection interface 2315.

[0452] In addition to providing alignment of the corresponding connectors between the print head and the print head support arm 2206, the guide rails 2335 can also reduce damage to the connectors by ensuring that the print head is always set in the correct orientation. If the print head is set in an incorrect orientation, the guide rails 2335 will not be received in the corresponding slots of the print head. Therefore, this will force an offset between the connectors of the print head and the corresponding connectors of the print head support arm 2206, preventing the user from attempting to force a connection between slightly misaligned connectors or between non-corresponding connectors, which may damage the connectors. This is because the guide rails 2335 must first be received in the guide slots 2338 defined by the corresponding print head and the removable cover. Then the print head can be guided towards the electrical connectors and fluid connectors of the print head support arm 2206. Therefore, the connection process of the print head to the ink system (i.e., the print head support arm) can be considered the following two-step process:

[0453] 1. Receiving the guide rails 2335 in the corresponding guide slots; and

[0454] 2. Connecting the corresponding fluid connectors and electrical connectors of the print head to the print head support arm.

[0455] In some embodiments, the second step may include the engagement of a self-coupling mechanical interlock.

[0456] It should be understood that Figure 11 the guide rails 2335 shown inFigures 6 to 11 the embodiments shown, and the guide rail 2335 can be replaced with other suitable alignment structures (such as guide pins). In addition, the guide rail can be provided on the print head, and the elongated strut 2333 can alternatively include corresponding guide slots, where the guide slots include diverging tapered end regions.

[0457] For completeness, the features of the print head support arm connection interface 2315 and the elongated strut 2333 can form part of an umbilical cable or a printer for connecting a removable print head. The elongated strut 2333 can also include Figures 6 to 10 product detection sensors of the type shown.

[0458] Figure 12 A perspective end view of a model of another print head support arm 3206 is shown, and Figure 13 an end view of the print head support arm 3206 is shown.

[0459] For ease of understanding, only the differences between the print head support arm 3206 and the print head support arms 1206 and 2206 will be described.

[0460] Like the print head support arms 1206 and 2206, the print head support arm 3206 includes a plurality of electrical connectors and a plurality of fluid connectors. In particular, the plurality of fluid connectors and the plurality of electrical connectors are provided on the print head support arm connection interface 3315. The print head 3208 includes a high-voltage connector 3327 and a low-voltage connector 3329. The high-voltage connector 3327 and the low-voltage connector 3329 can be the same type of connectors as described with respect to Figures 6 to 10 and Figure 11 However, it can be seen that compared with the print head support arm connection interface 1315, the high-voltage connector 3327 is a male connector. Although in the Figures 6 to 10 print head support arm connection interface 1315 of, the EHT connector 1327 is a female connector, this arrangement can further reduce the possibility of ink and / or solvent from the fluid connectors contacting the EHT connector.

[0461] The print head support arm connection interface 3315 also includes a slot line connector 3317, an exhaust line connector 3319, a drive line connector 3321, and a return line connector 3323, which together define the fluid connectors. The fluid connectors 3317, 3319, 3321, and 3323 can be the same type of connectors as described with respect to Figures 6 to 10 and Figure 11 described connectors.

[0462] The print head support arm connection interface 3315 also includes a mechanical latch barb 3325. Figure 12 The mechanical latch barb 3325 of Figures 6 to 10of the same type as shown.

[0463] The printhead support arm connection interface 3315 further includes a solenoid 3326. The solenoid 3326 functions in the same manner as the solenoid 1236 in Figures 6 to 10 and Figure 11 .

[0464] The arrangement (layout) of the connectors of the printhead support arm connection interface 3315 is respectively different from the arrangements of the printhead support arm connection interfaces 1315 and 2315 in Figures 6 to 10 and Figure 11 . In the orientations shown in Figure 12 and Figure 13 , the high-voltage connector 3327 and the low-voltage connector 3329 are provided on the upper region of the interface 3315. In addition, the high-voltage connector 3327, the low-voltage connector 3329, the solenoid 3326, and the mechanical latch barb 3325 are provided on a protruding structure 3330 that overhangs the face 3328 of the printhead support arm 3206. The channel line connector 3317, the exhaust line connector 3319, the drive line connector 3321, and the return line connector 3323 are provided below the protruding structure 3330. That is, the protruding structure 3330 overhangs the channel line connector 3317, the exhaust line connector 3319, the drive line connector 3321, and the return line connector 3323. The advantage of this arrangement is that when the printhead support arm 3206 and the printhead 3208 (not shown) are in the shown orientations, fluid can drip from the channel line connector 3317, the exhaust line connector 3319, the drive line connector 3321, and the return line connector 3323. This is the direction required to connect the printhead to the printhead support arm 3206 and to disconnect it from the printhead support arm 3206. The channel line connector 3317 and the exhaust line connector 3319 are provided between the drive line connector 3321 and the return line connector 3323.

[0465] The printhead support arm 3206 further includes an elongated strut 3333. The elongated strut 3333 extends in a direction away from the fluid and electrical connectors of the printhead support arm 3206 and provides support for the printhead (not shown). The printhead for connection to the printhead support arm 3206 may have a shape similar to that of the printhead 1208, but it should be understood that the connectors on the printhead for connection to the printhead support arm 3206 will be arranged to be complementary to the connectors of the printhead support arm connection interface 3315. In other embodiments, the printhead support arm 3206 may not include the elongated strut. The printhead 3208 may be supported by electrical, fluid, and / or mechanical connections between the printhead 3208 and the printhead support arm 3206. In other embodiments, the printhead 3208 may be supported by a support component of the printer that is not the printhead support arm.

[0466] The elongated support column 3333 includes a product detection sensor 3305. The product detection sensor is configured to sense the position of an external substrate that moves past the print arm 3204 for printing thereon. The product detection sensor 3305 can be of the same type as described with respect to Figures 6 to 10 the same type.

[0467] The elongated support column 3333 is different from the elongated support columns 1333 and 2333 of the print head support arms 1206 and 2206 in Figures 6 to 10 and Figure 11 that the elongated support column 3333 does not include a guide rail. The omission of the guide rail can allow for a faster connection of the print head 3208 to the print head support arm 3206. It should be understood that a print head including a guide groove can still be used with the print head support arm 3206, however, the guide groove would be redundant.

[0468] However, it should be understood that any guide rail described with respect to Figures 6 to 10 and Figure 11 can be applied to the print head support arm 3206.

[0469] Figure 14 A perspective end view showing another model of the print head support arm 4206 is shown.

[0470] For ease of understanding, only the differences between the print head support arm 4206 and the print head support arms 1206, 2206, and 3206 will be described.

[0471] Like the print head support arms 1206, 2206, and 3206, the print head support arm 4206 includes a plurality of electrical connectors and a plurality of fluid connectors. In particular, the plurality of fluid connectors and the plurality of electrical connectors are provided on the print head support arm connection interface 4315. The print head support arm 4206 includes a high voltage connector 4327 and a low voltage connector 4329. The high voltage connector 4327 and the low voltage connector 4329 can be connectors of the same type as described with respect to Figures 6 to 10 , Figure 11 as well as Figure 12 and Figure 13 and

[0472] The print head support arm connection interface 4315 further includes a groove line connector 4317, an exhaust line connector 4319, a drive line connector 4321, and a return line connector 4323, which together define the fluid connectors. The fluid connectors 4317, 4319, 4321, and 4323 can be connectors of the same type as those described with respect to Figures 6 to 10 , Figure 11 as well as Figure 12 and Figure 13 described.

[0473] The printhead support arm connection interface 4315 further includes a mechanical latch barb 4325. Figure 14 The mechanical latch barb 4325 is of the Figure 11 same type as that shown in

[0474] The printhead support arm connection interface 4315 further includes a solenoid 4326. The solenoid 4326 functions in the same manner as the solenoids in Figures 6 to 10 , Figure 11 and Figure 12 and Figure 13 .

[0475] The arrangement (layout) of the connectors of the printhead support arm connection interface 4315 is respectively different from the arrangements of the printhead support arm connection interfaces 1315, 2315, 3315 in Figures 6 to 10 , Figure 11 and Figure 12 and Figure 13 . In the orientation shown in Figure 14 , the high-voltage connector 4327 and the low-voltage connector 4329 are provided on the lower region of the interface 4315. In addition, the high-voltage connector 4327 and the low-voltage connector 4329 are provided on a protruding structure 4330 that extends from the face 4328 of the printhead support arm 4206. The slot line connector 4317, the exhaust line connector 4319, the drive line connector 4321, and the return line connector 4323, the latch barb 4325, and the solenoid 4326 extend from the face 4328 of the printhead support arm 4206. However, the high-voltage connector 4327 and the low-voltage connector 4329 are recessed into the surface of the protruding structure 4330 such that the protruding structure 4330 shields the high-voltage connector 4327 and the low-voltage connector 4329. In this way, because the fluid connectors are provided above the electrical connectors (in the orientation shown in Figure 14 ), any fluid that may drip from the fluid connectors will drip onto the outer edge 4332 of the protruding structure 4330, thereby reducing the likelihood of the fluid contacting the electrical connectors. This is the orientation that may be required to remove the printhead from the printhead support arm 4206. The slot line connector 4317 and the exhaust line connector 4319 are provided between the drive line connector 4321 and the return line connector 4323.

[0476] It should be understood that the printhead 4208 (not shown) will have corresponding connectors and complementary geometries to engage with the connectors of the printhead support arm 4208.

[0477] The printhead support arm 4206 further includes an elongate strut 4333. The elongate strut 4333 extends in a direction away from the fluid and electrical connectors of the printhead support arm 4206 and provides support for a printhead (not shown). The printhead adapted to be connected to the printhead support arm 4206 may have a shape similar to that of the printhead 1208, but it should be understood that the connectors on the printhead adapted to be connected to the printhead support arm 4206 will be arranged to be complementary to the connectors of the printhead support arm connection interface 4315.

[0478] The elongate strut 4333 includes elongate parallel guide rails 4335 and is the same as the elongate strut 1333 of the printhead support arm 1206 shown in Figure 6 , except that there is no product detection sensor. Instead, it can be seen that the elongate strut 4333 defines a recess 4336 for receiving a product detection sensor. The elongate guide rails 4335 allow the printhead and the printhead cover to be engaged with the printhead support arm 4206. The recess 4336 includes a plurality of electrical contacts 4338 for providing at least power to the product detection sensor. Thus, the printhead support arm 4206 is configured to receive a removable product detection sensor. In other embodiments, the corresponding printhead may include a product detection sensor and may be configured to receive a removable product detection sensor. Providing a removable product detection sensor is advantageous because during repair, maintenance, and servicing, only the necessary components need to be accessed or removed, and any component (such as the printhead, product detection sensor) can be easily replaced with a similar component. In this way, the downtime of the printer is reduced because the printer does not need to be stopped for a long time for repair and replacement of the printhead and other replaceable components.

[0479] Regarding Figures 3 to 14 the type of printhead described, the printhead can be removed from the printhead support arm, and another printhead can be connected to the printhead support arm, and the printing operation can resume within approximately 2 minutes.

[0480] When the user wants to remove the printhead, they can actuate the button 1377 (see Figure 10 ). Actuation of the button allows the latch to move as shown in Figure 9 , and results in the detachment of the latch and the latch barb, thereby allowing the removal and replacement of the printhead. The button can be used as a release trigger, which can initiate a release sequence. The release sequence may include terminating the power supply to the printhead.

[0481] In an embodiment using a solenoid electric locking latch, actuation of the latch can be prevented until the solenoid is in the retracted position (i.e., electromechanical unlocking occurs). Moving the solenoid to the retracted position can form part of the release sequence. For example, a printer can include a screen or a button that allows a user to select when they want to release the print head, and the screen or button can be used as a release trigger.

[0482] The solenoid can be configured such that it is in the retracted position when current is applied, or it can be configured such that it is in the retracted position when no current is applied.

[0483] When the solenoid is in the retracted position when current is applied, selection of the release trigger can first cause power supply to the components of the print head to be terminated, and then current is applied to the solenoid such that the solenoid moves from the extended position to the retracted position.

[0484] When the solenoid is in the retracted position when no current is applied, selection of the release trigger can first cause power supply to the components of the print head and the solenoid to be terminated, such that the solenoid moves from the extended position to the retracted position.

[0485] Once the solenoid is in the retracted position, the user can remove the print head by disconnecting the print head connection interface from the print head support arm interface.

[0486] The printer can include a controller, such as Figure 1 the controller 6 shown in, and the controller can be arranged to implement a security protocol, where the controller checks that at least one of the following conditions is met:

[0487] - There is no power transfer between the plurality of electrical connectors;

[0488] - There is no voltage drop across the plurality of electrical connectors;

[0489] - There is no fluid passage between the fluid connectors.

[0490] The controller can prevent removal of the print head until one or more predetermined safety conditions are met.

[0491] Once the solenoid is in the retracted position, the user can actuate the button as described above and then remove the print head. In other embodiments, movement of the latch can be automatically controlled as part of the release sequence such that the user only needs to remove the print head.

[0492] Once the printhead is removed, a new printhead can be provided (in some cases, the new printhead can simply be the same printhead that was just removed, inspected, and / or cleaned). To provide the new printhead, the user can simply position the printhead connection interface together with the printhead support arm connection interface. Once a fluid connection, a mechanical connection, and an electrical connection are formed, the solenoid (if present) can electrically lock the latch. Then power can be supplied to the printhead, and the printing operation can resume.

[0493] Figure 15 is an exemplary flowchart of steps that may occur when removing and replacing a printhead, including a release sequence.

[0494] For ease of understanding, the printer components will be provided with Figure 2 and Figures 5 to 10 reference numerals used in. However, it should be understood that the steps for removing and replacing the printhead described below apply to all embodiments of the present invention.

[0495] Step 5100 is the first step of performing an operation to shut off the inkjet. That is, the printer 1280 stops ejecting ink from the nozzles 134 of the printhead 1208. Shutting off the inkjet can be initiated by the user. For example, the user can engage a release trigger that initiates the release sequence. The release trigger can be a button or switch on the printhead 1208 or the printer that can be actuated manually, or it can be an interface on a touchscreen. Actuation of the release trigger can cause the inkjet to shut off. However, for example, if one of the electrical components of the printhead or the printer trips, it may cause the inkjet to shut off. For example, if the extra-high voltage electrical connector 1327 trips. If the inkjet stops due to a component or electrical failure, the printer can warn the user. As described in further detail below, step 5100 can include cleaning the nozzles 134 and the supply lines with a solvent.

[0496] The next step 5200 is to perform a safety check. This can include ensuring that one or more safety conditions are met. The safety check can be performed by the user and may require the user to confirm via an input mechanism (e.g., a switch, a touchscreen) that the safety check has been completed. However, the safety check can preferably be performed by the controller 6 of the printer. The safety check can include, but is not limited to, ensuring that the EHT is off, and / or stopping the power supply, and / or checking that the ink pump 130 is off, and / or checking that the solvent pump 130 is off, and / or checking that the sump pump 168 is off, and / or checking that the pressure transducer 138 shows a low reading; and / or checking whether the fluid valves 126, 142, 144, 146 are closed. Once the safety conditions are met, the solenoid 1326 can be released. It should be understood that the performance of the safety check is optional and not required in all embodiments.

[0497] Step 5300 is to disengage the solenoid 1326. In other words, the solenoid 1326 moves from an engaged position that prevents the latch 1373 from moving to a disengaged position that allows the latch 1373 to move and thus remove the printhead 1208. In particular, the solenoid 1326 can move from an extended position to a retracted position. The movement of the solenoid 1326 can be controlled by energizing the solenoid (applying current) or, in other embodiments, by de-energizing the solenoid (removing or absence of current). The controller 6 of the printer can control the movement of the solenoid 1326. As described above, the presence of the solenoid 1326 is not required in all embodiments. In embodiments that do not include a solenoid used as an electrical locking mechanism, step 5300 can be skipped. Similarly, in other embodiments, when using an electrical locking mechanism other than the solenoid 1326, step 5300 can include unlocking the electric lock.

[0498] Step 5400 is to remove the printhead 1208. The removal of the printhead occurs when the printhead 1208 moves such that the fluid connector and electrical connector of the printhead 1208 are not engaged with the corresponding connectors of the printhead support arm 1206. Alternatively, in other embodiments where the fluid connector and electrical connector of the printhead 1208 are not engaged with the corresponding connectors on the printer or umbilical cable. In some embodiments, to remove the printhead 1208, the user may need to disengage a self-latching locking mechanism (e.g., a latch and barb mechanism) by actuating a button and then pulling the printhead 1208 away from the corresponding connectors. In some embodiments, the user can use a pinch and withdraw mechanism to remove the printhead 1208. In some embodiments where the printhead 1208 includes guiding features, the printhead 1208 may have to move away from the printhead support member in a single direction, i.e., the printhead 1208 may have to slide away from the corresponding connectors. Steps 5300 and 5400 can take the user approximately 10 seconds or less to complete.

[0499] Steps 5100, 5200, 5300, and 5400 can define a release sequence 5500. However, it should be understood that in some embodiments, steps 5200 and 5300 can be omitted. Additionally, the release sequence 5500 need not be limited to steps 5100, 5200, 5300, 5400.

[0500] After the release sequence 5500, an alternative printhead 1208 may be provided. The alternative printhead 1208 will typically be a different printhead than the printhead 1208 removed during the release sequence 5500. However, the alternative printhead may be the same printhead 1208 that was removed. For example, a user may remove the printhead 1208, inspect and / or clean the printhead 1208, and then replace it. The step 5600 of providing an alternative printhead includes engaging the printhead connection interface 1339 with the printhead support arm connection interface 2315, or with the connection interface of an umbilical cable or the printer.

[0501] Once an alternative printhead has been provided, the printer's controller 6 may check whether the alternative printhead has been assembled, which is shown as step 5700. In some embodiments, the printhead 1208 may include a data storage device (e.g., an electronic data storage device of the type described in WO2017194913A). The controller 6 may be arranged to read the smart chip and authenticate the alternative printhead. In particular, the controller 6 may be able to determine the nozzle size of the printhead 1208 such that the printing operation can be adjusted accordingly. The smart chip may be arranged on the printhead 1208 such that it can only be read by the controller 6 once the fluid connector and electrical connector of the printhead 1208 are engaged with the corresponding connectors. In some embodiments, the smart chip may be arranged such that it can only be read once the self - coupling mechanical interlock 1371 is engaged and / or the electrical locking mechanism (e.g., solenoid 1326 is engaged). Step 5700 is an optional step.

[0502] Subsequently, the controller 6 may optionally check whether the printhead 1208 is correctly installed, as shown in step 5800. In some embodiments, checking whether the alternative printhead 1208 is correctly assembled may be performed by the user, as an alternative or supplement to the controller 6 checking whether the alternative printhead 1208 is correctly assembled. Step 5800 is an optional step, and in some embodiments, step 5800 may simply form part of step 5700.

[0503] Once an alternative printhead has been provided, the printing operation may be started, as shown in step 5900. Starting the printing operation includes ejecting ink from the nozzles 134 of the printhead 1208. The time taken to provide an alternative printhead (step 5600), check whether the alternative printhead is assembled (step 5700), check whether the alternative printhead is correctly assembled (step 5800), and start the printing operation (step 5900) may take approximately 50 seconds.

[0504] Steps 5100, 5200, 5300, 5400, 5500, 5600, 5700, 5800, 5900 may be completed in about 2 minutes.

[0505] Figure 16is a flowchart showing the steps that may occur within the step 5100 of shutting down the inkjet.

[0506] The controller 6 may first stop the inkjet 5102.

[0507] After stopping the inkjet, the printer applies suction to the nozzles 134 of the printhead 1208 using a pump to draw out any ink and / or solvent from the nozzles 134, as shown in step 5104. This protects the nozzles 134 from the accumulation of ink and / or deposits in the nozzles 134.

[0508] Then the nozzles 134 are cleaned with a solvent (step 5106). This may include supplying the solvent from the solvent compartment 110 via the solvent supply line 114 and the flushing line 170, and drawing the solvent out of the nozzles 134 via the side port 173 and the purge line 172.

[0509] Then the trough 164 is cleaned (step 5108). In particular, the trough 164 may be cleaned with a solvent. The trough 164 may be cleaned with a solvent by spraying the solvent through the nozzles 134 of the printhead 1208.

[0510] Then suction is applied to the nozzles 134 again (step 5110) to remove as much solvent as possible. It is desirable to remove as much solvent as possible to reduce clogging.

[0511] In step 5112, suction may also be applied to the return line 166 (which may be referred to as the trough line) to remove as much solvent as possible from the trough 164. It is desirable to remove as much solvent as possible to reduce clogging of the dried ink.

[0512] Then the pumps 126, 142, 144, 146 may be turned off in step 5114.

[0513] Steps 5112 and 5110 may be completed in the reverse order, or in parallel with the Figure 16 order shown in

[0514] Figure 17 is a flowchart showing the steps of checking for satisfaction of safety conditions in the Figure 15 step 5200 of

[0515] The first step 5202 is to check whether the EHT is turned off. This may be achieved by the controller 6 checking that no power is supplied to the printhead 1208 via the EHT connector 1327.

[0516] The next step 5204 is to check whether the power supply to the electrical components of the printhead 1208 (saved as a solenoid in some embodiments) is turned off.

[0517] The next step 5206 is to check whether the ink pump 130 is turned off.

[0518] The next step 5208 is to check whether the solvent pump is closed.

[0519] The next step 5210 is to check whether the tank pump 168 is closed.

[0520] The next step 5212 is to check whether the pressure sensor 138 is less than a predetermined pressure. In particular, the pressure can be less than about 0.1 bar.

[0521] The next step 5214 is to check whether the valves 126, 144, 146, 148 are closed.

[0522] In some embodiments, the controller 6 can be arranged such that it cannot perform the next safety check until the current check is satisfied. Figure 17 The safety checks shown are not restrictive, and further safety checks can be implemented. Similarly, not Figure 16 all of the safety checks shown are necessary, and the order of the safety checks can be changed. Additionally, some or all of the safety checks shown can be performed in parallel. However, in embodiments where the safety check 5200 needs to be performed, the release of the electric lock (e.g., solenoid) is prohibited unless the safety checks (5202 to 5214) are satisfied. In some embodiments, the printer can allow the user to manually override some or all of the safety checks.

[0523] Although multiple printhead support arms, printheads, and printers have been described, it should be understood that the printhead support arms, printheads, and printers are not limited to the exact features described, and the features of one printhead support arm, printhead, and printer can be combined with another. As an example, the described printhead support arm is shown as including an elongated strut; however, it should be understood that the elongated strut is not necessary for the printhead of the present invention to be connected to the corresponding printhead support arm. In other embodiments, the printhead support arm may not include an elongated strut. The printhead can be supported by an electrical connection, a fluid connection, and / or a mechanical connection between the printhead and the printhead support arm. In other embodiments, the printhead can be supported by a support component of the printer that is not the printhead support arm. The self - coupling mechanical interlock of the above type can exist when the printhead support arm does not include an elongated strut and / or a guide rail.

[0524] Similarly, it should be understood that a guide rail is not necessary for the printhead to be connected to and disconnected from the printhead support arm. In some embodiments, the printhead can be directly connected to the umbilical cable. In other embodiments, the umbilical cable may not exist.

[0525] Various arrangements of fluid connectors and electrical connectors have been described. Again, it should be understood that any suitable arrangement can be provided given connectors of appropriate positioning and dimensions are provided at the printhead connection interface and the printhead support arm connection interface. In addition, mechanical interlocking is not necessary for all embodiments of the printhead.

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: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; and A gutter configured to receive ink droplets not used for printing; and An ink system configured to store ink and supply ink to the print head; Wherein: The print head is releasably connected to the ink system via a print head connection interface, the print head connection interface including a plurality of fluid connectors and a plurality of electrical connectors; and The printer is configured to allow the print head to be removed from the printer and a replacement print head to be connected to the printer, and for a printing operation to commence within a period of approximately 2 minutes.

2. The continuous inkjet printer according to claim 1, wherein, The print head connection interface includes mating guide features configured to guide the print head from a disconnected configuration to a connected configuration.

3. A continuous inkjet printer for printing on an external substrate moving past the printer, the printer comprising: A print head, the print head comprising: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; and A gutter configured to receive ink droplets not used for printing; and An ink system configured to store ink and supply ink to the print head; Wherein: The print head is releasably connected to the ink system via a print head connection interface, the print head connection interface including a plurality of fluid connectors, a plurality of electrical connectors and mating guide features configured to guide the print head from a disconnected configuration to a connected configuration.

4. The continuous inkjet printer according to claim 3, wherein, The printer is configured to allow the print head to be removed from the printer, a replacement print head to be connected to the printer, and for a printing operation to commence within a period of approximately 2 minutes.

5. The continuous inkjet printer according to claim 1 or claim 4, wherein, The printer is configured to allow the print head to be removed from the printer within approximately 10 seconds or less from when one or more safety conditions are met.

6. The continuous inkjet printer according to any one of the preceding claims, wherein, The continuous inkjet printer includes a controller; The controller is arranged to check that no current is supplied to components of the print head before the print head is disconnected.

7. A continuous inkjet printer according to any one of claim 2 or claim 3 or claims 4 to 6 which are dependent on claim 2 or 3, wherein, A first guide feature is provided on the printer and a second guide feature is provided on the print head.

8. The continuous inkjet printer according to claim 2 or 3 or any one of claims 4 to 7 dependent on claim 2 or 3, wherein, The guide features include rails or guide grooves.

9. The continuous inkjet printer according to any one of claim 2 or claim 3 or claims 4 to 8 which are dependent on claim 2 or 3 further comprises a print head support for supporting the print head, wherein, The mating guide features are configured to allow only a substantially linear movement of the print head relative to the print head support.

10. The continuous inkjet printer according to any one of claim 2 or claim 3 or claims 4 to 9 dependent on claim 2 or 3, wherein, The guide features extend along 75% of the length of the print head.

11. A continuous inkjet printer according to any one of claim 2 or claim 3 or claims 4 to 10 dependent on claim 2 or 3, wherein, The guide features include a first guide region configured to provide coarse guidance, a second guide region configured to provide fine guidance, and a tapered region between the first guide region and the second guide region.

12. The continuous inkjet printer according to any one of the preceding claims, wherein, The print head connection interface includes a self - coupling mechanical interlock device.

13. The continuous inkjet printer according to any one of the preceding claims, wherein, The print head includes a removable cover.

14. A print head for a continuous inkjet printer, the print head comprising: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; And A gutter configured to receive ink droplets not used for printing, Wherein the printhead is releasably connected to an ink system of a continuous inkjet system via a printhead connection interface, the printhead connection interface includes a plurality of electrical connectors and a plurality of fluid connectors, and the printhead is configured to be removed from the printer and a replacement printhead is connected to the printer, and printing operations begin within a period of about 2 minutes.

15. The print head according to claim 14, wherein, The printhead connection interface includes mating guiding features configured to guide the printhead from a disconnected configuration to a connected configuration.

16. A printhead for a continuous inkjet printer, the printhead comprising: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; And A gutter configured to receive ink droplets not used for printing; And Wherein the printhead is releasably connected to an ink system of a continuous inkjet system via a printhead connection interface, the printhead connection interface includes a plurality of electrical connectors, a plurality of fluid connectors and mating guiding features configured to guide the printhead from a disconnected configuration to a connected configuration.

17. The print head according to claim 16, wherein, The printhead is configured to be removed from the printer and a replacement printhead is connected to the printer, and printing operations begin within a period of about 2 minutes.

18. The print head according to any one of claims 14 to 17, wherein, The printhead connection interface includes a self-coupling mechanical interlock device.

19. The print head according to any one of claims 14 to 18, wherein, The printhead includes a removable cover, and wherein the removable cover can be removed from the printhead only when the printhead is not connected to the ink system.

20. A method of operating a continuous inkjet printer for printing on an external substrate moving past the printer, the printer including a printhead and an ink system for storing ink and supplying ink to the printhead, wherein the printhead is releasably connected to the ink system; The printhead includes: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; A gutter configured to receive ink droplets not used for printing; Wherein the printhead is releasably connected to the ink system via a printhead connection interface, the printhead connection interface includes a plurality of fluid connectors and a plurality of electrical connectors; The method includes, within a period of about 2 minutes: Removing the printhead from the printer; Providing a replacement printhead; Connecting the plurality of fluid connectors of the replacement printhead to corresponding connection means of the printer; Connecting the plurality of electrical connectors of the replacement printhead to corresponding connection means of the printer; Resuming printing operations.

21. The method according to claim 20, wherein, The printhead connection interface includes mating guiding features configured to guide the printhead from a disconnected configuration to a connected configuration, and the method includes: Aligning the mating guiding features; Connect the plurality of fluid connectors to corresponding connection means of the printer; Connect the plurality of electrical connectors to corresponding connection means of the printer.

22. A method of operating a continuous inkjet printer for printing on an external substrate moving past the printer, the printer including a print head and an ink system for storing ink and supplying the ink to the print head, wherein, The printhead is releasably connected to the ink system; The printhead includes: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; A gutter configured to receive ink droplets not used for printing; Wherein the printhead is releasably connected to the ink system via a printhead connection interface including a plurality of fluid connectors, a plurality of electrical connectors, and mating guide features configured to guide the printhead from a disconnected configuration to a connected configuration; The method includes: Align the mating guide features; Connect the plurality of fluid connectors to corresponding connection means of the printer; Connect the plurality of electrical connectors to corresponding connection means of the printer.

23. The method according to claim 22, wherein, The method includes, within a period of about 2 minutes: Remove the printhead from the printer; Provide a replacement printhead; Connect the plurality of fluid connectors of the replacement printhead to corresponding connection means of the printer; Connect the plurality of electrical connectors of the replacement printhead to corresponding connection means of the printer; Resume the printing operation.

24. The method according to any one of claims 20 or 23, wherein, Removal of the printhead occurs within a period of about 10 seconds or less from when one or more safety conditions are met.

25. The method according to claim 20, 23 or 24, wherein, Before removing the printhead, use a controller to check that no current is being supplied to components of the printhead and / or Wherein removing the printhead includes sliding the printhead away from a printhead support member.

26. The method according to any one of claims 21, 22, 24 or 25, wherein, Providing a replacement printhead includes sliding the replacement printhead towards the printhead support member.

27. A continuous inkjet printer for printing on an external substrate moving past the printer, the printer including: A printhead, the printhead including: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; and A gutter configured to receive ink droplets not used for printing; and An ink system configured to store ink and supply ink to the printhead; Wherein: The printhead is releasably connected to the ink system via a printhead connection interface including a plurality of fluid connectors, a plurality of electrical connectors, and a self - coupling mechanical interlock.

28. The continuous inkjet printer according to claim 27, wherein, The printhead further includes a removable cover, and wherein the removable cover can be removed from the printhead only when the printhead is not connected to the ink system.

29. A continuous inkjet printer for printing on an external substrate moving past the printer, the printer including: A printhead, the printhead including: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; A gutter configured to receive ink droplets not used for printing; and A removable cover; and An ink system configured to store ink and supply ink to the printhead; Wherein: The printhead is removably connected to the ink system via a printhead connection interface, the printhead connection interface including a plurality of fluid connectors and a plurality of electrical connectors; and Wherein the removable cover can only be removed from the printhead when the printhead is not connected to the ink system.

30. The continuous inkjet printer according to claim 29, wherein, The printhead connection interface further includes a self - coupling mechanical interlock device.

31. The continuous inkjet printer according to any one of claims 27 to 30, when at least subordinate to claim 27 or claim 30, wherein, The mechanical interlock device is configured to prevent removal of the printhead unless a safety condition is met.

32. A continuous inkjet printer according to any one of claims 27 to 31, wherein, The printhead connection interface includes a release trigger configured to initiate a release sequence; optionally Wherein the release sequence includes determining whether the safety condition is met and releasing the mechanical interlock device only when the safety condition is met.

33. The continuous inkjet printer according to any one of claims 27 to 32, when dependent on at least claim 27 or claim 30, further comprising an electric lock configured to electrically lock the self - coupling mechanical interlock device.

34. The continuous inkjet printer according to any one of claims 27 to 33, when dependent on at least claim 27 or claim 30, wherein, The self - coupling mechanical interlock device includes a latch for engaging a corresponding locking body of the continuous inkjet printer; and / or Wherein the self - coupling mechanical interlock device is arranged to provide a quick and safe release of the printhead from the ink system.

35. The continuous inkjet printer according to any one of claims 27 to 34 further includes a controller, and wherein, At least one of the plurality of fluid connectors and / or at least one of the plurality of electrical connectors includes a sensor, and the controller is operable to receive a signal from the sensor.

36. The continuous inkjet printer according to any one of claims 27 to 35, when dependent on at least claim 27 or claim 30, wherein, The self - coupling mechanical interlock device is engaged and released without the use of tools; and / or Wherein, the self - coupling mechanical interlock device is configured to engage only when the plurality of fluid connectors and the plurality of electrical connectors are engaged with their corresponding connectors of the ink system.

37. The continuous inkjet printer according to any one of claims 27 to 36, wherein, The distal ends of the plurality of fluid connectors are offset from the distal ends of the plurality of electrical connectors.

38. The continuous inkjet printer according to any one of claims 27 to 37, wherein, At least one of the plurality of fluid connectors includes a self - sealing fluid valve for preventing leakage of the printing fluid when the printhead is removed; and / or Wherein, the printer is configured to allow the printhead to be removed from the printer and connected to the printer without the use of any tools.

39. The continuous inkjet printer according to any one of claims 27 to 38, wherein, The printer includes a printhead support coupled to the ink system, and the printhead connection interface is supported by components of the printhead support and the printhead; optionally Wherein, the printhead support is rotatably coupled to the printer.

40. The continuous inkjet printer according to any one of claims 27 to 39, wherein, The continuous inkjet printer includes a product detection sensor to sense the position of the external substrate; optionally When dependent on claim 39, the printhead support includes a product detection sensor.

41. The continuous inkjet printer according to any one of claims 27 to 40, when at least subordinate to claim 28 or 29, wherein, The removable cover prevents access to the droplet generator, the at least one electrode, and the trough when covering the printhead; and / or the removable cover can be removed from the printhead without tools.

42. The continuous inkjet printer according to any one of claims 27 to 41, wherein, The printhead connection interface includes mating guide features configured to guide the printhead from a disconnected configuration to a connected configuration.

43. The continuous inkjet printer according to any one of claims 27 to 42, wherein, The printer is configured to allow the printhead to be removed from the printer, to connect a replacement printhead to the printer, and to initiate a printing operation within a period of about 2 minutes.

44. A printhead for a continuous inkjet printer, the printhead comprising: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; And A gutter configured to receive ink droplets not used for printing; And Wherein the printhead is releasably connected to an ink system of a continuous inkjet system via a printhead connection interface, the printhead connection interface including a plurality of electrical connectors, a plurality of fluid connectors, and a self-latching mechanical interlock device.

45. The print head according to claim 44, wherein, The printhead includes a removable cover, and wherein the removable cover can only be removed from the printhead when the printhead is not connected to the ink system.

46. A printhead for a continuous inkjet printer, the printhead comprising: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; And A gutter configured to receive ink droplets not used for printing, and A removable cover; And Wherein the printhead is releasably connected to an ink system of a continuous inkjet system via a printhead connection interface, the printhead connection interface including a plurality of electrical connectors and a plurality of fluid connectors, and wherein the removable cover can only be removed from the printhead when the printhead is not connected to the ink system.

47. The print head according to claim 46, wherein, The printhead connection interface further includes a self-latching mechanical interlock device.

48. The printhead for a continuous inkjet printer according to any one of claims 44 to 47, wherein, The printhead connection interface includes mating guide features configured to guide the printhead from a disconnected configuration to a connected configuration.

49. The print head for a continuous inkjet printer according to any one of claims 44 to 48, wherein, The printer is configured to allow the printhead to be removed from the printer, and to connect a replacement printhead to the printer, and to initiate a printing operation within a period of about 2 minutes.

50. A method of operating a continuous inkjet printer for printing on an external substrate moving past the printer, the printer including a printhead and an ink system for storing and supplying ink to the printhead, wherein the printhead is releasably connected to the ink system; The printhead includes: A droplet generator configured to generate and eject a stream of ink droplets for printing; At least one electrode configured to deflect the stream of ink droplets; And A gutter configured to receive ink droplets not used for printing; Wherein the printhead is releasably connected to the ink system via a printhead connection interface, the printhead connection interface including a plurality of fluid connectors, a plurality of electrical connectors, and a self-latching mechanical interlock device; The method includes: Connecting the plurality of fluid connectors to corresponding connection means of the printer; Connecting the plurality of electrical connectors to corresponding connection means of the printer; and Engaging the self-latching mechanical interlock device to prevent removal of the printhead.

51. The method according to claim 50, wherein, The printhead further includes a removable cover, and the method includes removing the removable cover when the printhead is not connected to the ink system.

52. A method of operating a continuous inkjet printer for printing on an external substrate moving past the printer, the printer including a printhead and an ink system for storing ink and supplying ink to the printhead, wherein the printhead is releasably connected to the ink system; The printhead includes: a droplet generator configured to generate and eject a stream of ink droplets for printing; at least one electrode configured to deflect the stream of ink droplets; a removable cover; and a gutter configured to receive ink droplets not used for printing; wherein the printhead is releasably connected to the ink system via a printhead connection interface, the printhead connection interface including a plurality of fluid connectors and a plurality of electrical connectors; The method includes: disconnecting the plurality of fluid connectors from the corresponding connectors of the printer; disconnecting the plurality of electrical connectors from the corresponding connectors of the printer; and removing the removable cover when the printhead is not connected to the plurality of electrical connectors and the plurality of fluid connectors.

53. The method according to any one of claims 50 to 52, wherein The printhead connection interface includes mating guiding features configured to guide the printhead from a disconnected configuration to a connected configuration, and the method includes: aligning the mating guiding features; connecting the plurality of fluid connectors to the corresponding connection means of the printer; connecting the plurality of electrical connectors to the corresponding connection means of the printer.

54. The method according to any one of claims 50 to 53, wherein, The method includes: within a period of about 2 minutes: removing the printhead from the printer; providing a replacement printhead; connecting the plurality of fluid connectors of the replacement printhead to the corresponding connection means of the printer; connecting the plurality of electrical connectors of the replacement printhead to the corresponding connection means of the printer; resuming the printing operation.

Images