NL2015660B1

NL2015660B1 - Printhead assembly, printing system including printhead assembly, method for assembling printhead assembly and method for carrying out maintenance.

Info

Publication number: NL2015660B1
Application number: NL2015660A
Authority: NL
Inventors: Duijsters Jos; Klein Meuleman Peter
Original assignee: Spgprints B V
Priority date: 2015-10-26
Filing date: 2015-10-26
Publication date: 2017-05-23

Abstract

The invention relates to a printhead assembly comprising a frame and a printing unit, wherein the printing unit comprises: - a positioning unit; - a base plate; - a printhead; - a first support; - a second support; - a guiding mechanism; and - a lifting mechanism, wherein the positioning unit is fixed to the frame at a predetermined location and is configured to receive the base plate and position the base plate relative to the frame, wherein the printhead is exchangeably mounted to the base plate at a predetermined location, wherein the base plate is releasably connected to the second support in such a manner that the second support is able to move the base plate in a lifting direction from and to the positioning unit while allowing the base plate to move relative to the second support in six degrees of freedom when the base plate is received by the positioning unit, wherein the second support is mounted to the first support via the lifting mechanism allowing the second support to be moved relative to the first support in the lifting direction, and wherein the first support is mounted to the frame via the guiding mechanism allowing the first support to be moved in a direction other than the lifting direction between a maintenance position and a position in which the base plate is positioned above the positioning unit to be received by the positioning unit.

Description

Title: Printhead assembly, printing system including printhead assembly, method for assembling printhead assembly and method for carrying out maintenance

The invention relates to a printing system comprising a printhead assembly including one or more printheads. Issues when designing and using printhead assemblies, especially in industrial environments, include accurately aligning the printheads for operation purposes, and allowing easy maintenance of the printheads, including easy replacement of printheads.

Prior art printing systems usually lack easy access to printheads for maintenance purposes, or in case easy access is provided, a complex and lengthy alignment process is required following the maintenance resulting in relatively long downtime of the printing system.

It is therefore an object of the invention to provide an improved printing system allowing easy access to the printheads for maintenance and lacking a complex and lengthy alignment process after maintenance.

This object is achieved by providing a printhead assembly comprising a frame and a printing unit, wherein the printing unit comprises: - a positioning unit; - a base plate; - a printhead; - a first support; - a second support; - a guiding mechanism; and - a lifting mechanism, wherein the positioning unit is fixed to the frame at a predetermined location and is configured to receive the base plate and position the base plate relative to the frame, wherein the printhead is exchangeably mounted to the base plate at a predetermined location, wherein the base plate is releasably connected to the second support in such a manner that the second support is able to move the base plate in a lifting direction from and to the positioning unit while allowing the base plate to move relative to the second support in six degrees of freedom when the base plate is received by the positioning unit, wherein the second support is mounted to the first support via the lifting mechanism allowing the second support to be moved relative to the first support in the lifting direction, and wherein the first support is mounted to the frame via the guiding mechanism allowing the first support to be moved in a direction other than the lifting direction between a maintenance position and a position in which the base plate is positioned above the positioning unit to be received by the positioning unit.

An advantage of the printhead assembly according to the invention is the possibility to move the base plate including printheads mounted thereto in two different directions to a maintenance position allowing easy access of the printheads without removing the printheads from the base plate.

Another advantage of the printhead assembly according to the invention is the combination of the positioning unit and the releasable connection between the second support and the base plate, such that this connection allows accurate positioning of the base plate after maintenance without interference by the second support and other components attached thereto. In other words, the component to be positioned accurately, i.e. the base plate, can be decoupled during accurate positioning from the other components which may introduce disturbances and inaccuracies.

In an embodiment, multiple printheads are exchangeably mounted to the base plate at respective predetermined locations. This may be for instance advantageously used in full width printing, where the multiple printheads together have to cover the entire width. By mounting the multiple printheads to the same base plate, the position accuracy between printheads can be improved and during maintenance, the multiple printheads can be moved to the maintenance printhead allowing maintenance operations to be performed on the multiple printheads at the same time.

In an embodiment, the positioning unit comprises reference points to which the base plate can be pressed using resilient elements. By positioning the base plate against the reference points and pressing the base plate against the reference points using resilient members, the base plate can be positioned accurately in the same position every time and the position is in principle independent of operation of the resilient members as this, in a predetermined range, will only result in minor changes in pressing forces.

In an embodiment, the positioning unit is configured to position the base plate relative to the frame in six degrees of freedom.

In an embodiment, the printhead assembly comprises multiple printing units together forming an array of printheads. This may for instance be advantageous when each printing unit is used for a single type of material or colour, as in that case maintenance for printheads corresponding to a single type of material or colour can be performed at the same time.

The invention also relates to a printing system comprising a printhead assembly according to the invention, and a substrate holder for supporting a substrate to be printed on by the printhead assembly, wherein the printhead assembly and substrate holder are moveable relative to each other.

In an embodiment, the substrate holder is stationary and the printhead assembly is moveable relative to the substrate holder.

In an embodiment, the printhead assembly is stationary and the substrate holder is moveable relative to the printhead assembly.

In a less preferred embodiment, neither the printhead assembly nor the substrate holder is stationary, and both are moveable relative to a base frame of the printing system.

The invention further relates to a method for assembling a printhead according to the invention, comprising the following steps: a. providing the frame; b. fixing the positioning unit at the predetermined location to the frame; c. providing a base plate with the printhead mounted thereto at the predetermined location to the base plate; d. mounting the first support to the frame via the guiding mechanism; e. mounting the second support to the first support via the lifting mechanism; and f. connecting the base plate to the second support.

The invention also relates to a method for carrying out maintenance to a printhead assembly according to the invention, comprising the following steps: a. lifting the second support and thereby the base plate from the positioning unit in the lifting direction using the lifting mechanism; b. moving the first support in the direction other than the lifting direction to the maintenance position; c. carrying out maintenance to the printhead assembly; d. moving the first support to the position in which the base plate is positioned above the positioning unit; and e. lowering the base plate on the positioning unit.

In an embodiment, carrying out maintenance to the printhead assembly comprises removing the printhead from the base plate and mounting the same or a replacement printhead to the base plate.

The invention will now be described in a non-limiting way by reference to the accompanying drawings in which like parts are indicated by like reference symbols, and in which:

Fig. 1 depicts a printhead for a printhead assembly according to an embodiment of the invention;

Fig. 2 depicts a base plate to which the printhead of Fig. 1 can be connected;

Fig. 3A + 3B depict schematically how the base plate is accurately positioned by a positioning unit;

Fig. 4 depicts in detail a connection between the base plate of Fig. 2, 3A and 3B and a second support;

Fig. 5 depicts how the unit of Fig. 4 is connected to a first support;

Fig. 6 depicts how the unit of Fig. 5 is connected to a frame in an operational situation;

Fig. 7 depicts the printhead assembly of Fig. 6 when the base plate is completely lifted from the positioning unit;

Fig. 8 depicts the printhead assembly of Fig. 7 when the first support has been moved to the maintenance position;

Fig. 9 depicts schematically a printing system including a printhead assembly according to an embodiment of the invention; and Fig. 10 depicts schematically a base plate with multiple printheads corresponding to a printhead assembly according to another embodiment of the invention.

Figs. 1 to 8 all relate to a printhead assembly according to an embodiment of the invention. The printhead assembly according to this embodiment of the invention is based on the principle that the complex and lengthy process of accurately positioning and aligning the printheads takes place during manufacturing and assembling of the printhead assembly and in principle not during operation and maintenance of the printhead assembly.

As a result thereof, the printhead assembly may lack actuators or other position adjustment mistake is made during manufacturing or assembly of a component of the printhead assembly, the printhead assembly has no means available to correct this mistake, so that the component needs to be replaced with a properly manufactured or assembled component.

In case the printhead assembly comprises actuators or other position adjustment devices such as adjustment screws for this purpose, the actuators and other position adjustment devices are preferably configured such that once positioned in the desired position the actuators and other position adjustment devices can be locked or are otherwise not susceptible to significant drift or change. At least the actuators and other position adjustment devices are configured such that for releasable and exchangeable connections, the release and coupling of the respective components does not require operation of, i.e. is independent of the actuators and other position adjustment devices.

Fig. 1 depicts a printhead 1 suitable for a printhead assembly according to an embodiment of the invention. The type of printhead 1 in itself is not essential for the invention. The printhead 1 in this embodiment comprises a fluid supply 3 to provide fluid, e.g. ink, to an internally provided actuation chamber (not shown) from which ink can be ejected through a nozzle (not shown) at a bottom face 4 of the printhead 1. Forcing fluid through the nozzle may be performed using a piezoelectric actuator or a thermal actuator or any other suitable actuator principle, e.g. ultrasonic.

The printhead 1 may comprise a single nozzle, but usually the printhead comprises multiple nozzles arranged in an array. The array may extend all the way to the sides of the printhead, so that when printheads are positioned next to each other as will be shown below, the array from one printhead connects seamlessly to the array of the other printhead. If printheads are used which does not have this possibility, the printheads may be staggered to partially overlap.

To control the one or more actuators in the printhead 1, electronic connections 5 are provided connecting the printheads to a control unit. In case the printhead 1 is equipped with sensors, e.g. a temperature sensor, the electronic connections 5 can also be used to provide the output of the sensors to the control unit.

The printhead 1 further comprises connecting means 7 to connect the printhead to a base plate as will be explained below with reference to Fig. 2.

As the printhead assembly is based on accurate manufacturing and assembly of components, the nozzles in the printhead need to be positioned accurately with respect to the connecting means 7, for instance within 20 micrometer, preferably within 10 micrometer, more preferably within 5 micrometer, and most preferably within 1 micrometer from an intended position. Positioning of the fluid supply 3 and electronic connections 5 usually does not have to be very precise. To prevent undesired disturbance forces, the fluid supply 3 and electronic connections 5 may be (partially) flexible.

Fig. 2 depicts a base plate 9 for holding multiple printheads 1 as shown in Fig. 1. To hold the printheads 1, multiple connecting means 11 are mounted to the base plate 9 to cooperate with respective connecting means 7 on the printheads 1. Although in this embodiment, the base plate 9 is configured to hold multiple printheads, alternative embodiments may use base plates holding only one printhead. It is also not required that all connecting means 11 are used to hold operational printheads. For instance, the two outer connecting means 11 may be used to hold dummy printheads, so that all printheads in between (in this case six operational printheads) have a neighbouring printhead resulting in similar aerodynamics for each printhead. The number of printheads 1 connected to the base plate 9 may also be adapted based on a width of a substrate where the printhead assembly needs to print on. A smaller substrate may require less printheads.

It is to be noted that similar aerodynamics for the outer printheads may also be provided using elements positioned next to the outer printheads having similar geometric dimensions as a printhead thereby mimicking the presence of a printhead.

The connecting means 11 on the base plate 9 and the connecting means 7 on the printheads provide a releasable but accurate connection, so that later on during operation and maintenance a printhead can easily be exchanged, i.e. replaced. An example of such a connection is a dovetail connection. Other alternatives may use ball-groove mechanisms. Preferably, the connecting means 7 are clamped onto the connecting means 11 to remove play in the connection. The accuracy of the connection may for instance be within 20 micrometer, preferably within 10 micrometer, more preferably within 5 micrometer, and most preferably within 1 micrometer from an intended position.

The connecting means 11 on the base plate 9 have to be accurately mounted to the baseplate, preferably in six degrees of freedom, for instance within 20 micrometer, preferably within 10 micrometer, more preferably within 5 micrometer, and most preferably embodiment comprises four reference surfaces, but other number of reference surfaces can also be thought of depending on the desired position accuracy and construction of the base plate and printhead. A first reference surface RS1 is provided at a side face of the base plate 9 and can be used to accurately position the connecting means 11 in y-direction. A second reference surface RS2 is provided at the same side face of the base plate 9 and can be used, in combination with the first reference surface RS1, to accurately position the connecting means 11 in a rotation direction about the x-direction. A third reference surface RS3 is provided at another side face of the base plate 9 and can be used to accurately position the connecting means 11 in z-direction. A fourth reference surface RS4 is provided at a further side face of the base plate 9 and can be used to accurately position the connecting means 11 in x-direction. In this embodiment, the reference surface RS4 is large enough to provide three separate surface regions that can not only be used to position the connecting means 11 in x-direction, but also to position the connecting means 11 in a rotation direction about the z-direction and another rotation direction about the y-direction. As a result, the connecting means can be accurately positioned in six degrees of freedom.

The base plate may be made of a ceramic material or any other suitable material, which preferably has the advantage of a low thermal expansion coefficient and high stiffness. The connecting means 11 may also for instance be made of a suitable metal or alloy.

As a result of the accurate positioning of the connecting means 11 relative to the reference surfaces and the accurate positioning of the nozzles of each printhead 1 relative to the connecting means 9 of the respective printhead, connecting a printhead to the base plate using the connecting means 9 on the printhead and the connecting means 11 on the printhead, results in that the nozzles of the printhead are accurately positioned relative to the reference surfaces of the base plate.

Fig. 3A and 3B schematically depict how the base plate 9 can be positioned in the printhead assembly using a positioning unit. For simplicity reasons, only some parts of the positioning unit are shown to explain its function.

The positioning unit comprises six reference points that are configured to engage with the reference surfaces on the base plate 9 as will be explained below in more detail. By pressing the base plate 9 with its reference surfaces against the reference points, the base plate 9 is accurately positioned relative to the positioning unit, for instance within 50 micrometer, preferably within 30 micrometer, more preferably within 10 micrometer, and most preferably within 5 micrometer from an intended position.

For pressing the base plate against the reference surfaces, the positioning unit comprises resilient contact elements that are moveable between a retracted position to allow the reception or removal of the base plate respectively in and from the positioning unit and an operational position in which the contact elements engage with the base plate and apply a spring force to the base plate. An advantage of using resilient contact elements is that operation of the resilient contact elements has no or minimal influence on the position accuracy, because only the respective pressing force is influenced. As long as the pressing force is in a predetermined range, the base plate keeps its accurate position during operation of the printhead assembly.

In other words, the resilient contact elements preferably provide a minimum pressing force such that the position accuracy is not influenced by predefined accelerations of the base plate and other generally occurring disturbances, but preferably at the same time do not exceed a maximum pressing force to allow positioning movement in other directions. Hence, the clamping action of the resilient contact elements in one direction should not be that strong that positioning the base plate in other directions is impeded.

Fig. 3A and 3B also partially depict the connection between the base plate 9 and a second support (not shown here) allowing to move the base in a lifting direction parallel to the y direction from and to the positioning unit. This connection will be described below with reference to Fig. 4.

When the base plate 9 is lowered into the positioning unit as shown in Fig. 3A and Fig. 3B, the first reference surface RS1 engages a first reference point RP1 and the second reference surface RS2 engages a second reference point RP2. As a result thereof the base plate is positioned in y-direction and a rotation direction about the x-direction.

The base plate 9 can be positioned in z-direction by pulling or pushing the base plate 9 in the z-direction until the third reference surface RS3 of the base plate engages with a third reference point RP3. In this embodiment, a spring operates on a rod R3, which rod the third reference surface RS3 as shown in Fig. 3B. The pulling element PE upon releasing the spring urges the base plate 9 in a direction towards the third reference point RP3. Alternatively, a pushing arrangement instead of a pulling arrangement may be envisaged. This pulling arrangement has the advantage that an operating knob OK for releasing and holding the spring is located at a convenient location as will be explained below in more detail.

In this embodiment, four resilient contact elements CE1, CE2, CE3, CE4 can be operated to engage with a side face of the base plate opposite the fourth reference surface RS4 of the base plate to push the base plate with its fourth reference surface RS4 against a fourth reference point RP4, a fifth reference point RP5, and a sixth reference point RP6 to position the base plate relative to the positioning unit in x-direction and a rotational direction about the z-direction and a rotational direction about the y-direction.

It is noted that the fourth reference surface RS4 could also be pressed against the fourth RP4, fifth RP5 and sixth RP6 reference point using three resilient contact elements, but using an even number of resilient contact elements allows to use the same mechanism on either side of the base plate.

As a result, the positioning unit is able to accurately position the reference surfaces of the base plate relative to the reference points of the positioning unit. Due to the nozzles of the printheads 1 mounted to the base plate being accurately positioned relative to the reference surfaces, the nozzles are also accurately positioned relative to the reference points of the positioning unit.

The resilient contact elements CE1, CE2, CE3, CE4 may be simultaneously moved between the retracted position and the operation position using a single operation knob OK2.

Fig. 4 depicts in more detail a connection between the base plate 9 as shown in Figs. 2, 3A and 3B and a second support (not shown yet). Parts of this connection are also depicted in the Figs. 3A and 3B.

The base plate 9 comprises a member ME with an hollow space HS and an opening OP in its top wall TW through which a rod R1 extends into the hollow space HS. The rod R1 comprises a thickening TH that is not able to pass the opening OP, so that upon lifting the rod R1, the thickening will engage with the top wall TW and lift the base plate 9 via the top wall when the base plate is supported by the first and second reference points of the positioning unit. In this situation, the connection allows the base plate to move relative to the second support in six degrees of freedom when the base plate is received by the positioning unit.

Although gravity forces keep the base plate in contact with the first and second reference points, the base plate may additionally be pressed against the first and second reference points using a spring S1 arranged between a free end of the rod R1 and the base plate.

Figs. 3A also depicts the rod R1 and member ME. In Figs. 3B, the member ME with hollow space HS and opening OP is omitted. Figs. 3A and 3B also depict a rod R2 with thickening TH and a spring S2 arranged between the free end of the rod R2 and the base plate cooperating in a similar manner with a member ME as depicted in Fig. 4, so that lifting forces and pressing forces can be applied to the base plate at two distinct locations on the base plate.

Fig. 5 depicts the base plate 9 of Fig. 2 mounted to a second support SU2, which in turn is mounted to a first support SU1. Also depicted are rods R1 and R2 with which the base plate is releasably connected to the second support. The second support SU2 is connected to the first support SU1 via a lifting mechanism allowing the second support to be moved relative to the first support in the lifting direction, i.e. in the y-direction, to be received by and removed from the positioning unit.

The lifting mechanism can be manually operated by a crank CR and a spindle SP. However, other actuating principles are also envisaged.

The first support SU1 is fixed to a frame of the printhead assembly via a guiding mechanism of which a part is shown in Fig. 5, allowing the first support SU1 to be moved relative to the frame in a direction other than the lifting direction, in this case a direction parallel to the z-direction. The guiding mechanism, in this embodiment, comprises sliders SL mounted to the first support SU1 that can slide with respect to corresponding sliders arranged on the frame.

Fig. 6 depicts the unit shown in Fig. 5 arranged in a frame FR. The positioning unit (of which only two operating knobs OK, OK2 are visible, where operating knob OK can be used to position the base plate 9 in z-direction and the operating knob OK2 can be used to press the base plate with its fourth reference surface against the fourth, fifth and sixth reference points in Fig. 6, five additional positioning units are fixed to the frame FR allowing to receive similar base plates and accurately position the base plates relative to the frame FR. By accurately positioning the reference points of the positioning units, the base plates including printheads are aligned with respect to the frame and with respect to each other by positioning the respective base plates with the positioning units.

Upstanding frame parts UF allow to connect the first support to the frame via a guiding mechanism, in this embodiment embodied as a sliding mechanism in which sliders arranged on the frame cooperate with sliders on the first support SU1 allowing the first support to move relative to the frame in the z-direction.

In Fig. 6, the base plate 9 including printheads is positioned in the positioning unit and ready for operation in which the printhead assembly may be moved relative to a substrate for printing purposes.

When maintenance is required, easy access is required to the printheads mounted on the base plate. The following process is described by reference to all Figs. 1-8

Preferably, operating knob OK2 is first operated to release the resilient contact elements CE1, CE2, CE3, CE4, pressing the fourth reference surface RS4 of the base plate 9 against the fourth RP4, fifth RP5 and sixth RP6 reference points of the positioning unit. Subsequently or simultaneously the operating knob OK is operated to release the resilient contact element PE pressing the third reference surface RS3 of the base plate 9 against the third reference point RP3 of the positioning unit. The base plate 9 is now in principle free to be lifted.

By appropriate operation of the crank CR, the second support SU2 and thus the rods R1 and R2 are lifted relative to the first support SU1 until the thickenings TH on the rods R1 and R2 engage with the members ME on the base plate 9. Further lifting of the second support SU2 will then lift the base plate 9. The completely lifted base plate 9 including printheads 1 is shown in Fig. 7.

The base plate 9 and printheads 1 can now be moved forward in the z-direction by pulling the first support SU1 in the z-direction until the first support SU1 is in the maintenance position as shown in Fig. 8.

Maintenance personnel now has full and easy access to the printheads. If necessary, a printhead 1 can be taken from the base plate 9 and put back or replaced by another printhead 1, where the dovetail connection ensures that the printhead 1 and thus the nozzles are again positioned at substantially exactly the same position.

Once, maintenance is finished, the first support SU1 is first moved back to a position in which the base plate 9 is suspended above the positioning unit in the frame FR to be received by the positioning unit. Subsequently, the second support SU2 is lowered using the crank CR until the first and second reference surfaces RS1, RS2 contact the first and second reference points RP1, RP2, respectively. The second support SU2 is lowered further, so that the springs S1 and S2 apply vertical pressing forces to the base plate 9. Subsequently, operating knob OK is operated to position the base plate 9 in z-direction. Finally, operating knob OK2 is operated to position the base plate in x-direction and two rotation directions about respectively the z-direction and y-direction. As a result, the base plate 9 and thus the printheads 1 and nozzles thereof are positioned at the same location again. No complex and lengthy alignment is necessary after maintenance, so that the downtime of the printhead assembly is relatively low.

Fig. 9 schematically depicts a printing system according to an embodiment of the invention. The printing system comprises a printhead assembly PA according to the assembly, for instance a printhead assembly according to Figs. 1-8, and a substrate holder SH for supporting a substrate SU to be printed on by the printhead assembly PA, wherein the printhead assembly and substrate holder are moveable relative to each other in the x-direction.

Fig. 10 schematically depicts a base plate 9 with multiple printheads 1 corresponding to a printhead assembly according to another embodiment of the invention. To accurately position the printheads 1 to the base plate and for holding the printheads in that position, connecting means 11 are mounted to the base plate 9 to cooperate with respective connecting means 7 on the printheads 1. In this embodiment, the printheads 1 are arranged in a staggered manner so that their respective arrays can be connected in a longitudinal direction of the base plate.

The base plate may in a similar manner be releasably connected to a second support in such a manner that the second support is able to move the base plate in a lifting direction from and to a positioning unit while allowing the base plate to move relative to the second wherein the second support is mounted to a first support via a lifting mechanism allowing the second support to be moved relative to the first support in the lifting direction, and wherein the first support is mounted to a frame via a guiding mechanism allowing the first support to be moved in a direction other than the lifting direction between a maintenance position and a position in which the base plate is positioned above the positioning unit to be received by the positioning unit.

Claims

A printhead assembly comprising a frame and a printing unit, the printing unit comprising: - a positioning unit; - a base plate; - a printhead; - first aid; a second aid; a guide mechanism; - a lifting mechanism; wherein the positioning unit is attached to the frame at a predetermined location and is adapted to receive the base plate and position the base plate relative to the frame, the print head being interchangeably mounted on the base plate at a predetermined location, wherein the base plate is releasably connected to the second support in such a way that the second support is able to move the base plate in a lifting direction to and from the positioning unit while the base plate can move sufficiently relative to the second support in six degrees of freedom when the base plate is received by the positioning unit, the second support being mounted on the first support the lifting mechanism that makes it possible to move the second support relative to the first support in the lifting direction, and the first support being mounted on the frame via the guide mechanism that makes it possible to move the first support in a direction other than the lifting direction between a maintenance position and a position in which the base plate is positioned above the positioning unit to be received by the positioning unit.

A printhead assembly according to claim 1, wherein a plurality of printheads are interchangeably mounted on the base plate at respective predetermined locations.

A printhead assembly according to claim 1 or 2, wherein the positioning unit comprises reference points against which the base plate can be pushed by resilient elements.

A printhead assembly according to any of claims 1 to 3, wherein the positioning unit is adapted to position the base plate in six degrees of freedom.

A printhead assembly according to any of claims 1 to 4, comprising a plurality of printing units that together form an array of printheads.

A printing system comprising a printhead assembly according to claim 1 and a substrate holder for supporting a substrate to be printed by the printhead assembly, wherein the printhead assembly and substrate holder are movable relative to each other.

A printing system according to claim 6, wherein the substrate holder is stationary and the printhead assembly is movable relative to the substrate holder.

A printing system according to claim 6, wherein the printhead assembly is stationary and the substrate holder is movable relative to the printhead assembly.

A method for assembling a printhead assembly according to claim 1, comprising the following steps: a. Providing the frame; b. securing the positioning unit to the predetermined location on the frame; c. providing a base plate with the print head mounted thereon at the predetermined location on the base plate; d. applying the first support to the frame via the guide mechanism; e. applying the second support to the first support via the lifting mechanism; and f. connecting the base plate and the second support.

A method for performing maintenance on a printhead assembly according to claim 1, comprising the following steps: a. Lifting the second support and thereby the base plate from the positioning unit in a lifting direction using the lifting mechanism; b. moving the first support in the direction other than the lifting direction to the maintenance position; c. performing maintenance on the printhead assembly; d. moving the first support to the position in which the base plate is positioned above the positioning unit; and e. lowering the base plate onto the positioning unit.

A method according to claim 11, wherein performing maintenance on the printhead assembly comprises removing the printhead from the base plate and applying the same or a replacement printhead to the base plate.