JP7468046B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming device.

In recent years, inkjet image forming devices that eject ink from nozzles in an inkjet head (hereinafter simply referred to as a head) have become widespread as devices for recording high-definition images on various recording media such as paper and fabric (see, for example, Patent Document 1).

Here, the printing methods used in inkjet image forming devices are broadly divided into a scanning method, in which printing is performed by moving a head carriage (hereafter referred to as the "carriage housing") carrying an inkjet head back and forth in the sub-scanning direction, and a single-pass (also called one-pass) method, in which printing is completed while the carriage housing remains fixed (stationary).

In recent years, the performance (printing capacity) of industrial inkjet image forming devices has been improved from various perspectives, such as the diversification of inks and recording media used and printing productivity, and as this printing capacity improves, the size of the entire machine has increased.

In particular, single-pass inkjet image forming devices tend to have an increasing number of inkjet heads in order to meet demands for improved printing performance. As a result, it is becoming more difficult for operators to ensure ease of maintenance, such as inspecting and adjusting the ink ejection surface.

In this regard, the technology described in Patent Document 1 describes a configuration in which the inkjet head is moved in the transport direction of the recording medium during maintenance.

JP 2015-17182 A

However, the technology described in Patent Document 1 is based on the premise that the nozzles (ink ejection surface) of the inkjet head are automatically cleaned, and does not take into consideration the ease of performing maintenance that is performed manually by an operator, such as replacing the inkjet head, inspecting and cleaning the nozzles, etc.

Specifically, the technology described in Patent Document 1 is configured to move all inkjet heads together with the carriage housing during maintenance. For this reason, depending on the number of inkjet heads mounted and the configuration of the carriage housing (shape, weight, etc.), for example, workers may be forced into an uncomfortable position when performing the above manual work, resulting in poor workability.

The object of the present invention is to provide an image forming device that can improve the ease of maintenance of the inkjet head.

A first image forming apparatus according to the present invention comprises:
an inkjet head that ejects ink from nozzles while remaining stationary together with a carriage housing to form an image on a recording medium;
a guide unit that guides the inkjet heads ejecting ink of different colors so as to move integrally from the carriage housing during maintenance ,
The guide section guides the inkjet heads, which eject the different colors of ink, so that they can move horizontally from the carriage housing, and also guides them so that they can be pulled out in a direction along the transport direction in which the recording medium is transported.
A second image forming apparatus according to the present invention comprises:
an inkjet head that ejects ink from nozzles while remaining stationary together with a carriage housing to form an image on a recording medium;
a guide unit that guides the inkjet heads ejecting ink of different colors so as to move integrally from the carriage housing during maintenance,
The carriage housing holds a drive section that drives the inkjet heads before and after the inkjet heads are guided by the guide section.
A third image forming apparatus according to the present invention comprises:
an inkjet head that ejects ink from nozzles while remaining stationary together with a carriage housing to form an image on a recording medium;
a guide section that guides the inkjet heads ejecting ink of different colors so as to move integrally from the carriage housing during maintenance;
a locking unit that locks the inkjet heads that are housed in the carriage housing and eject the inks of different colors so as to prevent the inkjet heads from moving relative to the carriage housing;
a lock detection unit that detects a state of the lock unit;
and a control unit that performs control to permit an operation of changing the height of the inkjet head when a locked state is detected.
A fourth image forming apparatus according to the present invention is
an inkjet head that ejects ink from nozzles while remaining stationary together with a carriage housing to form an image on a recording medium;
a guide unit that guides the inkjet heads ejecting ink of different colors so as to move integrally from the carriage housing during maintenance,
The guide unit is
a carriage housing that guides a base on which a plurality of ink-jet heads that eject the inks of different colors are mounted, the base being movable in and out of the carriage housing;
a first guide portion that guides a first base on which a plurality of inkjet heads that eject the inks of different colors are mounted;
and a second guide portion that guides a second base on which a plurality of the inkjet heads that eject the inks of different colors are mounted.

The present invention makes it possible to improve the ease of maintenance of inkjet heads.

1 is a side view illustrating a schematic configuration of an inkjet image forming apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of the inkjet image forming apparatus in the state shown in FIG. 1 . FIG. 2 is a diagram showing the state in which the moisture retaining bucket is removed from the state shown in FIG. 1 before printing. FIG. 2 is a partially cutaway perspective view for explaining the configuration of a slide rail, a locking member, etc. 2 is a diagram showing a state in which an operator moves a downstream printing unit from the state shown in FIG. 1 . FIG. FIG. 6 is a plan view of the inkjet image forming apparatus in the state shown in FIG. 5 . 2 is a diagram showing a state in which an operator moves the upstream printing unit from the state shown in FIG. 1 . FIG. 2 is a diagram showing a state in which the carriage housing and the like are raised from the state shown in FIG. 1 and an operator moves a downstream printing unit. FIG. 13A and 13B are plan views for explaining modified examples of the carriage housing and the base, etc. FIG. 10 is a flowchart illustrating a process executed by a control unit during maintenance.

This embodiment will be described in detail below with reference to the drawings.

Figure 1 is a partially cutaway side view showing the schematic configuration of an inkjet image forming device 1 according to the present embodiment. Figure 2 is a plan view of the inkjet image forming device 1.

The inkjet image forming device 1 includes a belt conveying device 2, an image forming unit 3, and catwalks 4 and 5 that serve as footholds for a worker performing maintenance work (see the worker shown in FIG. 5, etc.; hereafter also referred to as "worker L").

In addition, the inkjet image forming device 1 is equipped with various switches operated by the operator, sensors for detecting the position and orientation of each part, a display unit that displays the status of the device, a communication interface for receiving image data and the like from an external device such as a PC, etc., but these are well-known configurations and therefore are not illustrated.

The belt conveying device 2 of the inkjet image forming device 1 has an endless conveying belt 23 of a predetermined width stretched across multiple (two in the illustrated example) rollers 21, 22 (see FIG. 2) that are arranged in parallel at a predetermined interval. The upper surface of the conveying belt 23 stretched between the rollers 21, 22 serves as a loading surface on which a recording medium (not shown) is placed in close contact with the belt.

The surface of the conveyor belt 23 is coated with an adhesive called a grounding agent to ensure that the recording medium adheres tightly to the top surface of the conveyor belt 23 during transport.

One roller, 21, is a drive roller driven by a sub-scanning motor (not shown), and the other roller, 22, is a driven roller. Under the control of the control unit, the roller 21 rotates in the direction of the arrow (counterclockwise) in FIG. 1 as the sub-scanning motor rotates.

In the belt conveying device 2, the drive roller 21 rotates at a predetermined speed in the counterclockwise direction (see arrow) in FIG. 1 due to the rotation of the sub-scanning motor, thereby rotating and moving the conveying belt 23 stretched between the driven roller 22. By this operation, the recording medium in close contact with the upper surface (mounting surface) of the conveying belt 23 is conveyed in the sub-scanning direction, that is, in the direction of arrow A in FIG. 2.

Hereinafter, the direction of arrow A, i.e., the direction in which the recording medium is transported, will be referred to as the "transport direction", and the upstream side (the side where catwalk 4 is located) and downstream side (the side where catwalk 5 is located) in this transport direction will sometimes be simply referred to as the "upstream side" and "downstream side". In addition, the direction perpendicular to the transport direction in a plan view will be referred to as the "width direction".

For ease of explanation, the surface of each component facing the center (inner side) in the conveying direction or width direction will be referred to as the "inner surface," and the opposite, that is, the surface facing the outer side (outer side) in the conveying direction or width direction, will be referred to as the "outer surface."

In the inkjet image forming apparatus 1 of this embodiment, the recording medium may be, for example, a recording medium that is typically used in inkjet recording, such as paper, fabric, plastic film, or glass plate. Such a recording medium may be in the form of a sheet cut to a predetermined size, or may be in the form of a long piece that is continuously unwound from a roll.

Catwalks 4 and 5 are members shaped like benches or benches (see also Figure 2, etc.), and each includes a horizontal platform with a width greater than that of conveyor belt 23, a wall portion extending upward from the end of the horizontal platform in the conveying direction, and legs extending downward from both ends of the horizontal platform in the width direction. In Figure 1, the legs of catwalks 4 and 5 are shown cut away, and this is the same in Figures 3, 5, 7, and 8.

Note that catwalks 4 and 5 have the same configuration, so catwalk 4 will be described here. Catwalk 4 has four legs that straddle the conveyor belt 23, and the tips of each leg are placed on the floor surface to support the entire catwalk 4.

Thus, catwalk 4 and catwalk 5 are positioned opposite each other on belt conveyor 2 so as to sandwich image forming unit 3, and are arranged so as not to interfere with the components of belt conveyor 2 and image forming unit 3.

As shown in FIG. 1, the image forming unit 3 includes an inkjet head 30 provided above the support surface of the conveyor belt 23, a planar frame-shaped (see FIG. 2) skeleton 32 that surrounds the periphery of the inkjet head 30, and an exterior part 31 (see dotted line in FIG. 1) that covers the periphery of the skeleton 32 and the entire image forming unit 3. Of the above, the inkjet head 30 is mounted on a planar, generally rectangular base 350, and is detached from the base 350 during maintenance (replacement).

In this embodiment, the inkjet head 30 and base 350 are divided into those constituting the upstream printing unit 35A and those constituting the downstream printing unit 35B, the details of which will be described later.

The image forming unit 3 also includes a carriage housing 34 that supports the base 350, and multiple (four in this example) columnar linear guides 33 (see also FIG. 2) that are fixed to the exterior part 31 and assist the movement of the carriage housing 34 in the up-down direction (lifting direction).

Of the above, the carriage housing 34 has a bottom 34a that has a roughly "H" shaped outline in plan view and is arranged parallel to the top surface of the conveyor belt 23, and a pair of side portions 34b (see FIG. 1 for each) that rise vertically from both ends of the width direction of the bottom 34a. In this embodiment, the carriage housing 34 is provided with a beam 34c, and the configuration of the beam 34c will be described later.

For ease of understanding, the front side portion 34b of the pair of side portions 34b is omitted in FIG. 1, and this also applies to FIGS. 3, 5, 7, and 8. Further details of the carriage housing 34 and other components will be described later with reference to FIG. 4, etc.

The image forming unit 3 further includes a pair of pillars 36, 36 (see also FIG. 2) fixed to the center in the transport direction on the outer surface of the side portion 34b of the carriage housing 34, and lifting motors 37, 37 provided in correspondence with each of the pillars 36.

The image forming unit 3 also includes an electrical circuit (inkjet head drive unit) for driving the inkjet heads 30, a circuit board 38 for each color of the inkjet heads 30 used (eight colors in this example), and a moisturizing bucket 39 arranged between the conveyor belt 23 and the inkjet heads 30.

The configuration of each of the above-mentioned parts is explained in more detail below.

The inkjet head 30 (hereinafter, abbreviated as "head") used in the inkjet image forming device 1 in this embodiment is a single-pass type head that ejects ink in a stationary state together with the carriage housing 34 when forming an image on a recording medium.

In other words, unlike the scanning method in which the head ejects ink while moving in the width direction together with the carriage (scanning in the scanning direction), the single-pass method ejects ink in a stationary state, so multiple heads need to be arranged so that ink can be ejected across the entire width.

In this regard, as shown in FIG. 2, the image forming unit 3 in this embodiment has multiple inkjet heads 30 arranged in a staggered pattern along the width direction for each color, and adjacent heads are arranged closely together so that no gaps occur in the ink ejected in the width direction.

The image forming unit 3 is also capable of selectively ejecting any of eight colors of ink. In one specific example, as shown in FIG. 2, eight inkjet heads 30 per color, totaling 64 (=8 colors x 8 rows), are mounted on a flat, roughly rectangular, plate-like base 350 (see FIG. 4).

In the illustrated example, from the upstream side, eight inkjet heads 30 each ejecting purple (V), yellow (Y), orange (O), blue (B), black (K), magenta (M), cyan (C), and white (W) ink are arranged so that there is an overlapping area of nozzles (inter-head overlap).

Although not shown, each inkjet head 30 is provided with multiple recording elements, each of which has a pressure chamber that stores ink, a piezoelectric element provided on the wall of the pressure chamber, and a nozzle that ejects ink. When a drive signal that causes the piezoelectric element to deform is input, the pressure chamber is deformed by the deformation of the piezoelectric element, changing the pressure inside the pressure chamber, and ink is ejected from the nozzle that communicates with the pressure chamber.

In addition, in this embodiment, for each row of heads, in other words for each color of ink used, a circuit board 38 is provided on which various electronic components that constitute the electrical circuit (inkjet head drive unit) that drives the heads are mounted (see also Figure 4).

The inkjet head driving unit, under the control of a control unit (not shown), supplies a driving signal to the recording elements of the inkjet head 30 at appropriate timing to deform the piezoelectric elements in accordance with the image data, thereby ejecting an amount of ink according to the pixel values of the image data from the nozzles of the inkjet head 30.

The control unit controls the overall operation of the inkjet image forming device 1 and includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), a storage unit, etc. Each unit that constitutes the control unit has a known configuration, so illustrations and detailed descriptions are omitted.

In this example, the eight inkjet heads 30 of the above colors are used, and as shown in FIG. 2, the eight circuit boards 38 that make up the inkjet head drive unit are arranged in approximately the center of the carriage housing 34 in the transport direction, straddling the beam 34c described below.

In one specific example, each circuit board 38 is arranged so as to be fixed to the upper part of the beam 34c in the carriage housing 34. In the example shown in FIG. 2, each circuit board 38 is arranged (fixed) at a predetermined angle to the transport direction in a plan view so as not to interfere with each other when replacing the inkjet head 30.

Referring to FIG. 4, the inkjet head 30 and the corresponding circuit board 38 are electrically connected via a head cable 343. An ink tube 344 is connected to the ink inlet of the inkjet head 30, forming an ink flow path that is connected to a pipe 345. The pipe 345 is connected to an ink storage tank via a pump, but the configuration of this ink flow path is publicly known and therefore will not be described here.

The head cable 343 and ink tube 344 are bundled together through a protective guide 342 such as a Cablebear (registered trademark) attached to the carriage housing 34 (bottom 34a in this example), thereby preventing or suppressing problems such as entanglement during maintenance.

For simplicity, FIG. 4 shows fewer head cables 343 and ink tubes 344 bundled by protective guide portion 342 than they actually are. For the same reason, FIG. 4 omits the illustration of head cables 343 and ink tubes 344 that are pulled out from protective guide portion 342 and connected to the corresponding inkjet head 30.

Meanwhile, in actual operation, when inspecting or cleaning the nozzles (ink ejection surface) of the inkjet head 30, the base 350 and the like will be moved significantly outward from the carriage housing 34 (see FIG. 8). For this reason, the lengths of the head cable 343 and ink tube 344 that are pulled out from the protective guide 342 and connected to the inkjet head 30 are set to be sufficient in consideration of the distance of movement.

As shown in FIG. 2, in this inkjet image forming device 1, a skeleton 32 is arranged to surround the multiple inkjet heads 30 described above (in this example, 8 colors x 8 rows = 64). Note that for ease of understanding, FIG. 1 shows only a partial cross-sectional shape of the skeleton 32.

As shown in Figures 1 and 2, the skeleton 32 is formed by combining four pipe-shaped members with a generally rectangular cross section. In one specific example, the inner surface of the exterior 31 is fixed to the outer surface of the skeleton 32, and legs are provided on the underside of the skeleton 32 or the exterior 31 to support the exterior 31 and the skeleton 32 and are placed on the floor (not shown).

As shown in FIG. 2, a linear guide 33 having a flat rectangular column shape is fixed to the inside of the members of the skeleton 32 arranged parallel to the edges (sides) of the conveyor belt 23 in the width direction to support or guide the vertical movement (lifting and lowering operation) of the carriage housing 34, etc.

In this embodiment, a total of four linear guides 33 are provided in a 2 x 2 arrangement, i.e., two in the width direction and two in the conveying direction, extending vertically within the exterior portion 31.

Note that in Figure 1, the upper side of the linear guide 33 is shown cut away, and this is also the case in Figures 3, 5, and 7. In reality, the upper part of each linear guide 33 extends up to near the ceiling of the exterior part 31 (see Figure 8).

Each linear guide 33 has the role of supporting the lifting and lowering operation so as to keep the carriage housing 34 etc. in a constant position when it is lifted and lowered, and is fixed to the exterior 31 and the skeleton 32. Specifically, the upper end of each linear guide 33 is connected to a frame (not shown) of the exterior 31, and a portion of the outer surface of each linear guide 33 is fixed to the inner surface of a member that is arranged parallel to the conveyor belt 23 among the members that make up the frame-shaped skeleton 32 (see FIG. 2).

The surface of each linear guide 33 that faces the carriage housing 34 is in contact with a receiving portion 34g that is fixed to the outer surface of the side portion 34b of the carriage housing 34. The function of the carriage housing 34 in this embodiment will be described below.

In this embodiment, the carriage housing 34 houses or accommodates the base 350 on which the inkjet heads 30 are mounted, and serves to set the base 350 and, by extension, all of the inkjet heads 30 in a predetermined position (i.e., to fix them in the image forming position) during image formation.

In addition, in this embodiment, the carriage housing 34 serves to support the base 350 so that it can move upstream and downstream in the transport direction, and to prohibit (lock) the base 350 from moving upstream and downstream and to release the lock.

Furthermore, the carriage housing 34 adjusts the height position of the base 350 and thus the ink ejection surface of the inkjet head 30 by raising and lowering the carriage housing 34 itself in the vertical direction.

More specifically, the carriage housing 34 has a generally "H" shaped planar shape with both the upstream and downstream ends open, as shown in Fig. 2. This shape has the advantage that there is no interference between the base 350 and the carriage housing 34 when the base 350 is moved in the upstream and downstream directions.

Referring to FIG. 4, the carriage housing 34 has a flat, approximately "H"-shaped bottom 34a and a pair of plate-shaped side portions 34b, 34b that form the sides of the carriage housing 34 and rise from the bottom 34a. In addition, a plate-shaped beam 34c is suspended across the center of the carriage housing 34 in the transport direction.

In FIG. 4, the upper side of side portion 34b is cut away to clearly show the engagement between the protruding portion of beam 34c (see the left end of beam 34c in FIG. 4) and the groove portion of side portion 34b. In reality, as shown in FIG. 1, the upper end of side portion 34b is located at a height position that is approximately half the height of exterior portion 31.

In this way, the central region of the carriage housing 34 is supported by the beam 34c, so that the rigidity of the carriage housing 34 can be ensured even after the base 350 is pulled out and removed.

In this embodiment, the beam 34c is a supporting member that prevents deformation of the carriage housing 34 (suppresses the amount of deformation) after the printing unit 35A (35B) including the base 350 is moved from the carriage housing 34, and corresponds to the "support portion" of the present invention.

Referring to FIG. 2, a pair of pillars 36, 36 are erected at the center of the carriage housing 34 in the transport direction and at both ends in the width direction (i.e., the outer surface of each side portion 34b). Each pillar 36 is fixed to the outer surface of the above-mentioned side portion 34b and has a height that is approximately half the height of the upper end of the side portion 34b (see FIG. 1).

The driving force of the corresponding lifting motors 37, 37 is transmitted to the pillars 36, 36, which act to move the carriage housing 34 and the base 350 on which the inkjet head 30 is mounted up and down together (raising and lowering operation).

Specifically, each lift motor 37 is fixed to a frame (not shown) within the exterior part 31 described above, a gear box 37b is attached to the shaft of the lift motor 37, and a part of the rotating shaft 37c protruding from the gear box 37b is screwed into the pillar 36. Here, a male thread is formed on the rotating shaft 37c, and a female thread is formed on the pillar 36. For ease of understanding, the gear box 37b is not shown in FIG. 2.

When the lift motor 37 is rotated in the forward direction, the driving force of the lift motor 37 is transmitted to the rotating shaft 37c, which rotates in a predetermined direction (e.g., clockwise on a plane), causing the pillar 36 and the carriage housing 34 to rise together.

After this, when the lift motor 37 is driven to rotate in the reverse direction, the rotation shaft 37c also rotates in the reverse direction (e.g., counterclockwise in plan view), causing the pillar 36 and the carriage housing 34, etc. to descend together.

During this lifting and lowering operation, multiple (in this example, 4 x 2 = 8 in total) receiving parts 34g fixed to the side parts 34b of the carriage housing 34 slide (lift) while being guided by the linear guides 33, thereby maintaining the posture of the side parts 34b and therefore the entire carriage housing 34.

In this embodiment, the various parts for raising and lowering the carriage housing 34 and the like, specifically, the lifting motor 37 on the exterior part 31 side, the gear box 37b, the rotating shaft 37c, the linear guide 33, the pillar 36 on the carriage housing 34 side, and the receiving part 34g function as the "lifting part" of the present invention.

As shown in Figures 1 and 2, the moisturizing bucket 39 has a rectangular planar shape and is disposed above the conveyor belt 23 and below the image forming unit 3. The moisturizing bucket 39 contains a predetermined liquid (e.g., water) and evaporates the contained liquid to humidify the ink ejection surface (nozzles) of each inkjet head 30 when not in use, thereby preventing nozzle clogging, etc.

In this embodiment, the moisturizing bucket 39 serves to moisturize the nozzles of the printing unit 35A (first inkjet head group) or the printing unit 35B (second inkjet head group) before and after they are moved from the carriage housing 34. The moisturizing bucket 39 corresponds to the "humidifying section" of the present invention, and a more detailed configuration will be described later.

Figure 3 shows the state in which the moisturizing bucket 39 is being pulled out downstream from the state shown in Figure 1 before a print job is executed. After this, under the control of the control unit, the above-mentioned lift motor 37 is driven to slightly lower the height of the carriage housing 34 (see the white arrow in Figure 3), and the gap (distance) between the ink ejection ports of the inkjet head 30 and the transport belt 23 approaches a predetermined distance.

Thus, during printing, under the control of the control unit, the conveyor belt 23 is rotated (recording medium conveyance control), the inkjet head 30 is driven based on input image data (V to W ink ejection control via the drive signal of the circuit board 38), and so on, forming a full-color image on the recording medium being conveyed at a predetermined speed.

However, as mentioned above, the overall size of inkjet image forming devices has increased in recent years, and this increase in size has placed an increasing burden on workers performing maintenance work.

In particular, in an industrial, single-pass inkjet image forming device 1 such as that of this embodiment, a large number of inkjet heads 30 are arranged in the transport direction and width direction for multiple colors, and even just maintaining these ink ejection ports (inspection, cleaning, etc.) requires a great deal of effort.

In this regard, the technology described in Patent Document 1 does not take into consideration the convenience of workers when performing manual maintenance.

Specifically, the technology described in Patent Document 1 is configured to move all inkjet heads together with the carriage housing during maintenance. For this reason, depending on the number of inkjet heads mounted and the configuration of the carriage housing (shape, weight, etc.), for example, workers may be forced into an uncomfortable position, resulting in poor workability.

In general, the technology described in Patent Document 1 is based on a configuration that can be commonly applied to both the scanning method and the single-pass method, and to both the monochrome printing method and the color printing method, and is therefore unable to address the above-mentioned issues with single-pass inkjet image forming devices that perform color printing.

In addition, conventionally, single-pass inkjet image forming devices that perform color printing were generally models in which the heads that could be inserted and removed at the same time for maintenance were for each color. For this reason, as the number of ink colors installed increased, there was a problem that the workability of manual maintenance by the operator became worse, and there were also the following problems:

In other words, in models like those mentioned above that perform color printing, the head position is prone to slight misalignment for each color depending on the amount of force applied by the operator when inserting and removing the head, or due to the durability of the device or mechanical errors, resulting in problems such as misalignment of each color and reduced image quality.

In light of the above issues, it would be desirable to have a configuration in which multiple heads ejecting multiple colors of ink can be inserted and removed at the same time during maintenance.

In addition, in many conventional industrial inkjet image forming devices, the mechanism for inserting and removing multiple heads was limited to a configuration that simply inserted and removed them horizontally (the width direction perpendicular to the transport direction). This caused problems such as the worker L being forced to adopt an uncomfortable position, such as crouching or lying on his back, when inspecting or cleaning the ink ejection surface, which reduced workability.

In consideration of the various problems described above, the inkjet image forming device 1 in this embodiment is provided with a "guide section" that guides the multiple inkjet heads 30 that eject ink of different colors so that they move together from the carriage housing 34 during maintenance.

By providing a "guide section" as described above, multiple inkjet heads 30 that eject ink of multiple colors can be inserted and removed at once, greatly reducing the burden on the worker L during maintenance and improving workability. In addition, the above-mentioned problem of misalignment between colors can be prevented or greatly reduced.

The "guide section" of this embodiment is configured to guide multiple inkjet heads 30 that eject multiple colors of ink so that they can move horizontally from the carriage housing 34.

In the illustrated example, a base 350 on which multiple inkjet heads 30 that eject ink of multiple colors are mounted is configured to be guided so that it can be moved (in and out) horizontally from the carriage housing 34.

With this configuration, multiple inkjet heads 30 that eject multiple colors of ink can be inserted and removed at once by moving the base 350 horizontally from the carriage housing 34, improving workability during maintenance.

Furthermore, according to this embodiment, the height of the carriage housing 34 can be adjusted by the "elevation unit" described above. With this configuration, the multiple inkjet heads 30 that eject multiple colors of ink can be inserted and removed at multiple height positions according to the work content, etc., so that the worker L can have freedom of posture during work, and the workability during maintenance can be improved.

From another perspective, it is desirable for the "guide section" of the present invention to be configured so that the base 350 can be pulled out by different amounts depending on the height of the carriage housing 34. Specific examples of such a configuration will be described later.

In the following, in order to clearly distinguish it from the "lifting section" described above, the "guide section" in this invention will be referred to as the "drawing section."

In this embodiment, the direction in which the base 350 is inserted and removed by the "drawer" (see the double-headed arrow in Figure 5) is the same as the transport direction of the recording medium (i.e., the same direction and the opposite direction).

In other words, the "drawer section" supports multiple inkjet heads 30 that eject multiple colors of ink so that they can be inserted and removed, and also serves to guide them so that they can be pulled out in the direction along the transport direction.

By adopting such a configuration, the extra space that had to be secured in the conventional model in which the inkjet head 30 is inserted and removed in the width direction (perpendicular to the transport direction) is minimized or eliminated. Furthermore, when multiple inkjet image forming devices 1 of this embodiment are installed (side by side) in a factory or the like, it is possible to install more units than before.

On the other hand, if all of the inkjet heads 30 (64 in this example) installed in the inkjet image forming device 1 were configured to be removable and retractable at once, this could actually result in poorer workability depending on the scale of the device, such as the total number of inkjet heads 30 installed.

Furthermore, if all the inkjet heads 30 mounted on the inkjet image forming device 1 are configured to be removable and retractable at once, there is a problem that the load on the supporting side (the carriage housing 34 in this example) when the inkjet heads 30 are pulled out may become excessive depending on the weight of the inkjet heads 30, etc. In other words, if a configuration is adopted in which all the inkjet heads 30 can be removable and retractable at once, the support structure of the carriage housing 34, etc. that supports the inkjet heads 30, etc. so that they can be removable and retractable, needs to be considerably robust, which leads to problems of increased costs and an increase in the size of the entire device.

In consideration of the above-mentioned problems, the pull-out section (guide section) in this embodiment does not pull out and insert all of the inkjet heads mounted on the inkjet image forming device 1 at once, but guides a first inkjet head group having multiple inkjet heads 30 so that they can be pulled out upstream in the transport direction, and guides a second inkjet head group having multiple inkjet heads 30 so that they can be pulled out downstream in the transport direction.

Specifically, in this embodiment, a configuration is adopted in which there are two drawers (i.e., separate islands), a "first drawer section (guide section)" and a "second drawer section (guide section)."

In this example, the base 350 carrying the multiple inkjet heads 30 assigned to the "first drawer section" and the base 350 carrying the multiple inkjet heads 30 assigned to the "second drawer section" are configured to be able to be pulled out separately so that they are separated into the upstream and downstream sides in the transport direction.

In the illustrated example, the base 350 of the upstream printing unit 35A corresponds to the "first base," and the base 350 of the printing unit 35B arranged downstream of the printing unit 35A corresponds to the "second base."

By adopting such a configuration, the upstream base 350 (printing unit 35A) and the downstream base 350 (printing unit 35B) are inserted and removed separately by their corresponding pull-out sections (guide sections). As a result, it is possible to ensure ease of operation during maintenance while simplifying and reducing the cost of the "pull-out section" configuration.

Next, we will explain the outline of the insertion and removal operations of printing units 35A and 35B with reference to the diagram.

In this embodiment, when performing maintenance, the printing units (35A, 35B) can be inserted or removed from the carriage housing 34 within a range where the moisturizing ability of the moisturizing bucket 39 can be enjoyed without moving the moisturizing bucket 39 from the state shown in FIG. 1. An overview of this insertion and removal operation will be described with reference to FIGS. 5 to 7.

Here, FIG. 5 is a diagram showing how an operator L performs maintenance work (e.g., replacing the head) on the downstream printing unit 35B from the state shown in FIG. 1. Also, FIG. 6 is a plan view of the inkjet image forming device 1 in the state shown in FIG. 5.

Furthermore, FIG. 7 shows the state in which worker L performs maintenance work (e.g., replacing the head) on the upstream printing unit 35A from the state shown in FIG. 1.

As shown in Figures 7 and 5, in this embodiment, worker L can step onto catwalk 4 or 5, stretch out his arms with his upper body close to the skeletal part 32, and replace the inkjet head 30 at the back (B ink or K ink in this example).

Therefore, according to this embodiment, the worker L can easily perform the replacement work regardless of which inkjet head 30 needs to be replaced, thereby improving maintainability.

In addition, in this embodiment, the end in the transport direction where the liquid in the moisturizing bucket 39 evaporates, in other words, the range of the humidifying capacity of the moisturizing bucket 39 (humidifying section) in the transport direction, is located outside the end of the base 350 under normal conditions (when an image is being formed).

In other words, the moisturizing bucket 39 has a size (planar shape) that can moisten the ink ejection surfaces of all inkjet heads 30 mounted on the base 350 when the amount of base 350 pulled out relative to the carriage housing 34 is within a predetermined range (up to the end of the moisturizing bucket 39).

Therefore, according to this embodiment, as shown in Figures 5 and 7, even if the base 350 is pulled out to replace the inkjet head 30, the nozzle surface of each inkjet head can be moistened by the liquid (water, etc.) evaporated from the moisture retaining bucket 39.

Next, referring to FIG. 4, we will explain a specific example of the configuration of the "drawer section (guide section)" that guides the printing units 35A and 35B (first and second inkjet head groups) to move together from the carriage housing 34 along the transport direction.

Note that Figure 4 shows only a portion of the configuration on the printing unit 35B side, but the configuration on the printing unit 35A side (upstream side) is similar, so illustration and description are omitted.

As shown in FIG. 4, a slide rail 341 is provided along the transport direction on the inner surface of the bottom 34a of the carriage housing 34 (more specifically, the surface parallel to the transport direction and facing the base 350).

For simplicity, FIG. 4 shows a slide rail 341 located at one end of the downstream printing unit 35B in the width direction, but the same slide rail 341 is also provided on the other end of the bottom 34a of the carriage housing 34.

The slide rails 341 are the "drawer section," or the "guide section" of the present invention, and a total of four are provided, two of each, so that printing unit 35A and printing unit 35B can be guided (removed or inserted) separately (see Figure 9).

In one specific example, the slide rail 341 supports the ends of the base 350 in the width direction from below, thereby holding the base 350 on which the inkjet head 30 is mounted so that it can slide in the transport direction (the upstream and downstream sides indicated by the double arrows in Figure 5, etc.; the same applies below).

In another example, the slide rails 341 hold the base 350 on which the inkjet head 30 is mounted so that it can slide in the transport direction by clamping the ends of the base 350 in the width direction from above and below.

In yet another example, the base 350 may be configured to have engagement members on two widthwise sides that movably engage with the slide rail 341 (see FIG. 9).

The drawer section (i.e., the "guide section" of the present invention) is not limited to the configuration described above, and various other configurations can be adopted.

Furthermore, in this embodiment, the printing units 35A and 35B can be pulled out at two locations in the vertical direction depending on the maintenance work related to the inkjet head 30.

The height position of the inkjet head 30 in these two withdrawal positions (the "maintenance positions" when the worker L performs maintenance manually) is set to a position different from the image forming position, i.e., the height position of the inkjet head 30 that is set (fixed) when a print job is executed (see the white arrow in Figure 3).

Specifically, as shown in Figures 5 and 7, a height position slightly higher than the image formation position, specifically a height position taking into consideration the size and moisture retention of the moisture retaining bucket 39 (hereinafter referred to as the "first position"), corresponds to the position where the worker L performs the replacement work of the inkjet head 30, etc.

The height position shown in FIG. 8, i.e., the "second position" higher than the first position shown in FIGS. 5 and 7, corresponds to the position where the worker L inspects and cleans the nozzle surface of the inkjet head 30.

In this embodiment, when an operator L replaces the inkjet head 30 or its accessories (such as the ink tube 344), the operator pulls out the printing unit 35A (35B) from the first position close to (directly above) the image forming position (see Figures 5 and 7).

At this time, it is sufficient that the base 350 is pulled out so that the inkjet head 30 to be replaced is within the reach of the worker L. Therefore, in the first position, it is sufficient that the printing unit 35A (35B) is inserted or removed above the moisture retaining bucket 39, i.e., within the range of the moisture retaining capacity of the moisture retaining bucket 39.

Therefore, when the inkjet heads 30 are replaced, the ink ejection surfaces (nozzles) of all the inkjet heads 30 are moistened by the liquid (water in this example) in the moisturizing bucket 39, so that printing operations can be resumed promptly after the maintenance work.

For simplicity, it is assumed that the first position is a predetermined fixed position (the height position shown in FIG. 5 or FIG. 7). However, the first position (height position) may be finely adjusted according to the arm length of the worker L, etc. However, the first position should be at a height where the inkjet head 30 does not interfere with the skeleton 32, etc. when the base 350 is pulled out.

On the other hand, when worker L inspects or cleans the nozzles (ink ejection surface) of the inkjet head 30, the printing unit 35A (35B) is pulled out from a second position that is higher than the first position (see FIG. 8).

At this time, in order to inspect and manually clean the nozzles (ink ejection surfaces) of all the inkjet heads 30 mounted on the base 350, the worker L needs to pull out most of the base 350, and eventually almost all of the base 350, from the carriage housing 34.

Figure 8 shows a scene in which worker L pulls out all of the bases 350, on which multiple (32) inkjet heads 30 for multiple colors (K, M, C, and W) are mounted, from the carriage housing 34 and is inspecting each nozzle, etc., with the heads exposed from the exterior part 31.

At this time, the worker L needs to support the total weight of the inkjet heads 30 that eject ink of different colors (K, M, C, and W), the base 350, etc., but the labor required by the worker L at this time is significantly less than in the case of conventional machines.

In other words, according to this embodiment, the carriage housing 34 remains inside the exterior part 31, and only the minimum number of parts can be inserted and removed by the guidance (guided movement) of the slide rail 341 described above, so the weight burden on the worker L is significantly reduced and workability is improved.

From the viewpoint of improving workability for the worker L, it is desirable that the second position be set at a height that allows the worker L to easily perform operations such as pulling out the base 350 and cleaning the ink ejection surface of the inkjet head 30.

For simplicity, it is assumed that the second position is a predetermined fixed position (height position shown in FIG. 8). However, the second position (height position) may be finely adjusted according to the height and arm length of the worker L. However, the second position should be at a height where the carriage housing 34 (side portion 34b, etc.) does not interfere with the exterior portion 31.

In addition, as shown in FIG. 8, in consideration of the possibility that the worker L may pull out the entire base 350 from the carriage housing 34, a support part having the same function as the slide rail 341 described above may also be provided on the inner surface of the exterior part 31. By providing such a support part, the effort required by the worker L to support the base 350 (such as the strain on the arms and legs) can be further reduced.

When cleaning the nozzles (ink ejection surface) of the inkjet head 30, the nozzles can be moistened appropriately by wiping the ink ejection surface with a moistened cloth (not shown) or the like. Therefore, there is no problem even if the second position is set at a position away from the moisturizing bucket 39.

Thus, in this embodiment, the carriage housing 34 and the base 350 on which the multiple heads (for multiple colors) are mounted can be switched to two height positions, a first position and a second position, depending on the maintenance work content (purpose), and the inkjet heads 30 for multiple colors can be pulled out at each height position.

With this configuration, the worker L can prevent the nozzle surface from drying out while replacing parts such as the head at the low position, i.e., the first position close to the moisture retaining bucket 39, and at the higher second position, he can perform tasks such as cleaning the nozzle surface in a more comfortable position.

In this embodiment, the carriage housing 34 remains inside the exterior part 31, and only the minimum number of parts can be inserted and removed by the guidance (guided movement) of the slide rail 341 described above. This significantly reduces the weight load on the worker L at any height position, improving workability.

In addition, according to this embodiment, at either the height position of the first position or the height position of the second position described above, the inkjet head 30 (the ink ejection section of multiple colors) is pulled out in a direction away from the circuit board 38 by the guidance (guided movement) of the slide rail 341 (see FIG. 6, etc.).

In other words, the carriage housing 34 in this embodiment holds the circuit board 38 (inkjet head drive unit) for driving the inkjet head group before and after the inkjet head group is guided (in and out) by the slide rail 341.

Thus, in this embodiment, even when the inkjet head group is pulled out of the carriage housing 34, the circuit board 38, which does not normally require maintenance (such as component inspection), remains inside the carriage housing 34, allowing the worker L to concentrate on inspecting the inkjet head group.

In addition, in this embodiment, when the inkjet head 30 (ink ejection sections of multiple colors) is pulled out downward (first position) by the slide rail 341 (see Figures 4 to 6), a moisture retaining bucket 39 (moisturizing section) is provided that can moisturize each ink ejection section.

This configuration allows the operator to reach the backmost inkjet head 30 (the head that ejects K ink in the example of Figure 4) and its head cable 343 and ink tube 344 on the lower side (first position), and also allows moisture (steam) from the moisture retaining bucket 39 to be supplied to the nozzle surface of the frontmost inkjet head 30 (the head that ejects W ink).

Furthermore, in this embodiment, as described in FIG. 4, the central area of the carriage housing 34 in the transport direction is supported by a beam 34c (support portion).

With this structure, even if, for example, one of the printing units 35A and 35B is pulled out and the load (stress) applied to the center of the carriage housing 34 fluctuates, the load (stress) is absorbed by the beam 34c, ensuring the rigidity (prevention of deformation) of the entire carriage housing 34.

Furthermore, in this embodiment, a locking mechanism is provided to completely fix (lock) the printing unit 35A (35B) to the carriage housing 34 when the printing unit 35A (35B) is stored in the carriage housing 34, in other words, to prevent the printing unit 35A (35B) from being guided by the guide portion.

As shown in FIG. 4, one specific example of a locking mechanism includes a toggle clamp 348 having a handle 348h and a clamp 348r, and a clamped portion 350a fixed by the toggle clamp 348.

In the example shown in FIG. 4, the toggle clamp 348 is disposed on the carriage housing 34 side (beam 34c) and the clamped portion 350a is disposed on the base 350 side (fixed with a screw or the like), but as will be described later in FIG. 9, the reverse arrangement may also be used.

In other words, in either arrangement, the base 350 on which the inkjet head group is mounted can be fixed to the carriage housing 34 (a locked state that prevents the inkjet head group from moving relative to the carriage housing 34).

In the example shown in FIG. 4, when the handle 348h of the toggle clamp 348 is rotated in the direction of arrow B, i.e., in the direction approaching the beam 34c, the clamp 348r rotates in the direction of arrow C, i.e., in the opposite direction, due to the principle of leverage.

Meanwhile, the base 350 on which the inkjet head 30 is mounted is attached to the slide rail 341 from the state shown in FIG. 4 and abutted against the opposing surface of the bottom 34a of the carriage housing 34, thereby being completely housed (stored) in the carriage housing 34.

In this stored state, by rotating the handle 348h of the toggle clamp 348 in the direction of arrow B, the clamp 348r rotates in the direction of arrow C and engages with the clamped portion 350a, and thereafter, a locked state is established in which movement of the base 350 relative to the carriage housing 34 is physically prevented.

In this manner, this embodiment is provided with a locking mechanism (locking section) that locks the slide rail 341 (guide section) by fixing the base 350 stored in the carriage housing 34 to the carriage housing 34, thereby making it possible to prevent injury to the worker L or damage to parts, etc., that may occur due to the movement of many inkjet heads 30, etc. at once.

In this embodiment, the control unit determines whether both printing unit 35A and printing unit 35B are locked, and if the determination result is YES, performs control to allow the carriage housing 34 to move up and down.

More specifically, when the worker L presses a switch (not shown) for raising or lowering the carriage housing 34, the control unit does not immediately drive the lift motor 37, but first determines whether all (four in this example) toggle clamps 348 are in the locked state.

In one specific example, this determination can be made based on the detection results of a sensor, such as a known proximity sensor, provided on the bottom 34a of the carriage housing 34 to detect the position of the handle 348h of the corresponding toggle clamp 348.

The above-mentioned proximity sensor corresponds to the "lock detection unit" of the present invention.

When the control unit determines that all (four) toggle clamps 348 are in a locked state (the locked state is detected by the proximity sensor), it permits the lifting and lowering operation and drives the lifting and lowering motor 37 to raise or lower the carriage housing 34.

On the other hand, if the control unit determines that one or more of the toggle clamps 348 are not locked, it does not drive the lift motor 37 and displays a warning to the worker L to that effect and that all of the toggle clamps 348 should be locked.

By adopting such a configuration, even if the worker L forgets to lock it due to carelessness, it is possible to prevent various troubles caused by the printing unit 35A (or 35B) moving in the transport direction while the carriage housing 34 is being raised and lowered. In this case, the troubles may include the worker L being injured or the printing unit 35A (35B) colliding with the frame 32 and being damaged.

In addition, if the control unit detects that any of the toggle clamps 348 have been unlocked after permitting the above-mentioned lifting and lowering operations, the control unit will stop driving the lifting and lowering motor 37 and perform control to urgently stop the lifting and lowering operations (i.e., changing the height positions of the inkjet head group).

With this configuration, even if the lock by the toggle clamp 348 is released during the above-mentioned lifting and lowering operation, the lifting and lowering motor 37 and the lifting and lowering operation are stopped, and vibrations caused by the rotation of the lifting and lowering motor 37 are not transmitted to the carriage housing 34. Therefore, by stopping the lifting and lowering operation, it is possible to prevent the printing unit 35A (or 35B) from moving in the transport direction.

Next, referring to FIG. 9, we will explain additional or alternative configurations to the above-described embodiment.

In the example shown in FIG. 9, the base 350 of each printing unit 35A (35B) is provided with "U"-shaped handles 355, 356 for the operator L to grasp. Of these, the handle 355 is provided on the side surface facing the upstream side of the base 350 of the printing unit 35A, and on the side surface facing the downstream side of the base 350 of the printing unit 35B.

On the other hand, the handle 356 is provided in the gap area between two inkjet heads 30 (between the Y head and the O head, and between the C head and the M head in the example shown in FIG. 9) approximately in the center of the upper surface of the base 350 on which the inkjet heads 30 are mounted.

It is desirable that the handle 356 be positioned so that it does not interfere with the inkjet head 30 when replacing the inkjet head 30 on the base 350, and does not get in the way of the replacement work.

This configuration allows the worker L to grasp the handle 355 or the handle 356 when moving the base 350 in the transport direction, improving convenience when performing such work.

In addition, by providing the handles 355, 356 as described above, it is possible to prevent inconveniences such as the operator L touching one of the inkjet heads 30 when moving the base 350 in the transport direction, causing slight deviations in the nozzle position or discharge angle of that head.

The example shown in FIG. 9 shows a schematic configuration in which the toggle clamp 348 described above is provided on the base 350 side, and a protrusion corresponding to the clamped portion 350a described above is provided on the carriage housing 34 side (bottom 34a). In this case, the proximity sensor described above can be provided on the base 350, or it may be provided on the carriage housing 34 (bottom 34a).

In addition, in the example shown in FIG. 9, a positioning pin 359 is provided on the side of the base 350 that comes into contact with the carriage housing 34 (bottom 34a), and a positioning hole 349 into which the positioning pin 359 fits is provided at the corresponding position of the bottom 34a (approximately the center in the width direction in this example).

In this case, even if the toggle clamp 348 is unlocked, due to friction or other factors that occur when the positioning pin 359 is engaged with the positioning hole 349, it is possible to prevent an unexpected situation in which the base 350 immediately moves out of the carriage housing 34 during lifting and lowering operations.

As described above, in this embodiment, a large number of inkjet heads 30 that eject ink of multiple colors are grouped into two islands, printing unit 35A and printing unit 35B, and each is configured to be able to move in and out of the carriage housing 34 in the transport direction.

As a result, this embodiment can minimize the problem with conventional technology in which slight misalignments (errors) occur in the image formation positions for each color when the printing unit is inserted or removed.

More specifically, even with the configuration adopted in this embodiment, slight positional deviations (errors) in the image formation position (ink ejection position) may occur due to slight distortion of the shape of the carriage housing 34 or base 350 due to, for example, durability or changes in temperature and humidity.

On the other hand, in this embodiment, even if a positional deviation (error in the nozzle position) occurs in the image formation position (ink ejection position), the head positional deviation (error) values for the four colors (K, M, C, and W in the example of Figure 4) are approximately the same. Therefore, in the inkjet image forming device 1 of this embodiment, it is easy to perform control to correct the deviation in the nozzle position of the inkjet head group.

In one specific example, a known linear encoder (magnetic scale and magnetic detection head) is used to detect deviations in the ink ejection position (errors in the nozzle positions of the inkjet head group). Specifically, the magnetic scale is arranged on the base 350, and the magnetic detection head is arranged on the carriage housing 34 side, or the reverse arrangement is also possible.

Then, when a print job is executed, the control unit determines the amount of deviation of the inkjet head 30 (ink ejection position) from a reference position based on the detection results from the linear encoder (magnetic detection head), and performs control for each head to correct the timing at which ink is ejected from the inkjet head 30 (ejection timing) according to the determined amount of deviation.

In this case, as described above, the head position deviation (error) values for the four colors (V, Y, O, and B in printing unit 35A, and K, M, C, and W in printing unit 35B) are almost the same, so the control unit can set the ejection timing correction value to be the same for each head in printing unit 35A (35B).

Next, the control executed by the control unit in relation to the locked state by the above-mentioned lock unit (toggle clamp 348) will be described with reference to the flowchart in FIG. 10.

In step S100, the control unit detects an instruction to move the carriage housing 34 (the entire printing units 35A and 35B) (in this example, an instruction to raise the carriage) by operating a switch by the worker L, and then proceeds to step S120.

In step S120, the control unit acquires the output signals of the proximity sensors in printing units 35A and 35B and proceeds to step S140.

In step S140, the control unit determines from the acquired output signal whether all of the toggle clamps 348 (locking units) are in the locked state.

If the control unit determines that all of the toggle clamps 348 are locked (step S140, YES), it determines that the above-mentioned pull-out unit (guide unit) is locked, and proceeds to step S160 to change the height of the carriage housing 34 using the above-mentioned lift unit.

On the other hand, if the control unit determines that any of the toggle clamps 348 are not in a locked state (step S140, NO), it outputs a warning to that effect (displays it on the display unit) and repeats the determination of step S140 until the determination of step S140 is YES.

In step S160 after determining that all of the toggle clamps 348 are in the locked state, the control unit controls the drive of the two lifting motors 37 described above to start raising the entire carriage housing 34 that houses the printing units 35A and 35B.

In the next step S180, the control unit monitors the torque of the lift motor 37 and the output signals of each proximity sensor to determine whether any of the toggle clamps 348 have been released from their locked state before the carriage housing 34 has completed lifting.

If the control unit determines that the lifting of the carriage housing 34 is complete without releasing the locked state of any of the toggle clamps 348 (step S180, NO), it determines that there is no abnormality and ends the series of processes.

On the other hand, if the control unit determines that the locked state of any of the toggle clamps 348 has been released before the lift is completed (step S180, YES), it determines that the lock on the drawer section (guide section) has been released, which may cause a malfunction, and emergency stops each lift motor 37 (step S200). At this time, the control unit outputs (displays on the display unit) a warning that the lift has been stopped because the lock has been released.

The inkjet image forming device 1 of this embodiment, which performs the above-mentioned control, can ensure the safety of the worker L and prevent accidents such as breakdowns and falling parts from occurring.

In the above embodiment, an example was described in which the operator L manually inserted and removed the printing units 35A and 35B from the carriage housing 34, but this is not limited to the above.

In other words, the printing unit 35A (35B) may be configured to be automatically or semi-automatically inserted and removed from the carriage housing 34.

In one example of this configuration, an actuator (not shown) is placed on the carriage housing 34 side or on the base 350, and the worker L operates a switch (not shown) to input a horizontal movement command (a command to take out or put away) to the control unit. The control unit controls the actuator to perform a movement operation according to the content of the horizontal movement command, and moves the printing unit 35A (35B) relative to the carriage housing 34.

At this time, the control unit controls the printing unit 35A (35B) that is the target of the horizontal movement instruction to move in the horizontal direction (transport direction) by an amount of movement that corresponds to the height position of the carriage housing 34 (inkjet head 30).

In one specific example, when the carriage housing 34 is in the first position described above (see FIG. 5, etc.), the control unit moves the printing unit 35A (35B) that is the target of the horizontal movement instruction within a range in which the moisture retaining bucket 39 can moisten the ink ejection surface.

On the other hand, when the carriage housing 34 is in the second position described above (see FIG. 8), the control unit moves the printing unit 35A (35B) that is the target of the horizontal movement instruction a longer distance (e.g., a predetermined set distance) than when the carriage housing 34 is in the first position.

In the case of the second position, depending on the set distance of horizontal movement, there is a risk that the printing unit 35A (35B) may fall from the carriage housing 34 when the operator L is not present. Therefore, in the case of the second position, the set distance of horizontal movement should be a distance that will not cause the above-mentioned risk of falling, and the operator L should then manually pull out the printing unit 35A (35B) (i.e., semi-automatic).

By configuring as described above, the printing unit 35A (35B) can be automatically moved in the transport direction by an appropriate amount of movement (different guiding amount by the slide rail 341) according to the height position of the carriage housing 34 and therefore the inkjet head 30.

As described above in detail, the inkjet image forming device 1 of this embodiment includes a single-pass inkjet head 30 that forms an image on a recording medium being transported by ejecting ink from a nozzle while stationary together with the carriage housing 34, and a guide section (slide rail 341) that guides the multiple inkjet heads 30 (printing units 35A, 35B) ejecting ink of different colors so that they move together from the carriage housing 34 during maintenance.

This configuration improves the ease of manual maintenance by the worker L, and also suppresses image quality degradation such as misalignment between colors during image formation after such work. Therefore, this embodiment can improve the ease of maintenance of the inkjet head 30.

The above-mentioned embodiments and modifications are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted in a limiting manner based on them. In other words, the present invention can be implemented in various forms without departing from its gist or main characteristics.

For example, the inkjet head group mounted on the base 350 of one of the printing units 35A and 35B may be configured to eject ink of one color.

REFERENCE SIGNS LIST 1 Inkjet image forming apparatus 2 Belt conveying device 3 Image forming section 4, 5 Catwalk 30 Inkjet heads (first inkjet head group, second inkjet head group)
31 Exterior part 32 Skeleton part 33 Linear guide 34 Carriage housing 34a Bottom part 34b Side part 34c Beam (support part)
34g Receiving portion 35A Printing unit (first inkjet head group)
35B Printing unit (second inkjet head group)
36 Pillar 37 Lifting motor (lifting part)
37b Gear box 37c Rotating shaft 38 Circuit board 39 Moisture retaining bucket (humidification section)
341 Slide rail (guide part)
342 Protective guide portion 343 Head cable 344 Ink tube 345 Pipe 348 Toggle clamp (lock portion)
348h Handle 348r Clamp 349 Positioning hole 350 Base (first base, second base)
350a Clamped part 355, 356 Handle 359 Positioning pin L Worker

Claims (13)

an inkjet head that ejects ink from nozzles while remaining stationary together with a carriage housing to form an image on a recording medium;
a guide unit that guides the inkjet heads ejecting ink of different colors so as to move integrally from the carriage housing during maintenance ,
the guide section guides the inkjet heads, which eject the inks of different colors, so as to be movable in a horizontal direction from the carriage housing, and guides the inkjet heads so as to be withdrawn in a direction along a transport direction in which the recording medium is transported.
Image forming device. the guide section guides a first inkjet head group including a plurality of the inkjet heads so as to be able to be pulled out to an upstream side in the transport direction.
The image forming apparatus according to claim 1 . the guide section guides a second inkjet head group including a plurality of the inkjet heads so as to be able to be pulled out to a downstream side in the transport direction.
The image forming apparatus according to claim 2 . At least one of the first inkjet head group and the second inkjet head group includes a plurality of inkjet heads that eject the inks of different colors.
The image forming apparatus according to claim 3 . the guide portion has a different guide amount depending on the heights of the inkjet heads.
The image forming apparatus according to claim 1 . a support portion provided at a center of the carriage housing in the transport direction to support the carriage housing so as to suppress a deformation amount of the carriage housing after the inkjet heads that eject the inks of different colors are moved;
The image forming apparatus according to claim 1 . an inkjet head that ejects ink from nozzles while remaining stationary together with a carriage housing to form an image on a recording medium;
a guide unit that guides the inkjet heads ejecting ink of different colors so as to move integrally from the carriage housing during maintenance,
the carriage housing holds a drive unit that drives the inkjet heads before and after the inkjet heads are guided by the guide unit .
Image forming device. a humidifying unit that humidifies the nozzles of the inkjet heads after the guiding unit guides the inkjet heads,
The image forming apparatus according to claim 1 . a control unit that performs control to correct a timing at which the ink is ejected from the inkjet head in accordance with a position of the nozzle of the inkjet head during image formation;
The image forming apparatus according to claim 1 . an inkjet head that ejects ink from nozzles while remaining stationary together with a carriage housing to form an image on a recording medium;
a guide section that guides the inkjet heads ejecting ink of different colors so as to move integrally from the carriage housing during maintenance;
a locking unit that locks the inkjet heads that are housed in the carriage housing and eject the inks of different colors so as to prevent the inkjet heads from moving relative to the carriage housing ;
a lock detection unit that detects a state of the lock unit;
and a control unit that performs control to permit an operation of changing the height of the inkjet head when a locked state is detected.
Image forming device. the locking portion fixes a base on which the inkjet heads that eject the different colors of ink are mounted to the carriage housing;
The image forming apparatus according to claim 10 . the control unit performs control to stop the operation of changing the height of the inkjet head when release of the locked state is detected after permitting the operation of changing the height of the inkjet head.
12. The image forming apparatus according to claim 10 or 11 . an inkjet head that ejects ink from nozzles while remaining stationary together with a carriage housing to form an image on a recording medium;
a guide unit that guides the inkjet heads ejecting ink of different colors so as to move integrally from the carriage housing during maintenance,
The guide unit is
a carriage housing that guides a base on which a plurality of ink-jet heads that eject the different colors of ink are mounted, the base being movable in and out of the carriage housing;
a first guide portion that guides a first base on which a plurality of inkjet heads that eject the inks of different colors are mounted;
a second guide portion that guides a second base on which the plurality of inkjet heads that eject the different colors of ink are mounted,
Image forming device.

Images