JP4774895B2 - Inkjet printing device - Google Patents

Description

The present invention relates to Lee inkjet printing devices, and particularly, a plurality of nozzles are arranged in the length of the width equivalent to the printing medium to print an image by ejecting ink towards the printing medium from the nozzle Rainhe' about line inkjet printing device provided with a de.

  In the inkjet printing apparatus, the inkjet head was moved in the main scanning direction while ejecting small droplets of ink, which were controlled by the image signal from the nozzles of the inkjet head, onto the printing medium, and image printing for one line was performed. Thereafter, the printing medium is conveyed in the sub-scanning direction for one line, and a small droplet of ink is ejected from the nozzle of the inkjet head to the printing medium again to print one line of the image. Some form an image on top.

  As another inkjet printing apparatus, an inkjet head is configured in a long shape in which nozzles for ejecting ink are arranged at an equal interval pitch in the length of the substantially maximum printing width of the printing medium, and is fixed to the apparatus main body. Some have line heads. According to this configuration, it is not necessary to move the inkjet head in the main scanning direction, and image formation can be performed only by transporting the printing medium in the sub-scanning direction orthogonal to the main scanning direction, so that high-speed image formation can be performed. it can.

  However, when image formation is performed with only one transport in the sub-scanning direction for high-speed image formation, the print resolution in the main scanning direction is determined by the nozzle pitch of the line head. Therefore, it is conceivable to reduce the dot pitch by reducing the nozzle pitch of the line head in order to reduce the dot pitch of the print in the main scanning direction, but there is a processing limit to reduce the nozzle pitch. There is a limit to the printing accuracy by reducing the dot pitch, and there is a problem that the cost becomes expensive.

Therefore, in order to improve the printing accuracy in the main scanning direction, a plurality of print heads in which nozzles are arranged on one straight line are arranged in the sub scanning direction, and each print head is a print head having a distance L between the nozzles. A line head is proposed in which a set of inkjet heads are sequentially shifted in the main scanning direction by a fraction, and a plurality of inkjet heads are arranged in a zigzag pattern across the entire width of the paper in the width direction of the paper. (See Patent Document 1).
Japanese Patent Laid-Open No. 11-34360

  However, in the line head disclosed in Patent Document 1, a plurality of print heads in which nozzles are arranged on a straight line are shifted in the main scanning direction to form a set of heads. Needs to arrange a large number of print heads. However, since each print head is an inkjet head that is independently completed, one by one while aligning each print head so that the nozzle faces of all the print heads are aligned. There is a problem that the assembly work is difficult because it must be positioned and attached.

  Moreover, since each print head is a completed inkjet head, there is a problem that when it is assembled, the finally obtained inkjet head is enlarged.

  Furthermore, in the case of head replacement, there is a problem that it is difficult to align and attach.

  Further, Patent Document 1 does not disclose how to connect a large number of print heads and ink tanks. Although it is conceivable to provide an ink supply pipe for each print head and connect it independently to the ink tank, the entire apparatus including the ink supply system becomes large.

The object of the present invention has been made in view of the above-mentioned problems, and enables high-definition printing by one scanning, is small in size, has high assembly productivity, and has a connection between the line head and the ink tank. and to provide a line-type inkjet printing device provided with a Rainhe' de can be simplified.

Another object of the present invention is that high-definition printing is possible by one scan, positioning between a plurality of heads is easy, and connection between a line head and an ink tank can be simplified. and to provide a line-type inkjet printing device provided with a Rainhe' de.

The object of the present invention is achieved by the following configurations.
( 1 )
A line head having a plurality of nozzles arranged at a length corresponding to the width of the print medium, ejecting ink from the nozzles toward the print medium, and relatively moving the print medium and the line head in the moving direction; A line-type inkjet printing apparatus that forms an image on the printing medium by moving the printing medium,
The line head is a line head in which a plurality of head modules are arranged in a staggered manner, and the head module has two ink droplet discharge substrates arranged with a plurality of pressure generating means attached to each other, A head module in which n heads each having a head chip having a common nozzle plate (n is an integer of 1 or more) are combined, and the nozzle pitch of the head module is 1 / nozzle pitch of the ink droplet ejection substrate. (2n), a common ink channel for supplying ink to each head is formed between the two-stage head modules arranged in a staggered manner, and an ink supply port is provided at one end of the common ink channel However, a bubble discharge port is provided at the other end, and a branch supply port for supplying ink to each head is provided between the ink supply port and the bubble discharge port. Te,
An intermediate tank that is connected to the ink supply port via an ink supply path and stores ink supplied to the ink supply port, and is disposed below each head module;
An ink cartridge that communicates with the intermediate tank and stores ink supplied to the intermediate tank;
A waste ink container connected to the bubble outlet through a first ink flow path;
A pressure pump connected to the intermediate tank via a second ink flow path;
A first on-off valve provided in the middle of the first ink flow path;
A second on-off valve provided in the middle of the second ink flow path;
Have
By operating the pressure pump with the first on-off valve and the second on-off valve opened, bubbles in the common ink flow path are discharged together with ink to the waste ink container through the bubble discharge port. ,
An inkjet printing apparatus that performs printing in a state where the first on-off valve and the second on-off valve are closed .
(2)
An ink remaining amount detecting means for detecting an ink remaining amount in the intermediate tank;
A second pressure pump for pumping ink from the ink cartridge to the intermediate tank;
A third on-off valve provided in the middle of an ink supply path connecting the ink cartridge and the intermediate tank;
Have
When the detected value by the ink remaining amount detecting means becomes a predetermined value or less, the third on-off valve is opened to replenish ink from the ink cartridge to the intermediate tank, and the second pressure pump is operated. The ink jet printing apparatus according to (1), wherein if the ink is not replenished to the intermediate tank even after a predetermined time has elapsed since the operation, the ink cartridge is determined to be empty.
( 3 )
The ink jet printing apparatus according to ( 1) or (2 ), wherein the branch supply port is provided with an O-ring.
( 4 )
N is an integer greater than or equal to 2, The inkjet printing apparatus as described in any one of ( 1 ) thru | or ( 3 ) characterized by the above-mentioned.
( 5 )
The inkjet printing apparatus according to any one of ( 1 ) to ( 4 ), wherein an image is formed on the printing medium by the movement once.

According to the present invention, is capable of high-definition printing in one scan, high assembling productivity is compact, and the line head and the ink tank connected to a line-type having a Rainhe' de can be simplified An ink jet printing apparatus can be provided.

Further, according to the present invention, is capable of high-definition printing by one scan, it is easy to align between a plurality of heads, and Rainhe' de connection between the line head and the ink tank can be simplified it is possible to provide a line-type inkjet printing device provided with a.

  Although the example of embodiment regarding this invention is shown below, the aspect of this invention is not limited to these.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a main part of an ink jet printing apparatus according to the present invention. Note that the line-type inkjet printing apparatus can perform image printing by relatively moving the line head and the printing medium in the sub-scanning direction (movement direction). Here, the relative movement of the line head and the print medium in the sub-scanning direction will be described by taking an example in which the line head is fixed and the print medium is moved in the sub-scanning direction. It may be moved in the sub-scanning direction.

  In the figure, reference numeral 2 denotes a line head installed in the ink jet printing apparatus 1, which is connected to a control board 4 of the apparatus main body by a flexible cable 3 as will be described in detail later. The line head 2 is covered by a cover 200 except for the surface facing the print medium P. Details of the configuration will be described later. In addition, when full-color image printing is performed, for example, a line head for ejecting ink of each color of YMCK is arranged for each color. Here, a description will be given of an apparatus provided with one line head 2.

  The printing medium P is sandwiched between the conveyance roller pairs 5b and 5c of the printing medium conveyance mechanism 5 that conveys the printing medium P, and the conveyance motor 5a is directly connected to the shaft of the conveyance roller pair 5b. , The print medium P is conveyed at a constant speed in the direction indicated by the arrow X in the figure.

  The line head 2 is installed between the conveying roller pairs 5b and 5c so as to face the surface PS of the printing medium P as shown in the figure, and its length direction is orthogonal to the conveying direction of the printing medium P indicated by the arrow Y direction. Extends in the direction of arrow Y in the figure.

  In the line head 2, a large number of nozzles are arranged at equal intervals along the Y direction in a length corresponding to the width of the printing medium P on a surface hidden in the figure facing the surface PS of the printing medium P. Has been. Ink is ejected from the large number of nozzles onto the printing medium P in accordance with the image signal from the control substrate 4, so that an image is formed on the surface PS of the printing medium P along with the conveyance of the printing medium P in the arrow X direction. The That is, image formation is performed at a high speed by completing the printing process of a predetermined image forming area in one transport.

  The line head 2 is supplied with ink from an intermediate tank 306 (not shown) through the ink supply pipe 6. Details of the configuration of the ink supply system will be described later.

  FIG. 2 is a perspective view of the line head 2 with the cover 200 removed. In this figure, a number of nozzles are arranged on the hidden lower surface. FIG. 3 is a cross-sectional view taken along the line AA of FIG. FIG. 4 is a block diagram of an ink supply system to the line head 2. All the components of the ink supply system are connected by an ink supply pipe.

  The cover 200 has a box shape having an opening 200a, and covers the entire line head 2 so as to cover the entire surface of the line head 2 from the opposite side of the surface (the lower surface in FIG. 2) of the line head 2 and supports the cover. It is fixed to the substrate 20 by fixing means such as screws (not shown). The cover 200 is preferably made of a metal such as aluminum.

  In the line head 2, a plurality of head modules 100 are arranged in a two-stage zigzag pattern and attached to a common support substrate 20. In the illustrated example, six head modules 100 are attached to a common support substrate 20 to constitute one line head 2, but the number of head modules 100 constituting one line head 2 is particularly limited. Not.

  If each head module 100 constituting one line head 2 is attached to one common support substrate 20, the mounting surface of each head module 100 can be made common. This is a preferred embodiment because the position accuracy of the nozzle row can be easily secured.

  Each head module 100 is configured by combining n heads 10 (n is an integer of 1 or more). In particular, n is preferably an integer of 2 or more. With this configuration, higher-definition printing is possible, and even if a nozzle 142 that cannot be recovered only by the recovery process is generated in the head module 100, only the head 10 having the nozzle is removed and this is replaced with a new one. Since the head 10 can be restored to the normal state by replacing it with the head 10, it is not necessary to remove and replace the entire head module 100, and the cost for replacement can be greatly reduced. Improvements can be made.

  In the illustrated example, two (n = 2) heads 10 are combined to form one head module 100. However, when the number of heads 10 constituting one head module 100 is n. , N is not particularly limited as long as it is an integer of 1 or more. In consideration of making the line head compact, more preferably, n is an integer of 6 or less.

  Furthermore, since the gap between the adjacent head modules 100 in each stage can be increased by arranging them in a staggered manner, the individual head 10 can be attached and detached without being obstructed by the adjacent head modules 100. Work can be done easily. Further, it is easy to adjust the nozzle pitch between the adjacent head modules 100.

  Each head 10 constituting the head module 100 is attached to the support substrate 20 in a state in which the tip portion on the nozzle side is inserted into the attachment hole 22 (FIG. 11) of the common support substrate 20.

  Since each head 10 has a head (nozzle) position adjusting mechanism described later, a gap is generated between the mounting hole 22 and the head 10. By providing this gap, the head 10 can be moved along the XY plane, and the head position can be adjusted. In order to fill this gap, a sponge sheet 321 as an elastic member is attached to the inner side (inner peripheral surface) of the attachment hole 22. As the sponge sheet, urethane foam is preferable.

  In an ink jet printing apparatus that performs printing by ejecting ink from a fine nozzle onto a printing medium, so-called ink mist is generated in which fine particles of ink float around the printed part during printing, and this adheres to the electrical board. It may cause failure of the electrical board. The line head 2 in this embodiment is covered with the cover 200, the common support substrate 20 and the sponge sheet 321, so that almost the entire surface other than the nozzle surface of the line head 2 is covered. This is a preferred embodiment. In addition, the sponge-like sheet 321 can protect against ink mist while providing a gap for adjusting the head position of each head 10 to be described later, which is a preferable mode.

  The ICB substrate 500 is a substrate on which a drive signal generation circuit is mounted, and converts various signals for driving the head 10 generated by the control substrate 4 into signals and power supply voltages according to the configuration of the head 10. In the present embodiment, a substrate having such a function will be described as an ICB substrate 500 below.

  The relay board 600 is connected to the control board 4 of the apparatus main body by the flexible cable 3, receives various control signals and image data from the control board 4, is connected via a flexible cable (not shown), and is connected to each head 10. It is sent to the ICB substrate 500 provided.

  Each head 10 includes two head drive boards 146 to be described later. The two head drive boards 146 and the ICB board 500 are connected to each other, and the ICB board 500 receives various control signals and image data from the relay board 600. In response, various signals for driving the head 10 are generated, distributed to the two head drive substrates 146 and transferred.

  With such a configuration, the connection is simplified as compared with the case where each head 10 is electrically and independently connected to the control board 4 by a flexible cable. For example, even when using heads having different specifications, This is a preferable aspect because it can be easily handled by generating various signals in accordance with the head specifications in the ICB substrate 500.

  The common support substrate 20 is integrally provided with a common ink flow path forming member 301 at a position between the two-stage head modules 100 arranged in a staggered manner. Are formed with a common ink flow path 301a. The common ink flow path 301a has an ink supply port 304 at one end and a bubble discharge port 303 at the other end.

  As described above, since the common ink flow path 301a is arranged in the dead space generated between the two head modules 100, the dead space can be used effectively. Therefore, in the printing apparatus, the space occupied by the line head and the ink supply system can be reduced. As a result, for example, the apparatus can be reduced in size as compared with the case where an ink supply pipe is provided for each head 10 and is connected to each ink tank independently. The common support substrate 20 and the common ink flow path forming member 301 may be formed of the same member or different members, and may be integrated.

  The ink supply port 304 is connected to the intermediate tank 306 via the filter 309, and ink is supplied from the intermediate tank 306.

  The intermediate tank 306 is connected to the ink cartridge 307 via the valve 311 and the pressure pump 312. Further, the air can be communicated with the atmosphere via the valve 313. Further, it is connected to a pressurizing pump 314 via a valve 315.

  The bubble discharge port 303 is connected to the waste ink container 310 via the valve 308.

  Further, in the common ink flow path 301a, between the ink supply port 304 and the bubble discharge port 303, a branch supply port 305 for supplying ink to each head module 100 is provided at a position corresponding to each head module 100. Only a few minutes (six in this example) are provided.

  The two heads 10 constituting each head module 100 are provided with a frame ink flow path 155 for each head 10, and the branch supply port 305 and the two frame ink flow paths 155 are connected by the ink supply pipe 6. Yes.

  In this way, the six head modules 100 are configured to receive ink supply from one intermediate tank 306 that determines the back pressure of the six head modules 100 via the common ink flow path 301a.

  Each of the head modules 100 is combined with two heads 10, and the ink stored in the intermediate tank 306 is supplied to the head unit 10 via the ink supply pipe 6 and the common ink flow path 301a. It has become. Further, an ink cartridge 307 is connected to the upstream of the intermediate tank 306 via a valve 311 and a pressure pump 312.

  As described above, the ink cartridge 307 is preferably provided in common to all the head modules 100. Ink cartridge replacement is facilitated. If each head module has an ink cartridge, there is a possibility that the color of printing differs between head modules due to variations in ink.

  The back pressure of each head module 100 is preferably determined by the intermediate tank 306. Below the ink cartridge 307, an intermediate tank 306 made of a flexible bag or a container having an air communication valve 313 as in this embodiment is provided via a valve 311 and a pressure pump 312. If the air communication valve 313 is opened and the valve 311 is closed, the ink in the intermediate tank 306 becomes atmospheric pressure. By placing the intermediate tank below the head module by a predetermined height, the ink in the head becomes a negative pressure by a predetermined water head value relative to the atmospheric pressure, and stable ejection can be realized. A remaining amount detection or empty detection is provided in the intermediate tank, and when the amount is less than a predetermined amount, the valve 311 is opened and the pressure pump 312 is operated to replenish ink from the ink cartridge 307 to the intermediate tank 306. If the ink is not replenished in the intermediate tank 306 even after a predetermined time has elapsed after the valve 311 is opened and the pressure pump 312 is operated, it can be detected that the ink cartridge 307 is empty. Compared with determining the back pressure directly at the position of the ink cartridge 307, there are advantages such as no influence of back pressure fluctuations due to fluctuations in the remaining amount of ink and empty detection of the ink cartridge 307. Further, when the ink cartridge 307 is replaced, the replacement of the ink cartridge 307 and the printing operation can be performed in parallel without interrupting the printing operation with the ink remaining in the intermediate tank 306.

  Thus, it is preferable to provide the intermediate tank 306 in common for all the head modules 100. If each head module 100 has an intermediate tank 306, the ejection characteristics of the heads change between the head modules 100 due to the difference in the position of the intermediate tank 306, and the color of the print medium may be different.

  As shown in FIG. 3, an O-ring 302 is provided at the insertion port of the ink supply pipe 6 in the common ink flow path 301a. With this configuration, for example, when the head 10 is replaced, the ink supply pipe 6 can be easily detached and attached by inserting and removing the ink supply pipe 6 from the O-ring.

  Further, in order to stably eject ink, it is necessary to remove bubbles in the common ink flow path 301a. For this purpose, as shown in FIG. 4, a bubble discharge port 303 for discharging bubbles in the ink is provided at the outlet of the common ink flow path 301a, and this bubble discharge port 303 is connected to the ink supply pipe 6 via the valve 308. And connected to a waste ink container 310. The intermediate tank 306 is connected to the pressurizing pump 314 via the valve 315.

  The pressurizing pump 314 includes a cylinder pump and a tube pump. The pressure pump 314 operates with the valve 315 and the valve 308 open, thereby generating pressure to push the bubbles in the common ink flow path 301a from the bubble discharge port 303 together with the ink.

  The valve 308 and the valve 315 are closed except when the bubbles are removed, and when the bubbles are removed, the valve 308 and the valve 315 are opened and the pressure pump 314 is operated to remove the bubbles together with the ink. The waste ink container 310 can be discharged. Further, the ink discharged to the waste ink container 310 may be reused.

  Further, the ink in the common ink flow path 301a can be discharged from the bubble discharge port 303.

  Next, the head 10 will be described with reference to FIGS. 5 and 6. Here, FIG. 5 is a side sectional view at a nozzle position showing a schematic configuration of the head 10, and FIG. 6 is an exploded perspective view of the head 10.

  As shown in FIG. 5, the head 10 is provided with a head chip 141 that ejects ink from a plurality of nozzles 142 arranged in a staggered manner in two rows in the arrow direction Y (the front and back direction in FIG. 5). The arrow direction Y is orthogonal to the print medium transport direction X.

  The head chip 141 serves as an ink channel 144 and a first ink droplet ejection substrate composed of a piezoelectric material substrate 141a and a cover substrate 141b provided with grooves to be ink channels 144 on both surfaces of a single substrate 170. The second ink droplet discharge substrate composed of the piezoelectric material substrate 141d provided with the groove and the cover substrate 141c is bonded by being shifted by P / 2 (where the nozzle pitch of the ink droplet discharge substrate is P). One nozzle plate 11 provided with nozzles 142 is bonded to a position corresponding to each ink channel so as to cover all the ink droplet discharge substrates and the front end surface of the substrate 170. The substrate 170 is not always necessary, and two ink droplet ejection substrates may be directly joined.

  The head chip 141 according to this embodiment is configured by adhering two ink droplet ejection substrates, each having a plurality of pressure generating means, to each other and adhering a common nozzle plate 11 to the front end surface thereof. Therefore, the size can be reduced.

  Further, the head chip 141 according to the present embodiment is configured by adhering two ink droplet ejection substrates, each having a plurality of pressure generating means, to each other and adhering a common nozzle plate 11 to the front end surface thereof. Therefore, it is not necessary to position and mount the nozzle surfaces one by one while aligning the nozzle surfaces for each head as in the prior art, and the assembly workability is excellent and the productivity is high.

  Furthermore, since the head chip 141 has a configuration in which two ink droplet ejection substrates are attached to each other, an electrode for applying a voltage to the drive electrode provided in the pressure generating means is drawn out of the head chip. The electrode can be easily pulled out during the formation. That is, when three or more ink droplet ejection substrates are attached, it is not easy to pull out the electrodes.

  The ink droplet discharge substrate is formed of piezoelectric material substrates 141a and 141d made of PZT (lead zirconate titanate) or the like in a number of grooves serving as ink channels 144 in parallel to the Y direction. By closing, side walls made of piezoelectric elements (existing on the paper surface side and the near side with respect to the ink channel 144 in FIG. 5) and the cylindrical ink channel 144 are alternately arranged in parallel. The piezoelectric element constituting the side wall is a shear mode type piezoelectric element that undergoes shear deformation by applying an electric field to a drive electrode formed on the surface of the side wall, and corresponds to the pressure generating means in this embodiment.

  The pressure generating means may be configured as a piezoelectric element other than the shear mode type or a thermal type. A piezoelectric element is particularly preferable, and a shear mode type piezoelectric element is particularly preferable.

  In the case of a piezoelectric element, since it is difficult to reduce the pitch of the ink channel, that is, the nozzle pitch, the effect is remarkably exhibited by the combination with the present invention.

  In the case of a shear mode type piezoelectric element, an ink jet head is configured using a channel substrate in which partition walls formed of a piezoelectric material such as PZT and ink channels recessed in a groove shape are alternately arranged. Since there is a limit to the size of the piezoelectric material substrate that can be obtained, the number of ink channels that can be arranged side by side is naturally limited, and it is difficult to form a long shape with a large number of nozzles. As in the present invention, by forming a plurality of independent head modules and mounting them alternately in a staggered manner, the number of ink channels arranged in parallel is increased to constitute a long inkjet head. Thus, the line head can be easily formed.

  Each ink channel 144 is cut into a linear, elongated groove shape extending from the front end (left end in FIG. 5) to the rear end (right end in FIG. 5) of the ink droplet discharge substrate, and the uncut piezoelectric material is separated from each other. Side walls between the ink channels 144. Each ink channel 144 is recessed from the front end of the ink droplet ejection substrate to a midway portion on the rear end side, and gradually becomes shallower toward the rear end side to form a shallow groove portion, and finally disappears.

  As shown in FIG. 5, the head 10 of the present embodiment has ink supply ports 143 provided in the cover substrates 141 b and 141 c on both side surfaces of the head chip 141, and ink formed inside the head chip 141. The ink supply port 143 and the nozzle 142 are continuous through the channel 144.

  On both sides of the head chip 141, a manifold 148 for guiding ink from the outside to the head chip 141 is bonded and fixed.

  The manifold 148 has ink flow paths 148e and 148f communicating with the ink supply port 143 therein.

  As shown in FIG. 5, ink inlets 481,... For introducing ink into the ink flow paths 148e, 148f are formed at one end of the manifold 148. As shown in FIG. The ink inlet 481 also serves as an inlet for injecting a cleaning liquid during internal cleaning in the manufacturing process. In this embodiment, two ink introduction ports 481 and 481 are formed at one end of the manifold 148, but only one or three or more may be formed. Also good.

  An ink receiving portion 488 is continuously provided in the ink introduction port 481. The ink receiver 488 guides the ink to the ink inlets 481,.

  On both sides of the manifold 148, ink heaters 149 for heating the ink inside the manifold 148 to a predetermined temperature via the manifold 148 are disposed. In addition, in FIG. 5 mentioned above, illustration of the ink heater 149 is abbreviate | omitted for convenience.

  The ink heater 149 includes heating units 149a and 149a that are electrically connected to each other through a connection unit 149d. The heating part 149a and the connection part 149d are obtained by wiring a heating wire (not shown) in a wave shape on a flexible film part (not shown).

  More specifically, the heating units 149a and 149a are substantially L-shaped by a manifold heating unit 149b that abuts on a side surface of the manifold 148 and a frame heating unit 149c that abuts on a side surface of a housing frame (housing) 153 described later. Is formed.

  Here, the manifold 148 is often made of resin, and the housing frame 153 is often made of metal or the like. Therefore, normally, a large amount of heat generated from the ink heater 149 is transmitted to the housing frame 153.

  The heater surfaces of the manifold heating portions 149b and 149b are parallel to the rows of nozzles 142,..., And heat the ink supplied to the nozzles 142 in each row.

  The frame heating unit 149c heats the ink inside the housing frame 153 via the housing frame 153, and heats the ink supplied to the manifold 148 in advance. The frame heating unit 149c may be in contact with the inner surface of the housing frame 153.

  Here, the heating wires of the heating units 149a and 149a may be wired in the same pattern, or may be wired in non-identical patterns.

  A cutout portion 149e is provided at a connection portion between the heating portions 149a and 149a and the connection portion 149d. This notch 149e is for widening the movable range of the heating part 149a with respect to the connection part 149d. Further, the cutout portion 149e prevents a cut from occurring in the connection portion as a result of dispersing stress applied to the connection portion between the heating portion 149a and the connection portion 149d even when the shape of the ink heater 149 changes. It has become. As a result, the operation of attaching the ink heater 149 to the manifold 148 is facilitated.

  In order to make the thermal coupling between the ink heater 149 and the manifold 148 uniform within the heater surface, a predetermined member may be provided between the ink heater 149 and the manifold 148 or an adhesive may be filled. good. Further, the ink heater 149 may be provided in contact with the manifold 148, or may be disposed away from the manifold 148. The heating units 149a and 149d are not necessarily connected, and may be separated and heated individually.

  A temperature sensor (not shown) for detecting temperature is disposed between the ink heater 149 and the head chip 141.

  A holding plate 151 for holding the manifold 148 and the head chip 141 is attached to the lower part of the head chip 141.

  The holding plate 151 is provided with an opening 151a so that the discharge surface is exposed.

  Further, on the upper part of the head chip 141, head drive substrates 146 and 146 for applying a drive voltage to the drive electrodes formed on the surface of the partition made of piezoelectric elements based on a control signal from the ICB substrate 500 are flexible wirings. It is connected via a plate (not shown).

  Each head drive board 146 is provided with a connector 461, and the ICB board 500 is electrically connected to the connector 461 so that a control signal and electric power are supplied to the head drive board 146. ing.

  Further, the ICB substrate 500 is formed with a heater circuit for supplying power to the ink heater 149, and the heating wire of the ink heater 149 is electrically connected to the heater circuit via the head drive substrate 146. Connected. The temperature sensor is also electrically connected to the heater circuit via the head drive substrate 146.

  The head chip 141, the manifold 148, the head driving substrate 146, the holding plate 151, and the like are fixed to the housing frame 153. More specifically, an adhesive is filled between the housing frame 153 and the manifold 148 so as to include at least the ink heater 149. This adhesive suppresses heat conduction from the ink heater 149 to the housing frame 153.

  The housing frame 153 is provided with a frame ink flow path (ink flow path) 155 for supplying ink to the ink receiving portion 488, and the ink from the common ink flow path 301 a is provided in the frame ink flow path 155. A supply pipe 6 is connected. A support beam 156 that supports the head drive substrates 146 and 146 is provided inside the housing frame 153.

  An opening 157 is provided in the upper part of the housing frame 153, and the ICB substrate 500 and the head drive substrate 146 are connected via the opening 157 after the head 10 is assembled.

  Next, a method for manufacturing the head 10 will be described.

  The head chip 141 is manufactured by the method described above.

  Manifolds 148 are bonded to both sides of the head chip 141.

  Next, head driving substrates 146 and 146 are connected to the upper portion of the head chip 141 via the flexible wiring substrate. An ink heater 149 is attached along the surface of the manifold 148. At this time, since the heating parts 149a and 149a are connected along the surface of the manifold by the connection part 149d, it is not necessary to supply power to each heating part 149a independently.

  Next, the holding plate 51 is attached to the lower ends of the head chip 141 and the manifold 148.

  Next, the integrated head chip 141, manifold 148, ink heater 149, holding plate 51, flexible wiring board and head driving boards 146 and 146 are attached to the housing frame 153 to complete the manufacture of the head 10.

  Then, the ICB substrate 500 is electrically connected to connectors 461 and 461 provided on the head drive substrates 146 and 146.

  In addition, since the ink can be heated by the heating unit 149a and the connection unit 149d, the ink inside the manifold can be set to a uniform temperature.

  In the above embodiment, two heating parts 149a are described. However, three or more heating parts 149a may be provided as long as they are connected by the connection part 149d.

  In the example shown in FIG. 6, the ink heater 149 is provided in contact with the manifold 148, but the ink heater 149 may be disposed away from the manifold 148.

  The ink heater 149 may be installed on each of the two sides of the manifold 148, or may be installed on only one of them.

  In an inkjet head, an ink that is highly viscous at room temperature and decreases in viscosity as the temperature rises may be used, such as an ultraviolet curable ink. However, as in this embodiment, the ink is heated before being ejected to the head 10. By providing the heater 149 for reducing the viscosity, stable discharge can be secured, which is a preferable mode.

  Further, in the case of the line head 2 of the present embodiment, since ink is supplied to the head 10 via the common ink flow path 301a, the ink temperature in the common ink flow path 301a (which depends on the environmental temperature) is increased. If it is too low, the ink heater 149 may not be able to heat the ink sufficiently. Therefore, the housing frame 153, the common support substrate 20, and the common ink flow path forming member 301 provided integrally therewith are made of a material having good thermal conductivity with a thermal conductivity of 10 W / m · K or more, for example, aluminum. It is preferable to use a metal such as In particular, it is preferable that it is formed by die casting using aluminum as a material.

  With such a configuration, the heat generated from the ink heater 149 is conducted from the housing frame 153 to the common ink flow path forming member 301 via the common support substrate 20, thereby preheating the ink in the common ink flow path 301a. Heating efficiency is improved.

  Further, in the case where ink is supplied from the ink supply port 304 at one end to the long common ink flow path 301a as in the present embodiment, if a high viscosity ink is used, the high viscosity ink is used. Pressure loss due to flow path resistance increases in the common ink flow path 301a), and high-viscosity ink cannot be stably supplied from the intermediate tank to the head, and ink ejection of the head may become unstable. By reducing the viscosity by preheating in the common ink flow path 301a, a more stable ink supply is possible, which is a preferable mode.

  Further, when low-viscosity ink such as ordinary water-based ink is ejected from the head 10, it is necessary to perform the ejection operation at room temperature without providing the ink heater 149 or operating it. Therefore, it is preferable that the housing frame 153 and the common support substrate 20 are made of a material having a thermal conductivity of 10 W / m · K or more, for example, a metal such as aluminum. In particular, it is preferable that it is formed by die casting using aluminum as a material. Conversely, the common ink flow path forming member 301 is preferably formed of a material having poor thermal conductivity, such as a resin, having a thermal conductivity of 1 W / m · K or less.

  With such a configuration, heat generated from the pressure generating means and the circuit board can be conducted to the common support substrate 20 via the housing frame 153, and can be radiated. Further, this heat is not conducted to the common ink flow path forming member 301 so that the ink is not heated in the common ink flow path 301a, which is a preferable mode.

  FIG. 7A is a diagram of the line head 2 as viewed from the nozzle 42 side. FIGS. 7B and 7C are schematic views enlarging the A portion in the circle of FIG.

  The line head 2 has a plurality of head modules 100 arranged in a staggered manner as described above. A plurality of nozzles 142 are arranged in each of the plurality of head modules 100.

  Each of the two heads 10 constituting the head module 100 has two rows of nozzles arranged in a staggered manner shifted by P / 2 as described above. As shown in FIGS. 7B and 7C, the nozzles of the four rows of the two heads 10 (each row corresponds to the nozzle row of the ink droplet ejection substrate) The nozzle pitch P of the discharge substrate is arranged to be shifted by ¼, and the nozzle pitch (phase between nozzles) of the head module 100 can be made high definition with P / 4. In addition, since this P / 4 is very small, in FIG. 7A, the nozzle 142 is arranged without apparently shifting.

  Further, as shown in FIG. 7B, each head module 100 arranged in a staggered pattern has a center line of the rightmost nozzle 142 of the upper head module 100 shown in the drawing at the leftmost end of the lower head module shown in the drawing. The nozzle rows of the head modules 100 in the upper and lower parts of the figure are arranged in the same manner with the common ink flow path 301a interposed therebetween, as shown in FIG. Yes.

  Thereby, the nozzle rows of the entire line head 2 are arranged at the same nozzle pitch P / 4 along the length direction of the line head 2. Further, as shown in FIG. 7C, one or a plurality of nozzles 142 (four nozzles 142 are overlapped in this figure) at the ends of the upper and lower head modules 100 shown across the common ink flow path 301a. May be arranged so as to overlap each other. In this case, it is easy to align the phases of the nozzles 142 between the head modules 100. In the overlapped part, when one of the nozzles is used for normal discharge and a discharge failure occurs, the other nozzle can be used for interpolation of the discharge failure nozzle, which is a preferable mode. Further, in the overlapping portion, the ink droplets are alternately ejected from the nozzles 142 every one or several lines, so that the size of the ink droplets ejected from the end nozzles 142 between the head modules 100 is reduced. Even if there is a difference, large and small ink droplets are alternately landed in the conveyance direction of the printing medium, so that it is possible to prevent the occurrence of white streaking at the joint between the head modules 100, which is a preferable mode.

  This processing is preferably performed by the relay substrate 600 described above.

  As described above, the line head 2 according to the present invention and the line-type ink jet printing apparatus 1 including the line head 2 are line heads in which a plurality of head modules 100 are arranged in a staggered manner. The head module 100 includes n heads 10 each having two heads 141 each having a common nozzle plate 11 in which two ink droplet discharge substrates each having a plurality of pressure generating units arranged are attached to each other (n is An integer of 1 or more) a combined head module, wherein the nozzle pitch of the head module 100 is 1 / (2n) of the nozzle pitch of the ink droplet ejection substrate, and the two-stage heads arranged in a staggered manner A common ink flow path for supplying ink to each head is formed between the modules, so high-definition printing is possible with a single scan. , And the small size and high assembly productivity, and, and the line head can be connected to simplify the line head and the ink tank may be a line type ink jet printing apparatus having the same. Also provided is a line head capable of high-definition printing by one scan, easy alignment between the plurality of heads 10 and simplifying the connection between the line head and the ink tank. A line-type ink jet printing apparatus can be obtained.

  Further, in the case of the line head 2 in which the head modules 100 having the plurality of heads 10 are arranged in a staggered manner in this way, each head 10 has a position in the Y direction (position along the nozzle arrangement direction) and an X direction (printing). It is preferable that the angle θ with respect to the medium conveyance direction can be adjusted independently. The position in the X direction is obtained by an electrical means that acquires information on the position of each head 10 by a known method and adjusts the ink ejection timing from the information on the time deviation corresponding to the interval between the heads. The ink may be landed at the position of.

  A head (nozzle) position adjusting mechanism provided in each head 10 will be described with reference to FIGS.

  The head position adjusting mechanism is common to each head.

  FIG. 8 is a plan view of the head 10 and its surroundings, FIG. 9 is an enlarged view of a cross section along the plane II-II in FIG. 8, and FIG. 10 is along the plane III-III in FIG. FIG. 11 is a perspective view of a part of the head 10 and the common support substrate 20. FIG. 12 is an enlarged view of a cross section taken along the plane IV-IV in FIG.

  As described above, the line head 2 is provided with the common support substrate 20 as a head mounting portion on which the plurality of heads 10 are mounted, and one side 21 of the common support substrate 20 is the mounting surface on which the head 10 is mounted. It becomes. The mounting surface 21 of the common support substrate 20 is provided with a plurality of mounting holes 22 (in the present example, 12 in the number of heads) formed in a rectangular shape (rectangular shape). Is attached with a gap (play). In order to fill this gap, a sponge sheet 321 as an elastic member is attached to the inner side (inner peripheral surface) of the attachment hole 22. In the drawing, one mounting hole 22 and one head 10 are shown.

  Here, the direction of the normal of the mounting surface 21 of the common support substrate 20 (the direction in which the mounting surface 21 of the common support substrate 20 is directed) is defined as the −Z direction, and the opposite direction of the −Z direction is defined as the + Z direction. One of the longitudinal directions of the mounting hole 22 is defined as the + Y direction, the opposite direction of the + Y direction is defined as the -Y direction, one direction orthogonal to the + Y direction and the + Z direction is defined as the + X direction, and the + Y direction The other direction orthogonal to the + Z direction is defined as the −X direction. As described above, when the XYZ directions are defined, the direction in which the print medium is conveyed is the + X direction, the direction opposite to the print medium conveyance direction is the -X direction, and the arrangement direction of the nozzles 142 is the Y direction.

  The head 10 is provided such that the length along the + Y direction and the height along the + Z direction are longer than the width along the + X direction. A plurality of nozzles 142 are arranged in two rows along the + Y direction on the nozzle plate 11 on the lower surface of the head 10. The head 10 is provided so as to eject ink from these nozzles 142. A side surface 12 oriented in the −X direction of the head 10 is provided on the head 10 as an outer surface of the head 10. When the head 10 is mounted in the mounting hole 22, the side surface 12 of the head 10 is provided perpendicular to the mounting surface 21 of the common support substrate 20 and is parallel to the ± Z direction and the ± Y direction. Furthermore, it is orthogonal to the ± X direction.

  Next, a fixing structure for fixing the head 10 to the common support substrate 20 will be described.

  On the side surface 12 of the head 10, plate-like fixing portions 13 parallel to the mounting surface 21 of the common support substrate 20 are provided integrally with the head 10 at corners in the + Z direction and the −Y direction. When the fixed portion 13 is viewed in the + Z direction, a V-shaped cutout 14 is formed at the end portion on the −Y direction side of the fixed portion 13, and both side surfaces 14 a and 14 b of the cutout 14 also serve as the outer surface of the head 10. It is provided in the head 10. Both side surfaces 14 a and 14 b of the notch 14 are also orthogonal to the mounting surface 21 of the common support substrate 20.

  Further, a hole 15 penetrating in the ± Z direction is formed in the fixing portion 13, and a screw 23 is inserted into the hole 15. The screw 23 is screwed into a screw hole 25 formed in the mounting surface 21 of the common support substrate 20. The diameter of the hole 15 is smaller than the diameter of the head portion of the screw 23 and larger than the diameter of the shaft portion (threaded portion) of the screw 23. Therefore, if the screw 23 is loosened, the head 10 is placed on the XY plane by the amount of play between the shaft portion of the screw 23 and the hole 15 even when the screw 23 is screwed into the screw hole 25 of the common support substrate 20. Can be moved along. On the other hand, when the screw 23 is tightened, the fixing portion 13 is sandwiched between the head of the screw 23 and the mounting surface 21 of the common support substrate 20, and the head 10 can be fixed to the common support substrate 20.

  A plate-like fixing portion 17 parallel to the mounting surface 21 of the common support substrate 20 is provided integrally with the head 10 at corners in the + Z direction and + Y direction on the side surface 16 opposite to the side surface 12. The fixing portion 17 is also formed with a hole 18 penetrating in the ± Z direction, and a screw 24 is inserted into the hole 18. The screw 24 is screwed into a screw hole 26 formed in the mounting surface 21 of the common support substrate 20. Match. The diameter of the head of the screw 24 is larger than the diameter of the hole 18, the diameter of the shaft portion of the screw 24 is smaller than the diameter of the hole 18, and play is provided between the shaft portion of the screw 24 and the hole 18. . The fixing portion 17 includes a spring receiving portion 17W, and the position of the head 10 in the X and Y directions is determined by the spring receiving portion 17W coming into contact with the leaf spring 38 fixed to the common support substrate 20. This contact is achieved by a screw support shaft 41, which will be described later, by the component force F2 (−X direction component force) and F3 (−Y direction component force) of the load F1 at which the leaf spring 38 presses the spring receiving portion 17W. This is performed by urging the inclined surfaces 45a and 45b of 51.

  Next, the θ-direction position adjustment structure 40 in the embodiment to which the head position adjustment structure of this embodiment is applied will be described. This θ-direction position adjustment structure 40 adjusts the angle of the nozzle row by adjusting the angle of the head 10 along the ± θ direction by rotating the head 10 along the ± θ direction.

  The θ-direction position adjustment structure 40 includes a screw support shaft 41 provided on the mounting surface 21 in a state parallel to the side surface 12 of the head 10 and standing with respect to the mounting surface 21 of the common support substrate 20. ing.

  The screw support shaft 41 has a thread 41a as a male screw, and is rotatably supported by screwing with a female screw 20a provided on a common support substrate 20 on the −X direction side from the mounting position of the head 10. Has been. The screw support shaft 41 is provided perpendicular to the mounting surface 21 of the common support substrate 20, and the center line of the screw support shaft 41 is parallel to the ± Z direction. An inclined surface 45 a is formed on the outer periphery of the screw support shaft 41.

  The inclined surface 45 a is in point contact with the corner portion 12 a of the side surface 12 of the head 10.

  The normal line of the inclined surface 45 a intersects with the normal line of the side surface 12 of the head 10 obliquely, and the inclined surface 45 a is inclined with respect to the side surface 12 of the head 10. Furthermore, the inclined surface 45a is formed in an inclined state with respect to the mounting surface 21 of the common support substrate 20, and crosses obliquely with respect to the ± Z direction (the direction of the center line of the screw support shaft 41). The inclined surface 45 a inclined in this way has a shorter distance to the center line of the screw support shaft 41 toward the mounting surface 21 of the common support substrate 20, and the screw support as it moves away from the mounting surface 21 of the common support substrate 20. It inclines so that the distance to the centerline of the axis | shaft 41 may become long.

  Next, the Y-direction position adjustment structure 50 in the embodiment to which the head position adjustment structure of this embodiment is applied will be described. The Y-direction position adjustment structure 50 adjusts the position of the head 10 along the ± Y direction by moving the head 10 along the ± Y direction, and adjusts the position of the nozzle row.

  The Y-direction position adjusting structure 40 includes a screw support shaft 51 provided on the mounting surface 21 in a state parallel to the side surface 12 of the head 10 and standing with respect to the mounting surface 21 of the common support substrate 20. ing.

  The Y-direction position adjusting structure 50 is formed from a screw support shaft 51 provided on the mounting surface 21 in a state parallel to the surfaces 14 a and 14 b of the head 10 and standing with respect to the mounting surface 21 of the common support substrate 20. It is configured.

  The screw support shaft 51 has a thread 51a as a male screw, and can rotate by being screwed with a female screw 20b provided on a common support substrate 20 on the -Y direction side of the surfaces 14a and 14b of the head 10. It is supported by. The screw support shaft 51 is provided perpendicular to the mounting surface 21 of the common support substrate 20, and the center line of the screw support shaft 51 is parallel to the ± Z direction. An inclined surface 45 b is formed on the outer periphery of the screw support shaft 51.

  The inclined surface 45 b is in point contact with the −Z side corners of the surfaces 14 a and 14 b of the head 10.

  The inclined surface 45b is formed in an inclined state with respect to the mounting surface 21 of the common support substrate 20, and crosses obliquely with respect to the ± Z direction (the direction of the center line of the screw support shaft 51). The inclined surface 45b has a shorter distance to the center line of the screw support shaft 51 as it goes toward the mounting surface 21 of the common support substrate 20, and the center line of the screw support shaft 51 as it moves away from the mounting surface 21 of the common support substrate 20. It is inclined so that the distance to it becomes longer. The normal surface of the inclined surface 45b also obliquely intersects the normal line of the surface 14a of the head 10 and the normal line of the surface 14b, and the inclined surface 45b is inclined with respect to the surfaces 14a and 14b of the head 10.

  In the present embodiment, the fixing portion 13 is provided on the side surface 12 of the head 10, and the fixing portion 17 is provided on the opposite side surface 16, but the position where the fixing portion is provided is not particularly limited in the present embodiment. For example, in FIG. 8, the fixed portion 13 may be provided on one of the end surfaces 400 and 401 of the head facing in the Y-axis direction, and the fixed portion 17 may be provided on the other. With such an arrangement, the substantial thickness of the head 10 in the X direction can be reduced. Therefore, the interval between the plurality of heads 10 in the head module can be reduced, which is a preferable mode. In such an arrangement, it is more preferable that at least a part of the fixing portion 13 and the fixing portion 17 overlap in the X direction.

  Next, a method for adjusting the position of the head 10 using the θ-direction position adjustment structure 40 and the Y-direction position adjustment structure 50 will be described.

  First, when the user loosens the screws 23 and 24, the head 10 becomes movable with respect to the common support substrate 20.

  Next, when the user rotates the screw support shaft 41 to bring the screw support shaft 41 closer to the mounting surface 21 of the common support substrate 20, the head 10 is pushed by the inclined surface 45 a and + θ around the screw support shaft 51. Move in the direction.

  On the other hand, when the user rotates the screw support shaft 41 in the reverse direction to move the screw support shaft 41 away from the mounting surface 21 of the common support substrate 20, the head 10 is pushed by the urging force F <b> 2 of the leaf spring 38 and the screw support shaft 51. It becomes possible to move in the -θ direction about the axis. Then, the head 10 is moved in the −θ direction.

  As described above, the user rotates the screw support shaft 41 to determine the position of the head 10 along the ± θ direction. θ is set so that the + Y direction, which is the direction of the nozzle row, is 90 ° with respect to the print medium transport direction + X direction.

  Next, when the user rotates the screw support shaft 51 in one direction and brings the screw support shaft 51 closer to the mounting surface 21 of the common support substrate 20, the head 10 is pushed by the inclined surface 45b and moves in the + Y direction.

  When the user rotates the screw support shaft 51 in the reverse direction to move the screw support shaft 51 away from the mounting surface 21 of the common support substrate 20, the head 10 can be moved in the −Y direction by the biasing force F <b> 3 of the leaf spring 38. It becomes like this. Then, the head 10 is moved in the −Y direction.

  As described above, the user determines the position of the head 10 along the ± Y direction by rotating the screw support shaft 51. The positioning in the Y direction is adjusted and positioned so that the nozzle arrangement is as shown in FIG. 7B or 7C, for example.

  After the positions of the heads 10 in the ± θ direction and the ± Y direction are determined, the user tightens the screws 23 and 24 to fix the head 10 to the common support substrate 20.

  If the screw support shaft 41 is replaced with a screw support shaft having a larger outer diameter, the head 10 can be positioned further on the + θ direction side than the position of the head 10 using the screw support shaft 41. If the screw support shaft having a smaller outer diameter is replaced, the head 10 can be positioned further on the −θ direction side than the position of the head 10 using the screw support shaft 41. Similarly, by replacing the screw support shaft 51 with a screw support shaft having a different outer diameter, the head 10 can be positioned further on the ± Y direction side than the position of the head 10 using the screw support shaft 51.

  As described above, according to the present embodiment, each of the individual heads 10 arranged in a staggered manner has the head position (nozzle position) adjustment mechanism, so that the position adjustment of the head 10 is facilitated.

  Further, since the inclined surfaces 45a and 45b are not provided in the head 10, but are provided in the screw support shaft, it is not necessary to design the head 10 with high accuracy. Further, since the inclined surfaces 45a and 45b are provided on the screw support shafts 41 and 51 which are not replacement parts, once the dimensional error of the inclined surfaces 45a and 45b is confirmed, the dimensional error is confirmed every time the head 10 is replaced. There is no need to do it.

  Since the screw support shafts 41 and 51 are provided in a cylindrical shape, even when the screw support shaft 41 rotates around the center line, the inclined surface 45a maintains the state in contact with the corner portion 12a of the side surface 12 of the head 10. Even when the screw support shaft 51 rotates around the center line, the inclined surface 45b maintains a state in which it contacts any of the + Z side corners of the surfaces 14a and 14b of the head 10.

  The head position adjusting mechanism is not limited to the present embodiment, and various improvements and design changes may be made.

1 is a perspective view showing a main part of an ink jet printing apparatus according to the present invention. It is a perspective view in the state where the cover of line head 2 concerning the present invention was removed. It is a figure which shows the cross section of the ink supply part to the head module of the line head 2 which concerns on this invention. It is a block diagram of the ink supply system to the line head 2 which concerns on this invention. It is a sectional side view in the nozzle position which shows schematic structure of the head 10 which comprises the line head 2 which concerns on this invention. It is a disassembled perspective view of the head 10 which comprises the line head 2 which concerns on this invention. It is a figure explaining the structure of the line head 2 which concerns on this invention, (a) is the figure which looked at the line head 2 from the nozzle side, (b), (c) expanded the A part in the circle | round | yen of (a). FIG. It is a top view of the head 10 which comprises the line head 2 which concerns on this invention, and its periphery. It is sectional drawing along surface II-II of FIG. It is sectional drawing along the surface III-III of FIG. FIG. 2 is a perspective view of a head 10 and a common support substrate 20. FIG. 10 is a cross-sectional view taken along a plane IV-IV in FIG. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printing apparatus 2 Line head 3 Flexible cable 4 Control board 5 Print medium conveyance mechanism 10 Head 11 Common nozzle plate 20 Common support board 22 Mounting hole 100 Head module 141 Head chip 142 Nozzle 301a Common ink flow path 306 Intermediate tank 307 ink cartridge

Claims (5)

A line head having a plurality of nozzles arranged at a length corresponding to the width of the print medium, ejecting ink from the nozzles toward the print medium, and relatively moving the print medium and the line head in the moving direction; A line-type inkjet printing apparatus that forms an image on the printing medium by moving the printing medium,
The line head is a line head in which a plurality of head modules are arranged in a staggered manner, and the head module has two ink droplet discharge substrates arranged with a plurality of pressure generating means attached to each other, A head module in which n heads each having a head chip having a common nozzle plate (n is an integer of 1 or more) are combined, and the nozzle pitch of the head module is 1 / nozzle pitch of the ink droplet ejection substrate. (2n), a common ink channel for supplying ink to each head is formed between the two-stage head modules arranged in a staggered manner, and an ink supply port is provided at one end of the common ink channel However, a bubble discharge port is provided at the other end, and a branch supply port for supplying ink to each head is provided between the ink supply port and the bubble discharge port. Te,
An intermediate tank that is connected to the ink supply port via an ink supply path and stores ink supplied to the ink supply port, and is disposed below each head module;
An ink cartridge that communicates with the intermediate tank and stores ink supplied to the intermediate tank;
A waste ink container connected to the bubble outlet through a first ink flow path;
A pressure pump connected to the intermediate tank via a second ink flow path;
A first on-off valve provided in the middle of the first ink flow path;
A second on-off valve provided in the middle of the second ink flow path;
Have
By operating the pressure pump with the first on-off valve and the second on-off valve opened, bubbles in the common ink flow path are discharged together with ink to the waste ink container through the bubble discharge port. ,
An inkjet printing apparatus that performs printing in a state where the first on-off valve and the second on-off valve are closed. An ink remaining amount detecting means for detecting an ink remaining amount in the intermediate tank;
A second pressure pump for pumping ink from the ink cartridge to the intermediate tank;
A third on-off valve provided in the middle of an ink supply path connecting the ink cartridge and the intermediate tank;
Have
When the detected value by the ink remaining amount detecting means becomes a predetermined value or less, the third on-off valve is opened to replenish ink from the ink cartridge to the intermediate tank, and the second pressure pump is operated. 2. The ink jet printing apparatus according to claim 1, wherein if the ink is not replenished to the intermediate tank even after a predetermined time has elapsed since the operation, the ink cartridge is determined to be empty. The inkjet printing apparatus according to claim 1, wherein an O-ring is provided at the branch supply port. The inkjet printing apparatus according to claim 1, wherein n is an integer of 2 or more. The inkjet printing apparatus according to claim 1, wherein an image is formed on the printing medium by the movement once.

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