Inkjet heads and inkjet printing equipment

Abstract

To provide an inkjet head that is less prone to pressure loss due to the filter and has a long lifespan. The above problem is solved. The inkjet head that solves the above problem is an inkjet head having a plurality of head chips, a plurality of individual channel substrates corresponding to each of the head chips for supplying ink to each of the head chips, and a common channel substrate for supplying ink to each of the individual channel substrates, wherein the common channel substrate has a structure in which a plurality of layered channel members are stacked, and at least two of the plurality of layered channel members are filter members including a filter section.

Description

Technical Field

[0001] The present invention relates to an inkjet head and an inkjet printing apparatus.

Background Art

[0002] Conventionally, various inkjet heads for inkjet printing have been developed, and inkjet heads including a plurality of head chips have also been developed. As an inkjet head having a plurality of head chips, there is known a head having a substrate (referred to as "individual flow path substrate" in this specification) having an individual flow path for supplying ink to each head chip and a common flow path substrate for supplying ink to the individual flow path substrate (for example, Patent Document 1). In the common flow path substrate of such an inkjet head, in order to cope with complicated flow paths and the like, it is common to use a laminate of a plurality of layered flow path substrates.

[0003] Here, when foreign matter, air, or the like enters the head chip of the inkjet head, it becomes difficult to eject ink normally. Therefore, a filter for removing foreign matter is usually disposed between the ink inlet (inlet port) of the inkjet head and the head chip. Also in Patent Document 1 described above, a plurality of filters corresponding to each head chip are disposed in the flow path of the common flow path substrate. More specifically, a plurality of filters are arranged side by side in one layer in the common flow path substrate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, as described in Patent Document 1, arranging multiple filters on a single layer of a common flow channel substrate not only reduces the freedom of filter shape but also makes it difficult to secure sufficient area. This configuration has problems such as a high processing load per unit area of ​​the filter, leading to filter degradation and a shortened lifespan of the inkjet head. In particular, with high-viscosity inks for industrial use, there is also the problem that the filter tends to increase pressure loss.

[0006] This invention has been made in view of the above problems, and aims to provide an inkjet head that is less prone to pressure loss due to the filter and has a long lifespan, and an inkjet printing apparatus using the same. [Means for solving the problem]

[0007] To achieve at least one of the above-mentioned objectives, the following inkjet head and inkjet printing apparatus are provided.

[0008] An inkjet head reflecting one aspect of the present invention is an inkjet head having a plurality of head chips, a plurality of individual channel substrates corresponding to each of the head chips for supplying ink to each of the head chips, and a common channel substrate for supplying ink to each of the individual channel substrates, wherein the common channel substrate has a structure in which a plurality of layered channel members are stacked, and at least two of the plurality of layered channel members are filter members including a filter section.

[0009] An inkjet printing apparatus that reflects one aspect of the present invention is an inkjet printing apparatus comprising the above-described inkjet head, an ink supply unit that supplies ink to the inkjet head, a head drive unit that operates the inkjet, and a transport unit that transports a recording medium. [Effects of the Invention]

[0010] An inkjet head according to one embodiment of the present invention can be used stably for a long period of time and is less prone to pressure loss due to the filter. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a diagram showing a schematic configuration of an inkjet printing apparatus according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing the arrangement of inkjet heads in the drawing section of an inkjet printing apparatus. [Figure 3] Figure 3 is a perspective view showing the external appearance of an inkjet head according to one embodiment of the present invention. [Figure 4] Figure 4 is an exploded perspective view of the inkjet head shown in Figure 3. [Figure 5] Figure 5 is a schematic cross-sectional view of the inkjet head in line AA of Figure 3. [Figure 6] Figures 6A to 6G are schematic plan views illustrating the structure of the layered channel members that constitute the common channel substrate of the inkjet head shown in Figure 3. [Figure 7] Figure 7 is a perspective view showing the structure of the layered channel member shown in Figure 6G. [Figure 8] Figure 8 is a schematic cross-sectional view of the area around the head tip along line AA in Figure 3. [Modes for carrying out the invention]

[0012] Hereinafter, an inkjet printing apparatus and inkjet head according to one embodiment of the present invention will be described in detail with reference to the drawings. However, the inkjet printing apparatus and inkjet head of the present invention are not limited to the embodiments shown below.

[0013] [Inkjet printer] Figure 1 is a schematic diagram showing the configuration of an inkjet printing apparatus equipped with an inkjet head according to this embodiment. As shown in Figure 1, the inkjet printing apparatus 100 includes a transport unit 110, a supply unit 120, an ejection unit 130, an ink supply unit 140, a drawing unit 150, a reading unit 160, a control unit (not shown), and the like.

[0014] The transport unit 110 has multiple transport components, including a transport belt 111, a drive roller 112, and a driven roller 113. The transport unit 110 transports the recording medium M by the transport operation of the transport belt 111 and other components. Specifically, in the transport unit 110, the transport belt 111 is stretched over the drive roller 112 and the driven roller 113, and is driven by rotating the drive roller 112. As a result, the recording medium M supplied from the supply unit 120 is transported to the drawing unit 150 while placed on the transport surface 111a of the transport belt 111, and after being drawn (also called image formation or printing) in the drawing unit 150, it is transported to the discharge unit 130.

[0015] The recording medium M can be any medium capable of fixing the ink ejected from the inkjet head (not shown) located in the drawing unit 150. The recording medium M is, for example, a sheet of paper, cloth, or resin. The recording medium M is not limited to a sheet; it may also be a roll of paper, cloth, or resin. An example of a resin-based recording medium M is a PCB (Printed Circuit Board) substrate. In the case of a PCB substrate, the inkjet printing device 100 can be used to print solder resist or marking ink onto the PCB substrate. Other recording media M that can be used for drawing include metal car bodies, building materials (exterior walls, roofing materials, tiles, etc.), and metal cans (for storing food and beverages). In the case of various building materials and metal products, the inkjet printing device 100 can be used to paint these materials.

[0016] Here, as an example, a transport unit 110 that transports a recording medium M by a transport belt 111 is illustrated. However, the transport unit 1110 is not limited to the transport belt 111, and may be configured to transport the recording medium M by a drum or a roller.

[0017] The supply unit 120 includes a supply loading unit 121 that stacks and stores a plurality of recording media M, a supply transport unit 122 that transports and supplies the recording medium M from the supply loading unit 121 to the transport unit 110, and the like. The supply loading unit 121 is configured to be able to move up and down. When the uppermost recording medium M is transported by the supply transport unit 122 to the transport unit 110, the supply loading unit 121 rises so that the recording medium M that has become the uppermost after the transport can be transported to the supply transport unit 122.

[0018] The discharge unit 130 includes a discharge loading unit 131 that stacks and stores a plurality of recording media M, a discharge transport unit 132 that transports the recording medium M discharged from the transport unit 110 to the discharge loading unit 131, and the like. The discharge loading unit 131 is configured to be able to move up and down. When the recording medium M is transported from the discharge transport unit 132 to the discharge loading unit 131, the discharge loading unit 131 descends.

[0019] The supply transport unit 122 and the discharge transport unit 132 each have, for example, a plurality of rollers, and transport the recording medium M by rotating the rollers. The supply transport unit 122 and the discharge transport unit 132 are not limited to rollers, and may be configured by a belt, or may be configured by a combination of rollers and a belt.

[0020] When a roll-shaped medium is used as the recording medium M, instead of the supply loading unit 121 and the discharge loading unit 131, a pay-out roller on which the roll-shaped medium is wound and stored and a take-up roller that takes up the roll-shaped medium are used. The roll-shaped medium is transported to the transport unit 110 by rotating the pay-out roller, and is wound around the take-up roller by rotating the take-up roller.

[0021] Furthermore, a post-processing device (not shown) for performing post-processing on the recording medium M, on which an image has been formed by the drawing unit 150, may be provided between the transport unit 110 and the discharge unit 130. One example of a post-processing device is a fixing device for fixing ink to the recording medium M. If, for example, an ultraviolet-curable ink is used as the ink, a fixing device is used that irradiates the recording medium M with ultraviolet light to fix the ink to the recording medium M. If, for example, a water-based ink or solvent ink is used as the ink, a fixing device is used that fixes the ink to the recording medium M by drying or other methods. In addition, devices other than a fixing device may be used as post-processing devices, such as a cutting device for cutting the recording medium M to a desired length.

[0022] The configurations of the transport unit 110, the supply unit 120, and the discharge unit 130 can be changed in various ways depending on the type of recording medium M to be drawn on.

[0023] The ink supply unit 140 is a device that supplies ink to the drawing unit 150, which will be described later. In this embodiment, as will be described later, the inkjet head has multiple (two) head chips. Therefore, the ink supply unit 140 includes ink supply mechanisms 141 and 142 corresponding to each head chip. Each ink supply mechanism 141 and 142 may also be equipped with temperature control means to maintain a constant temperature according to the type of ink.

[0024] Each ink supply mechanism 141, 142 may include a main tank (not shown), a supply sub-tank (not shown), and a recirculation tank (not shown). The main tank is a tank for storing ink and supplies ink to the supply sub-tank by the operation of a liquid transfer pump or the like. The supply tank is connected to the supply channel of the inkjet head of the drawing unit 150, and temporarily stores ink and supplies ink to the inkjet head as needed. The recirculation sub-tank is a tank that stores ink recovered from the inkjet head that is not discharged from the nozzle. The recirculation sub-tank is connected to the recovery channel of the inkjet head. The recirculation sub-tank is also connected to the supply sub-tank, and ink is sent from the recirculation sub-tank side to the supply sub-tank side by a liquid transfer pump or the like. This allows ink to be circulated between the ink supply unit 140 and the inkjet head, making it possible to utilize ink that has been recovered but not used in the inkjet head.

[0025] The drawing unit 150 includes an inkjet head (described later), a carriage to support it, and a head drive unit (none of which are shown) for driving the inkjet head. In Figure 1, for the sake of simplicity, only one set of the ink supply unit 140 and the drawing unit 150 is shown, but there may be multiple sets of the ink supply unit 140 and the drawing unit 150. When there are multiple sets, the drawing units 150 are arranged at predetermined intervals along the transport direction T.

[0026] The carriage in the drawing unit 150 is a housing that internally holds equipment and components necessary for image formation, such as a head drive unit and an inkjet head. The carriage may also be equipped with a temperature control mechanism for adjusting the ink temperature.

[0027] The head drive unit in the drawing unit 150 applies a drive voltage to the piezoelectric element in the inkjet head, corresponding to the image data of the image to be formed, based on the control of a control unit (not shown) described later. The inkjet head, described later, ejects an amount of ink from its nozzles corresponding to the image data, based on the drive voltage from the head drive unit. The configuration of the inkjet head will be described in detail later.

[0028] The drawing unit 150 may be configured to be a single-pass (one-pass) system that forms an image in a single scan, or a scan (multi-pass) system that forms an image in multiple scans. In the single-pass system, the carriage of the drawing unit 150 has an inkjet head 10 equal to the image formation width in the width direction of the recording medium M (in the direction perpendicular to the transport direction T of the recording medium M) (see Figure 2). As shown in Figure 2, the multiple inkjet heads 10 are arranged in one or more rows with their longitudinal direction aligned with the width direction of the recording medium M, and in each inkjet head 10, the multiple nozzles N are arranged linearly or in a grid along the longitudinal direction of the inkjet head 10.

[0029] The reading unit 160 is located downstream of the drawing unit 150 in the transport direction T of the recording medium M and reads the image (for example, a predetermined pattern image) formed on the recording medium M that is transported by the transport belt 111. The reading unit 160 outputs the reading result of the predetermined pattern image to the control unit (not shown). Based on the reading result, the control unit changes the image formation conditions, such as the image formation position and the driving conditions of the inkjet head.

[0030] Although not shown in the illustrations, the inkjet printer 100 may also include a maintenance unit for performing maintenance such as cleaning the inkjet head. Furthermore, although not shown in the illustrations, it may also include an operation display unit for receiving various user input operations, and an input / output interface for mediating the transmission and reception of data between an external device and the control unit. The external device may be, for example, a personal computer or a facsimile machine, which supplies print jobs, image data, etc., to the control unit via the input / output interface.

[0031] The control unit includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a storage unit. The CPU reads various control programs and setting data stored in the ROM, stores them in the RAM, and executes the programs to perform various calculations. For example, the control unit generates a drive signal for the image to be formed based on image data received from the input / output interface and outputs it to the inkjet head.

[0032] RAM provides the CPU with a working memory space and stores temporary data. RAM may also include non-volatile memory.

[0033] ROM stores various control programs and configuration data executed by the CPU. Alternatively, rewritable non-volatile memory such as EEPROM (Electrically Erasable Programmable Read Only Memory) or flash memory may be used instead of ROM.

[0034] The memory unit stores print jobs and image data related to print jobs that are input from external devices via an input / output interface. For the memory unit, for example, non-volatile semiconductor memory (so-called flash memory) or an HDD (Hard Disk Drive) may be used, and DRAM (Dynamic Random Access Memory) may also be used in combination.

[0035] The control unit is connected to the transport unit 110, supply unit 120, discharge unit 130, ink supply unit 140, drawing unit 150, reading unit 160, operation display unit, input / output interface, etc. The control unit provides overall control of the inkjet printing device 100. The transport unit 110, supply unit 120, discharge unit 130, ink supply unit 140, drawing unit 150, reading unit 160, operation display unit, input / output interface, etc. are controlled by the control unit to perform predetermined processes.

[0036] The inkjet printing apparatus 100 having the above configuration supplies the recording medium M from the supply unit 120 to the transport unit 110 under the control of the control unit, performs drawing on the recording medium M transported to the transport unit 110 with the drawing unit 150, and transports the image-formed recording medium M to the discharge unit 130.

[0037] Here, the ink that can be used in the inkjet printing apparatus 100 of this embodiment is not particularly limited. The ink may be any of the following: water-based pigment ink, solvent-based ink, and active light-curable ink. Water-based pigment ink contains water, pigment, fixative, etc., and in this water-based pigment ink, the pigment, etc. is fixed on the recording medium M by the absorption or evaporation of water into the recording medium M. Solvent ink is an ink containing an organic solvent, and after landing on the recording medium M, the organic solvent erodes the recording medium to form a receiving layer, and the colorant, etc. is fixed on the receiving layer. Active light-curable ink contains an active light-cured product that hardens when exposed to active light (e.g., ultraviolet light, radiation, electron beam, gamma rays, etc.), and the colorant, etc. is fixed by forming a film of the active light-cured product on the recording medium M. Active light-curable ink may also contain a gelling agent, etc.

[0038] The inkjet printing apparatus 100 of this embodiment is equipped with an inkjet head described later. The inkjet head described later is less prone to pressure loss due to the filter. Therefore, even when using ink with high viscosity during ejection, pressure loss is less likely to occur. Accordingly, the inkjet printing apparatus of this embodiment is suitable for printing using ink with a viscosity of 12 mPa·s or higher during ejection. A rotational viscometer, rheometer, or vibration viscometer can be used to measure this viscosity.

[0039] [Inkjet head] The configuration of the inkjet head 10 according to this embodiment will be described in detail. The configuration described here is that of the inkjet head 10 alone. Note that the configuration of all inkjet heads 10 in the inkjet printing apparatus 100 described above may be the same, or the inkjet printing apparatus 100 may include inkjet heads with configurations different from the configuration described below.

[0040] Figure 3 shows the external appearance (perspective view) of the inkjet head 10 according to this embodiment. Figure 4 shows an exploded perspective view of the inkjet head 10, and Figure 5 shows a cross-sectional view along line AA in Figure 3. However, in Figure 5, the shapes of the head chips HCa and HCb are omitted, and Figure 8 shows the structure of the head chip HCb. As shown in Figures 3 to 5, the inkjet head 10 comprises a housing 1, a drive control member 2, a pair of circuit boards 3a and 3b, a common flow path board 4, a holder 5, individual flow path boards 6a and 6b, head chips HCa and HCb, a reinforcing plate 7, and a fixing plate 8.

[0041] The housing 1 is a hollow member for housing the drive control member 2, a pair of circuit boards 3a and 3b, and a common flow path board 4. The housing 1 has an opening 11 for exposing a part of the drive control member 2 to the outside. The housing 1 also has through holes 12 for inserting supply tubes 41a and 41b, one end of which is connected to the inlet ports 42a and 42b of the common flow path board 4 described later, and recovery tubes 49a and 49b, the other end of which is connected to the outlet ports 48a and 48b of the common flow path board 4. The other ends of the supply tubes 41a and 41b are connected to the supply sub-tanks of the ink supply unit 140 of the inkjet printing apparatus 100 described above. On the other hand, the other ends of the recovery tubes 49a and 49b are connected to the recirculation sub-tanks of the ink supply unit 140 of the inkjet printing apparatus 100 described above.

[0042] The drive control member 2 includes a circuit board and a drive chip (such as an IC) for outputting drive signals to the head chips HCa and HCb, respectively. The drive control member 2 is connected to the head drive unit of the drawing unit 150 of the inkjet printing apparatus 100 described above. In addition, the pair of circuit boards 3a and 3b are connected to the drive control member 2 and the head chips HCa and HCb, respectively.

[0043] The common channel substrate 4 is a structure having channels for supplying ink to multiple (two in this embodiment) head chips HCa and HCb. The common channel substrate 4 has a structure in which multiple layered channel members L1 to L7 (hereinafter also referred to as "first layered channel member L1", "second layered channel member L2", etc., in order from the drive control member 2 side) are stacked. The plan view structure of each layered channel member L1 to L7 is shown in Figures 6A to 6G. In Figures 6A to 6G, through holes and openings are shown in white to make the structure easier to understand, and hatching is applied to the other parts. Furthermore, different hatching is applied to parts with different heights and mesh-like parts. Also, in Figures 6A to 6G, the main flow of ink introduced from inlet port 42a is shown by solid arrows, and the main flow of ink introduced from inlet port 42b is shown by dotted arrows.

[0044] The first layered flow channel member L1 is a flat plate-shaped member having two inlet ports (through holes) 42a and 42b for introducing ink and two outlet ports (through holes) 48a and 48b for recovering ink. As described above, supply tubes 41a and 41b are connected to the inlet ports 42a and 42b, and recovery tubes 49a and 49b are connected to the outlet ports 48a and 48b. One inlet port 42a communicates with the supply channel 44a of the second layered flow channel member L2, and the other inlet port 42b communicates with the supply channel 44b of the second layered flow channel member L2. One outlet port 48a communicates with the recovery channel 47a of the second layered flow channel member L2, and the other outlet port 48b communicates with the recovery channel 47b of the second layered flow channel member L2.

[0045] The second layered flow channel member L2 has through holes that form part of the supply channels 44a and 44b, and through holes that form part of the recovery channels 47a and 47b. Furthermore, the second layered flow channel member L2 has an opening (inlet) 442a between the supply channels 44a and 44b and the recovery channels 47a and 47b. There is no wall between the opening (inlet) 442a and the supply channel 44a, and they are in communication. On the other hand, the opening (inlet) 442a is separated from the supply channel 44b and the recovery channel 47b by a wall. In addition, although there is a wall between the opening (inlet) 442a and the recovery channel 47a, a recess (flow channel) 441a made of a notch is formed in the wall, and the opening 442a and the recovery channel 47a are configured to communicate through the recess (flow channel) 441a. The recess (flow channel) 441a is located on the side of the first layered flow channel member L1.

[0046] The third layered flow channel member L3 has through holes that form part of the supply channel 44b and through holes that form part of the recovery channels 47a, 47b. Furthermore, the third layered flow channel member L3 has a filter section 45a made of filter material between the supply channel 44b and the recovery channels 47a, 47b. The filter section 45a has a predetermined mesh opening and is configured to allow ink to flow from the second layered flow channel member L2 side to the fourth layered flow channel member L4 side.

[0047] The fourth layered flow channel member L4 has through holes that form part of the supply channels 44a and 44b, and through holes that form part of the recovery channels 47a and 47b. The fourth layered flow channel member L4 has a recess (outlet) 46a between the supply channels 44a and 44b and the recovery channels 47a and 47b. There is no wall between the recess (outlet) 46a and the supply channel 44a, and they are in communication with each other. On the other hand, the recess (outlet) 46a is separated from the supply channel 44b and the recovery channels 47a and 47b by a wall.

[0048] The fifth layered flow channel member L5 has through holes that form part of the supply channels 44a and 44b, and through holes that form part of the recovery channels 47a and 47b. Furthermore, the fifth layered flow channel member L5 has an opening (inlet) 442b between the supply channels 44a and 44b and the recovery channels 47a and 47b. There is no wall between the opening (inlet) 442b and the supply channel 44b, and they are in communication. On the other hand, the opening (inlet) 442b is separated from the supply channel 44a and the recovery channel 47a by a wall. Although there is a wall between the opening 442b and the recovery channel 47b, a recess (flow channel) 441b made of a notch is formed in the wall, and the opening (inlet) 442b and the recovery channel 47b are configured to communicate through the recess (flow channel) 441b. The recess (flow channel) 441b is located on the side of the fourth layered flow channel member L4.

[0049] The sixth layered flow channel member L6 has through holes that form part of the supply channel 44a and through holes that form part of the recovery channels 47a and 47b. Furthermore, the sixth layered flow channel member L6 has a filter section 45b made of filter material between the supply channel 44a and the recovery channels 47a and 47b. The filter section 45b has a predetermined mesh opening and is configured to allow ink to flow from the fifth layered flow channel member L5 side to the seventh layered flow channel member L7 side.

[0050] The seventh layered flow channel member L7 has through holes that form part of the supply channels 44a and 44b, and through holes that form part of the recovery channels 47a and 47b. The seventh layered flow channel member L7 has a recess (outlet) 46b between the supply channels 44a and 44b and the recovery channels 47a and 47b. There is no wall between the recess (outlet) 46b and the recovery channel 47b, and they are in communication. On the other hand, the recess (outlet) 46b is separated from the supply channels 44a and the recovery channels 47a and 47b by a wall.

[0051] In the common channel substrate 4, the second layered channel member L2, the third layered channel member L3, and the fourth layered channel member L4 function as filter units 43a for filtering ink supplied from the inlet port 42a. Furthermore, the fifth layered channel member L5, the sixth layered channel member L6, and the seventh layered channel member L7 function as filter units 43b for filtering ink supplied from the inlet port 42b. In other words, the common channel substrate 4 has separate filter units 43a and 43b (filter sections 45a and 45b) for the two head chips HCa and HCb, respectively, and these are arranged in different layers of the common channel substrate 4.

[0052] In this specification, a flow channel member having a filter is also referred to as a filtered flow channel member. Furthermore, a layered flow channel member located upstream of a filtered flow channel member and having an introduction section for introducing ink into the filter section is also referred to as the upstream flow channel member. Moreover, a layered flow channel member located downstream of a filtered flow channel member and having an outlet section for discharging the ink filtered by the filter section is also referred to as the downstream flow channel member.

[0053] The flow of ink in the common flow channel substrate 4 will now be explained in detail. Ink supplied from the inlet port 42a of the first layered flow channel substrate L1 is introduced into the supply channel 44a of the second layered flow channel member L2. This supply channel 44a is blocked by the third layered flow channel member L3, and as shown in Figure 6B, the ink is guided into the space surrounded by the bottom surface of the first layered flow channel member L1, the inner wall of the opening (inlet) 442b of the second layered flow channel member L2, and the upper surface of the filter section 45a of the third layered flow channel member L3. The ink guided into this space flows to the recess (outlet) 46a side of the fourth layered flow channel member L4 via the filter section 45a. In other words, filtration is performed by the filter section 45a. Then, as shown in Figure 6D, the ink flows from the recess (outlet) 46a of the fourth layered flow channel member L4 to the supply channel 44a of the fifth layered flow channel member L5. Then, the fluid flows through the supply channels 44a of the sixth layered flow channel member L6 and the seventh layered flow channel member L7 towards the individual flow channel substrate 6.

[0054] Furthermore, if bubbles are generated in the ink flowing through the supply channel 44a, it may cause malfunctions in the nozzle N of the head tip HCa, as described later. Therefore, of the ink introduced into the space of the second layered channel member L2 described above, the ink on the side of the first layered channel member L1 (the side where bubbles tend to accumulate) is recovered from the recovery channel 47a via the recess (channel) 441a of the second layered channel member L2, as shown in Figure 6B.

[0055] Meanwhile, the ink introduced from the inlet port 42b of the first layered channel substrate L1 is guided to the fifth layered channel member L5 via the supply channels 44b of the second layered channel member L2, the third layered channel member L3, and the fourth layered channel member L4. The supply channel 44a is blocked by the sixth layered channel member L6, and the ink is guided into the space surrounded by the bottom surface of the fourth layered channel member L4, the wall surface of the opening (inlet) 442b of the sixth layered channel member L6, and the upper surface of the filter section 45b of the sixth layered channel member L6, as shown in Figure 6E. The ink guided into this space flows to the recess (outlet) 46b side of the seventh layered channel member L via the filter section 45b. In other words, filtration is performed by the filter section 45b. Then, as shown in Figure 6G, the ink flows from the recess (outlet portion) 46b of the seventh layered flow channel member L7 through the supply channel 44b to the individual flow channel substrate 6 side.

[0056] Furthermore, of the ink introduced into the space of the fifth layered flow channel member L5, the ink on the side of the fourth layered flow channel member L4 (the side where air bubbles tend to accumulate) is recovered from the recovery channel 47a via the recess (flow channel) 441b of the fifth layered flow channel member L5, as shown in Figure 6E.

[0057] Here, the material of each layered flow channel member L1 to L7 is not particularly limited and may be resin or other materials. However, resin is preferred from the viewpoint of being easy to form by injection molding, etc. Also, the material of the filter media of the filter sections 45a and 45b of the third layered flow channel member L3 and the sixth layered flow channel member L6 is not particularly limited. However, it is preferable that the materials of the filter sections 45a and 45b are the same from the viewpoint of making it easier to make the pressure loss of the two filter units 43a and 43b equal. The type of filter media of the filter sections 45a and 45b may be any material that has high durability and does not deteriorate or alter the ink due to components in the ink. For example, it may be resin, but metal is preferred from the viewpoint of durability, etc. Also, it is preferable that each filter section 45a and 45b has fibrous filter media that is plain weave, twill weave, plain fold weave, or twill fold weave.

[0058] The mesh size of each filter section 45a and 45b is not particularly limited, but it is preferable that it be smaller than the diameter of the nozzle N of the head tip HCa and HCb described later. For example, the mesh size of the filter sections 45a and 45b is preferably 0.9 times or less, preferably 0.6 times or less, and more preferably 0.4 times or less, the diameter (inner diameter) of the nozzle N. The lower limit is appropriately selected according to the desired processing volume.

[0059] Here, in the third layered flow channel member L3 and the sixth layered flow channel member L6, the areas of each filter section 45a and 45b may be the same or different, but it is preferable that they be substantially the same. It is preferable that the areas of each filter section 45a and 45b are substantially the same (particularly preferably the same) from the viewpoint that the pressure loss of the two filter units 43a and 43b can be made equal. By substantially the same, it means that the area of ​​the filter section of one filter section is in the range of 0.9 to 1.1 times the area of ​​the other filter section. Furthermore, although the plan view shape of the filter sections 45a and 45b in this embodiment is rectangular, the plan view shape of the filter section is not limited to this. It can be any shape according to the outer shape of the common flow channel substrate, the shape and position of the supply flow channels 44a and 44b, the shape and position of the recovery flow channels 47a and 47b, etc. However, it is preferable to design so that the areas of each filter section 45a and 45b are substantially the same (particularly preferably the same).

[0060] Furthermore, it is preferable that the filter sections 45a and 45b are arranged so that parts of them overlap when the common flow path substrate 4 is viewed from above. By arranging multiple filter sections 45a and 45b so that they overlap when the common flow path substrate 4 is viewed from above, it becomes possible to miniaturize the common flow path substrate 4.

[0061] Furthermore, if the common flow path substrate 4 includes multiple filter units 43a and 43b, each consisting of an upstream flow path member, a filtered member, and a downstream flow path member, the design of the common flow path substrate 4 becomes easier even when the number of head chips increases. Moreover, if some of the filter parts deteriorate, maintenance can be easily performed by replacing the filter unit including the affected filtered member.

[0062] In addition, in the common flow channel substrate 4 described above, the multiple layered flow channel members L1 to L7 may be bonded together with an adhesive (not shown) or the like. However, it is preferable that each layer is detachably laminated by a known locking structure (not shown). In particular, if the filter-equipped member, including the filter member, is formed to be detachably, the replacement and inspection of the filter-equipped member can be easily performed.

[0063] On the other hand, the holder 5 for the inkjet head 10 has a hollow structure for housing the individual channel substrates 6a, 6b and the head chips HCa, HCb. The holder 5 has through holes 51 for connecting the supply channels 44a, 44b of the common channel substrate 4 to the supply channels 61a, 61b of the individual channel substrates 6a, 6b, and through holes 52 for connecting the recovery channels 47a, 47b of the common channel substrate 4 to the supply channels 61a, 61b of the individual channel substrates 6a, 6b. Furthermore, it also has openings 53 for electrically connecting the circuit boards 3a, 3b to the piezoelectric elements 204 of the head chips HCa, Hcb. The holder 5 also has recesses inside for housing and supporting the individual channel substrates 6a, 6b and the head chips HCa, HCb. The shape of the holder 5 can be any shape to match the shape of the individual channel substrates 6a, 6b and the head chips HCa, HCb. The holder 5 is attached to the housing 1, etc., by adhesive or the like.

[0064] The individual channel substrates 6a and 6b only need to have supply channels 61a and 61b for supplying ink to the head chips HCa and HCb, respectively, and recovery channels 69a and 69b for recovering ink that was not applied by the head chips HCa and HCb. The individual channel substrates 6a and 6b and the common channel substrate 4 are bonded together with an adhesive or the like so that the supply channels 61a and 61b of the individual channel substrates 6a and 6b communicate with the supply channels 44a and 44b of the common channel substrate 4, and the recovery channels 69a and 69b of the individual channel substrates 6a and 6b communicate with the recovery channels 47a and 47b of the common channel substrate 4.

[0065] The reinforcing plate 7 is positioned between the holder 5 and the fixing plate 8 and is a component for reinforcing the fixing plate 8. The reinforcing plate 7 is fixed to the fixing plate 8 with adhesive or the like. The reinforcing plate 7 has openings 71 corresponding to the head tips HCa and HCb.

[0066] The fixing plate 8 is a component for fixing the individual flow path substrates 6a and 6b and the head chips HCa and HCb to the holder 5. The fixing plate 8 has through holes 81 for exposing the nozzles N of the head chips HCa and HCb.

[0067] The structure of the head chips HCa and HCb is not particularly limited as long as it includes a plurality of nozzles N and has a structure for ejecting ink onto the recording medium M, as shown in Figure 2. The structure of the head chips HCa and HCb can be the same as that of various known head chips. However, head chips having a constricted section in which the cross-sectional area of ​​the flow path narrows in the direction in which the ink is discharged tend to have a large pressure loss. Therefore, by combining such a head chip with the above-mentioned common flow path substrate with low pressure loss, the overall pressure loss of the inkjet head can be reduced. That is, the head chips HCa and HCb of this embodiment preferably have the structure shown below. However, the structure of the head chips HCa and HCb is not limited to these.

[0068] Figure 8 is a cross-sectional view of the area around the head chip HCb along line AA in Figure 3. Figure 8 shows the structure around only one of the two head chips HCa and HCb, but the structure of the other head chip HCa is similar. Also, Figure 8 shows the portion corresponding to one of the multiple nozzles N contained in the head chip HCb, but the portions corresponding to the other nozzles N are similar. The head chips HCa and HCb with this structure are connected to the individual flow channel substrate 6.

[0069] As shown in Figure 8, the head chip HCb has a flow channel substrate 201 on a flat plate extending in the X direction. The flow channel substrate 201 has a first opening 92 extending in the X direction, and second openings 93 and third openings 94 partitioned for each nozzle N. The flow channel substrate 201 also has a thin region (restricted portion) 99 between the second opening 93 and the third opening 94, and on the side of the elastic member 211 described later.

[0070] The head chip HCb further has a common housing 206 on the individual channel board 6 side of the channel board substrate 201. The housing 206 has a width approximately the same as the width of the first opening 92 and has a recess 91 extending in the X direction. The housing 206 also has a through hole 90 that is directly or indirectly connected to the supply channel 61b of the individual channel board 6. Furthermore, although not shown, the housing 206 also has a through hole on the opposite side in the X direction that is directly or indirectly connected to the recovery channel 68b of the individual channel board 6.

[0071] Furthermore, the head chip HCb has a pressure chamber substrate 202, a diaphragm 203, a piezoelectric element 204, and a sealing plate 205 on the individual channel substrate 6 side of the channel substrate 201. The pressure chamber substrate 202 is a substrate extending in the X direction and has openings (pressure chambers) 95 partitioned for each nozzle N. The diaphragm 203 is an elastically vibrable flat plate extending in the X direction. The piezoelectric element 204 is a driving element formed for each nozzle N, with a piezoelectric layer interposed between mutually opposing electrode layers. The piezoelectric element 204 is electrically connected to the circuit board 3b described above. The sealing plate 205 is a member for sealing each piezoelectric element 204 and is a plate-shaped member having recesses for sealing the piezoelectric elements 204.

[0072] Furthermore, the head chip HCb has a nozzle plate 220 extending in the X direction on the side of the flow channel substrate 201 opposite to the individual flow channel substrate 6. The nozzle plate 220 has a plurality of nozzles N, which are arranged in a line in the X direction. The diameter of each nozzle N is not particularly limited, but it is preferable that it is larger than the opening of the filter portions 45a and 45b of the common flow channel substrate 4 described above. On the other hand, from the viewpoint of enabling precise image formation, it is preferable that it is 28 μm or less.

[0073] Furthermore, the head chip HCb has an elastic member 211 and a support plate 212 extending in the X direction on the side of the flow channel substrate 201 opposite to the individual flow channel substrate 6. The elastic member 211 is a flexible member formed in a film shape and is positioned opposite the diaphragm 203 described above. The elastic member 211 is supported by the support plate 212 so that it bends toward the flow channel substrate 201, approaching the constricted portion 99 and closing the space between the first opening 92 and the second opening 93. Alternatively, it is supported by the support plate 212 so that it bends toward the fixed plate 8, opening the space between the first opening 92 and the second opening 93. On the other hand, the support plate 212 is a plate-shaped member having an opening (damper chamber) 213 extending in the X direction. This opening 213 is in communication with the atmosphere. The gap between the support plate 212 and the fixed plate 8 and the nozzle plate 220 is filled with a filler material 230.

[0074] In the HCb head chip, the space formed by the recess 91 in the housing 206 and the first opening 92 in the flow path substrate 201 functions as a common liquid chamber (reservoir) that stores ink supplied from the individual flow path substrate 6. From this common liquid chamber, ink is sent to each nozzle N via a flow path formed by the throttling section 99 and the second opening 93, and the ink is stored in the opening (pressure chamber) 95 of the pressure chamber substrate 292. When a driving voltage is applied to the piezoelectric element 204, the diaphragm 203 vibrates, causing the volume of the opening (pressure chamber) 95 to expand or contract. This creates pressure inside the opening (pressure chamber) 95, and the ink is ejected from the nozzle N through the third opening 94. In the HCb head chip, the elastic member 211 deforms in accordance with the pressure of the ink in the common liquid chamber (reservoir), thereby absorbing pressure fluctuations in the common liquid chamber (reservoir) and suppressing pressure fluctuations in the pressure chamber 95. Furthermore, pressure fluctuations (crosstalk) caused by the pressure generated in the pressure chamber 95 when a driving voltage is applied to the piezoelectric element 204, via the common liquid chamber (reservoir), to the pressure chambers of adjacent nozzles can also be suppressed. In this case, the elastic member 211 bends toward the flow channel substrate 201, and as the cross-sectional area of ​​the throttling portion 99 narrows, the pressure loss increases. By combining the head chip HCb having a throttling portion with the common flow channel substrate 4 which has low pressure loss, the overall pressure loss of the inkjet head 10 can be reduced. The ink not used by the head chip HCb is recovered through through holes (not shown) in the housing 206, via the recovery channel 68b of the individual flow channel substrate 6b, the recovery channel 47b of the common flow channel substrate 4, the recovery tube 49b, etc., to the ink supply unit 140 of the inkjet printing apparatus 100.

[0075] [Differentiation] In the above description, the inkjet head 10 has two head chips HCa and HCb, and the common channel substrate 4 includes two layers of filter members L3 and L6 corresponding to these head chips HCa and HCb. However, the inkjet head of the present invention is not limited to this structure. For example, the inkjet head may have three or more head chips. In this case, the common substrate 4 may have three or more individual filter sections for each head chip, and the filter sections corresponding to each head chip may be arranged on different layers of the common channel substrate. That is, the common channel substrate may include three or more layers of filter members.

[0076] Furthermore, the above description described an embodiment in which the single-layer filter members L3 and L6 of the common flow channel substrate 4 each have one filter section 45a and 45b. However, a single-layer filter member may have multiple filter sections.

[0077] Furthermore, the above explanation described the case where only one row of nozzles is arranged on a single head chip. However, a single head chip may have two or more rows of nozzles. In that case, the individual channel substrates and the common channel substrate may have supply channels and recovery channels for each respective row of nozzles, and the common channel substrate may include filter sections corresponding to each row of nozzles. The filter sections corresponding to each row of nozzles may be arranged on the same layer of the common channel substrate, but from the viewpoint of ensuring sufficient area for the filter sections, it is preferable that they be arranged on different layers.

[0078] (effect) In the inkjet head of this embodiment, the common flow channel substrate includes two or more layers of filter-equipped members, including a filter section. Therefore, the area of ​​each filter section can be increased and freely designed, making it difficult to cause pressure loss in the filter section. Furthermore, the lifespan of each filter section can be extended. Generally, in inkjet heads with small nozzle diameters, the opening diameter of the filter for filtering the ink must be reduced to match the nozzle diameter, which makes it easy for pressure loss to occur due to the filter. In contrast, in the inkjet head of this embodiment, as described above, the area of ​​each filter section can be increased, so pressure loss due to the filter is less likely to occur even when the nozzle diameter (filter opening diameter) is small. Furthermore, it is possible to suppress pressure loss even when using ink with high viscosity during ejection (for example, a viscosity of 12 mPa·s or more as measured by a rotational viscometer, rheometer, or vibrating viscometer). [Industrial applicability]

[0079] According to the present invention, an inkjet head with a long lifespan and reduced pressure loss due to the filter is provided, as well as an inkjet printing apparatus using the same. Therefore, it is extremely useful in various printing fields, for example. [Explanation of Symbols]

[0080] HCa, HCb head tip L1~L7 Layered flow channel members 10 inkjet heads 1 cabinet 2 Drive control member 3a, 3b circuit board 4 Common channel board 5 holders 6 Individual channel board 7 Reinforcement plate 8 Fixed plate 11, 53, 71 openings 12, 51, 52, 81, 90 through holes 41 Supply tube 42a, 42b Inlet Ports 43a, 43b filter unit 44a, 44b Supply channel 45a, 45b filter section 46a, 46b recess 47a, 47b Recovery channel 48a, 48b Outlet Ports 49a, 49b Recovery tubes 91 Recess 92 First opening 93 Second opening 94 Third opening 95 Opening (pressure chamber) 99 Aperture section 100 inkjet printing devices 110 Conveying section 111 Conveyor belt 111a Conveying surface 112 Drive rollers 113 Driven roller 120 Supply section 121 Supply and Loading Section 122 Supply and transport section 130 Discharge section 131 Discharge and Loading Section 132 Discharge and Conveying Section 140 Ink supply unit 141, 142 Ink supply mechanism 150 Drawing section 160 Reading section 201 Flow channel substrate 202 Pressure chamber substrate 203 Diaphragm 204 Piezoelectric element 205 Sealing plate 206 cabinets 211 Elastic members 212 Support plate 213 Opening (Damper Room) 230 Filling material 441a, 441b Recess (channel) 442a, 442b opening

Claims

1. Multiple head chips, A plurality of individual channel boards corresponding to each of the head chips and for supplying ink to each of the head chips, A common channel board for supplying ink to each of the individual channel boards, It is an inkjet head having, The common channel substrate has a structure in which multiple layered channel members are stacked, Of the multiple layered flow channel members, at least two layers are filter members including a filter section. The common channel substrate includes an individual filter section for each head chip. The number of head chips corresponding to the layered flow channel member, which is the filter member, is less than the number of the plurality of head chips. Inkjet head.

2. The material of the filter media in the filter section of the multiple filter-equipped members is the same as that of the others. The inkjet head according to claim 1.

3. The material of the aforementioned filter media is metal. The inkjet head according to claim 2.

4. In each of the filter sections, the filter material is plain weave, twill weave, plain woven, or twill woven. The inkjet head according to claim 2.

5. When the common flow path substrate is viewed from above, the multiple filter members are arranged such that at least a portion of the multiple filter sections overlap. The inkjet head according to claim 1.

6. Each of the filter sections corresponding to the head chip is arranged on a different layer of the common flow path substrate. The inkjet head according to claim 1.

7. Each of the head tips includes two or more rows of nozzles, The common flow channel substrate includes an individual filter section for each of the nozzle rows. The inkjet head according to claim 1.

8. Each of the filter sections corresponding to the nozzle row is arranged on a different layer of the common flow path substrate. The inkjet head according to claim 7.

9. The aforementioned common channel substrate, The aforementioned filter-equipped member, An upstream channel member is positioned upstream of the filter-equipped member and has an introduction section for introducing ink into the filter section, A downstream channel member is provided, which is located downstream of the filter-equipped member and has a discharge section for discharging the ink filtered by the filter section. A filter unit including The inkjet head according to claim 1.

10. The aforementioned common channel substrate, It has a recovery channel for recovering some of the ink, The upstream channel member has a channel that communicates with the introduction section and the recovery channel. The inkjet head according to claim 9.

11. The diameter of the nozzle of each head tip is 28 μm or less. The inkjet head according to claim 1.

12. Each of the head chips Piezoelectric element and A diaphragm that operates by applying a drive signal to the piezoelectric element, A pressure chamber whose volume expands or contracts due to the movement of the diaphragm, A flow path for supplying ink to the pressure chamber, An elastic member facing the aforementioned flow path and positioned opposite the aforementioned diaphragm, It has, The aforementioned flow path has a constricted section in which the cross-sectional area narrows in the direction from which the ink is discharged. The elastic member is arranged in the constricted portion. The inkjet head according to claim 1.

13. The viscosity of the ink used at the time of ejection is 12 mPa·s or higher. The inkjet head according to claim 1.

14. The filter-equipped member has a locking structure that allows it to be attached to and detached from other layered flow channel members. The inkjet head according to claim 1.

15. The inkjet head according to claim 1, An ink supply unit that supplies ink to the inkjet head, A head drive unit for operating the inkjet head, A transport unit that transports the recording medium, Equipped with, Inkjet printing device.

16. The ink supply unit supplies ink with a viscosity of 12 mPa·s or more to the inkjet head. The inkjet printing apparatus according to claim 15.

17. The ink is circulated between the ink supply unit and the inkjet head while forming an image. The inkjet printing apparatus according to claim 15.

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