Liquid ejection head and liquid ejection device

Abstract

To provide a liquid ejection head that can make maintaining and improvement of the quality of ejection of liquid ink and improvement of the production efficiency thereof compatible each other.SOLUTION: A liquid ejection head is provided, comprising: an ejection unit that ejects liquid; an intermediate liquid chamber portion composing a part of a flow passage for the liquid to the ejection unit; and a head tank portion having a plurality of head tanks composing a part of a flow passage for the liquid to the intermediate chamber portion. The intermediate liquid chamber portion has: a first communicating portion communicating with a first head tank of the plurality of head tanks; a second communicating portion communicating with a second head tank of the plurality of head tanks; and a flow passage space composing a circulation flow passage which causes a liquid flowing in from the first head tank via the first communicating portion to flow out to the second head tank via the second communicating portion. In the liquid ejection head, a diameter of an imaginary circle in a position coaxial with the first communicating portion or second communicating portion, which is an imaginary position in the flow passage space, is equal to or less than a diameter of the first communicating portion or second communicating portion.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head and a liquid ejection apparatus that ejects liquid. [Background technology]

[0002] 2. Description of the Related Art There is known a liquid ejection device that includes a liquid ejection head for ejecting liquid and ejects liquid onto a recording medium based on an image formation instruction from an information processing device, etc. Such a device is called an inkjet printer, for example.

[0003] Inkjet printers with various configurations are known, and in recent years, printers that form (print) images directly on fabrics such as clothing have become known. These printers are called "DTG (Direct To Garment) printers." One example of a DTG printer is known to have a head tank that holds liquid ink above the ejection nozzles, and a pump is used to send and circulate the liquid ink from the ink cartridge to the head tank, supplying the liquid to the ejection nozzles (see Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] The liquid ink used in DTG printers has different properties from that used on regular paper, and its color components tend to settle out easily. Liquid ink whose color components tend to settle out easily tends to settle out and accumulate in, for example, the head tank or in an intermediate liquid chamber located between the head tank and the ejection head. The settling and accumulation of color components reduces the fluidity of the liquid ink and can also cause a decrease in the ejection performance from the ejection nozzles. Therefore, when using liquid ink whose color components tend to settle out easily, a configuration is required that controls the operation to flow the liquid ink at regular intervals and agitate the color components.

[0005] To stir and fluidize the color components, a discharge operation can be performed by discharging liquid ink from the discharge nozzles at regular intervals. However, this discharge operation is not related to the image formation operation and therefore only consumes liquid ink and does not contribute to productivity. While this operation is necessary to stir the color components and maintain discharge performance, it reduces the number of images that can be formed with the liquid ink stored in a single ink cartridge. Therefore, while it is desirable to minimize the frequency and amount of this operation, failing to perform it with an appropriate frequency and amount will result in a decrease in image quality. In other words, in conventional technology, when performing image formation processes using liquid ink that is prone to settling, there is a trade-off between maintaining and improving discharge quality and improving production efficiency, and achieving both is challenging.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid ejection head that maintains and improves the ejection quality of liquid ink while also improving production efficiency, and a liquid ejection apparatus that includes the liquid ejection head. [Means for solving the problem]

[0007] In order to solve the above technical problems, one aspect of the present invention is a liquid ejection head that ejects liquid onto a medium, comprising: a first head tank for storing the liquid; a first intermediate liquid chamber for storing the liquid flowing out from the first head tank; a second intermediate liquid chamber for storing the liquid flowing out from the first intermediate liquid chamber; a second head tank for storing the liquid flowing out from the second intermediate liquid chamber; a first communication part for communicating the first head tank with the first intermediate liquid chamber; a second communication part for communicating the second head tank with the second intermediate liquid chamber; a discharge unit that discharges the liquid; an intermediate through-portion formed by penetrating a partition wall that separates the first intermediate liquid chamber and the second intermediate liquid chamber; Equipped with the first intermediate liquid chamber includes a portion in a flow path extending from the first communicating portion to the intermediate through portion that is formed narrower than the flow path in the first communicating portion, and the second intermediate liquid chamber includes a portion in a flow path extending from the second communicating portion to the intermediate through portion that is formed narrower than the flow path in the second communicating portion. It is characterized by: [Effects of the Invention]

[0008] According to the present invention, it is possible to maintain and improve the ejection quality of liquid ink while also improving production efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic plan view showing the main parts of the internal structure of the liquid ejection device according to the present invention. [Figure 2] FIG. 2 is a block diagram showing the configuration of a control block of the liquid ejection head according to the embodiment. [Figure 3]FIG. 1 is a schematic diagram illustrating the configuration of a liquid ejection head according to an embodiment of the present invention. [Figure 4] FIG. 2 is a configuration diagram illustrating the main parts of the liquid ejection head according to the embodiment. [Figure 5] FIG. 10 is a configuration diagram illustrating a main part of a liquid ejection head according to another embodiment. [Figure 6] FIG. 10 is a structural view illustrating a main part of a liquid ejection head according to yet another embodiment. [Figure 7] FIG. 10 is a structural view illustrating a main part of a liquid ejection head according to yet another embodiment. [Figure 8] FIG. 10 is a structural view illustrating a main part of a liquid ejection head according to yet another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a liquid ejection unit 1 as an embodiment of a liquid ejection device according to the present invention, and an ejection head 100 as an embodiment of a liquid ejection head according to the present invention will be described with reference to the drawings.

[0011] 1 is a schematic plan view showing the main parts of a liquid ejection unit 1 according to this embodiment. In the liquid ejection unit 1, a platen member 300 is arranged at a position corresponding to the top surface of a cassette 200. This cassette 200 is held so as to be movable in the direction of arrow A (feed direction, sub-scanning direction) relative to an apparatus main body including the liquid ejection unit 1. Movable guide members 106L and 106R are arranged along the direction of arrow A as members for holding a stage that holds the cassette 200 so as to be movable in the sub-scanning direction.

[0012] The ejection head 100, which functions as an image forming unit, is held by a carriage 102. The carriage 102 is held so as to move in the direction of arrow B (main scanning direction) relative to a platen member 300. The carriage 102 is movably held by a carriage guide member 109 arranged along the direction of arrow B. The carriage 102 is moved back and forth along the carriage guide member 109 by a main scanning motor 139, which will be described later. The ejection head 100 operates to eject a predetermined amount of liquid ink droplets at predetermined timing while being moved in the main scanning direction by the carriage 102.

[0013] In the liquid ejection unit 1, a fabric medium is set on the platen member 300 of the cassette 200, and the cassette 200 is then attached to a stage that is movably held by the movable guide members 106L and 106R inside the liquid ejection device main body. Then, by repeatedly moving the stage in the direction of arrow A and reciprocating the ejection head 100 in the direction of arrow B, a predetermined amount of liquid ink is ejected onto a predetermined position on the fabric held on the platen member 300, thereby printing a desired image.

[0014] The platen member 300 is detachable from the cassette 200 and is replaceable. This allows multiple platen members 300 to be prepared, and clothing can be wrapped around another platen member 300 during printing operations. After printing and fixing are complete, printing on the next fabric can be started quickly by simply replacing the platen member 300.

[0015] When placing the fabric in the cassette 200, the outer cover of the platen member 300 is opened and the fabric is set (held) on the platen member 300. At this time, the excess part of the fabric (surplus part) can be accommodated in the internal space of the cassette 200.

[0016] When an image is to be formed on the fabric, the cassette 200 is mounted (set) on the stage of the liquid ejection device main body.

[0017] In this way, the fabric to be printed can be set on the platen member 300 with the cassette 200 removed entirely from the liquid ejection device body, making it easy to set the fabric on the platen member 300.

[0018] Figure 1 As shown in Fig. 1, a maintenance and recovery mechanism 104 for maintaining the state of the ejection head 100 in a state suitable for image formation operation is disposed at one end in the main scanning direction, outside the cassette 200. In addition, at the end opposite the maintenance and recovery mechanism 104 in the main scanning direction, a blank ejection receiver 105 for collecting liquid ejected when a "blank ejection operation" is performed to prevent liquid from clogging the nozzle openings 31 is disposed.

[0019] [Outline of control block] Next, the configuration of the control block of the liquid ejection unit 1 according to this embodiment will be described with reference to Fig. 2. As shown in Fig. 2, the control unit 130 of the liquid ejection unit 1 includes a CPU 131, a ROM 132, a RAM 133, an NVRAM 134, and an ASIC 135.

[0020] The CPU 131 is connected to an operation panel 101 for inputting and displaying information required for the liquid ejection unit 1, and is responsible for overall control of the liquid ejection unit 1. The CPU 131 also has the function of controlling the transport operation (movement in the sub-scanning direction) of the platen member 300, the movement operation of the carriage 102 in the main scanning direction, and the liquid ejection operation by the ejection head 100.

[0021] The ROM 132 is a non-volatile storage medium that stores programs and other fixed data to be executed by the CPU 131. The programs stored in the ROM 132 are executed by the arithmetic processing function of the CPU 131, thereby forming a program control unit, which will be described later.

[0022] The RAM 133 temporarily stores image data used in the image forming process, etc. The RAM 133 also functions as a work area when the program control unit is executed.

[0023] The NVRAM 134 is a rewritable non-volatile storage medium for retaining data even while the power supply to the liquid ejection unit 1 is cut off.

[0024] The ASIC 135 processes various types of signal processing for image data, image processing such as sorting, and input / output signals for controlling the entire device.

[0025] The control unit 130 also includes a host interface (I / F) 143 , a print control unit 137 , a main scanning motor drive unit 138 , a sub scanning motor drive unit 140 , and an input / output (I / O) unit 136 .

[0026] The host I / F 143 plays a role in transmitting and receiving data and control signals to and from the host side such as a printer driver 501 included in the external device 500 .

[0027] The print control unit 137 generates a drive waveform for driving the ejection head 100 , and outputs image data for selectively driving the pressure generating means of the ejection head 100 and various data associated therewith to the head driver 144 .

[0028] The main scanning motor drive unit 138 drives the main scanning motor 139 .

[0029] The sub-scanning motor driving unit 140 drives a sub-scanning motor 141 that moves the cassette 200 in the sub-scanning direction.

[0030] The I / O section 136 receives detection signals from various sensors required for the operation of the liquid ejection unit 1.

[0031] The control unit 130 receives print data and other data used in image formation processing from a printer driver 501 included in an external device 500 via a cable or network via the host I / F 143. The print data is generated by the printer driver 501 included in the external device 500, which may be an information processing device such as a personal computer (PC). In the control unit 130, which receives print data as an image formation instruction, the CPU 131 reads and analyzes the print data from a receive buffer included in the host I / F 143. Furthermore, based on the analysis results, the ASIC 135 performs necessary image processing, data rearrangement, and the like, and transfers the data to the print control unit 137. The print control unit 137 then outputs image data and drive waveforms to the head driver 144 at the required timing. Note that dot pattern data for image output may be generated by storing font data in the ROM 132, for example, or by having the host-side printer driver 501 convert image data into bitmap data and transfer it to the device. Here, it is assumed that this is performed by the printer driver 501, for example.

[0032] The drive waveform generation unit of the print control unit 137 is composed of a D / A converter that performs D / A conversion on drive pulse pattern data stored in the ROM 132 and read out by the CPU 131, an amplifier, etc. Then, it outputs a drive waveform composed of one drive pulse or multiple drive pulses to the head driver 144. The head driver 144 drives the ejection head 100 based on image data (dot pattern data) corresponding to one line of the ejection head 100 that is input serially. To achieve this, the head driver 144 selectively applies drive pulses that make up the drive waveform provided by the drive waveform generation unit of the print control unit 137 to the pressure generation means of the ejection head 100. Therefore, the CPU 131 and the print control unit 137 constitute an image formation processing unit.

[0033] The head driver 144 includes, for example, a shift register that inputs serial data such as a clock signal and image data, and a latch circuit that latches the register value of the shift register with a latch signal. It also includes a level conversion circuit (level shifter) that changes the level of the output value of the latch circuit, and an analog switch array (switch means) whose on / off is controlled by this level shifter. Functionally, one example is when a required drive pulse included in the drive waveform is selectively applied to the pressure generating means of the ejection head 100 by controlling the on / off of the analog switch array.

[0034] Furthermore, the control unit 130 controls the operation of a supply pump 52 (described later) to circulate the liquid ink in the ejection head 100 .

[0035] [First embodiment of liquid ejection head] Next, the configuration of the ejection head 100 according to this embodiment will be described, along with the circulation operation of the liquid ink performed in the ejection head 100. Fig. 3 is a schematic diagram of the ejection head 100. Fig. 4 is a plan view illustrating the features of the head unit 110.

[0036] 3, the ejection head 100 includes a head unit 110, an ink cartridge 51 serving as a liquid storage unit that stores liquid ink to be supplied to the head unit 110, and a supply pump 52 for sending the liquid ink from the ink cartridge 51 to the head unit 110. The ink cartridge 51 and the head unit 110 are in communication with each other via a supply tube 53.

[0037] The supply tube 53 has two paths that communicate from the ink cartridge 51 to the head unit 110, and one path that branches into the two paths communicates with the ink cartridge 51. A first check valve 55 and a second check valve 56 are disposed in each of the two paths. A filter 54 is also disposed midway along the supply tube 53.

[0038] The supply pump 52 corresponds to the power source in the circulation mechanism of the liquid ink in each embodiment described below.

[0039] [Configuration of head unit 110] As shown in Figure 4, the head section 110 includes a head tank section 10 that stores liquid ink, an intermediate liquid chamber section 20 that stores the liquid ink flowing in from the head tank section 10 and supplies it to the common liquid chamber section 30, and a common liquid chamber section 30 that ejects the liquid ink flowing in from the intermediate liquid chamber section 20 toward a medium.

[0040] The head tank unit 10 includes multiple head tanks (a first head tank 11 and a second head tank 12). The first head tank 11 and the second head tank 12 have similar shapes and independently form spaces for storing liquid ink. In this embodiment, the first head tank 11 is disposed upstream in the circulation direction when circulating the liquid ink, and the second head tank 12 is disposed downstream.

[0041] The middle liquid chamber section 20 is disposed at a lower position relative to the head tank section 10, and is provided with a plurality of middle liquid chambers (first middle liquid chamber 21 and second middle liquid chamber 22) corresponding to each head tank. The first head tank 11 and the first middle liquid chamber 21 are in communication with each other, and a first communication section 41 is disposed at this communication section. The second head tank 12 and the second middle liquid chamber 22 are in communication with each other, and a second communication section 42 is formed at this communication section. The first communication section 41 and the second communication section 42 form the joint section between the head tank section 10 and the middle liquid chamber section 20.

[0042] A space capable of storing liquid ink is formed in the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22. The shapes of these spaces are the same. An intermediate through-portion 43 is formed between the liquid ink storage space provided in the first intermediate liquid chamber 21 and the liquid ink storage space provided in the second intermediate liquid chamber 22. The intermediate through-portion 43 is also a hole formed by penetrating the partition wall that separates the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22. Liquid flows between the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 through this intermediate through-portion 43.

[0043] The common liquid chamber 30 is disposed below the intermediate liquid chamber 20 and includes a plurality of nozzle openings 31 for ejecting liquid ink as droplets. The nozzle openings 31 are arranged in a plane toward the ejection destination. array Therefore, the ejection head 100 has a nozzle surface that is made up of a plurality of nozzle openings 31.

[0044] Liquid ink flows from the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 into the common liquid chamber 30 through a common through portion 44 formed in the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22. As shown in FIG. 4(c), the common through portion 44 is formed near the center of the intermediate liquid chamber 20 in the path (flow path) through which the liquid ink flows, near the intermediate through portion 43.

[0045] [Operation flow of the ejection head 100] Next, a description will be given of an example of the operation of the ejection head 100. The dotted arrow L shown in Fig. 4 illustrates the flow direction of the liquid ink when it is circulated.

[0046] When the control unit 130 starts the image forming operation, the print control unit 137 controls the operation of the head driver 144, and liquid ink is ejected from the nozzle openings 31. The ejection of liquid ink from the nozzle openings 31 is due to pressure generated by pressure generating means provided in the common liquid chamber unit 30, which serves as an ejection unit. When the liquid ink is ejected, liquid ink flows from the two intermediate liquid chambers (the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22) into the common liquid chamber unit 30, preparing for the subsequent ejection operation. The flow path for the liquid ink from this intermediate liquid chamber unit 20 to the common liquid chamber unit 30 is the common through portion 44.

[0047] When the supply pump 52 is rotated forward to supply liquid ink to be ejected from the nozzle opening 31 of the common liquid chamber 30 during image formation, the liquid ink delivered from the ink cartridge 51 flows into the first head tank 11 through the supply tube 53. At this time, foreign matter in the liquid ink is removed by passing through a filter 54 disposed along the way.

[0048] A first check valve 55 disposed in the supply tube 53 allows the flow of liquid ink from the ink cartridge 51 to the first head tank 11 and blocks the flow in the opposite direction. A second check valve 56 also disposed in the supply tube 53 blocks the flow of liquid ink from the ink cartridge 51 to the second head tank 12 and allows the circulating outflow from the second head tank 12.

[0049] The supply tube 53 branches into a tube connected to the first head tank 11 and a tube connected to the second head tank 12, and constitutes a circulation flow path for liquid ink in each flow path.

[0050] When liquid ink flows into the first head tank 11 through the supply tube 53, that flow causes the liquid ink to flow from the first head tank 11 into the first intermediate liquid chamber 21 through the first communicating portion 41. The liquid ink that has flowed into the first intermediate liquid chamber 21 passes through the intermediate through portion 43 and flows into the second intermediate liquid chamber 22. The liquid ink that has flowed into the second intermediate liquid chamber 22 flows from the second intermediate liquid chamber 22 into the second head tank 12, and then flows into the supply tube 53.

[0051] The liquid ink that flows into the supply tube 53 from the second head tank 12 passes through the second check valve 56 and flows toward the ink cartridge 51. At this time, because the supply pump 52 continues to pump liquid ink from the ink cartridge 51, the liquid ink does not return to the ink cartridge 51 but flows toward the first check valve 55. It then flows into the first head tank 11. In this way, the liquid ink is configured to circulate inside the ejection head 100 while the supply pump 52 is rotating in the forward direction.

[0052] In this way, in the flow of liquid ink according to this embodiment, the first head tank 11 is located upstream in the flow direction of the liquid ink, and the second head tank 12 is located downstream in the flow direction of the liquid ink.

[0053] The speed at which the liquid ink circulates in the ejection head 100 varies depending on the operation of the ejection head 100. In the case of sedimentary ink, in which color components are prone to settling, if the frequency of flow of the liquid ink decreases or the flow speed slows, the color components will stagnate in the circulation flow path. To prevent this, the effectiveness of the stirring operation can be improved by increasing the fluidity of the liquid ink (increasing the flow speed) in the circulation flow path that circulates the liquid ink. Therefore, the ejection head 100 according to this embodiment is provided with a shape and the like for locally increasing the flow speed of the liquid in the circulation flow path, as described below.

[0054] [Agitation Operation in Discharge Head 100] The stirring operation performed in the ejection head 100 will now be described. First, the supply pump 52 is reversed. This causes the liquid ink stored in the second head tank 12 to flow out to the supply tube 53, pass through the second check valve 56, and return to the ink cartridge 51. By emptying the second head tank 12, the damping effect of the liquid can be suppressed, improving circulation performance. This improves the ability to stir any accumulated color components with the circulating liquid.

[0055] As a result, liquid ink flows from the ink cartridge 51 into the first head tank 11 through the supply tube 53, and then flows into the empty second head tank 12. At this time, the liquid ink flows from the first communicating portion 41 to the first intermediate liquid chamber 21, passes through the intermediate through portion 43, and flows from the second intermediate liquid chamber 22 to the second communicating portion 42 and into the second head tank 12. This operation continues until the second head tank 12 is filled.

[0056] As described above, by circulating the liquid ink, it is possible to agitate the settled color components, and the quality of the ink ejected from the nozzle openings 31 can be improved.

[0057] The stirring operation may be performed at predetermined intervals. For example, in the case of liquid ink in which color components tend to settle, the stirring operation may be performed every few hours. Alternatively, the stirring operation may be performed as part of the initial operation when the device main body is started up, before the ejection head 100 is operated.

[0058] The stirring operation of this embodiment can stir the liquid ink without performing unnecessary ejection operations, thereby preventing a reduction in the amount of image that can be formed from one ink cartridge 51 and increasing the so-called "yield."

[0059] [Configuration to improve the fluidity of liquid ink] Next, a configuration for locally increasing the flow rate within the circulation flow path when the liquid ink is caused to flow during the above-mentioned stirring operation will be described with reference to FIG.

[0060] Fig. 4(b) is a cross-sectional view taken along line AA, and Fig. 4(c) is a cross-sectional view taken along line A'-A'.

[0061] As shown in FIG. 4(b), the first communication portion 41 and the second communication portion 42 are located on the bottom surface of the head tank unit 10. As shown in FIG. 4(c), imaginary circles coaxial with the first communication portion 41 and the second communication portion 42 are indicated by dashed circles R1 and R2. These dashed circles R1 and R2 exemplify imaginary positions within the flow path space. The internal spaces (flow path spaces) of the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 are formed so that the diameter of these imaginary positions is equal to or smaller than the diameters of the first communication portion 41 and the second communication portion 42. That is, the first intermediate liquid chamber 21 is formed so that the flow path cross-sectional area of ​​the first intermediate liquid chamber 21 downstream of the first communication portion 41 in the path through which liquid ink flows from the first head tank 11 to the first intermediate liquid chamber 21 is equal to or smaller than the flow path cross-sectional area of ​​the first communication portion 41.

[0062] Similarly, in the second intermediate liquid chamber 22, when the second communication portion 42, which is the portion communicating with the second head tank 12, is compared with a portion of the internal space of the second intermediate liquid chamber 22 that is coaxial with the second communication portion 42, the diameter of the coaxial portion is formed to be equal to or smaller than the diameter of the second communication portion 42. In other words, the second intermediate liquid chamber 22 is formed so that, in the path along which the liquid ink flows from the second head tank 12 to the second intermediate liquid chamber 22, the flow path cross-sectional area within the second intermediate liquid chamber 22 upstream of the second communication portion 42 is equal to or smaller than the flow path cross-sectional area of ​​the second communication portion 42. With this shape, when the liquid ink is ejected from the nozzle port 31, the flow velocity of the liquid ink flowing from the second intermediate liquid chamber 22 to the common liquid chamber portion 30 can be locally increased, thereby improving stirring efficiency.

[0063] The cross-sectional area of ​​the flow path of the intermediate through-hole 43 that penetrates the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 is 1 / 2 mm from the first communicating portion 41 to the common through-hole 43 that is the flow path when the liquid ink flows to the nozzle opening 31 that is the common liquid chamber portion 30. 44 In other words, the cross-sectional area of ​​the flow path from the first intermediate liquid chamber 21 to the common through-hole portion 22 is equal to or less than the cross-sectional area of ​​the flow path from the first intermediate liquid chamber 21 to the common through-hole portion 22. 44 The flow rate of the liquid ink in the intermediate through-portion 43 is configured to be faster than the flow rate of the liquid ink toward the intermediate through-portion 43.

[0064] In the circulation flow path provided in the ejection head 100, the flow path cross-sectional area of ​​the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 is made narrower than the flow path cross-sectional area of ​​the connection portion between the first head tank 11 and the first intermediate liquid chamber 21 and the flow path cross-sectional area of ​​the connection portion between the second head tank 12 and the second intermediate liquid chamber 22. In this case, the shape of the flow path may be a shape that gradually narrows from the upstream side to the downstream side in the flow direction of the liquid ink, or a shape that sharply narrows at a specific position.

[0065] Regardless of the shape, by using a shape that increases the momentum of the liquid ink flowing in the ejection head 100, it is possible to increase the force that washes away and stirs the color components that accumulate in the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 when the liquid ink is circulating. In other words, the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 are provided with shapes that improve stirring performance.

[0066] In addition, the cross-sectional area of ​​the flow path at the intermediate through-portion 43 is made the narrowest in the circulation flow path of the liquid ink. 44 The flow path leading to the first intermediate liquid chamber 21 is formed narrower than the flow paths in the first communicating portion 41 and the second communicating portion 42. The intermediate through portion 43 is formed narrower than the narrowest portion of the flow paths formed in the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22. In other words, the intermediate through portion 43 is made the narrowest portion in terms of flow path cross-sectional area in the intermediate liquid chamber portion 20. This makes it possible to increase the momentum of the liquid flowing from the first intermediate liquid chamber 21 to the second intermediate liquid chamber 22 during the circulation operation of the liquid ink. Therefore, by configuring the circulation flow path to be locally narrow, it is possible to more efficiently flush out the color components that have accumulated in the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22.

[0067] It is desirable that the flow path cross-sectional area of ​​the intermediate through portion 43 be narrower than the flow path cross-sectional areas of other locations in the liquid ink circulation flow path, so for example, the width of the intermediate through portion 43 may be narrower or the height may be lower than the width of the first intermediate liquid chamber 21 or the second intermediate liquid chamber 22. Regardless of which dimension is narrowed, by making the flow path cross-sectional area of ​​the intermediate through portion 43 the narrowest in the liquid ink circulation flow path, the flow rate of the circulating liquid ink increases when it passes through the intermediate through portion 43. This allows the color components that accumulate in the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 to be moved and circulated by flow, improving the agitation force.

[0068] The vertical cross-sectional shapes of the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 are shown in FIG. (a) As shown in Fig. 1, it is desirable that the bottom surfaces of the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 are inclined downwards toward the common through portion 44, which serves as a liquid flow path to the common liquid chamber 30. In particular, the bottom surfaces of the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22 are inclined downwards toward the common through portion 44, which is in the direction of flow of the liquid ink. This increases the fluidity of the color components contained in the liquid ink, and further improves the degree of agitation of color components that tend to settle. In other words, the circulation performance of the liquid ink can be improved.

[0069] 8, the common through portion 44 provided in the intermediate liquid chamber portion 20 is formed near the intermediate through portion 43, which serves as a narrow portion, in the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22. That is, the common through portion 44 is disposed at a position included in the circulation flow path of the liquid ink. In other words, the common through portion 44 is formed near the end of the intermediate through portion 43, which connects the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22.

[0070] By forming the intermediate through portion 43 and the common through portion 44 in the arrangement exemplified above, it is possible to prevent the position of the common through portion 44 from becoming a blind spot in the flow path of the liquid ink flowing between the first intermediate liquid chamber 21 and the second intermediate liquid chamber 22, thereby improving the circulatory flow of the liquid ink and the ejection performance.

[0071] [Second embodiment of liquid ejection head] Next, another configuration of the head unit 110 provided in the ejection head 100 will be described with reference to Fig. 5. Hereinafter, components similar to those already described will be given the same reference numerals, and detailed description will be omitted. As shown in Fig. 5, the head unit 110a according to this embodiment is characterized by the shape of the head tank portion 10a.

[0072] The first head tank 11a and the second head tank 12a according to this embodiment have a shape that slopes toward the first communicating portion 41 and the second communicating portion 42, respectively, and the lower portion connected to the first communicating portion 41 or the second communicating portion 42 is narrower than the upper portion connected to the supply tube 53. Because the color components settle downward in the first head tank 11a or the second head tank 12a, the sloped shape allows the color components to naturally flow downward in the first head tank 11a or the second head tank 12a. This improves the fluidity of the color components. In particular, this prevents the color components from accumulating at the joints between the first head tank 11a or the second head tank 12a and the first communicating portion 41 or the second communicating portion 42.

[0073] The angle θ1 inside the head tank portion 10a at the joint between the first head tank 11a and the first communication portion 41 may be an acute angle. Similarly, the angle θ2 inside the head tank portion 10a at the joint between the second head tank 12a and the second communication portion 42 may also be an acute angle.

[0074] [Third embodiment of liquid ejection head] Next, another configuration of the head section 110 provided in the ejection head 100 will be described with reference to Fig. 6. Hereinafter, components similar to those already described will be given the same reference numerals, and detailed description will be omitted. As shown in Fig. 6, the head section 110b according to this embodiment is characterized by the configuration of the head tank section 10b and the middle liquid chamber section 20a.

[0075] In the ejection head 100b, a supply tube 53a serving as a first supply tube is connected to a head tank portion 10b serving as a head tank that integrates the first head tank 11 and the second head tank 12 according to the first embodiment. Liquid flows into the head tank portion 10b via the supply tube 53a.

[0076] In addition, in the ejection head 100b, a supply tube 53b is connected to the first intermediate liquid chamber 21b as a second supply tube that communicates with the first communication portion 41 and the second communication portion 42 and circulates the liquid that flows in from the head tank portion 10b.

[0077] That is, when the supply pump 52 (see FIG. 3) is rotated in the normal direction to circulate the liquid ink, the ink is drawn from the head tank portion 10b to the first intermediate liquid chamber 21b and the second intermediate liquid chamber 22b The liquid ink that flows into the first intermediate liquid chamber 21b From the supply tube 53b It circulates through.

[0078] As in the ejection head 100 already described, when liquid is sent from the second intermediate liquid chamber 22 to the second head tank 12 as a circulation flow path, there is a concern that the liquid ink stored in the second head tank 12 will act as a damper and impede the momentum of the liquid ink from the second intermediate liquid chamber 22. In this case, there is also a concern that the ink supply flow rate by the supply pump 52 will greatly exceed the recommended value, and the load on the supply pump 52 will be excessive.

[0079] Therefore, as in the case of the head tank portion 10b, the liquid ink is sent from the ink cartridge 51 to the head tank portion 10b via the supply tube 53, and then sent from the head tank portion 10b to the intermediate liquid chamber portion 20b, and then circulated without passing through the head tank portion 10b. Because the liquid ink can be circulated without passing through the head tank portion 10b when it flows from the intermediate liquid chamber portion 20b, the load on the supply pump 52 during ink circulation can be reduced and the life of the supply pump 52 can be extended.

[0080] [Fourth embodiment of liquid ejection head] Next, another configuration of the head unit 110 provided in the ejection head 100 will be described with reference to Fig. 7. Hereinafter, components similar to those already described will be given the same reference numerals, and detailed description will be omitted. As shown in Fig. 7, the head unit 110c according to this embodiment is characterized by the shape of the head tank portion 10c.

[0081] The first head tank 11c and the second head tank 12c according to this embodiment have a shape that tapers toward the first communicating portion 41 and the second communicating portion 42. In other words, the cross-sectional area of ​​the flow path in the direction of liquid flow is tapered so that it changes gradually in the flow direction. That is, in the portion that continues from the upper portion connected to the supply tube 53 to the first communicating portion 41 or the second communicating portion 42, the lower portion is narrower than the upper portion. For example, the wall surface that continues from the upper portion, which is the connecting portion between the first head tank 11c and the supply tube 53, to the first communicating portion 41 has a shape that is widest near the center in the height direction and has a bag-like shape that narrows toward the first communicating portion 41. The second head tank 12c has a similar shape.

[0082] Since the color components settle below the first head tank 11c and the second head tank 12c, by tapering the shape in the direction of the flow of the liquid ink, the color components naturally flow below the first head tank 11c and the second head tank 12c, and retention can be suppressed. This improves the fluidity of the color components. In particular, 11c and second head tank 12c The color components tend to accumulate near the joints between the first communicating portion 41 and the second communicating portion 42. Therefore, it is desirable that the material for the first head tank 11c and the second head tank 12c has a hardness that prevents the areas near the first communicating portion 41 and the second communicating portion 42 from loosening outward due to the mass of the color components that have settled.

[0083] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist thereof. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0084] 1: Liquid discharge unit 10: Head tank section 11: First head tank 20: Intermediate liquid chamber 21:First intermediate liquid chamber 22:Second intermediate liquid chamber 30: Common liquid chamber 31: Nozzle mouth 33: Common penetration part 41:First communication section 42:Second communication part 43: Intermediate penetration 44: Common penetration part 51: Ink cartridge 52: Supply pump 53: Supply tube 54: Filter 55:First check valve 56:Second check valve 100: Discharge head 110: Head 130: Control unit 137: Printing control unit [Prior art documents] [Patent documents]

[0085] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-153183

Claims

1. A liquid ejection head that ejects liquid onto a medium, a first head tank for storing the liquid; a first intermediate liquid chamber that stores the liquid flowing out from the first head tank; a second intermediate liquid chamber that stores the liquid flowing out from the first intermediate liquid chamber; a second head tank that stores the liquid flowing out from the second intermediate liquid chamber; a first communication portion that communicates the first head tank with the first intermediate liquid chamber; a second communication portion that communicates the second head tank with the second intermediate liquid chamber; a discharge portion that discharges the liquid supplied from the first intermediate liquid chamber and the second intermediate liquid chamber; an intermediate through-portion formed by penetrating a partition wall that separates the first intermediate liquid chamber and the second intermediate liquid chamber; Equipped with the first intermediate liquid chamber includes a portion in a flow path extending from the first communicating portion to the intermediate penetrating portion that is formed narrower than a flow path in the first communicating portion, the second intermediate liquid chamber includes a portion in a flow path extending from the second communicating portion to the intermediate penetrating portion that is formed narrower than a flow path in the second communicating portion; A liquid ejection head characterized by:

2. 2. The liquid ejection head according to claim 1, wherein the intermediate through-portion has a cross-sectional area smaller than the cross-sectional areas of the portions included in the first intermediate liquid chamber and the second intermediate liquid chamber.

3. a liquid storage portion that stores the liquid to be supplied to the first head tank; a supply tube connected to the liquid storage portion and the first head tank; a supply pump that supplies the liquid from the liquid storage portion to the first head tank through the supply tube; 3. The liquid ejection head according to claim 1, further comprising:

4. The supply tube a path connected to the first head tank, the path including a first check valve that allows the liquid to flow from the liquid storage portion to the first head tank and blocks the liquid from flowing from the first head tank to the liquid storage portion; a path connected to the second head tank, the path including a second check valve that blocks the flow of the liquid from the liquid storage portion to the second head tank and allows the flow of the liquid from the second head tank to the liquid storage portion; 4. The liquid ejection head according to claim 3.

5. the first head tank and the second head tank have a tapered shape in which a flow path cross-sectional area in a flow direction of the liquid changes gradually in the flow direction; The liquid ejection head according to claim 1 .

6. the first intermediate liquid chamber and the second intermediate liquid chamber have a common through-portion through which the liquid flows into the discharge portion, The common through portion is formed in the vicinity of the intermediate through portion. The liquid ejection head according to claim 1 .

7. the liquid is a sedimentary ink whose components settle out; The liquid ejection head according to claim 1 .

8. the sedimentary ink is a liquid ink containing a white color component; The liquid ejection head according to claim 7 .

9. an image forming processing unit that executes image forming processing to form an image on the medium based on an image forming instruction from an external device; a liquid ejection head according to claim 1 , which ejects the liquid under control of the image forming processing unit; A liquid ejection device comprising:

Images