Liquid ejection head

Abstract

A liquid ejection head is provided that can reduce the circuit scale by sharing a driving pulse when using a first energy generating element and a second energy generating element. [Solution] A liquid ejection head having first and second individual ejection units each having an ejection port, a pressure chamber, a first energy generating element provided in the pressure chamber, an individual flow path communicating with the pressure chamber, and a second energy generating element provided in the individual flow path, and a common flow path for supplying liquid, characterized in that a common drive pulse and the first and second energy generating elements in each ejection unit have a common drive timing, but are controlled differently for each individual ejection unit.

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head. [Background technology]

[0002] Circulation-type liquid ejection devices are known that circulate ink in a liquid ejection head (hereinafter also referred to as the "head") to expel air bubbles from the flow path and prevent ink from thickening near the ejection ports. A well-known method of circulating ink is a method using a pressure difference (hereinafter also referred to as the "differential pressure method"). This method uses a pressure adjustment mechanism or the like to increase the pressure on the side that supplies ink to the ejection ports (the "inside") compared to the side that recovers ink (the "outside"), thereby causing ink to flow from the "inside" to the "outside." To circulate the ink, the ink that has flowed to the "outside" must be returned to the "inside," which requires a pump as a mechanism. Some liquid ejection devices circulate the liquid between the liquid ejection head and the main body by installing a pump outside the head, such as the recording device main body, while others circulate the liquid within the liquid ejection head by installing a pump inside the liquid ejection head. However, such a differential pressure method requires mechanisms such as a pressure adjustment mechanism and a pump, which can lead to an increase in the size of the recording device main body and the head.

[0003] Therefore, ink circulation methods other than the differential pressure method have been investigated. Specifically, a circulation flow path that communicates with the ejection port is provided, and an energy generating element (hereinafter also referred to as a "flow energy generating element") that is separate from the energy generating element for ejecting ink (hereinafter also referred to as an "ejection energy generating element") is arranged in the circulation flow path, and the ink is circulated in the circulation path by driving the flow energy generating element.

[0004] Patent Document 1 discloses a configuration in which a circulation flow path is provided that extends so as to intersect with an array of ejection ports in which a plurality of ejection ports are arranged, and a flow energy generating element is provided in the circulation path. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-104312 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, Patent Document 1 does not go so far as to describe what kind of drive pulses or drive timing should be used to drive the ejection energy generating elements and the flow energy generating elements. Generally, it is conceivable to use only the drive of the ejection energy generating elements, provide drive pulse waveforms appropriate for each energy generating element, and distribute the drive timing for each energy generating element using time-division control while providing a delay for each time-division block. However, this creates the problem of increasing the circuit size depending on the type and number of energy generating elements.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to reduce the circuit scale in a liquid ejection head of an ink circulation type that uses both ejection energy generating elements and flow energy generating elements. [Means for solving the problem]

[0008] In order to solve the above problems, the liquid ejection head of the present invention comprises: a first individual discharge unit, a second individual discharge unit, and a common flow path; A liquid ejection head having The first individual dispensing unit and the second individual dispensing unit each include: a discharge port for discharging a liquid; a pressure chamber communicating with the discharge port; a first energy generating element provided in the pressure chamber and configured to generate energy for ejecting liquid from the ejection port; an individual flow channel communicating with the pressure chamber; a second energy generating element provided in the individual flow path; Including, the common flow path supplies liquid to the individual flow paths of the first individual discharge unit and the second individual discharge unit; the first energy generating elements in the first individual discharging unit and the second energy generating elements in the second individual discharging unit are all driven by a common driving pulse; The first energy generating element and the second energy generating element in the first individual discharging unit The energy generating elements are driven at the same timing, that is, the first timing, The first energy generating element and the second energy generating element in the second individual discharging unit The energy generating element is driven at the second timing, which is the same timing, The first timing and the second timing are controlled to be different from each other. It is characterized by: [Effects of the Invention]

[0009] According to the present invention, it is possible to reduce the circuit scale in an ink circulation type liquid ejection head that uses both ejection energy generating elements and flow energy generating elements. [Brief explanation of the drawings]

[0010] [Figure 1] Overall view of a device using a liquid ejection head [Figure 2] Overall view of a liquid ejection head and an overall view of a liquid ejection chip [Figure 3] Schematic diagram of the vicinity of the ejection port of the liquid ejection head [Figure 4] Schematic diagram of the vicinity of the ejection port of the liquid ejection head [Figure 5] Schematic diagram of the vicinity of the ejection port of the liquid ejection head [Figure 6] Schematic diagram of the vicinity of the ejection port of the liquid ejection head [Figure 7] Schematic diagram of the vicinity of the ejection port of the liquid ejection head according to the first embodiment. [Figure 8] Circuit configuration diagram for comparison [Figure 9] First circuit configuration diagram in the first embodiment [Figure 10] Second circuit configuration diagram in the first embodiment [Figure 11] Schematic diagram of the vicinity of the ejection port of the liquid ejection head according to the second embodiment. [Figure 12] 10 is a schematic diagram of the vicinity of the ejection port of the liquid ejection head according to the third embodiment; [Figure 13] 10 is a schematic diagram of the vicinity of the ejection port of the liquid ejection head according to the fourth embodiment; [Figure 14] 13 is a schematic diagram of the vicinity of the ejection port of the liquid ejection head according to the fifth embodiment; [Figure 15] 13 is a schematic diagram of the vicinity of the ejection port of the liquid ejection head according to the sixth embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the present disclosure, and not all combinations of features described in the present embodiments are necessarily essential to the solutions of the present disclosure. Note that identical components are designated by the same reference numerals. In the following description, the basic configuration of the present disclosure will first be described, followed by a description of the features of the present disclosure.

[0012] <Liquid discharge device> First, a schematic configuration of a liquid ejection device 50 according to this embodiment will be described. FIG. 1 is an enlarged view of a liquid ejection head 1 and its surroundings of the liquid ejection device 50, and FIGS. 1(a) and 1(b) are perspective views schematically illustrating a liquid ejection device using a liquid ejection head. The liquid ejection device 50 shown in FIG. 1 is a serial-type liquid ejection device that records an image by ejecting liquid onto a recording medium P using a liquid ejection head that scans in a direction intersecting the transport direction of the recording medium P. The present invention is not limited to serial-type liquid ejection devices, but can also be applied to page-wide-type liquid ejection devices that use a line head (page-wide-type head) that is long in the page width direction of the recording medium to eject liquid onto a recording medium transported in the transport direction. The liquid ejection head according to this embodiment is capable of ejecting four types of ink: black (K), cyan (C), magenta (M), and yellow (Y), and full-color images can be recorded using these inks. The inks that can be ejected from the liquid ejection head are not limited to the four types mentioned above. The present disclosure can also be applied to liquid ejection heads for ejecting other types of ink. In other words, the types and numbers of inks ejected from the liquid ejection head are not limited.

[0013] In a serial type liquid ejection device 50, the liquid ejection head 1 is mounted on a carriage 60. The carriage 60 moves back and forth in the main scanning direction (X direction) along a guide shaft 51. The recording medium is transported in a sub-scanning direction (Y direction) that intersects (in this example, orthogonal to) the main scanning direction by transport rollers (transport means) 55, 56, 57, and 58. Note that in each figure referred to below, the Z direction indicates the vertical direction, and intersects (in this example, orthogonal to) the XY plane defined by the X and Y directions.

[0014] FIG. 1(a) shows a configuration in which a main ink tank 2 serving as a liquid storage unit is provided outside the liquid ejection head. The liquid (ink) stored in the ink tank 2 is supplied to a sub-ink tank 54 on the liquid ejection head 1 side via an ink supply tube (liquid communication path) 59 or the like by the driving force of an external pump 28. On the other hand, FIG. 1(b) shows a configuration in which an ink tank 54 is provided directly above the liquid ejection head 1 (without a main ink tank 2 serving as a liquid storage unit outside the liquid ejection head). In this case, the liquid ejection head 1 may be provided integrally with the ink tank 54 and configured to be removable / attachable to / from a carriage 60, or the liquid ejection head 1 may be provided integrally with the carriage 60 and only the ink tank 54 may be removable / attachable. The following explanation will use the configuration of FIG. 1(a) as a representative example.

[0015] The liquid ejection head 1 is configured to include individual ejection units, which will be described later (see FIG. 2). The specific configuration will be described later, but each individual ejection unit is provided with an ejection port for ejecting liquid, a pressure chamber communicating with the ejection port, a first energy generating element (ejection energy generating element) that is provided in the pressure chamber and generates energy for ejecting liquid from the ejection port, an individual flow path that communicates with the pressure chamber, and a second energy generating element (flow energy generating element) that is provided in the individual flow path. The liquid ejection head 1 has a plurality of individual ejection units, each of which has an opening that serves as a supply flow path for supplying liquid to the individual flow path in the individual ejection unit.

[0016] When using a liquid ejection head, the liquid ejection may become unstable due to evaporation of volatile components such as water from the ejection ports and the resulting concentration of solids near the ejection ports, and various measures have been taken to prevent this. For example, the liquid ejection device may be provided with a cap member (not shown) that can cover the ejection port surface on which the ejection ports of the liquid ejection head are formed, at a position offset in the X direction from the conveyance path of the recording medium. The cap member is used to cover the ejection port surface of the liquid ejection head when no recording operation is being performed, and to prevent the ejection ports from drying out and to protect them. Furthermore, an ink suction mechanism (not shown) may be provided, and in that case the cap member is used for sucking ink from the ejection ports, etc. This ink suction operation This refreshes the ink near the ejection orifices, maintaining the quality of the resulting image. Other known methods include performing a process known as preliminary ejection (pre-ejection) when printing is not in progress to discard concentrated ink, and pre-ejecting ink in a position and amount that is not noticeable in terms of image quality on the printing medium during printing (paper preliminary ejection / intra-page preliminary ejection). While these methods contribute greatly to improving image quality, they also waste some ink to refresh the ejection orifices, so it is necessary to reduce the amount of wasted ink as much as possible.

[0017] To address this issue, a second energy generating element (flow energy generating element) is installed in each individual flow path to circulate the ink within the flow path, which can suppress the amount of wasted ink while also preventing the nozzles from drying out and the ink from concentrating near the nozzles. More specifically, this can minimize the number of preliminary ejections and suction recovery operations. Furthermore, minimizing the number of preliminary ejections and other operations can also lead to improvements in throughput and yield.

[0018] The second energy generating element (flow energy generating element) does not need to be provided in all of the individual discharge units of the liquid discharge head. If it is provided in some of the individual discharge units, the above-mentioned effects can be obtained compared to when it is not provided.

[0019] 1(a) may be configured so that all of the locations corresponding to the four types of ink are provided with second energy generating elements, or so that only the locations corresponding to one type of ink are provided with second energy generating elements. In other words, the liquid ejection head may be configured so that only at least one type of ink is circulated, rather than all four types of ink.

[0020] <Basic configuration of liquid ejection head> Fig. 2(a) is an exploded perspective view of the liquid ejection head of this embodiment. As shown in Fig. 2, the liquid ejection head is configured to include a sub-ink tank 54 that temporarily stores ink in the head, and a liquid ejection chip 3 that ejects ink supplied from the sub-ink tank 54 onto a recording medium P. The liquid ejection head of this embodiment is fixedly supported on the carriage of the liquid ejection device by positioning means and electrical contacts (not shown) that are provided on the carriage. The liquid ejection head ejects ink while moving together with the carriage in the main scanning direction (X direction) shown in Fig. 1, and performs recording on the recording medium P.

[0021] An ink supply tube 59 is provided to the external pump 28, which is connected to the ink tank 2, which serves as the ink supply source (see FIG. 1( a)). A liquid connector (not shown) is provided at the end of this ink supply tube. When the liquid ejection head 1 is mounted on the liquid ejection device 50, the liquid connector provided at the end of the ink supply tube 59 is liquid-tightly connected to a liquid connector insertion port, which is a liquid inlet port provided in the head housing of the liquid ejection head 1. This forms an ink supply path from the ink tank 2 to the liquid ejection head 1 via the external pump 28. In this embodiment, four types of ink are used, so four sets of ink tanks 2, external pumps 28, ink supply tubes 59, and sub-ink tanks 54 are provided, one for each ink, and four independent ink supply paths are formed corresponding to each ink. In this way, the liquid ejection device of this embodiment is provided with an ink supply system to which ink is supplied from the ink tank 2 provided outside the liquid ejection head 1. Note that the liquid ejection device of this embodiment is not provided with an ink recovery system that recovers ink in the liquid ejection head back to the ink tank. Therefore, the liquid ejection head is provided with a liquid connector insertion port for connecting the ink supply tube of the ink tank, but is not provided with a connector insertion port for connecting a tube for recovering ink from the liquid ejection head to the ink tank. Note that a liquid connector insertion port is provided for each ink.

[0022] 2(b), (c), and (d) are overall views of the liquid ejection chips that make up the liquid ejection head. Fig. 2(b) shows a configuration of one chip for four colors, Fig. 2(c) shows a configuration of one chip for two colors, Figure 2(d) shows a configuration with one chip per color. Each liquid ejection chip is provided with an ejection port and pads used for electrical mounting. Figure 2(a) shows the chip configuration of Figure 2(b).

[0023] FIG. 2(b) shows a first embodiment in which one chip is configured for four colors. The four colors are, for example, black, cyan, magenta, and yellow, and each color has its own column, which is aligned in the Y direction. The ejection openings in each column are adjacent to each other but offset in the X direction, and are equally spaced along the Y direction. However, the ejection openings in each column may be aligned in a single column along the Y direction without being offset in the X direction. Alternatively, black may be arranged in two columns, for a total of five columns for the four colors.

[0024] 2(c) shows a second embodiment in which two chips are used, one chip for each of two colors. When mounting two chips on a liquid ejection head, two chips may be mounted on one liquid ejection head, or two heads may be prepared in which one chip is mounted on one liquid ejection head.

[0025] Fig. 2(d) shows a third embodiment in which four chips are used, one for each color. As in Fig. 2(c), four chips may be mounted on one liquid ejection head, or four liquid ejection heads, each mounted with one chip, may be prepared.

[0026] Also, when the chip is divided into multiple parts, as shown in Figure 2(c)(d), not all of them need to be the same chip length. Also, various combinations of other colors for the chip are possible, and the same applies when the total number of colors is more than four.

[0027] <Components of the circulation unit> (Straight type) Fig. 3 is a schematic diagram illustrating the vicinity of the ejection ports of a straight-type liquid ejection head. In this specification, the term "straight-type" refers to a straight shape in which individual flow paths in which first energy generating elements (ejection energy generating elements) and second energy generating elements (flow energy generating elements) are arranged extend in a direction intersecting the ejection port array (in the case of Fig. 3, a direction perpendicular to the ejection port array) so that both ends of the individual flow paths are located on either side of the ejection port array. In other words, in the individual flow paths of the individual ejection units, the first energy generating elements and the second energy generating elements are arranged in a direction intersecting the ejection port array.

[0028] Fig. 3(a) is a plan view seen from the direction in which droplets are ejected from the ejection port. Fig. 3(b) is a cross-sectional view taken along line A-A' in Fig. 3(a). Fig. 3(c) is another cross-sectional view taken along line A-A' in Fig. 3(a). Fig. 3(d) is a diagram illustrating ink flow when the first energy generating element is driven.

[0029] 3(a) to 3(c), pressure chambers 12 are formed between a substrate 18 and an orifice plate 19, each separated by a partition wall 21 and corresponding to a respective ejection port 11, and individual flow paths 23 are formed for causing ink to flow through the pressure chambers 12. An ink meniscus is formed at the ejection port 11, forming an ejection port interface as an interface between the ink and the atmosphere.

[0030] The substrate 18 is provided with a first energy generating element 14 that generates energy for ejecting ink in the pressure chamber. In this example, an electrothermal conversion element is used. The first energy generating element 14, together with the ejection port 11 and the pressure chamber 12, is located closer to the second supply opening 32 (second opening) than to the first supply opening 22 (first opening). By driving the first energy generating element 14 to generate heat and causing the ink in the pressure chamber 12 to bubble, the resulting bubbling energy can be used to eject ink from the ejection port 11. The first energy generating element is not limited to an electrothermal conversion element as in this example, and a piezo element or the like can be used. It is possible.

[0031] The substrate 18 is also provided with a second energy generating element 24 that generates energy to cause the ink in the individual flow paths to circulate in a circulating flow 27, as indicated by the arrows. In this example, an electrothermal conversion element is used. Therefore, the second energy generating element 24 is also referred to as a circulation heater 24.

[0032] Furthermore, the substrate 18 is provided with an opening for supplying liquid from the common flow path to the individual flow paths. This opening may be configured to have multiple openings (independent supply openings) as shown in Fig. 3(a), or may be a supply groove as a single large opening as shown in Fig. 7(a) described below. The second energy generating element 24 is located closer to the first supply opening 22 than the second supply opening 32.

[0033] The individual flow paths 23 extend in a second direction intersecting (in this example, perpendicular to) the direction (first direction) in which the ejection ports are aligned in a row. The individual flow paths 23 include a pressure chamber 12, an inlet (upstream) connection flow path 13 in FIG. 3(b) that communicates with one end of the pressure chamber 12, and an outlet (downstream) flow path in FIG. 3(b) that communicates with the other end of the pressure chamber 12. The individual flow paths 23 communicate at one upstream end and the other downstream end with a first supply opening 22 and a second supply opening 32 that penetrate the substrate 18, respectively. Therefore, the connection flow path 13 is located closer to the second energy generating element than the ejection port row. Both ends of the individual flow paths 23 are located on opposite sides of the ejection port row. The first supply opening 22 and the second supply opening 32 are supplied with liquid from a common flow path 38.

[0034] The ink flows in the individual flow paths are broadly classified into two types: (1) a first ink flow for driving the first energy generating element 14 and refilling after ejection, and (2) a second ink flow for driving the second energy generating element 24 and forming a circulating flow.

[0035] When the first energy generating element 14 is driven and liquid is ejected from the ejection port 11, ink is supplied from the first supply opening 22 and the second supply opening 32 as shown in Figure 3(d), and ink flows into the pressure chamber from both supply openings.

[0036] When the second energy generating element 24 is driven to form a circulating flow, ink flows into the individual flow path 23 through the first supply opening 22, which is on the connecting flow path side, and flows out to the outside through the second supply opening 32, which is not on the connecting flow path side. In this example, ink flowing out from the second supply opening 32 is returned to the first supply opening 22 and circulated, thereby forming a circulating flow 27, indicated by the arrow, in the individual flow path 23. Note that FIG. 3(b) shows a configuration in which the first supply opening 22 and the second supply opening 32 are shared within the chip. Also, FIG. 3(c) shows a configuration in which the first supply opening 22 and the second supply opening 32 are connected to individual flow paths and shared outside the recording head; either configuration is acceptable.

[0037] Filters 31 for removing foreign matter from the ink may be provided in the ink circulation paths inside and outside the recording head 20. In FIG. 3, the filters are arranged on the inlet and outlet sides, which are outside the individual paths. Also, filters may be arranged between the first energy generating element and the second energy generating element in the individual paths. In this case, it is not necessary to arrange a filter on the upstream side (the second energy generating element side), which is outside the individual paths.

[0038] (U-shaped) Here, the vicinity of the ejection port of the U-shaped liquid ejection head will be described using Figure 7 of the first embodiment described later. In this specification, the "U-shaped" refers to a flow path in which the first energy generating element (ejection energy generating element) and the second energy generating element (flow energy generating element) are arranged. This means that the individual flow path has a U-shaped configuration. That is, in the individual flow path, the first energy generating element and the second energy generating element are arranged along the ejection port array. The individual flow path is configured so that both ends are located on one side of the ejection port array. Fig. 7(a) is a plan view seen from the direction in which droplets are ejected from the ejection port. Fig. 7(b) is an AB cross-sectional view of Fig. 7(a). Fig. 7(c) is an enlarged schematic view explaining the names of elements in the individual flow path section of Fig. 7(a).

[0039] In FIG. 7, both the first energy generating element 14 and the second energy generating element 24 are located near the supply groove 42. The individual flow paths 23 are formed in a U-shape by alternately arranging the first energy generating elements and the second energy generating elements in a direction (first direction) in which the ejection ports are aligned in a row. The individual flow paths 23 include a pressure chamber 12, an inlet (upstream) connecting flow path 13 in FIG. 7(b) that communicates with one end of the pressure chamber 12, and an outlet (downstream) flow path in FIG. 7(b) that communicates with the other end of the pressure chamber 12. The individual flow paths 23 communicate with a supply groove 42 that penetrates the substrate 18 on both its upstream and downstream sides. Both ends of the individual flow paths 23 are located adjacent to one side of the supply groove 42.

[0040] The ink flows in the individual flow paths are classified into two types, (1) the first ink flow and (2) the second ink flow, just like in the straight type.

[0041] When the first energy generating element 14 is driven to eject liquid from the ejection port 11, ink is supplied from the supply groove 42 during ejection, and ink flows into the pressure chamber from both the connecting flow channel side and the opposite side.

[0042] When the second energy generating element 24 is driven to form a circulating flow, the flow enters the individual flow channels 23 from the inlet (upstream) side, which is the connecting flow channel side, and flows out to the outlet (downstream) side. In this example, both flow into and out of a common supply groove 42, forming a circulating flow 27 indicated by the arrows in the individual flow channels 23. Note that although this embodiment is shown as a supply groove 42, it may be replaced with a row of supply openings aligned in the first direction as shown in FIG. 3. If replaced with a supply opening, the supply opening will have a common configuration within the chip, similar to FIG. 3(b).

[0043] (Pump principle) FIG. 4 illustrates the principle of the generation of a circulating flow of ink when a second energy generating element (circulation heater) 24, which is an electrothermal conversion element, is used. FIGS. 4(a), 4(b), and 4(c) are cross-sectional views similar to FIG. 3(b), respectively illustrating the generation, growth, contraction, and post-death processes of a bubble B caused by film boiling of ink when ink is heated by the circulation heater 24. In FIG. 4(a), the circulation heater 24 is located closer to the first supply opening 22 than the second supply opening 32. Therefore, the flow resistance R1 between the circulation heater 24 and the first supply opening 22 is smaller than the flow resistance R2 between the circulation heater 24 and the second supply opening 32. FIG. 4(a) also includes an equivalent circuit that expresses these flow resistances R1 and R2 as electrical resistances. Due to the difference between the flow resistances R1 and R2, the bubble B generated by film boiling of ink grows toward the first supply opening 22, which has the smaller flow resistance R1, as shown in FIG. 4(a). Therefore, in the individual flow path 13, the ink flow Fa toward the first supply opening 22 is larger than the ink flow Fb toward the second supply opening 32.

[0044] FIG. 4(b) is an explanatory diagram of the flow of ink during the contraction process of bubble B. During the contraction process of bubble B, ink flows in to compensate for the volume of the contracted bubble. At this time, as shown in FIG. 4(b), the flow Fc of ink flowing in from the first supply opening 22 on the side with small flow resistance R1 is larger than the flow Fd of ink flowing in from the second supply opening 32 on the side with large flow resistance R2. In addition, the position where bubble B collapses is shifted from above the circulation heater 24 toward the second supply opening 32. This becomes the case.

[0045] 4(c) is an explanatory diagram showing the process after the collapse of bubble B. Due to the relationship Fc>Fd that occurred in FIG. 4(b), a circulating flow F of ink is generated from the first supply opening 22 to the second supply opening 32.

[0046] The magnitude of the circulating flow F is affected by the ratio of flow resistances R1 and R2 and the size of the bubbles B. For example, assuming that a circulation heater 24, which is an electrothermal conversion element, is used as the second energy generating element 24, it is preferable that the second energy generating element 24 be positioned closer to one of the two ends of the individual flow path 23 than the first energy generating element. More specifically, it is preferable that the flow resistance ratio R1 / R2 be set in the range of 0.05 to 0.40. By setting the flow resistance ratio R1 / R2 in this range, the circulating flow F can be maximized. It is important for the circulating flow F to increase the ink flow Fa toward the first supply opening 22 and increase the ink flow Fc flowing in from the first supply opening 22, as shown in FIGS. 4(a) and 4(b). Therefore, it is effective to reduce the flow resistance R1. It is also important to minimize the ink flow Fb toward the outlet flow path 15 and reduce the ink flow Fd flowing in from the second supply opening 32. Therefore, it is effective to increase the flow resistance R2. For these reasons, it is important to reduce the flow resistance R1 and increase the flow resistance R2, that is, to reduce the flow resistance ratio R1 / R2. Furthermore, if the bubbles B are large, that is, if the bubble volume is large, this leads to an increase in the excluded volume of the fluid generated in the individual flow paths 23, and therefore the circulating flow F becomes larger.

[0047] As a means of increasing the bubble volume, ·Increased size of circulating heater 24 - Widen the width and height of the flow path 13 to reduce flow resistance -Reducing ink viscosity -Increased head temperature Double pulse drive pulse Examples include:

[0048] When part of the ink circulation flow F enters the ejection port 11, the concentrated ink in the ejection port 11 is sent to the second supply opening 32 side, and fresh ink flows into the ejection port 11 from the first supply opening 22 side through the connecting flow path 13. In this way, by making it difficult for the concentrated ink to accumulate in the ejection port 11, the influence of the concentrated ink can be suppressed and the initial ink ejection state can be maintained.

[0049] The circulating flow F is a transient flow that occurs during the growth and contraction process of the bubble B when it is generated. Therefore, after the bubble B collapses, the inertial flow attenuates over time and stops after a certain period of time. Therefore, to steadily generate the circulating flow F for a certain period of time, the heating element of the circulation heater 24 must be repeatedly driven. The driving cycle of the circulation heater 24 is not particularly limited as long as it can discharge the concentrated ink from the ejection port 11. However, because the circulating flow F is a transient flow that occurs during the growth and contraction process of the bubble B when it is generated, taking into account the 10 μs cycle from bubble generation to collapse, driving the circulation heater 24 at a high driving frequency, such as 100 kHz, reduces its effectiveness. Therefore, it is preferable to drive the circulation heater 24 at a frequency of, for example, 100 Hz to several tens of kHz. The higher the driving frequency, the more the circulating flow F is maintained, resulting in a greater discharge effect of the concentrated ink. However, at the same time, it is necessary to consider the increase in ink temperature due to heat generated by driving the circulation heater 24. Therefore, the circulation heater 24 must be driven at an appropriate frequency.

[0050] (recirculation concentration) Figures 5 and 6 are diagrams for explaining the elimination of concentration due to the circulating flow of ink caused by the second energy generating element. Figure 5 shows a straight configuration in which the inlet and outlet of the circulating flow in the individual flow paths are separate, while Figure 6 shows a U-shaped configuration in which the inlet and outlet of the circulating flow in the individual flow paths are adjacent. Note that areas where the ink has concentrated are shown in a dark color, and the degree of concentration is expressed by the shade of color.

[0051] First, in Figure 5, Figure 5(a) shows the state after a temporary pause. During a temporary pause, volatile components evaporate from the ejection orifice, causing ink to concentrate near the orifice. Figure 5(b) shows the state immediately after a circulating flow is subsequently generated by the second energy generating element. The circulating flow eliminates the concentration near the orifice. The ink that has concentrated near the orifice is discharged from the outlet, and concentration is eliminated throughout the individual flow paths. Figure 5(c) shows the state after another temporary pause. As in Figure 5(a), ink concentration again progresses near the orifice. From there, Figure 5(d) shows the state immediately after a circulating flow is generated by the second energy generating element. As in Figure 5(b), concentration near the orifice is again eliminated, and concentration is eliminated throughout the individual flow paths. As described above, in a straight-type inkjet printer in which the inlet and outlet of the individual flow paths are separated, the concentration state is reset each time the temporary pause and circulation operation are repeated.

[0052] Meanwhile, in Figure 6, Figure 6(a) shows the state after a temporary pause. During this pause, ink concentration progresses near the ejection orifices, as in Figure 5(a). Figure 6(b) shows the state immediately after a circulatory flow is subsequently generated by the second energy generating element. Here, because the inlet and outlet of the individual flow path are adjacent, concentrated ink near the ejection orifices is discharged from the outlet, but re-enters from the inlet. This results in the entire individual flow path being replaced with slightly concentrated ink rather than fresh ink (hereafter referred to as recirculation concentration). Figure 6(c) shows the state after a further pause. In this case, in addition to the state shown in Figure 6(b), ink concentration again progresses near the ejection orifices, as explained in Figure 6(a). Figure 6(d) shows the state immediately after a circulatory flow is further generated by the second energy generating element. In this case, as explained in Figure 6(b), the entire individual flow path is replaced with even more concentrated ink than in Figure 6(b) due to the effects of recirculation concentration. As described above, in a U-shaped configuration where the inlet and outlet of the individual flow path are adjacent, the concentration state is not reset each time a temporary pause and circulation operation are repeated, and concentration gradually progresses throughout the individual flow paths, causing the concentration state to worsen. Furthermore, even if the circulation operation is not repeated, if the area near the discharge port has become highly concentrated due to a long pause, for example, the concentration state is unlikely to improve even with the first circulation operation. This is because the improvement in the concentration state due to recirculation concentration is small.

[0053] Therefore, between a straight type where the inlet and outlet of the individual flow paths are separate and a U-shaped type where the inlet and outlet of the individual flow paths are adjacent, there is a difference in the state of concentration elimination that occurs with temporary pauses and circulation operations due to differences in the influence of the discharged concentrated ink.With a straight type, the concentrated state is easily eliminated including the entire individual flow path, so there is little risk of reduced ejection stability due to concentrated ink.On the other hand, with a U-shaped type, it is difficult to eliminate the concentrated state including the entire individual flow path through recirculation concentration, so ejection is likely to become unstable depending on the concentration of the entire individual flow path.

[0054] (ink) As shown above, although the degree of elimination of concentration differs depending on the flow path configuration, by generating an ink circulation flow in the individual flow paths using the second energy generating element, it is possible to suppress the effects of concentrated ink that has thickened due to evaporation at the ejection port. In other words, since the ink ejection state can be maintained in a good condition, the effects of changes in ejection speed and the like can be further reduced, making it easier to stabilize ejection.

[0055] On the other hand, depending on the application of the liquid ejection head or the liquid ejection device in which the head is mounted, it is expected that inks with different types of coloring materials and solid content will be used. In other words, regardless of the ink used, maintaining a high level of ejection stability is an important performance feature of a liquid ejection head. is preferable. For example, to address issues that may arise due to the water in the ink, such as curling (warping) and cockling (wavy wrinkles) on plain paper, it is possible to use ink with a reduced water content. Ink with a low water content has a high concentration of solids, such as organic solvents other than water, pigments, and resins, and is therefore prone to a sudden increase in viscosity as the water evaporates, which can lead to a decrease in ink ejection stability. For such inks, the method of generating a circulating flow within a pressure chamber, as in the present invention, is very effective because it can suppress the increase in ink viscosity. Generally, ink with a high solid content is defined as a solid content of 10 wt%. In other words, the present invention is preferably applied to inks with a solid content of 10 wt% (mass%) or more.

[0056] Furthermore, the head operating temperature can be controlled by placing heaters over the entire chip and controlling them to maintain a constant temperature. Since ink viscosity changes depending on the temperature, the ink viscosity at the head operating temperature affects ejection stability.

[0057] When a circulating flow is formed using the second energy generating element, the instantaneous circulating flow velocity can be several tens of mm / s to 1,000 mm / s. The average flow velocity over a time span of several hundred microseconds depends on the drive frequency of the circulating heater. This is because the circulating heater produces a transient circulating flow that decays over time and stops after a certain period of time. When driven at a frequency of approximately 10 to 20 kHz, which is the same as the drive frequency (discharge frequency) of the first energy generating element, the average flow velocity can be several mm / s to 100 mm / s.

[0058] When using ink with a high pigment concentration, for example, ink with a viscosity of 3 cP to 6 cP at the head operating temperature, the ink tends to thicken at the nozzle opening depending on the non-ejection time (rest time). This can easily cause changes in ejection speed and lead to a decrease in ejection stability. Therefore, it is necessary to circulate the ink while the rest time is short, and it is necessary to eliminate concentration by performing regular or transient ink circulation at high frequency. When a circulation heater is used as the second energy generating element, transient ink circulation occurs, so performing circulation at high frequency can contribute to eliminating concentration at the nozzle opening.

[0059] On the other hand, when using ink with a low pigment concentration—for example, ink with a viscosity of 1 cP or more but 2 cP or less at the head operating temperature—the ejection speed may change depending on the non-ejection time (pause time), but the effect is relatively small compared to that of high-concentration ink. On the other hand, if the pause time is long, for example, the ink at the ejection port increases in viscosity depending on the non-printing operation time (stop time). Therefore, when restarting after a period of no printing and stopping, recovery procedures involving waste ink, such as suction, wiping, and preliminary ejection combined with these, are required. When a circulation heater is used as the second energy generating element, the recovery procedure creates a circulation flow, contributing to the elimination of condensation at the ejection port without generating waste ink. Depending on the pause time, it is possible to prevent the generation of waste ink by recovery procedures using only circulation operations. Alternatively, recovery procedures using circulation operations can be combined with suction operations to remove air bubbles in the head, separate from the elimination of condensation, to minimize waste ink generation.

[0060] Whether the ink is high-concentration or low-concentration, it is desirable to return the ink to its original, fresh state as much as possible to reduce the effects of concentrated ink. Therefore, even when a circulation heater is used as the second energy generating element, the lower the effects of recirculation concentration, the better the circulation effect can be obtained. In other words, a straight-type configuration is more effective than a U-type configuration.

[0061] (First embodiment) Fig. 7 is a schematic diagram illustrating in detail the vicinity of the ejection ports of a liquid ejection head that ejects liquid such as ink in the first embodiment. Fig. 7(a) is a plan view seen from the direction in which droplets are ejected from the ejection ports. Fig. 7(b) is an AB cross-sectional view of Fig. 7(a). Fig. 7(c) is an enlarged schematic diagram illustrating the names of elements in the individual flow path section in Fig. 7(a). Fig. 8 is a block diagram illustrating the selective drive circuit configuration on a substrate in a comparative configuration, and Fig. 9 is a block diagram illustrating the selective drive circuit configuration on a substrate in this embodiment.

[0062] 7(a) and 7(b), an ejection port 11 for ejecting liquid is formed in an orifice plate 19. A first energy generating element 14 is formed directly below the ejection port 11 in a substrate 18. A second energy generating element 24 is similarly formed on the substrate 18 together with the first energy generating element 14 to form a circulating flow 27 in an individual flow path 23. Liquid is supplied to the individual flow path 23 including the ejection port 11 from a supply groove 42. At this time, both ends of the individual flow path are adjacent in the first direction, which is the direction in which the ejection ports are arranged.

[0063] Here, the flow path shape shown in Figure 7(a) is referred to as a U-shape, and both ends of the individual flow path are adjacent in the first direction, which is the direction in which the ejection ports are arranged. The names of each element, which are also used in Figures 8, 9, and 10, will be explained. As shown in Figure 7(c), each individual flow path 23 is provided with a first energy generating element 14 and a second energy generating element 24. To distinguish between the elements, the first energy generating element is designated as Ai (i = 1, 2, 3, ..., n), and the second energy generating element is designated as Bi (i = 1, 2, 3, ..., n). In this case, it is indicated that, for example, A1 and B1 are in the same individual flow path.

[0064] (Driving method of comparative configuration) In the comparative configuration, a selection drive circuit 200 as shown in FIG. 8 is formed on a substrate 18. A voltage source (+V) and a controller 110 are provided outside the substrate and connected to the selection drive circuit 200 on the substrate. An on-off drive circuit (on-off switch) 210 is included, which drives the first energy generating elements (A1 to A8) or the second energy generating elements (B1 to B8) on or off in response to control signals at each address (N1 to N16 in this configuration) received from the control data supply circuit 100. That is, the first energy generating elements and the second energy generating elements are independently controlled by switches configured to be switchable between a drivable state and a non-drivable state. Here, the control data supply circuit controls separate drive pulses (P1, P2) for driving the first energy generating elements or the second energy generating elements and the time intervals at which the drive pulses are applied to each element at separate drive timings.

[0065] In the comparative configuration, the first energy generating elements and the second energy generating elements are linked to separate addresses, and the first energy generating elements and the second energy generating elements are driven together in a distributed manner. In this comparative configuration, with eight first energy generating elements and eight second energy generating elements, shifting the drive timing by 16 time divisions reduces instantaneous power consumption and averages out power consumption. The shift time for each time division depends on the number of time divisions and the drive frequency, but is on the order of several microseconds to tens of microseconds. In cases with a larger number of energy generating elements, time division blocks are formed by 16 time divisions, and a delay is provided for each time division block. In addition to the 16 time divisions, the drive timing of energy generating elements with the same number of time divisions also differs slightly. This further reduces instantaneous power consumption and averages out power consumption. The delay time for each time division block is on the order of several nanoseconds, gradually increasing depending on the number of time division blocks, with the maximum shift being on the order of several hundred to 1,000 nanoseconds.

[0066] It is also possible to set separate drive pulses for the first energy generating element responsible for ejection and the second energy generating element responsible for circulation. This means that the energy generating elements are supplied with multiple drive timings. In this way, the optimal drive pulse can be controlled for each energy generating element, and can be supplied with each drive timing. However, wiring is required to supply separate drive pulses to the first energy generating element and the second energy generating element, and in addition to a circuit for time-division driving according to the total number of energy generating elements, a circuit for shifting the drive timing to provide a delay is also required. Therefore, the circuit size increases depending on the type and total number of energy generating elements.

[0067] (First driving circuit of the embodiment) In this embodiment, a selection drive circuit 200 as shown in FIG. 9 is formed on a substrate 18. A voltage source and a controller 110 are provided outside the substrate and connected to the selection drive circuit 200 on the substrate. The selection drive circuit 200 includes an on-off drive circuit (on-off changeover switch) 210 that drives the first energy generating elements (A1 to A16) and the second energy generating elements (B1 to B16) on or off in response to control signals at each address (N1 to N16 in this embodiment) received from the control data supply circuit 100. That is, the first energy generating elements and the second energy generating elements are each independently controlled by a switch configured to be switchable between a drivable state and a non-drivable state.

[0068] Here, the control data supply circuit 100 controls a common drive pulse (P1) that drives the first energy generating element or the second energy generating element, and the time interval for applying the common drive pulse to each element at a common drive timing. Here, the first energy generating element and the second energy generating element in the same individual flow path have a common drive timing without a delay, and are represented by sharing the same address. For example, in the case of address N1, the set of the first energy generating element A1 and the second energy generating element B1 is.

[0069] In the configuration of this embodiment, first, by using a common drive pulse for the first energy generating element and the second energy generating element, wiring can be shared, thereby reducing the circuit size due to the wiring. The first energy generating element, which is responsible for ejection, requires highly accurate pulse control because its drive significantly affects the printing of output characters, images, etc. On the other hand, the second energy generating element, which is responsible for circulation, does not require highly accurate pulse control because, once a circulation flow is generated, a slight increase or decrease in the circulation flow rate has almost no effect on printing. For example, if a circulation heater is used as the second energy generating element, a circulation flow will be generated if bubbles are generated, so the same high accuracy of pulse control as for the first energy generating element is not required.

[0070] Furthermore, the drive energy applied to the second energy generating element for circulation can be lower than the normal drive energy applied for ejection. For example, if a circulation heater is used as the second energy generating element, the generation of bubbles will result in a circulating flow, and therefore the drive energy required for the first energy generating element is not as high. In contrast, a discharge heater generally requires more drive energy to stably generate film boiling than is required for film boiling, thereby stabilizing ejection. In contrast, from the perspective of generating a circulating flow, the drive energy can be reduced to a certain extent, although bubbles are still required. It is known that when a heater is used as the energy generating element, kogane (burning) due to ink components accumulates on the heater surface depending on the number of times it is driven. This is also true when a circulation heater is used as the second energy generating element. Lowering the drive energy reduces the amount of excess energy applied, thereby suppressing the effects of kogane. Therefore, reducing the drive energy of the circulation heater is also preferable from this perspective.

[0071] Next, the first energy generating element and the second energy generating element in the same individual flow path are By using a common drive timing without a delay, the circuitry that shifts the drive timing to generate a delay and applies drive pulses is halved, thereby reducing the circuit size accordingly. Since the drive timing is the same for the first and second energy generating elements in the same individual flow path without any delay, if both are selected, they will be driven at exactly the same timing. However, since there is no need to simultaneously drive the first energy generating element responsible for ejection and the second energy generating element responsible for circulation in the same individual flow path, there is no problem with using a common drive timing that results in simultaneous drive.

[0072] Here, one individual ejection unit included in the liquid ejection head is referred to as a first individual ejection unit, and another individual ejection unit is referred to as a second individual ejection unit. In this case, the first energy generating element and the second energy generating element included in the first individual ejection unit are driven at the same timing (first timing). Also, the first energy generating element and the second energy generating element included in the second individual ejection unit are driven at the same timing (second timing). However, the first timing and the second timing do not necessarily have to be the same timing. By controlling the first timing and the second timing to be different timings, it is possible to reduce the power flowing through the circuit at one time. Of course, the number of individual ejection units is not limited to two, and the liquid ejection head may have three or more individual ejection units.

[0073] To summarize the above, in the first drive circuit of this embodiment, the drive pulse is common to the first energy generating element and the second energy generating element, and the first energy generating element and the second energy generating element in the same individual flow path have a common drive timing without delay, thereby reducing the circuit size.

[0074] Furthermore, the first energy generating element and the second energy generating element do not necessarily have to be the same size. If the first energy generating element responsible for ejection and the second energy generating element responsible for circulation require different sizes of energy generating elements, the same drive pulse can be used by adjusting the aspect ratio of the energy generating element. Alternatively, if the energy generating element is a heater, the same drive pulse can be used by changing the sheet resistance value.

[0075] Furthermore, as described above, the second energy generating element responsible for circulation may be driven with a lower drive energy than the normal drive energy required for ejection. In other words, the second energy generating element may be driven with a lower energy for circulation than the first energy generating element for ejection. Even when the drive energy of the second energy generating element is reduced, the size and aspect ratio of the energy generating element can be adjusted accordingly. For example, the size of the second energy generating element can be made smaller than the size of the first energy generating element. Furthermore, for example, if the first and second energy generating elements are thin-film resistors, the second energy generating element may be designed to be smaller than the first energy generating element in at least one of the vertical and horizontal dimensions. Furthermore, for example, if the first and second energy generating elements are thin-film resistors, the sheet resistance of the second energy generating element may be designed to be smaller than the sheet resistance of the first energy generating element.

[0076] (Second driving circuit of the embodiment) In the second embodiment, a selection drive circuit 200 as shown in FIG. 10 is provided on the substrate 18. A voltage source and a controller 110 are provided outside the substrate and are connected to a selection drive circuit 200 on the substrate. In response to a control signal at each address (N1 to N16 in this embodiment) received from the control data supply circuit 100, either the first energy generating elements (A1 to A16) or the second energy generating elements (B1 to B16) are turned on and driven. The device includes an on-on drive circuit (first switch for switching on and off) 230. That is, it has a switch configured to be able to switch the first energy generating element and the second energy generating element mutually exclusively so that only one of them can be driven. This switch ensures that when the first energy generating element is in a driveable state, the second energy generating element is always in a non-driveable state, and conversely, when the second energy generating element is in a driveable state, the first energy generating element is always in a non-driveable state.

[0077] Here, the control data supply circuit controls a common drive pulse (P1) that drives the first or second energy generating element, and the time interval for applying the common drive pulse to each element at a common drive timing. Here, the common drive timing applies to the first energy generating element and the second energy generating element in the same individual flow path, and they are represented by sharing the same address. For example, address N1 corresponds to the pair of first energy generating element A1 and second energy generating element B1.

[0078] Even when the second energy generating element side is selected by the on-on drive circuit 230, the drive is further controlled by the on-off drive circuit (second switch for switching on and off) 240 of the second energy generating element in accordance with the drive enable / disable signal 300 of the second energy generating element. That is, the second energy generating element is further controlled by a switch configured to be switchable between a drive enable / disable state and a drive disable state. Therefore, when the first energy generating element is in a drive disable state, the second energy generating element is in a drive enable state, but is actually driven only when it receives a drive signal (drive enable / disable signal) instructing it to be driven. If there is no drive enable / disable signal, the second energy generating element is not driven even if the second energy generating element side is selected by the on-on drive circuit 230. That is, in this case, neither the first energy generating element nor the second energy generating element is driven.

[0079] To summarize the above, the second drive circuit of this embodiment is characterized in that the drive circuit for controlling the drive of the first energy generating element and the second energy generating element has a first switch configured to be able to switch the first energy generating element and the second energy generating element mutually exclusively so that only one of them is in a driveable state, and a second switch configured to be able to switch the second energy generating element between a driveable state and an indriveable state, and by using this drive circuit, the first energy generating element and the second energy generating element are configured to be drive-controlled under the following conditions.

[0080] Condition: When the first energy generating element is driven, the second energy generating element is not driven, and when the first energy generating element is not driven, the second energy generating element is driven when a drive signal instructing the second energy generating element to be driven is received.

[0081] Furthermore, it is preferable that the on-off drive circuit (second switch) is provided closer to the second energy generating element than the on-on drive circuit (first switch) and electrically downstream of the second energy generating element. It is also preferable that a common drive signal is used to drive and control a plurality of second energy generating elements.

[0082] For comparison, the following describes measures to deal with thickened ink in a liquid ejection head that does not form a circulating flow. These measures include a preliminary ejection operation that ejects ink from the ejection ports and a suction operation that sucks ink from the ejection ports. For example, in a serial liquid ejection device, the preliminary ejection operation and suction operation are performed in the head standby area before the head leaves the cap that protects it and heads off to the printing operation. Or, the printing operation is performed when the carriage moves back and forth. A preliminary ejection operation is performed in a non-printing area away from the medium. This is at a different timing from the printing operation. Furthermore, in the case of ink that is prone to thickening, a preliminary ejection operation may be performed in addition to the printing operation in the printing area during reciprocating movement, to an extent that does not affect the image on the printing medium.

[0083] In the second drive circuit of this embodiment, the number of preliminary ejection and suction operations can be reduced by driving the second energy generating elements to perform circulation operations. In this case, the timing of circulation operations in the head standby area or non-printing areas during reciprocating movement is similarly different from the timing of printing operations. Therefore, in the second drive circuit of this embodiment, the drive of the second energy generating elements can be easily controlled using the drive enable / disable signal 300 for the second energy generating elements. Furthermore, for ink that tends to thicken easily, in circulation operations in the printing areas of reciprocating movement, it is necessary to prioritize the ejection operation at a timing close to the printing operation. On the other hand, by providing multiple timings for the circulation operation or setting a fixed period for the timing of the circulation operation, it is not necessary to drive the circulation operation and the printing operation simultaneously. Therefore, in the second drive circuit of this embodiment, when the first energy generating element is selected, the first energy generating element is driven, allowing the circulation operation to be controlled appropriately without affecting the printing operation.

[0084] To summarize the above, in the second drive circuit of this embodiment, similar to the first drive circuit, the drive pulse is shared between the first energy generating element and the second energy generating element, and the drive timing of the first energy generating element and the second energy generating element in the same individual flow path is exclusively controlled by the shared drive pulse, thereby reducing the circuit size. Furthermore, the drive of the second energy generating element is controlled according to the drive data and drive enable / disable signal of the first energy generating element. This eliminates the need to provide drive data for the second energy generating element, which has the advantage of further reducing the circuit size.

[0085] Furthermore, even when there are multiple second energy generating elements, drive control is possible based on a common drive enable / disable signal. Note that, in both the first drive circuit and the second drive circuit of this embodiment, the first energy generating elements Ai and the second energy generating elements Bi are controlled as one group, totaling 32 elements (16 pairs) up to n=16, but the total number of elements in one group can also be various numbers such as 16 (8 pairs), 24 (12 pairs), etc.

[0086] In this embodiment, the drive enable / disable signal 300 is provided on the substrate 18 to control the drive of the second energy generating element, but the drive of the second energy generating element may also be controlled by providing it on a liquid ejection head outside the substrate or on a liquid ejection device outside the liquid ejection head.

[0087] (Second embodiment) Figure 11 is a schematic diagram illustrating in detail the vicinity of the ejection ports of a liquid ejection head that ejects liquid such as ink in the second embodiment. Figure 11(a) is a plan view seen from the direction in which droplets are ejected from the ejection ports. Figures 11(b) and 11(c) are two examples of AB cross-sectional views of Figure 11(a).

[0088] Here, FIGS. 11(b) and (c) show two examples because the shape of the back side of the substrate changes depending on the type of etching method used for the substrate, but the cross section may have either shape.

[0089] The present embodiment differs from the first embodiment in that the inlet and outlet of each individual flow path are separated into a straight configuration. In this embodiment, both ends of each individual flow path are separated and arranged at opposite positions in a second direction perpendicular to a first direction in which the ejection ports are arranged.

[0090] The advantage of this configuration is that the inflow and outflow of the circulation flow are separated into opposite directions, so that ink that has become concentrated at the ejection port due to circulation does not re-flow into the individual flow paths, thereby suppressing the effects of concentration.

[0091] (Third embodiment) Fig. 12 is a schematic diagram illustrating in detail the vicinity of the ejection orifices of a liquid ejection head that ejects liquid such as ink in the third embodiment. Fig. 12(a) is a plan view seen from the direction in which droplets are ejected from the ejection orifices. Figs. 12(b) and (c) are two examples of AB cross-sectional views of Fig. 12(a), which are similar to Figs. 11(b) and (c).

[0092] This embodiment differs from the second embodiment in that three supply opening arrays are provided, resulting in a double array of ejection openings, with each ejection opening array located closer to the central supply opening array. In other words, ejection opening arrays are formed on both sides of the direction in which the multiple supply openings are arranged. These ejection opening arrays can also be called the first ejection opening array and the second ejection opening array.

[0093] The advantage of this configuration is that by increasing the number of supply openings by one, from two to three, the number of ejection opening rows can be doubled from one to two. As shown in the figure, it is also possible to arrange the two ejection opening rows with a different pitch. In addition, a configuration is possible in which no wiring area is required between the openings in the central supply opening row, allowing for a high degree of freedom in the size and resolution of the openings in the central supply opening row. This makes it easier to speed up refilling of the nozzles and achieve high productivity.

[0094] In this embodiment, the three supply opening rows are positioned at the same location in the direction between the nozzle rows, but they may be shifted in each row in accordance with the nozzle position and the wiring layout between the openings. This also applies to the following embodiments.

[0095] (Fourth embodiment) 13A and 13B are schematic diagrams illustrating in detail the vicinity of the ejection ports of a liquid ejection head that ejects liquid such as ink in a fourth embodiment. Fig. 13A is a plan view seen from the direction in which droplets are ejected from the ejection ports. Fig. 13B is an AB cross-sectional view of Fig. 13A.

[0096] This embodiment differs from the third embodiment in that there is an ejection port array near the supply opening arrays on both sides, and a second energy generating element is located near the central supply opening array, thereby reversing the direction of the circulating flow.

[0097] The advantage of this configuration is that ink concentrated near the ejection ports is branched off and discharged to the supply opening arrays on both sides, which reduces the effect of concentrated ink when it re-flows into the individual flow paths in response to ejection, etc. Also, because the ejection port arrays are spaced apart, the effect of interference caused by meniscus vibrations accompanying ejection from each ejection port is reduced.

[0098] (Fifth embodiment) 14A and 14B are schematic diagrams illustrating in detail the vicinity of the ejection ports of a liquid ejection head that ejects liquid such as ink in the fifth embodiment. Fig. 14A is a plan view seen from the direction in which droplets are ejected from the ejection ports. Fig. 14B is an AB cross-sectional view of Fig. 14A.

[0099] This embodiment differs from the third embodiment in that the second energy generating element is close to the first energy generating element, and the second energy generating element is closer to the central row of supply openings than to the supply openings on either side, thereby reversing the direction of the circulation flow.

[0100] The advantage of this configuration is that, like the third embodiment, the size of the central supply opening row is In addition to the fact that there is a high degree of freedom in terms of size and resolution, which makes it easy to achieve high productivity by speeding up refilling, the ink concentrated near the ejection port is branched off and discharged to the supply opening rows on both sides, which reduces the impact of concentrated ink when it re-flows into individual flow paths depending on ejection, etc.

[0101] (Sixth embodiment) Figure 15 is a schematic diagram illustrating in detail the vicinity of the ejection ports of a liquid ejection head that ejects liquid such as ink in the sixth embodiment. Figure 15(a) is a plan view seen from the direction in which droplets are ejected from the ejection ports. Figures 15(b) and 15(c) are cross-sectional views taken along lines A-A' and B-B' in Figure 15(a), respectively.

[0102] This embodiment differs from the first embodiment in that the rows of ejection ports on either side of the supply groove are arranged in a staggered pattern, and that a filter is also provided at the inlet of each individual flow path (near the second energy generating element). Even with this configuration, the effects of the present invention can be similarly obtained.

[0103] As mentioned at the beginning, the present disclosure aims to optimize the drive pulse and drive timing to reduce the circuit size in an ink circulation type liquid ejection head that uses both ejection energy generating elements and flow energy generating elements. To achieve this, the present disclosure uses a common drive pulse when using first and second energy generating elements. Typically, the ejection energy generating elements and flow energy generating elements are driven with a single drive pulse, and further, the ejection energy generating elements and flow energy generating elements in the same circulation path are driven with a common drive timing without any delay. This reduces the circuit size.

[0104] [Configuration 1] a first individual discharge unit, a second individual discharge unit, and a common flow path; A liquid ejection head having The first individual dispensing unit and the second individual dispensing unit each include: a discharge port for discharging a liquid; a pressure chamber communicating with the discharge port; a first energy generating element provided in the pressure chamber and configured to generate energy for ejecting liquid from the ejection port; an individual flow channel communicating with the pressure chamber; a second energy generating element provided in the individual flow path; Including, the common flow path supplies liquid to the individual flow paths of the first individual discharge unit and the second individual discharge unit; the first energy generating elements in the first individual discharging unit and the second energy generating elements in the second individual discharging unit are all driven by a common driving pulse; The first energy generating element and the second energy generating element in the first individual discharging unit The energy generating elements are driven at the same timing, that is, the first timing, The first energy generating element and the second energy generating element in the second individual discharging unit The energy generating element is driven at the second timing, which is the same timing, The first timing and the second timing are controlled to be different from each other. A liquid ejection head characterized by: [Configuration 2] The first energy generating element and the second energy generating element are thin-film resistors, and at least one of the vertical and horizontal dimensions is different. The liquid ejection head according to configuration 1. [Configuration 3] The first energy generating element and the second energy generating element are thin film resistors having different sheet resistance values. 3. The liquid ejection head according to configuration 1 or 2. [Configuration 4] The second energy generating element performs a circulation drive to circulate the liquid in the individual flow paths, and the first energy generating element performs a discharge drive to discharge the liquid from the discharge port. 4. The liquid ejection head according to any one of configurations 1 to 3. [Configuration 5] The circulation drive is a drive with weaker energy than the ejection drive. 5. The liquid ejection head according to configuration 4. [Configuration 6] The first energy generating element and the second energy generating element belonging to the same individual discharge unit are selectively controlled to be exclusively driven at the same timing. 6. The liquid ejection head according to any one of configurations 1 to 5. [Configuration 7] a plurality of individual dispensing units including the first individual dispensing unit and the second individual dispensing unit; Having a unit, The plurality of ejection ports belonging to the plurality of individual ejection units form an ejection port array. 7. The liquid ejection head according to any one of configurations 1 to 6. [Configuration 8] The individual flow paths belonging to the individual discharge units are connected to the common flow path via openings. 7. The liquid ejection head according to any one of configurations 1 to 6. [Configuration 9] In the individual flow path of the individual discharge unit, the first energy generating element and the second energy generating element are arranged in a direction intersecting the discharge port array. 8. The liquid ejection head according to configuration 7. [Configuration 10] 10. The liquid ejection head according to configuration 9, wherein the individual flow paths extend in a direction intersecting the ejection port array so that both ends of the individual flow paths are positioned on either side of the ejection port array. [Configuration 11] One ends of the individual flow paths of the individual discharge units are connected to the common flow path via a plurality of first openings arranged along the discharge port array, and the other ends of the individual flow paths are connected to the common flow path via a plurality of second openings arranged along the discharge port array. 11. A liquid ejection head according to configuration 10. [Configuration 12] 12. The liquid ejection head according to configuration 11, wherein a first ejection port array and a second ejection port array are formed on both sides of the direction in which the second openings are arranged. [Configuration 13] In the plurality of individual flow paths, the plurality of first energy generating elements are arranged on a side closer to the plurality of second openings. 13. The liquid ejection head according to claim 12. [Configuration 14] In the plurality of individual flow paths, the plurality of second energy generating elements are arranged on a side closer to the plurality of second openings. 13. The liquid ejection head according to claim 12. [Configuration 15] In at least one individual flow path of the plurality of individual flow paths, the first energy generating element and the second energy generating element are arranged along the ejection port row. 8. The liquid ejection head according to configuration 7. [Configuration 16] The individual flow paths are configured such that both ends thereof are located on one side of the ejection port array. 16. A liquid ejection head according to configuration 15. [Explanation of symbols]

[0105] 11: Discharge port, 12: Pressure chamber, 14: First energy generating element, 24: Second energy generating element, 38: Common flow path

Claims

1. a first individual discharge unit, a second individual discharge unit, and a common flow path; A liquid ejection head having The first individual dispensing unit and the second individual dispensing unit each include: a discharge port for discharging a liquid; a pressure chamber communicating with the discharge port; a first energy generating element provided in the pressure chamber and configured to generate energy for ejecting liquid from the ejection port; an individual flow channel communicating with the pressure chamber; a second energy generating element provided in the individual flow path; Including, the common flow path supplies liquid to the individual flow paths of the first individual discharge unit and the second individual discharge unit; the first energy generating elements in the first individual discharging unit and the second energy generating elements in the second individual discharging unit are all driven by a common driving pulse; The first energy generating element and the second energy generating element in the first individual dispensing unit The energy generating elements are driven at the same timing, that is, the first timing, The first energy generating element and the second energy generating element in the second individual discharging unit The energy generating element is driven at the second timing, which is the same timing, The first timing and the second timing are controlled to be different from each other. A liquid ejection head characterized by:

2. The first energy generating element and the second energy generating element are thin-film resistors, and at least one of the vertical and horizontal dimensions is different. The liquid ejection head according to claim 1 .

3. The first energy generating element and the second energy generating element are thin film resistors having different sheet resistance values.

3. The liquid ejection head according to claim 1.

4. The second energy generating element performs a circulation drive to circulate the liquid in the individual flow paths, and the first energy generating element performs a discharge drive to discharge the liquid from the discharge port.

3. The liquid ejection head according to claim 1.

5. The circulation drive is a drive with weaker energy than the ejection drive. The liquid ejection head according to claim 4 .

6. The first energy generating element and the second energy generating element belonging to the same individual discharge unit are selectively controlled to be exclusively driven at the same timing.

3. The liquid ejection head according to claim 1.

7. a plurality of individual dispensing units including the first individual dispensing unit and the second individual dispensing unit; Having a unit, The plurality of ejection ports belonging to the plurality of individual ejection units form an ejection port array.

3. The liquid ejection head according to claim 1.

8. The individual flow paths belonging to the individual discharge units are connected to the common flow path via openings.

3. The liquid ejection head according to claim 1.

9. In the individual flow path of the individual discharge unit, the first energy generating element and the second energy generating element are arranged in a direction intersecting the discharge port array. The liquid ejection head according to claim 7 .

10. The liquid ejection head according to claim 9 , wherein the individual flow paths extend in a direction intersecting the ejection port array so that both ends of the individual flow paths are positioned on either side of the ejection port array.

11. One ends of the individual flow paths of the individual discharge units are connected to the common flow path via a plurality of first openings arranged along the discharge port array, and the other ends of the individual flow paths are connected to the common flow path via a plurality of second openings arranged along the discharge port array. The liquid ejection head according to claim 10.

12. 12. The liquid ejection head according to claim 11, wherein a first ejection port array and a second ejection port array are formed on both sides of the direction in which the plurality of second openings are arranged.

13. In the plurality of individual flow paths, the plurality of first energy generating elements are arranged on a side closer to the plurality of second openings. The liquid ejection head according to claim 12.

14. In the plurality of individual flow paths, the plurality of second energy generating elements are arranged on a side closer to the plurality of second openings. The liquid ejection head according to claim 12.

15. In at least one individual flow path of the plurality of individual flow paths, the first energy generating element and the second energy generating element are arranged along the ejection port array. The liquid ejection head according to claim 7 .

16. The individual flow paths are configured such that both ends thereof are located on one side of the ejection port array. The liquid ejection head according to claim 15.

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