Liquid ejection head and liquid ejection apparatus

Abstract

To provide a liquid discharge head excellent in discharge performance, and a liquid discharge device.SOLUTION: A liquid ejecting head includes a pressure chamber substrate extending in a first direction and provided with a pressure chamber that applies pressure to a liquid, a communication plate extending in a second direction intersecting the first direction and provided with a communication flow path communicating with the pressure chamber, and a nozzle substrate provided with a nozzle that ejects the liquid, the pressure chamber substrate, the communication plate, and the nozzle substrate being stacked in this order from top to bottom along the second direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Liquid ejection devices equipped with a liquid ejection head that ejects liquid such as ink onto a medium such as printing paper have been proposed. A known liquid ejection head ejects liquid filled in a pressure chamber from a nozzle by vibrating a vibration plate that forms the wall of the pressure chamber using a piezoelectric element.

[0003] The liquid ejection head described in Patent Document 1 has a nozzle plate in which nozzles are formed, a flow path substrate that forms a flow path through which ink flows, a pressure chamber substrate, and a diaphragm, which are layered in this order. Piezoelectric elements are disposed on the diaphragm. Pressure chambers corresponding to the piezoelectric elements are provided in the pressure chamber substrate. The pressure chambers are defined by the pressure chamber substrate, the surface of the flow path substrate, and the diaphragm. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-123085 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the surface of the flow path substrate is used as a partition wall between pressure chambers. If the surface of the flow path substrate is used as a partition wall between pressure chambers as in Patent Document 1, the following problems occur, especially when high-viscosity ink is used.

[0006] The volume of the pressure chamber directly below the diaphragm is directly related to the amount of ink pushed toward the nozzle by the vibration of the diaphragm, and ultimately the amount of ink ejected from the nozzle. For this reason, in order to achieve the desired ejection volume, the pressure chamber's volume must be set to match that ejection volume. In particular, when considering image quality, the volume of the pressure chamber is generally kept relatively small.

[0007] However, this rate-limiting effect of the pressure chamber significantly increases flow path resistance and pressure loss, which can affect the ejection speed, etc. In particular, since pressure loss increases due to ink viscosity in addition to flow path resistance, this problem becomes more pronounced with high-viscosity ink.

[0008] This problem could be solved by increasing the cross-sectional area of ​​the pressure chamber, but the height of the pressure chamber is determined by the size of the pressure chamber substrate in the first place, and increasing the width would result in a thinner wall separating adjacent pressure chambers, causing the pressure of one pressure chamber to affect adjacent pressure chambers and degrading the ejection characteristics, a problem known as structural crosstalk. [Means for solving the problem]

[0009] A preferred aspect of the present invention is a liquid ejection head in which a pressure chamber substrate extending in a first direction and provided with pressure chambers that apply pressure to liquid, a communication plate extending in a second direction intersecting the first direction and provided with communication channels that communicate with the pressure chambers, and a nozzle substrate provided with nozzles that eject liquid are stacked in this order from top to bottom along the second direction, and the upper surface of the communication plate is provided with a groove-like space that communicates with the pressure chambers, extends in the first direction, and overlaps with the pressure chambers when viewed in the second direction.

[0010] A liquid ejection apparatus according to a preferred aspect of the present invention includes a liquid ejection head and a control unit that controls the ejection operation of the liquid ejection head. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 1 is a schematic view illustrating the configuration of a liquid ejection device according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an electrical configuration of the liquid ejection device according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing a specific configuration of the head chip shown in FIG. [Figure 4] FIG. 4 is a plan view of the head chip shown in FIG. [Figure 5] 4 is a cross-sectional view of the head chip shown in FIG. 3 as seen in a direction along the X axis. [Figure 6] 4 is a cross-sectional view of the head chip shown in FIG. 3 as seen in a direction along the X axis. [Figure 7] FIG. 10 is a cross-sectional view of a head chip according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The dimensions and scale of various parts in the drawings may differ from those of the actual parts, and some parts are shown schematically for ease of understanding. The scope of the present invention is not limited to these embodiments unless otherwise specified in the following description. Furthermore, "element β on element α" is not limited to a configuration in which element α and element β are in direct contact with each other, but also includes a configuration in which element α and element β are not in direct contact with each other. Furthermore, "element α and element β being substantially equal" includes not only cases in which they are strictly equal, but also cases in which there is a difference in the order of manufacturing error and measurement error. The X1 direction is an example of the "first direction." The Z2 direction is an example of the "second direction." The Y2 direction is an example of the "third direction."

[0013] 1. First embodiment 1-1. Overall configuration of the liquid ejection device 100 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100 according to an embodiment. The liquid ejection device 100 is an inkjet printing device that ejects liquid such as ink as droplets onto a medium 90. The medium 90 is, for example, printing paper. Note that the medium 90 is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0014] As shown in FIG. 1, the liquid ejection device 100 includes a liquid container 10, a control unit 20, a transport mechanism 30, a moving mechanism 40, a liquid ejection head 50, and a circulation mechanism 60.

[0015] The liquid container 10 stores ink. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 10 is arbitrary.

[0016] The control unit 20 controls the operation of each element of the liquid ejection device 100. The control unit 20 controls the ejection operation from the liquid ejection head 50. The control unit 20 includes, for example, one or more processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and one or more storage circuits such as a semiconductor memory.

[0017] The transport mechanism 30 transports the medium 90 in the Y1 direction under the control of the control unit 20. The movement mechanism 40 reciprocates the liquid ejection head 50 along the X axis under the control of the control unit 20. The movement mechanism 40 has a substantially box-shaped carriage 41 that houses the liquid ejection head 50, and an endless transport belt 42 to which the carriage 41 is fixed. Note that the number of liquid ejection heads 50 mounted on the carriage 41 is not limited to one, and may be multiple. In addition to the liquid ejection head 50, the carriage 41 may also be equipped with the aforementioned liquid container 10.

[0018] The liquid ejection head 50 ejects ink supplied from the liquid container 10 from each of the multiple nozzles onto the medium 90 under the control of the control unit 20 based on the print data Img. This ejection is performed in parallel with the transport of the medium 90 by the transport mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the movement mechanism 40, so that an image corresponding to the print data Img is formed in ink on the surface of the medium 90.

[0019] The liquid container 10 is connected to the liquid ejection head 50 via a circulation mechanism 60. The circulation mechanism 60 is a mechanism that supplies ink to the liquid ejection head 50 and recovers ink discharged from the liquid ejection head 50 for resupply to the liquid ejection head 50 under the control of the control unit 20. The operation of the circulation mechanism 60 can suppress an increase in the viscosity of the ink and reduce the accumulation of air bubbles in the ink.

[0020] As described above, the liquid ejection device 100 includes the liquid ejection head 50 and the control unit 20 that controls the ejection operation from the liquid ejection head 50. Because the liquid ejection device 100 includes the liquid ejection head 50 described below, it can exhibit excellent ejection performance even when using highly viscous ink.

[0021] 1-2: Electrical configuration of the liquid ejection device 100 Fig. 2 is a diagram showing the electrical configuration of the liquid ejection device 100 according to the embodiment. As shown in Fig. 2, the liquid ejection head 50 has a head chip 51 and a supply circuit 52. The head chip 51 has a plurality of piezoelectric elements 51e. As will be described later, for example, two piezoelectric elements 51e are provided for one nozzle. Alternatively, one piezoelectric element 51e may be provided for one nozzle N.

[0022] Under the control of the control unit 20, the supply circuit 52 switches whether or not to supply the drive signal Com output from the control unit 20 as the supply signal Vin to each of the plurality of piezoelectric elements 51e.

[0023] As shown in FIG. 2, the control unit 20 includes a control circuit 21, a memory circuit 22, a power supply circuit 23, and a drive signal generation unit 24.

[0024] The control circuit 21 has a function to control the operation of each part of the liquid ejection device 100 and a function to process various data. The control circuit 21 includes, for example, one or more processors such as a CPU (Central Processing Unit). Note that the control circuit 21 may include a programmable logic device such as an FPGA (Field-Programmable Gate Array) instead of or in addition to a CPU. Furthermore, when the control circuit 21 is made up of multiple processors, the multiple processors may be mounted on different boards or the like.

[0025] The memory circuit 22 stores various programs executed by the control circuit 21 and various data such as print data Img processed by the control circuit 21. The memory circuit 22 includes, for example, one or both of semiconductor memories: a volatile memory such as RAM (Random Access Memory) and a non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable ROM). The print data Img is supplied from an external device 200 such as a personal computer or digital camera. The memory circuit 22 may be configured as part of the control circuit 21.

[0026] The power supply circuit 23 receives power from a commercial power supply (not shown) and generates various predetermined potentials. The generated potentials are supplied to various parts of the liquid ejection device 100 as appropriate. For example, the power supply circuit 23 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection head 50. The power supply potential VHV is also supplied to the drive signal generation unit 24.

[0027] The drive signal generation unit 24 is a circuit that repeatedly generates a drive signal Com for driving each piezoelectric element 51e. Specifically, the drive signal generation unit 24 has, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation unit 24, the DA conversion circuit converts the waveform designation signal dCom from the control circuit 21 from a digital signal to an analog signal. The amplifier circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 23, thereby generating the drive signal Com. Of the waveforms included in the drive signal Com, the signal with the waveform that is actually supplied to each piezoelectric element 51e is the aforementioned supply signal Vin. The waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com.

[0028] The control circuit 21 executes a program stored in the memory circuit 22 to control the operation of each part of the liquid ejection device 100. Here, by executing the program, the control circuit 21 generates control signals Sk1 and Sk2, a print data signal SI, a waveform designation signal dCom, a latch signal LAT, a change signal CNG, and a clock signal CLK as signals for controlling the operation of each part of the liquid ejection device 100.

[0029] The control signal Sk1 is a signal for controlling the driving of the transport mechanism 30. The control signal Sk2 is a signal for controlling the driving of the movement mechanism 40. The print data signal SI is a digital signal for specifying the operating state of each piezoelectric element 51e. The latch signal LAT and change signal CNG are used in conjunction with the print data signal SI and are timing signals that determine the timing of ink ejection from each nozzle. These timing signals are generated, for example, based on the output of an encoder that detects the position of the carriage 41 mentioned above.

[0030] 1-3. Specific structure of head chip 51 FIG. 3 is a cross-sectional view showing a specific configuration of head chip 51 shown in FIG.

[0031] 3, the head chip 51 has a nozzle substrate 51a, a communication plate 51b, a pressure chamber substrate 51c, a vibration plate 51d, multiple piezoelectric elements 51e, a case 51f, a protective plate 51g, and a wiring substrate 51h. The vibration plate 51d, the pressure chamber substrate 51c, the communication plate 51b, and the nozzle substrate 51a are layered in this order from top to bottom along the Z2 direction.

[0032] The nozzle substrate 51a, the communication plate 51b, the pressure chamber substrate 51c, and the vibration plate 51d are stacked in this order in the Z1 direction. Each of these components extends along the Y axis and is manufactured, for example, by processing a silicon single crystal substrate using semiconductor processing technology. These components are also bonded to each other with an adhesive or the like. Note that another layer, such as an adhesive layer, or a substrate may be appropriately interposed between two adjacent components of these components.

[0033] The nozzle substrate 51a is provided with a plurality of nozzles N. Each of the plurality of nozzles N extends along the Z axis and penetrates the nozzle substrate 51a, and is a through-hole that allows ink to pass through.

[0034] The communication plate 51b is provided with a communication channel Na1, a communication channel Na2, a nozzle channel Nf, an individual supply channel Ra1, an individual discharge channel Ra2, a groove-shaped space C2a, a groove-shaped space C2b, a liquid chamber R1a, and a liquid chamber R2a.

[0035] Each of the liquid chambers R1a and R2a is a space that penetrates the communication plate 51b. A vibration absorber 51i that closes the opening of the space is provided on the surface of the communication plate 51b facing the Z2 direction.

[0036] The vibration absorber 51i is a layered member made of an elastic material. The vibration absorber 51i forms part of the wall surfaces of the liquid chambers R1a and R2a, and absorbs pressure fluctuations in the liquid chambers R1a and R2a.

[0037] The communication flow path Na1 and the communication flow path Na2 are each a space that penetrates the communication plate 51b. The communication flow path Na1 and the communication flow path Na2 each extend in the Z2 direction. The communication flow path Na1 and the communication flow path Na2 communicate with each other via the nozzle flow path Nf. The communication flow path Na1 communicates with each of the pressure chambers C1a and the nozzle flow path Nf. The communication flow path Na2 communicates with each of the pressure chambers C1b and the nozzle flow path Nf. The nozzle flow path Nf is a space within a groove provided on the surface of the communication plate 51b facing the Z2 direction, and extends along the X-axis. The nozzle substrate 51a constitutes part of the wall surface of the nozzle flow path Nf. The nozzle flow path Nf communicates the communication flow path Na1 and the communication flow path Na2 with the nozzle N.

[0038] The individual supply flow path Ra1 and the individual discharge flow path Ra2 are each a space that penetrates the communicating plate 51b. The individual supply flow path Ra1 connects the liquid chamber R1a to the pressure chamber C1a, and supplies ink from the liquid chamber R1a to the pressure chamber C1a. On the other hand, the individual discharge flow path Ra2 connects the liquid chamber R2a to the pressure chamber C1b, and discharges ink from the pressure chamber C1b to the liquid chamber R2a.

[0039] The groove-shaped spaces C2a and C2b are spaces within grooves provided on the surface of the communicating plate 51b facing the Z1 direction. The groove-shaped spaces C2a and C2b extend along the X axis. The groove-shaped spaces C2a are provided for each pressure chamber C1a and overlap with the pressure chamber C1a when viewed in the Z2 direction. The groove-shaped spaces C2b are provided for each pressure chamber C1b and overlap with the pressure chamber C1b when viewed in the Z2 direction.

[0040] The pressure chamber substrate 51c is provided with pressure chambers C1a and C1b that apply pressure to ink. Each of the pressure chambers C1a and C1b penetrates the pressure chamber substrate 51c and is a gap between the communication plate 51b and the vibration plate 51d. The pressure chamber C1a communicates with the nozzle N via a communication channel Na1 and a nozzle channel Nf. The pressure chamber C1b communicates with the nozzle N via a communication channel Na2 and a nozzle channel Nf.

[0041] The pressure chamber C1a and the groove-like space C2a form an ejection space Ca related to the ejection of ink. The pressure chamber C1b and the groove-like space C2b form an ejection space Cb related to the ejection of ink. Note that hereinafter, the pressure chamber C1a and the pressure chamber C1b will be collectively referred to as the pressure chamber C1. The groove-like space C2a and the groove-like space C2b will be collectively referred to as the groove-like space C2. The ejection space Ca and the ejection space Cb will be collectively referred to as the ejection space C.

[0042] In addition, the individual supply flow path Ra1, pressure chamber C1a, groove-shaped space C2a, communicating flow path Na1, nozzle flow path Nf, communicating flow path Na2, groove-shaped space C2b, pressure chamber C1b, and individual discharge flow path Ra2 constitute an individual flow path IP provided for each piezoelectric element 51e.

[0043] The diaphragm 51d is a plate-like member that can vibrate elastically. The diaphragm 51d is, for example, a laminate including a first layer made of silicon oxide (SiO2) and a second layer made of zirconium oxide (ZrO2). Another layer, such as a metal oxide, may be interposed between the first and second layers. Part or all of the diaphragm 51d may be integrally formed with the pressure chamber substrate 51c using the same material. For example, the diaphragm 51d and the pressure chamber substrate 51c can be integrally formed by selectively removing a portion of a plate-like member of a predetermined thickness in the thickness direction in a region corresponding to the pressure chamber C1. The diaphragm 51d may also be formed from a layer of a single material.

[0044] A plurality of piezoelectric elements 51e are provided on the surface of the vibration plate 51d facing the Z1 direction, corresponding to different pressure chambers C1. The plurality of piezoelectric elements 51e are provided in a one-to-one correspondence with the plurality of pressure chambers C1. The piezoelectric elements 51e apply pressure fluctuations to the ink in the pressure chamber C1 in response to the drive signal Com. Each piezoelectric element 51e is configured, for example, by laminating a first electrode and a second electrode facing each other and a piezoelectric layer disposed between the two electrodes. Each piezoelectric element 51e fluctuates the pressure of the ink in the pressure chamber C1, thereby ejecting the ink in the pressure chamber C1 from the nozzle N. When the drive signal Com is supplied, the piezoelectric element 51e deforms, causing the vibration plate 51d to vibrate. This vibration causes the pressure chamber C1 to expand and contract, fluctuating the pressure of the ink in the pressure chamber C1.

[0045] The case 51f is a case for storing ink. The case 51f is provided with a liquid chamber R1b, a liquid chamber R2b, an inlet R01, and an outlet R02. The liquid chamber R2a and the liquid chamber R2b are each recessed portions provided on the surface of the case 51f facing the Z2 direction. The inlet R01 is a through-hole that opens on the surface of the case 51f facing the Z1 direction and communicates with the liquid chamber R1b. The outlet R02 is a through-hole that opens on the surface of the case 51f facing the Z1 direction and communicates with the liquid chamber R2b.

[0046] The liquid chambers R1a and R1b form a common supply flow path R1. The liquid chambers R2a and R2b form a common discharge flow path R2. The inlet port R01 and the outlet port R02 are connected to the circulation mechanism 60. The circulation mechanism 60 supplies ink to the common supply flow path R1 and recovers ink discharged from the common discharge flow path R2. The recovered ink is then re-supplied to the common supply flow path R1 by the circulation mechanism 60.

[0047] The protective plate 51g is a plate-like member placed on the surface of the diaphragm 51d facing the Z1 direction, and protects the multiple piezoelectric elements 51e and reinforces the mechanical strength of the diaphragm 51d. A space is formed between the protective plate 51g and the diaphragm 51d to accommodate the multiple piezoelectric elements 51e.

[0048] The wiring board 51h is mounted on the surface of the diaphragm 51d facing the Z1 direction, and is a mounting component for electrically connecting the control unit 20 and the head chip 51. For example, a flexible wiring board 51h such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) is preferably used. The supply circuit 52 described above is mounted on the wiring board 51h.

[0049] In the head chip 51 configured as described above, ink flows through the common supply channel R1, the individual supply channel Ra1, the ejection space Ca, the communicating channel Na1, the nozzle channel Nf, the ejection space Cb, the individual ejection channel Ra2, and the common ejection channel R2 in this order due to the operation of the circulation mechanism 60. Furthermore, the supply signal Vin from the supply circuit 52 simultaneously drives the piezoelectric elements 51e corresponding to both the ejection spaces Ca and Cb, thereby fluctuating the pressure in the ejection spaces Ca and Cb, and ink is ejected from the nozzle N in accordance with this pressure fluctuation.

[0050] 1-4. Groove-shaped space configuration FIG. 4 is a plan view of the head chip 51 shown in FIG.

[0051] 3 and 4, the groove-shaped space C2a communicates with the pressure chamber C1a, extends in the X1 direction, and overlaps with the pressure chamber C1a when viewed in the Z2 direction. Similarly, the groove-shaped space C2b communicates with the pressure chamber C1b, extends in the X1 direction, and overlaps with the pressure chamber C1b when viewed in the Z2 direction.

[0052] The groove-shaped space C2a and the pressure chamber C1a form an ejection space Ca related to the ejection of ink. Similarly, the groove-shaped space C2b and the pressure chamber C1b form an ejection space Cb related to the ejection of ink. The volumes of the ejection space Ca and the ejection space Cb are directly related to the ink ejection amount. The provision of the groove-shaped space C2a and the groove-shaped space C2b makes it easier to design the volumes of the ejection space Ca and the ejection space Cb to match the desired ejection amount compared to a case in which the groove-shaped space C2a and the groove-shaped space C2b are not provided.

[0053] In particular, since the ejection space Ca is composed of the groove-shaped space C2a and the pressure chamber C1a, the volume of the ejection space Ca can be made larger than when the ejection space Ca is composed of only the groove-shaped space C2a. Therefore, the volume of the ejection space Ca can be made larger without increasing the thickness of the head chip 51 in the Z2 direction and the width of the head chip 51 in the X1 direction. This makes it possible to prevent the flow path resistance in the ejection space Ca from increasing. Therefore, it is possible to prevent excessive pressure loss. The same applies to the ejection space Cb.

[0054] Furthermore, when the ink is highly viscous, the pressure loss is greater than when the ink is low viscous. Therefore, by providing the groove spaces C2a and C2b, the increase in flow path resistance can be suppressed compared to when the groove spaces C2a and C2b are not provided, even when high-viscosity ink is used. Therefore, excellent ejection performance can be achieved even when high-viscosity ink is used.

[0055] Furthermore, by providing the groove-shaped space C2a, the height of the ejection space Ca in the Z1 direction is greater than when the groove-shaped space C2a is not provided, but it is not necessary to increase the lengths of the ejection space Ca in the X1 direction and the Y1 direction. This makes it less likely that the pressure of one pressure chamber C1a will affect an adjacent pressure chamber C1a, thereby degrading the ejection characteristics, a problem known as structural crosstalk. The same applies to the groove-shaped space C2b.

[0056] Fig. 5 and Fig. 6 are cross-sectional views of the head chip 51 shown in Fig. 3 as viewed from the direction along the X axis. Fig. 5 is a cross-sectional view of the ejection space Ca, and Fig. 6 is a cross-sectional view of the ejection space Cb.

[0057] As shown in Fig. 5, the width B1 of the groove space C2a in the Y2 direction is smaller than the width A1 of the pressure chamber C1a in the Y2 direction. As shown in Fig. 6, the width B2 of the groove space C2b in the Y2 direction is smaller than the width A2 of the pressure chamber C1b in the Y2 direction.

[0058] By making width B1 smaller than width A1, the risk of the above-mentioned crosstalk problem occurring can be more effectively reduced than when width B1 is larger. Also, by making width B2 smaller than width A2, a similar effect can be obtained.

[0059] In particular, the width B1 of the groove space C2a in the Y2 direction is preferably smaller than 80% of the width A1 of the pressure chamber C1a in the Y2 direction, and the width B2 of the groove space C2b in the Y2 direction is preferably smaller than 80% of the width A2 of the pressure chamber C1b in the Y2 direction.

[0060] By making width B1 smaller than 80% of width A1, the risk of the aforementioned crosstalk problem occurring can be more effectively reduced than if width B1 were larger. Furthermore, by making width B2 smaller than 80% of width A2, a similar effect can be achieved. Note that width B1 may be greater than width A1, and width B2 may be greater than width A2.

[0061] Furthermore, it is preferable that width B1 is greater than 50% of width A1. By making width B1 greater than 50% of width A1, the volume of the ejection space Ca can be increased compared to when width B1 is smaller, and an increase in pressure loss can be suppressed. Furthermore, by making width B2 greater than 50% of width A2, a similar effect can be obtained. Note that width B1 may be 50% or less of width A1, and width B2 may be 50% or less of width A2.

[0062] Furthermore, the center O2 of the groove-shaped space C2a in the Y2 direction is located at the same position in the Y2 direction as the center O1 of the pressure chamber C1a in the Y2 direction. Note that "the same position" only needs to be substantially the same, and this includes manufacturing errors and the like.

[0063] For example, if the center O2 is misaligned in the Y2 direction from the center O1, the groove-shaped space C2a may come too close to the adjacent ejection space Ca. However, by locating the center O2 at the same position as the center O1 in the Y2 direction, the groove-shaped space C2a can be prevented from coming too close to the adjacent ejection space Ca. This prevents the occurrence of crosstalk problems.

[0064] From the same viewpoint, it is preferable that the center P2 of the groove space C2b in the Y2 direction is located at the same position as the center P1 of the pressure chamber C1b in the Y2 direction. Note that the center O2 may be shifted in the Y2 direction from the center O1. The center P2 may be shifted in the Y2 direction from the center P1.

[0065] The height D1 of the groove space C2a in the Z2 direction is greater than the height E1 of the pressure chamber C1a in the Z2 direction. The height D2 of the groove space C2b in the Z2 direction is greater than the height E1 of the pressure chamber C1b in the Z2 direction.

[0066] When height D1 is greater than height E1, pressure loss can be reduced compared to when height D1 is smaller. This is particularly suitable when using high-viscosity ink. The same effect can also be achieved when height D2 is greater than height E2. Note that height D1 may be equal to or less than height E1, and height D2 may be equal to or less than height E2.

[0067] In particular, the height D1 of the groove space C2a in the Z2 direction is preferably greater than twice the height E1 of the pressure chamber C1a in the Z2 direction, and the height D2 of the groove space C2b in the Z2 direction is preferably greater than twice the height E2 of the pressure chamber C1b in the Z2 direction.

[0068] When height D1 is greater than twice height E1, pressure loss can be reduced more effectively than when height D1 is less than twice height E1. The same effect can be obtained when height D2 is greater than twice height E2. Note that height D1 may be less than twice height E1, and height D2 may be less than twice height E2.

[0069] Furthermore, it is preferable that height D1 is less than three times height E1. When height D1 is less than three times height E1, the occurrence of crosstalk problems and a decrease in rigidity of communication plate 51b can be suppressed compared to when height D1 is greater. Furthermore, when height D2 is less than three times height E2, similar effects can be obtained. However, height D1 may be three or more times height E1, and height D2 may be three or more times height E2.

[0070] As shown in FIG. 3, the pressure chamber C1a is communicated with the communication channel Na1 and the individual supply channel Ra1. The pressure chamber C1a overlaps with the groove-shaped space C2a, the communication channel Na1, and the individual supply channel Ra1 in a planar view. The length of the groove-shaped space C2a in the X1 direction is shorter than the length of the pressure chamber C1a in the X1 direction. Similarly, the pressure chamber C1b is communicated with the communication channel Na1 and the individual discharge channel Ra2. The pressure chamber C1b overlaps with the groove-shaped space C2b, the communication channel Na2, and the individual discharge channel Ra2 in a planar view. The length of the groove-shaped space C2b in the X1 direction is shorter than the length of the pressure chamber C1b in the X1 direction.

[0071] Further, a nozzle flow path Nf is provided on the lower surface of the communicating plate 51b, extending in the X1 direction and connecting the communicating path Na1 to the nozzle N. The sum of the height D1 of the groove-shaped space C2a in the Z2 direction and the height F0 of the nozzle flow path Nf in the Z2 direction is smaller than the height G0 of the communicating plate 51b in the Z2 direction. In other words, the groove-shaped space C2a is set to a height D1 that does not overlap the nozzle flow path Nf in the Z2 direction. Because the sum of the height D1 and the height F0 is smaller than the height G0, a decrease in the rigidity of the communicating plate 51b can be suppressed compared to when the sum is larger.

[0072] Similarly, the sum of the height D2 of the groove space C2a in the Z2 direction and the height F0 of the nozzle flow path Nf in the Z2 direction is smaller than the height G0 of the communicating plate 51b in the Z2 direction. In other words, the groove space C2b is set to a height D2 that does not overlap with the nozzle flow path Nf in the Z2 direction. Because the sum of the height D2 and the height F0 is smaller than the height G0, a decrease in the rigidity of the communicating plate 51b can be suppressed compared to when the sum is larger.

[0073] The sum of the height D1 and the height F0 may be equal to or greater than the height G0, and the sum of the height D2 and the height F0 may be equal to or greater than the height G0.

[0074] As described above, the communication plate 51b is provided with a common supply flow path R1 that is commonly connected to the pressure chambers C1a and C1b and supplies liquid to the pressure chambers C1a and C1b, and a common discharge flow path R2 that is commonly connected to the pressure chambers C1a and C1b and discharges ink from the pressure chambers C1a and C1b. Therefore, the liquid ejection head 50 is a circulation-type head that has the function of circulating ink. In a circulation-type head, the ink circulation tends to increase flow path resistance when high-viscosity ink is used. Therefore, by providing the groove-like spaces C2a and C2b, the increase in flow path resistance can be effectively suppressed even when high-viscosity ink is used in a circulation-type head. As a result, excellent ejection performance can be achieved.

[0075] There are no particular limitations on the viscosity of the ink, but the liquid ejection head 50 can exhibit excellent ejection performance even when using ink with a high viscosity of 40 mPa·s or more.

[0076] As described above, it is preferable that the width B1 is smaller than the width A1 and the height D1 is larger than the height E1. The details of this are explained below. The pressure chamber C1a must have an optimal volume to achieve the desired ejection rate. Therefore, the cross-sectional area of ​​the pressure chamber C1a as viewed from the X direction is a rate-limiting factor. Therefore, even if you want to reduce the resistance, it is difficult to change the cross-sectional area of ​​the pressure chamber C1a. Therefore, it is desirable to reduce the resistance of the groove-shaped space C2a. To achieve this, you can increase the width B1 or the height D1. However, increasing the width B1 causes structural crosstalk between adjacent groove-shaped spaces C2a. Therefore, it is preferable that the width B1 is small, specifically, smaller than the width A1. Therefore, to reduce the resistance of the groove-shaped space C2b, the height D1 must be large. Since the partition between adjacent groove-shaped spaces C2b is thicker due to the reduced width B1, even if the height D1 is increased, the impact of structural crosstalk is unlikely to occur. In this way, since width B1 cannot be made larger than width A1, by making height D1 larger than height E1, which has no particular disadvantage in increasing width B1, it is possible to achieve both low resistance due to groove space C2a and suppression of structural crosstalk. The reason why width B2 is preferably smaller than width A2 and height D2 is preferably larger than height E2 is the same.

[0077] 2. Second embodiment A second embodiment will be described. In the following examples, elements that have the same functions as those in the first embodiment will be designated by the same reference numerals as those in the first embodiment, and detailed descriptions thereof will be omitted where appropriate.

[0078] Fig. 7 is a cross-sectional view of a head chip 51A according to the second embodiment. The head chip 51A shown in Fig. 7 has an ejection space CaA which includes a pressure chamber C1aA and a groove-shaped space C2aA. The ejection space CbA also includes a pressure chamber C1bA and a groove-shaped space C2bA.

[0079] The pressure chamber C1aA has a first pressure chamber portion C11a and a second pressure chamber portion C12a. The first pressure chamber portion C11a is closer to the nozzle N in the X1 direction than the second pressure chamber portion C12a. The second pressure chamber portion C12a is farther from the nozzle N in the X1 direction than the first pressure chamber portion C11a.

[0080] The pressure chamber C1bA has a first pressure chamber portion C11b and a second pressure chamber portion C12b. The first pressure chamber portion C11b is closer to the nozzle N in the X1 direction than the second pressure chamber portion C12b. The second pressure chamber portion C12b is farther from the nozzle N in the X1 direction than the first pressure chamber portion C11b.

[0081] The groove-shaped space C2aA is provided at a position corresponding to the first pressure chamber portion C11a but not at a position corresponding to the second pressure chamber portion C12a. Specifically, the groove-shaped space C2aA overlaps with the first pressure chamber portion C11a when viewed in the Z2 direction but does not overlap with the second pressure chamber portion C12a when viewed in the Z2 direction.

[0082] The groove-shaped space C2bA is provided at a position corresponding to the first pressure chamber portion C11b but not at a position corresponding to the second pressure chamber portion C12b. Specifically, the groove-shaped space C2bA overlaps with the first pressure chamber portion C11b when viewed in the Z2 direction but does not overlap with the second pressure chamber portion C12b when viewed in the Z2 direction.

[0083] Because the groove-shaped spaces C2a and C2b are provided on the side closer to the nozzle N, it is possible to reduce the effects of structural crosstalk that affects the ejection characteristics from the nozzle N while controlling the volumes of the pressure chambers C1aA and C1bA, as in the first embodiment. In addition, because the groove-shaped spaces C2a and C2b are not provided on the side farther from the nozzle N, it is possible to make the resistance lower on the side closer to the nozzle N than on the side farther from the nozzle N. This allows pressure to be transmitted effectively to the nozzle N side, reducing the backflow of ink, and as a result improving the ejection efficiency.

[0084] 3. Variations The above-described exemplary embodiment may be modified in various ways. Specific modifications that may be applied to the above-described exemplary embodiment are exemplified below.

[0085] In the above-described embodiment, the liquid ejection device 100 is configured to circulate ink in the individual flow paths IP by including the circulation mechanism 60. However, for example, the ink in the individual flow paths IP may be circulated by driving two piezoelectric elements 51e provided for one nozzle N. In this case, the circulation mechanism 60 may be omitted.

[0086] In the above-described embodiment, two piezoelectric elements 51e are provided for one nozzle N. However, the liquid ejection device 100 may be configured so that only one piezoelectric element 51e is provided for one nozzle N. Furthermore, the "liquid ejection device" does not have to be configured to have a circulation type head.

[0087] In the above-described embodiment, the liquid ejection device 100 is a serial type in which the carriage 41 is reciprocated, but it may also be a line type in which a plurality of nozzles N are distributed across the entire width of the medium 90.

[0088] A "liquid ejection device" can be employed in various devices such as facsimile machines and copiers, as well as devices dedicated to printing. The uses of a liquid ejection device are not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device for forming color filters for display devices such as liquid crystal display panels. A liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board. A liquid ejection device that ejects a solution of an organic substance related to a living organism is used as a manufacturing device for manufacturing biochips, for example.

[0089] Although the present invention has been described above based on preferred embodiments, the present invention is not limited to the above-described embodiments. Furthermore, the configuration of each part of the present invention can be replaced with any configuration that exhibits the same function as the above-described embodiments, and any configuration can be added. [Explanation of symbols]

[0090] 10...liquid container, 20...controller, 50...liquid ejection head, 51...head chip, 51a...nozzle substrate, 51b...communicating plate, 51c...pressure chamber substrate, 51d...diaphragm, 51e...piezoelectric element, 51f...case, 51g...protective plate, 51h...wiring substrate, 51i...vibration absorber, 52...supply circuit, 60...circulation mechanism, 100...liquid ejection device, A1...width, A2...width, B1...width, B2...width, C1...pressure chamber, C11a...first pressure chamber portion, C11b...first pressure chamber portion, C12a...second pressure chamber portion, C12b...second pressure chamber portion, C1a...pressure chamber, C 1b...pressure chamber, C2a...groove-shaped space, C2b...groove-shaped space, Ca...discharge space, Cb...discharge space, D1...height, D2...height, E1...height, E2...height, F0...height, G0...height, N...nozzle, Na1...communicating flow path, Na2...communicating flow path, Nb1...communicating flow path, Nf...nozzle flow path, O1...center, O2...center, P1...center, P2...center, R01...inlet, R02...outlet, R1...common supply flow path, R2...common discharge flow path, R1a...liquid chamber, R1b...liquid chamber, R2a...liquid chamber, R2b...liquid chamber, Ra1...individual supply flow path, Ra2...individual discharge flow path.

Claims

1. a pressure chamber substrate extending in a first direction and having pressure chambers that apply pressure to liquid; a communication plate extending in a second direction intersecting the first direction and having a communication flow path communicating with the pressure chamber; a nozzle substrate provided with nozzles for ejecting liquid; and a liquid ejection head in which these are stacked in this order from top to bottom along the second direction, a groove-shaped space that communicates with the pressure chamber, extends in the first direction, and overlaps with the pressure chamber when viewed in the second direction, the groove-shaped space being provided on the upper surface of the communication plate;

2. 2. The liquid ejection head according to claim 1, wherein the width of the groove-shaped space in a third direction intersecting the first direction and the second direction is smaller than the width of the pressure chamber in the third direction.

3. 3. The liquid ejection head according to claim 2, wherein the width of the groove-shaped space in the third direction is smaller than 80% of the width of the pressure chamber in the third direction.

4. 3. The liquid ejection head according to claim 2, wherein the center of the groove-shaped space in the third direction is located at the same position as the center of the pressure chamber in the third direction.

5. 3. The liquid ejection head according to claim 1, wherein the height of the groove-shaped space in the second direction is greater than the height of the pressure chamber in the second direction.

6. 3. The liquid ejection head according to claim 1, wherein the height of the groove-shaped space in the second direction is greater than twice the height of the pressure chamber in the second direction.

7. a nozzle flow path extending in the first direction and communicating between the communication flow path and the nozzle is provided on a lower surface of the communication plate; 3. The liquid ejection head according to claim 1, wherein the sum of the height of the groove-shaped space in the second direction and the height of the nozzle flow path in the second direction is smaller than the height of the communicating plate in the second direction.

8. 3. The liquid ejection head according to claim 1, wherein the communication plate is further provided with a common supply flow path that is in common communication with the plurality of pressure chambers and that supplies liquid to the plurality of pressure chambers, and a common discharge flow path that is in common communication with the plurality of pressure chambers and that discharges liquid from the plurality of pressure chambers.

9. 3. The liquid ejection head according to claim 1, wherein the viscosity of the liquid is 40 mPa·s or more.

10. the pressure chamber has a first pressure chamber portion close to the nozzle in the first direction and a second pressure chamber portion far from the nozzle in the first direction, 3. The liquid ejection head according to claim 1, wherein the groove-shaped space is provided at a position corresponding to the first pressure chamber portion, and is not provided at a position corresponding to the second pressure chamber portion.

11. The liquid ejection head according to claim 1 or 2; a control unit that controls the ejection operation of the liquid ejection head.

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