Liquid ejection head

Abstract

To provide a liquid discharge head which can set a width of a pressure chamber to be smaller than an inlet diameter of a nozzle.SOLUTION: A liquid discharge head includes: an actuator; a plurality of nozzle chambers; and a nozzle plate. The actuator has a plurality of pressure chambers and varies volume of the plurality of pressure chambers. The plurality of nozzle chambers are provided at each one end of the plurality of pressure chambers. The nozzle plate is provided to face the plurality of nozzle chambers and is formed with a plurality of nozzles for discharging liquid, each of which has an inlet diameter larger than a width of the pressure chamber.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a liquid ejection head. [Background technology]

[0002] In order to improve the drive frequency of a shear-mode liquid ejection head that ejects liquid such as ink, there has been a conventional head that alternately arranges multiple pressure chambers that eject liquid from nozzles and air chambers that do not eject liquid. These air chambers are sealed with walls made of photosensitive resin to prevent liquid from flowing into the air chambers. The nozzles that eject liquid are formed so as to directly communicate with the pressure chambers, which are formed by groove processing on a piezoelectric member.

[0003] However, this conventional technology requires the width of the pressure chamber to be larger than the diameter of the nozzle inlet, which can lead to a risk of not being able to provide the appropriate viscous resistance to the ink. As a result, even after the liquid is ejected, the flow of the liquid toward the nozzle cannot be suppressed, causing the meniscus to bulge from the nozzle surface, which can lead to a decrease in ejection speed at high drive frequencies and a decrease in print quality. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-189031 Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid ejection head in which the width of a pressure chamber can be made smaller than the inlet diameter of a nozzle. [Means for solving the problem]

[0006] The liquid ejection head includes an actuator, a plurality of nozzle chambers, and a nozzle plate. The actuator has a plurality of pressure chambers and varies the volume of the plurality of pressure chambers. The plurality of nozzle chambers are provided at one end of the plurality of pressure chambers, respectively. The nozzle plate is provided opposite the plurality of nozzle chambers and has a plurality of nozzles formed therein that eject liquid, each nozzle having an inlet diameter larger than the width of the pressure chamber. The actuator has an inclined surface on a side surface in a lateral direction of the actuator, and an end surface of the nozzle chamber facing the pressure chamber extends from a ridge between the inclined surface of the actuator and a bottom surface of the pressure chamber toward the nozzle plate. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a configuration of a liquid ejection head according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing the configuration of a head main body of the liquid ejection head according to the embodiment. [Figure 3] FIG. 2 is a plan view showing the configuration of a head main body according to the embodiment, with some parts omitted. [Figure 4] FIG. 2 is a cross-sectional view showing the configuration of a head main body according to the embodiment. [Figure 5] FIG. 2 is an enlarged plan view showing the configuration of a head main body according to the embodiment. [Figure 6] FIG. 2 is an enlarged cross-sectional view showing the configuration of a head main body according to the embodiment. [Figure 7] FIG. 2 is a cross-sectional view showing the configuration of a head main body according to the embodiment. [Figure 8] FIG. 4 is an explanatory diagram showing an example of a driving waveform of the liquid ejection head according to the embodiment. [Figure 9] 10A and 10B are explanatory diagrams showing examples of changes in meniscus position over time in the liquid ejection head according to the embodiment and a conventional liquid ejection head. [Figure 10] FIG. 1 is an explanatory diagram showing the configuration of a liquid ejection apparatus using a liquid ejection head according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A liquid ejection head 1 according to an embodiment and a liquid ejection device 2 using the liquid ejection head 1 will be described below with reference to FIGS. 1 to 10. FIG. 1 is a perspective view showing the configuration of the liquid ejection head 1 according to an embodiment, and FIG. 2 is a perspective view showing the configuration of a head main body 11 of the liquid ejection head 1. FIG. 3 is a plan view showing the configuration of the head main body 11 with some parts omitted. FIG. 4 is a cross-sectional view showing the configuration of the head main body 11 along line IV-IV in FIG. 3. FIG. 5 is a plan view showing an enlarged view of the configuration of an actuator 113 of the head main body 11, FIG. 6 is a cross-sectional view showing the configuration of the head main body 11 along line VI-VI in FIG. 5, and FIG. 7 is a cross-sectional view showing the configuration of the head main body 11 along line VII-VII in FIGS. 5 and 6.

[0009] Fig. 8 is an explanatory diagram showing an example of a drive waveform of the liquid ejection head 1 according to the embodiment, and Fig. 9 is an explanatory diagram showing an example of the change in meniscus position over time in the nozzle 1141 for the liquid ejection head 1 according to the embodiment and a conventional liquid ejection head. Fig. 10 is an explanatory diagram showing the configuration of a liquid ejection device 2 using the liquid ejection head 1. Note that in each figure, the configuration is enlarged, reduced, or omitted as appropriate for ease of explanation.

[0010] The liquid ejection head 1 is a share mode inkjet head provided in a liquid ejection device 2 such as the inkjet recording device shown in Fig. 10. The liquid ejection head 1 is provided in a head unit 2130 provided in the liquid ejection device 2 and including a supply tank 2132 as a liquid storage section.

[0011] The liquid ejection head 1 is supplied with ink as a liquid stored in a supply tank 2132. The liquid ejection head 1 is a non-circulation type head that does not circulate ink. The liquid ejection head 1 is also connected to a temperature adjustment device provided in the liquid ejection device 2, and is supplied with temperature adjustment liquid (temperature adjustment water) that controls the temperature of the ink.

[0012] 1, the liquid ejection head 1 includes a head main body 11, a manifold unit 12, and a circuit board 13. For example, the liquid ejection head 1 may be configured to include one head main body 11 having a pair of actuators 113, or may be configured to include two sets of head main bodies 11.

[0013] 2 to 7, the head body 11 includes a substrate 111, a frame 112, an actuator 113 having a plurality of pressure chambers 1131, a plurality of air chambers 1132, and a plurality of nozzle chambers 1133, and a nozzle plate 114. The head body 11 has a common liquid chamber 116 that communicates with the plurality of pressure chambers 1131 of the actuator 113.

[0014] The head main body 11 has electrodes 118 on the substrate 111 and the actuator 113, which drive the multiple pressure chambers 1131 of the actuator 113. As shown in Fig. 3, the electrodes 118 have, for example, multiple individual electrodes 1181 which drive the multiple pressure chambers 1131 individually, and one or multiple common electrodes 1182 which are shared by the multiple pressure chambers 1131 or all the pressure chambers 1131. In addition, the electrodes 118 have, at the ends of the substrate 111 in the shorter direction, multiple mounting pads 1183 which are connection portions on which the circuit board 13 is mounted.

[0015] The substrate 111 is formed, for example, in the shape of a rectangular plate from a ceramic material. The substrate 111 is formed, for example, in the shape of a rectangle that is long in one direction. A wiring pattern that becomes part of the electrode 118 is formed on one surface of the substrate 111. A pair of actuators 113 is provided on one surface of the substrate 111, lined up in the short direction of the substrate 111. The one surface of the substrate 111 refers to one of the main surfaces of the substrate 111. The substrate 111 has, for example, a single supply port 1111. Note that the substrate 111 may be configured to have multiple supply ports. The substrate 111 also has, for example, a single or multiple discharge ports. The supply port 1111 and the discharge port are through holes that penetrate between both main surfaces of the substrate 111.

[0016] The supply port 1111 is an inlet for supplying ink to the common liquid chamber 116. The supply port 1111 is a through-hole formed in the center of the substrate 111 in the short direction and extending along the longitudinal direction of the substrate 111. The supply port 1111 extends along the longitudinal direction of the substrate 111. In other words, the supply port 1111 is, for example, an elongated hole that is long in one direction along the longitudinal direction of the actuators 113 and the longitudinal direction of the common liquid chamber 116. The supply port 1111 is provided between the pair of actuators 113 and opens at a position facing the common liquid chamber 116.

[0017] The discharge port is an ink outlet for discharging ink from the common liquid chamber 116. A plurality of discharge ports are provided. The plurality of discharge ports, for example, face the common liquid chamber 116 and open at positions adjacent to both longitudinal ends of the pair of actuators 113. Note that the plurality of discharge ports may also open at positions adjacent to one longitudinal end of the pair of actuators 113.

[0018] The frame 112 is bonded to one main surface of the substrate 111 with an adhesive or the like. The frame 112 surrounds the supply port 1111, the plurality of discharge ports, and the actuator 113 provided in the substrate 111.

[0019] For example, the frame 112 is formed in a rectangular frame shape, thereby forming an opening that is long in one direction along the longitudinal direction of the frame 112. In the opening of the frame 112, a pair of actuators 113, a supply port 1111, and a plurality of discharge ports are arranged.

[0020] A pair of actuators 113 are bonded to the mounting surface of the substrate 111. The pair of actuators 113 are arranged in two rows on the substrate 111 with a supply port 1111 between them. The actuators 113 are formed in the shape of a plate that is long in one direction. The actuators 113 are placed inside the opening of the frame 112. The actuators 113 are bonded to the main surface of the substrate 111. The surface of the actuators 113 opposite to the substrate 111 is bonded to the nozzle plate 114.

[0021] 2 to 7, the actuator 113 has a plurality of pressure chambers 1131 arranged at equal intervals along the longitudinal direction of the actuator 113, and air chambers 1132 arranged at equal intervals along the longitudinal direction of the actuator 113 and between adjacent pressure chambers 1131. In other words, the actuator 113 has a plurality of pressure chambers 1131 and air chambers 1132 arranged alternately along the longitudinal direction.

[0022] The actuator 113 also has a plurality of nozzle chambers 1133 that are continuous with one end of the plurality of pressure chambers 1131. The actuator 113 is equipped with a plurality of first liquid barrier walls 1136 and one or more second liquid barrier walls 1137 that form a plurality of air chambers 1132 and a plurality of nozzle chambers 1133.

[0023] The actuator 113 has a plurality of grooves formed therein that are arranged at equal intervals in the longitudinal direction and extend in a direction perpendicular to the longitudinal direction. The grooves form a plurality of pressure chambers 1131 and a plurality of air chambers 1132. In other words, the actuator 113 has a plurality of piezoelectric bodies 1134 that are driving elements that are arranged at equal intervals in the longitudinal direction and that constitute walls that form the grooves between them. The piezoelectric bodies 1134 drive the pressure chambers 1131. The piezoelectric bodies 1134 form a plurality of pressure chambers 1131 and a plurality of air chambers 1132 between adjacent piezoelectric bodies 1134, and the volume of the pressure chambers 1131 is changed by applying a driving voltage.

[0024] For example, the width of the actuator 113 in the short side direction gradually increases from the top side to which the nozzle plate 114 is bonded toward the substrate 111. The cross section of the actuator 113 along the direction perpendicular to the longitudinal direction (short side direction) is formed into a trapezoidal shape. That is, the actuator 113 has an inclined surface 1135 on a side surface in the short side direction. One side surface (inclined surface 1135) is disposed opposite the common liquid chamber 116. In addition, a second liquid barrier 1137 that forms a plurality of nozzle chambers 1133 is provided on the other side surface, and a portion of the second liquid barrier 1137 is located inside the plurality of nozzle chambers 1133, and another portion is covered by the second liquid barrier 1137.

[0025] As a specific example, the actuator 113 is formed of a laminated piezoelectric member in which two rectangular piezoelectric material plates elongated in one direction are bonded together facing each other so that their polarization directions are opposite to each other. Here, the piezoelectric material is, for example, PZT (lead zirconate titanate). The actuator 113 is bonded to the mounting surface of the substrate 111 with, for example, a thermosetting epoxy adhesive. The actuator 113 then forms an inclined surface 1135 by, for example, cutting. Additionally, the surfaces of the substrate 111 and the actuator 113 on which the electrodes 118 are patterned are polished, for example, by polishing, to form polished surfaces. Furthermore, the actuator 113 has, for example, a cutting process to form a plurality of grooves that form a plurality of pressure chambers 1131 and a plurality of air chambers 1132, and a piezoelectric body (driving element) 1134 that serves as a side wall separating adjacent grooves.

[0026] Furthermore, a wiring pattern that becomes part of the electrode 118 is formed on the actuator 113. Furthermore, the actuator 113 is formed, in the short side direction, with a plurality of first liquid barrier walls 1136 that close one end side of the groove that constitutes the air chamber 1132, and a second liquid barrier wall 1137 that closes the other end side of the groove that constitutes the air chamber 1132 and forms a plurality of nozzle chambers 1133 on the other end side of the groove that constitutes the pressure chamber 1131.

[0027] The pressure chamber 1131 deforms when the liquid ejection head 1 performs an operation such as printing, thereby ejecting ink from the nozzle 1141. The pressure chamber 1131 has an inlet that opens to the common liquid chamber 116 and an outlet that opens to the nozzle chamber 1133. Ink flows into the pressure chamber 1131 from the inlet, and flows out of the pressure chamber 1131 to the nozzle chamber 1133 from the outlet.

[0028] 2, the air chamber 1132 is separated from the common liquid chamber 116 by having its inlet opening blocked by a first liquid barrier 1136 formed of a photosensitive resin or the like. The air chamber 1132 is blocked by the nozzle plate 114, and no nozzles 1141 are disposed therein. Therefore, ink does not flow into the air chamber 1132.

[0029] The nozzle chamber 1133 is a closed chamber that is disposed opposite the outlet opening of the pressure chamber 1131 and is fluidly connected to the pressure chamber 1131. As shown in FIG. 5 , the width Wa of the nozzle chamber 1133 is larger than the width Wb of the pressure chamber 1131 and is equal to or larger than the inlet diameter ΦDi of a nozzle 1141 (described later) formed in the nozzle plate 114. Preferably, the width Wa of the nozzle chamber 1133 is larger than the inlet diameter ΦDi of the nozzle 1141. Here, the width Wa of the nozzle chamber 1133 and the width Wb of the pressure chamber 1131 are dimensions along the longitudinal direction of the actuator 113. The width Wa of the nozzle chamber 1133 is the width of an opening at an end portion that is covered by the nozzle plate 114. The width of the nozzle chamber 1133 that is perpendicular to the width Wa of the opening at the end portion that is covered by the nozzle plate 114 is equal to or larger than the inlet diameter ΦDi of the nozzle 1141.

[0030] The first liquid barrier 1136 closes the end on the inlet side of the groove that forms the air chamber 1132, and prevents ink from entering the air chamber 1132. For example, the first liquid barrier 1136 is formed by pouring ultraviolet curing resin into the groove that forms the air chamber 1132, and then using a mask plate or the like to irradiate the necessary parts, for example, the end on the inlet side of the groove that forms the air chamber 1132, with ultraviolet light.

[0031] The second liquid barrier wall 1137 closes the outlet end of the groove that forms the air chamber 1132, and forms a nozzle chamber 1133 at the outlet end of the groove that forms the pressure chamber 1131. The second liquid barrier wall 1137 prevents ink from entering the air chamber 1132, and guides the ink in the pressure chamber 1131 to the nozzle chamber 1133.

[0032] The second liquid barrier wall 1137 is formed in a comb-like shape when viewed from the nozzle plate 114 side. As a specific example, as shown in Figure 6, an end face 1139 of the second liquid barrier wall 1137 (nozzle chamber 1133) facing the pressure chamber 1131 in the short-side direction of the actuator 113 extends, for example, from an edge portion between the inclined surface 1135 of the actuator 113 and the bottom surface 1138 of the groove (pressure chamber 1131) toward the nozzle plate 114 side. Specifically, the end face 1139 of the second liquid barrier wall 1137 faces the pressure chamber 1131 in the flow direction of ink flowing through the pressure chamber 1131. The end face 1139 of the second liquid barrier wall 1137 extends from the edge portion of the inclined surface 1135 and the bottom surface 1138 of the groove toward the nozzle plate 114 side in a direction perpendicular to both the long-side direction and the short-side direction of the actuator 113 (toward the main surface of the substrate 111). In other words, the nozzle chamber 1133 forms a chamber that extends from the end of the bottom of the pressure chamber 1131 toward the nozzle plate 114 in directions perpendicular to both the longitudinal and lateral directions of the actuator 113 .

[0033] The nozzle plate 114 is formed in a plate shape. The nozzle plate 114 is bonded to the main surface of the frame 112 opposite the substrate 111 with an adhesive or the like. The nozzle plate 114 has a plurality of nozzles 1141 formed at positions facing the plurality of nozzle chambers 1133. In this embodiment, the nozzle plate 114 has two nozzle rows 1142 in which the plurality of nozzles 1141 are aligned in one direction. As shown in FIG. 6 , for example, the nozzle 1141 has an inlet diameter ΦDi on the nozzle chamber 1133 side that is larger than an outlet diameter ΦDo on the outer surface side of the nozzle plate 114.

[0034] The common liquid chamber 116 is formed between the pair of actuators 113 in the short direction and on the end sides of the pair of actuators 113 in the long direction, and forms an ink flow path from the supply port 1111 to the primary side openings (inlets) of the multiple pressure chambers 1131 of each actuator 113. The common liquid chamber 116 extends along the long direction of the actuators 113.

[0035] The electrode 118 applies a driving voltage to the plurality of piezoelectric elements 1134, which are piezoelectric elements. The electrode 118 is formed by a wiring pattern formed on the substrate 111 and a wiring pattern formed on the actuator 113. The electrode 118 is formed as a film on the inner surface of a groove formed in the actuator 113, the inclined surface 1135 of the actuator 113, and the substrate 111. The electrode 118 extends from the actuator 113 to the end of the substrate 111 in the short side direction to which the circuit board 13 is connected.

[0036] For example, the multiple individual electrodes 1181 of the electrode 118 apply a drive voltage individually to the multiple piezoelectric bodies 1134. The multiple individual electrodes 1181 are provided, for example, on both end sides in the short side direction of the substrate 111. For example, one or multiple common electrodes 1182 of the electrode 118 apply the same voltage to the multiple piezoelectric bodies 1134 or to all of the piezoelectric bodies. The piezoelectric bodies 1134 individually deform each pressure chamber 1131 due to a voltage difference generated between the individual electrodes 1181 and the common electrode 1182. The common electrode 1182 is provided, for example, in the center part in the short side direction of the substrate 111, and is patterned from the center part to both end parts or one end part in the short side direction of the substrate 111, avoiding the individual electrodes 1181.

[0037] 1, the manifold unit 12 includes a manifold 121, an ink supply pipe 123, an ink discharge pipe 124, and a pair of temperature control pipes, namely, a temperature-controlled water supply pipe 125 and a temperature-controlled water discharge pipe. The numbers of the ink supply pipes 123, the ink discharge pipes 124, the temperature-controlled water supply pipes 125, and the temperature-controlled water discharge pipes can be set as appropriate.

[0038] The manifold 121 is formed in a plate or block shape. The manifold 121 includes a supply flow path connecting the supply port 1111 of the substrate 111 and the ink supply pipe 123, a discharge flow path connecting the discharge port of the substrate 111 and the ink discharge pipe 124, and a temperature control flow path forming a flow path for a temperature control fluid. To the manifold 121, for example, the ink supply pipe 123, the ink discharge pipe 124, the temperature control water supply pipe 125, and the temperature control water discharge pipe are fixed.

[0039] The circuit board 13 comprises a wiring film 131 having one end joined to a mounting pad 1183 provided at the end of the electrode 118 of the substrate 111, a driver IC 132 mounted on the wiring film 131, and a printed wiring board 133 mounted on the other end of the wiring film 131.

[0040] The circuit board 13 drives the actuator 113 by applying a drive voltage to the wiring pattern of the actuator 113 via the driver IC 132 , thereby increasing or decreasing the volume of the pressure chamber 1131 and causing droplets to be ejected from the nozzle 1141 .

[0041] The wiring film 131 is connected to the electrode 118. As a specific example, the wiring film 131 is connected to a plurality of individual electrodes 1181 and a common electrode 1182. For example, the wiring film 131 is an ACF (anisotropic conductive film) fixed to the connection portion of the substrate 111 by thermocompression bonding or the like. For example, a plurality of wiring films 131 to be connected are provided for one head main body 11. In this embodiment, two wiring films 131 are connected to one actuator 113. The wiring film 131 is, for example, a COF (chip on film) on which a driver IC 132 is mounted.

[0042] The driver IC 132 is connected to the plurality of individual electrodes 1181 and the common electrode 1182 via the wiring film 131. The driver IC 132 may be connected to the plurality of individual electrodes 1181 and the common electrode 1182 by other means such as ACP (anisotropic conductive paste), NCF (non-conductive film), and NCP (non-conductive paste) instead of the wiring film 131.

[0043] The printed wiring board 133 is a PWA (Printing Wiring Assembly) on which various electronic components and connectors are mounted.

[0044] Next, the operation of the liquid ejection head 1 and the change in meniscus position over time will be described using Figures 8 and 9. Note that, in order to compare with the change in meniscus position over time of the liquid ejection head 1 of this embodiment, as shown in Figure 9, the change in meniscus position over time of a liquid ejection head of conventional technology that does not have a nozzle chamber 1133 and in which a nozzle 1141 faces a pressure chamber 1131 will be used as a comparative example. Note that the liquid ejection head 1 of this embodiment and the liquid ejection head of the conventional technology are shown as examples in which the drive waveform shown in Figure 8 is applied.

[0045] First, the drive waveform shown in FIG. 8 will be described. The drive waveform is composed of ejection pulses Pa to Pc and a cancel pulse Pd. When this drive waveform is applied to the electrode 118, the piezoelectric element 1134 constituting the pressure chamber 1131 of the actuator 113 undergoes shear deformation, pressurizing the ink filled inside the pressure chamber 1131 and generating pressure vibrations. When the ejection pulses Pa to Pc are applied, the pressure vibrations cause one droplet of ink to be continuously ejected from the nozzle 1141. At this time, in the liquid ejection head 1 according to the embodiment, ink is ejected from the nozzle 1141 through the nozzle chamber 1133 from the pressure chamber 1131. In the liquid ejection head of the comparative example, the nozzle chamber 1133 is not provided, and the nozzle 1141 is disposed opposite the pressure chamber 1131. Therefore, in the liquid ejection head of the comparative example, ink moves from the pressure chamber 1131 to the nozzle 1141 and is ejected from the nozzle 1141.

[0046] When the cancel pulse Pd is applied, the piezoelectric element 1134 that forms the pressure chamber 1131 vibrates, canceling out the pressure vibrations caused by the ejection pulses Pa to Pc. When ink is ejected continuously by a series of multiple ejection pulses Pa to Pc, as in this drive waveform, a flow of ink is generated in the pressure chamber 1131 to replenish the ink toward the nozzle 1141, and even after the ejection operation is completed, the ink continues to flow from the pressure chamber 1131 to the nozzle 1141 due to the inertia of the ink.

[0047] In the conventional technology, the nozzle 1141 is disposed opposite the pressure chamber 1131. Therefore, the width Wb of the pressure chamber 1131 is larger than the inlet diameter Di of the nozzle 1141. This means that the viscous resistance to this flow is small, and the flow of ink after the ejection operation is not suppressed. This results in a phenomenon in which a meniscus protrudes from the nozzle 1141, as shown by the dashed line in FIG. 9 . Furthermore, as shown by NS in FIG. 9 , if the next drive timing of the actuator 113 (pressure chamber 1131) arrives while the meniscus is protruding, and the next ejection operation begins with the meniscus protruding, the ejection speed of the ink ejected from the nozzle 1141 during the next ejection operation drops significantly. This reduction in ink ejection speed can result in misalignment of the ink deposited on the recording medium and variations in the ejection volume, potentially resulting in poor print quality.

[0048] In contrast, the liquid ejection head 1 of the embodiment has a nozzle chamber 1133 in which a nozzle 1141 is disposed outside the pressure chamber 1131. Therefore, the width Wa of the nozzle chamber 1133 can be set relative to the inlet diameter Di of the nozzle 1141, and the width Wb of the pressure chamber 1131 can be made smaller than the inlet diameter Di of the nozzle 1141. This increases the viscous resistance to the flow of ink refilling the pressure chamber 1131. As a result, as shown by the solid line in FIG. 9 , it is possible to prevent the meniscus from swelling, preventing the position of ink deposited on the recording medium from shifting, resulting in poor print quality, and preventing variations in ejection volume. In this way, the liquid ejection head 1 of the embodiment can prevent the meniscus from swelling, even compared to the comparative example shown in FIG. 9 .

[0049] A liquid ejection device 2 having a liquid ejection head 1 will be described below with reference to Fig. 10. The liquid ejection device 2 includes a housing 2111, a medium supply unit 2112, an image forming unit 2113, a medium ejection unit 2114, a transport device 2115 which is a support device, a maintenance device 2117, and a control unit 2118. The liquid ejection device 2 also includes a temperature adjustment device which adjusts the temperature of the ink supplied to the liquid ejection head 1.

[0050] The liquid ejection device 2 is an inkjet printer that performs an image formation process on paper P by ejecting liquid such as ink while transporting the paper P as a recording medium, which is the object of ejection, along a predetermined transport path 2001 that runs from a medium supply section 2112 through an image forming section 2113 to a medium ejection section 2114.

[0051] The medium supply unit 2112 includes a plurality of paper feed cassettes 21121. The image forming unit 2113 includes a support unit 2120 that supports paper, and a plurality of head units 2130 that are arranged above and facing the support unit 2120. The medium discharge unit 2114 includes a paper discharge tray 21141.

[0052] The support section 2120 includes a conveyor belt 21201 that is looped in a predetermined area where image formation is performed, a support plate 21202 that supports the conveyor belt 21201 from the back side, and a plurality of belt rollers 21203 that are provided on the back side of the conveyor belt 21201.

[0053] The head unit 2130 includes liquid ejection heads 1 which are multiple inkjet heads, multiple supply tanks 2132 as liquid tanks mounted on each liquid ejection head 1, a pump 2134 which supplies ink, and a connection flow path 2135 which connects the liquid ejection heads 1 and the supply tanks 2132.

[0054] In this embodiment, the liquid ejection heads 1 are provided with four colors of liquid ejection heads 1 (cyan, magenta, yellow, and black), and four color supply tanks 2132 that respectively store ink of each color. The supply tanks 2132 are connected to the liquid ejection heads 1 by connection flow paths 2135.

[0055] The pump 2134 is a liquid-transfer pump that is configured, for example, as a piezoelectric pump. The pump 2134 is connected to the control unit 2118, and is controlled by the control unit 2118.

[0056] The connection flow path 2135 includes a supply flow path that is connected to the ink supply pipe 123 of the liquid ejection head 1. The connection flow path 2135 also includes a recovery flow path that is connected to the ink discharge pipe 124 of the liquid ejection head 1. For example, since the liquid ejection head 1 is of a non-circulation type, the recovery circuit is connected to a maintenance device 2117.

[0057] The transport device 2115 transports the paper P along a transport path 2001 that runs from a paper feed cassette 21121 in the medium supply unit 2112, through the image forming unit 2113, to a paper discharge tray 21141 in the medium discharge unit 2114. The transport device 2115 includes a plurality of guide plate pairs 21211-21218 and a plurality of transport rollers 21221-21228 that are arranged along the transport path 2001. The transport device 2115 supports the paper P so that it can move relative to the liquid ejection head 1.

[0058] The maintenance device 2117, for example, during maintenance, sucks and recovers ink remaining on the outer surface of the nozzle plate 114. Furthermore, if the liquid ejection head 1 is of a non-circulation type, the maintenance device 2117 recovers ink inside the head main body 11 during maintenance. Such a maintenance device 2117 has a tray, tank, or the like for storing the recovered ink.

[0059] The control unit 2118 includes a CPU 21181 as an example of a processor, a ROM (Read Only Memory) for storing various programs, a RAM (Random Access Memory) for temporarily storing various variable data and image data, and other memories, and an interface unit for inputting data from the outside and outputting data to the outside.

[0060] The liquid ejection head 1 configured in this manner and the liquid ejection device 2 using the liquid ejection head 1 have a nozzle chamber 1133 in the head main body 11 that is continuous with the pressure chamber 1131, and a nozzle 1141 is disposed opposite this nozzle chamber 1133. Therefore, the inlet diameter of the nozzle 1141 can be set in relation to the width of the nozzle chamber 1133, so there is no need to set the width of the pressure chamber 1131 to match the inlet diameter of the nozzle 1141. In other words, the width of the pressure chamber 1131 can be made smaller than the inlet diameter of the nozzle 1141. Therefore, the width of the pressure chamber 1131 can be set to a width that provides appropriate viscous resistance and inertial resistance for the ink.

[0061] By configuring the pressure chamber 1131 in this manner, the head main body 11 can impart appropriate viscous resistance and the like to the ink, and therefore can control the flow of ink from the pressure chamber 1131 toward the nozzle 1141 after the ink is ejected from the nozzle 1141. In other words, when ink is continuously ejected from the nozzle 1141, a flow of ink replenishing toward the nozzle 1141 occurs in the pressure chamber 1131, and the flow continues due to the inertia of the ink even after the ejection operation has ended. However, in the liquid ejection head 1 of the embodiment, the width of the pressure chamber 1131 is made smaller than the inlet diameter of the nozzle 1141, so that the viscous resistance to the flow of ink replenishing can be increased.

[0062] Therefore, the liquid ejection head 1 can prevent a meniscus from rising after ink is ejected from the nozzle surface of the nozzle 1141, and prevent a decrease in ink ejection speed at high drive frequencies. The liquid ejection head 1 can suppress variations in ejection speed and ejection volume even at high drive frequencies, and therefore can stabilize good print quality.

[0063] Furthermore, the multiple pressure chambers 1131 and multiple air chambers 1132 of the actuator 113 are covered by a second liquid barrier 1137 that forms multiple nozzle chambers 1133 on the end (outlet) side of the substrate 111 in the short direction of the actuator 113. Therefore, there is no need to arrange a common liquid chamber 116 between the end of the substrate 111 in the short direction and the actuator 113. Therefore, the width of the substrate 111 in the short direction can be reduced, which makes it possible to make the liquid ejection head 1 smaller.

[0064] According to the liquid ejection head 1 and liquid ejection device 2 described above, by providing the nozzle chamber 1133 that is continuous with the pressure chamber 1131, the width of the pressure chamber 1131 can be made smaller than the inlet diameter ΦDi of the nozzle 1141.

[0065] It should be noted that the embodiments of the present invention are not limited to the above-described configurations. Several example embodiments will be described below. In the embodiments described below, the same components as those in the first embodiment will be designated by the same reference numerals, and detailed description thereof will be omitted.

[0066] For example, in the above example, the head main body 11 is described as having a configuration including the frame 112, but this is not limiting. For example, the frame 112 may not be provided, and the second liquid barrier 1137 may be a rectangular frame that surrounds the pair of actuators 113, the supply port 1111, and the plurality of discharge ports. With this configuration, there is no need to provide the frame 112, and therefore the width of the substrate 111 in the short side direction can be reduced, enabling the head main body 11 to be made smaller.

[0067] In the above example, an example has been described in which one nozzle 1141 is provided facing the nozzle chamber 1133, but this is not limiting. For example, there may be a plurality of nozzles 1141 facing the nozzle chamber 1133, and the shape of the nozzle 1141 can also be set appropriately.

[0068] According to at least one of the embodiments described above, the width of the pressure chamber can be made smaller than the inlet diameter of the nozzle.

[0069] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. The following is a description equivalent to the invention described in the original claims of the present application. [1] An actuator having a plurality of pressure chambers and varying the volumes of the plurality of pressure chambers; a plurality of nozzle chambers provided at one end of the plurality of pressure chambers; a nozzle plate provided opposite the plurality of nozzle chambers and having a plurality of nozzles formed therein for ejecting liquid, the nozzles having an inlet diameter larger than the width of the pressure chambers; A liquid ejection head comprising: [2] The liquid ejection head according to [1], which has a plurality of air chambers arranged alternately with the plurality of pressure chambers. [3] The liquid ejection head according to [1] or [2], wherein the actuator is in a shear mode. [4] The liquid ejection head according to any one of [1] to [3], wherein the width of the nozzle chamber is equal to or greater than the inlet diameter of the nozzle. [5] The actuator has an inclined surface on a side surface in a short side direction, A liquid ejection head according to any one of [1] to [4], wherein the end face of the nozzle chamber facing the pressure chamber extends from the ridge between the inclined surface of the actuator and the bottom surface of the pressure chamber toward the nozzle plate. [Explanation of symbols]

[0070] 1...liquid ejection head, 2...liquid ejection device, 11...head body, 12...manifold unit, 13...circuit board, 111...substrate, 112...frame body, 113...actuator, 114...nozzle plate, 116...common liquid chamber, 118...electrode, 121...manifold, 123...ink supply pipe, 124...ink discharge pipe, 125...temperature-controlled water supply pipe, 131...wiring film, 132...driver IC, 133...printed wiring board, 1111...supply port, 1131...pressure chamber, 1132...air chamber, 1133...nozzle chamber, 1134...piezoelectric body (drive element), 1135...inclined surface, 1136...first liquid barrier, 1137...second liquid barrier, 1138...bottom surface, 1139...end surface, 11 41...nozzle, 1142...nozzle row, 1181...individual electrode, 1182...common electrode, 1183...mounting pad, 2001...transport path, 2111...housing, 2112...medium supply section, 2113...image forming section, 2114...medium discharge section, 2115...transport device, 2117...maintenance device, 2118...control section, 2120...support section, 2130...head unit, 2132...supply tank, 2134...pump, 2135...connecting flow path, 21121...paper feed cassette, 21141...paper discharge tray, 21201...transport belt, 21202...support plate, 21203...belt roller, 21211-21218...guide plate pair, 21221-21228...transport rollers.

Claims

1. an actuator having a plurality of pressure chambers and varying the volumes of the plurality of pressure chambers; a plurality of nozzle chambers provided at one end of the plurality of pressure chambers; a nozzle plate provided opposite the plurality of nozzle chambers and having a plurality of nozzles formed therein for ejecting liquid, the nozzles having an inlet diameter larger than the width of the pressure chambers; Equipped with the actuator has an inclined surface on a side surface in a short side direction of the actuator, a liquid ejection head, wherein an end surface of the nozzle chamber facing the pressure chamber extends from a ridge between the inclined surface of the actuator and a bottom surface of the pressure chamber toward the nozzle plate;

2. The liquid ejection head according to claim 1 , further comprising a plurality of air chambers arranged alternately with the plurality of pressure chambers.

3. 3. The liquid ejection head according to claim 1, wherein the actuator is in a shear mode.

4. 4. The liquid ejection head according to claim 1, wherein a width of the nozzle chamber is equal to or greater than a diameter of an inlet of the nozzle.

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