Liquid ejection head and recording device

Abstract

This liquid ejection head comprises a flow passage member, a pressurizing part, a flexible substrate, a cover member, and a reservoir. The flow passage member has an ejection hole that ejects a liquid. The pressurizing part is positioned over the flow passage member. The flexible substrate is electrically connected to the pressurizing part. The reservoir has a slit through which the flexible substrate is inserted, and the reservoir supplies the liquid to the flow passage member. A protective sheet is positioned between the flexible substrate and an inner wall surface that faces the flexible substrate in the width direction of the slit.

Description

Liquid ejection head and recording apparatus

[0001] The disclosed embodiments relate to a liquid ejection head and a recording apparatus.

[0002] 2. Description of the Related Art Known printing devices include inkjet printers and inkjet plotters that use an inkjet recording method. Such inkjet printing devices are equipped with a liquid ejection head for ejecting liquid.

[0003] Such a liquid ejection head has a flexible substrate connected to a pressure applying portion on a flow path member that ejects liquid. The flexible substrate is inserted into a slit portion of a reservoir that supplies liquid to the flow path member, and is drawn out from the slit portion above the reservoir.

[0004] JP 2010-227759 A

[0005] A liquid ejection head according to one aspect of the embodiment includes a flow path member, a pressure applying unit, a flexible substrate, a reservoir, and a protective sheet. The flow path member has an ejection hole for ejecting liquid. The pressure applying unit is located on the flow path member. The flexible substrate is electrically connected to the pressure applying unit. The reservoir has a slit portion through which the flexible substrate is inserted and supplies liquid to the flow path member. The protective sheet is located between the flexible substrate and an inner wall surface of the slit portion that faces the flexible substrate in the width direction.

[0006] FIG. 1 is a front view schematically showing the front of a printer according to an embodiment. FIG. 2 is a plan view schematically showing the plane of a printer according to an embodiment. FIG. 3 is an exploded perspective view showing the general configuration of a liquid ejection head according to an embodiment. FIG. 4 is a perspective view showing the configuration of a main part of a liquid ejection head according to an embodiment. FIG. 5 is an enlarged plan view of a head main body according to an embodiment. FIG. 6 is an enlarged view of an area surrounded by a dashed dotted line shown in FIG. 5. FIG. 7 is a cross-sectional view taken along line VII-VII shown in FIG. 5. FIG. 8 is an enlarged cross-sectional view taken along line VIII-VIII shown in FIG. 4. FIG. 9 is a side view of a protective sheet as viewed from the negative direction of the X axis. FIG. 10 is an explanatory diagram for explaining an example of a method for adhering a protective sheet.

[0007] Hereinafter, embodiments of a liquid ejection head and a recording apparatus disclosed in the present application will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to the embodiments described below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of elements may differ from reality. Furthermore, the dimensional relationships and ratios may differ between the drawings.

[0008] Furthermore, in the following embodiments, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not necessarily mean "constant," "orthogonal," "perpendicular," or "parallel" in the strict sense. In other words, the above expressions allow for deviations due to, for example, manufacturing precision, installation precision, etc.

[0009] Furthermore, the embodiments can be combined as appropriate within the scope of not causing any contradiction in the processing content. Furthermore, the same components in the following embodiments are denoted by the same reference numerals, and redundant explanations will be omitted.

[0010] <Printer Configuration> First, an overview of a printer 1, which is an example of a recording apparatus according to an embodiment, will be described with reference to Figures 1 and 2. Figure 1 is a front view that schematically shows the front surface of the printer 1 according to an embodiment. Figure 2 is a plan view that schematically shows the plane of the printer 1 according to an embodiment. The printer 1 according to an embodiment is, for example, a color inkjet printer.

[0011] As shown in FIG. 1, the printer 1 includes a paper feed roller 2, a guide roller 3, an applicator 4, a head case 5, a plurality of conveying rollers 6, a plurality of frames 7, a plurality of liquid ejection heads 8, a conveying roller 9, a dryer 10, a conveying roller 11, a sensor unit 12, and a recovery roller 13.

[0012] Furthermore, the printer 1 includes a control unit 14 that controls each part of the printer 1. The control unit 14 controls the operations of the paper feed roller 2, the guide roller 3, the coater 4, the head case 5, the plurality of transport rollers 6, the plurality of frames 7, the plurality of liquid ejection heads 8, the transport roller 9, the dryer 10, the transport roller 11, the sensor unit 12, and the recovery roller 13.

[0013] The printer 1 records images and characters on the printing paper P by causing droplets to land on the printing paper P. The printing paper P is an example of a recording medium. Before use, the printing paper P is wound around a paper feed roller 2. The printer 1 transports the printing paper P from the paper feed roller 2, via a guide roller 3 and a coater 4, into the inside of a head case 5.

[0014] The coater 4 applies the coating agent evenly to the printing paper P. This allows the printing paper P to be surface treated, thereby improving the printing quality of the printer 1.

[0015] The head case 5 houses a plurality of transport rollers 6, a plurality of frames 7, and a plurality of liquid ejection heads 8. Inside the head case 5, a space is formed that is isolated from the outside, except for a portion that is connected to the outside, such as a portion where the printing paper P enters and leaves.

[0016] At least one of the control factors such as temperature, humidity, and air pressure of the internal space of the head case 5 is controlled by the control unit 14 as necessary. The transport rollers 6 transport the printing paper P inside the head case 5 to the vicinity of the liquid ejection head 8.

[0017] The frame 7 is a rectangular flat plate, and is positioned above and in close proximity to the print paper P being transported by the transport rollers 6. As shown in Figure 2, the frame 7 is positioned so that its longitudinal direction is perpendicular to the transport direction of the print paper P. Inside the head case 5, multiple (for example, four) frames 7 are positioned at predetermined intervals along the transport direction of the print paper P.

[0018] A liquid, such as ink, is supplied from a liquid tank (not shown) to the liquid ejection head 8. The liquid ejection head 8 ejects the liquid supplied from the liquid tank.

[0019] The control unit 14 controls the liquid ejection head 8 based on data such as images and characters, and ejects liquid toward the printing paper P. The distance between the liquid ejection head 8 and the printing paper P is, for example, about 0.5 to 20 mm.

[0020] The liquid ejection head 8 is fixed to the frame 7. The liquid ejection head 8 is positioned so that its longitudinal direction is perpendicular to the direction in which the printing paper P is transported.

[0021] That is, the printer 1 according to the embodiment is a so-called line printer in which the liquid ejection head 8 is fixed inside the printer 1. Note that the printer 1 according to the embodiment is not limited to a line printer, and may also be a so-called serial printer.

[0022] A serial printer is a printer that alternates between recording by moving the liquid ejection head 8 back and forth in a direction that intersects the transport direction of the printing paper P, for example, in a direction that is approximately perpendicular to the direction, and transporting the printing paper P.

[0023] As shown in Fig. 2, a plurality of (for example, five) liquid ejection heads 8 are fixed to one frame 7. Fig. 2 shows an example in which three liquid ejection heads 8 are positioned in front and two in the rear in the transport direction of the printing paper P, and the liquid ejection heads 8 are positioned in the transport direction of the printing paper P so that the centers of the liquid ejection heads 8 do not overlap.

[0024] A head group 8A is made up of multiple liquid ejection heads 8 positioned on one frame 7. The four head groups 8A are positioned along the transport direction of the printing paper P. The same color ink is supplied to the liquid ejection heads 8 belonging to the same head group 8A. This allows the printer 1 to print with four colors of ink using the four head groups 8A.

[0025] The colors of ink ejected from each head group 8A are, for example, magenta (M), yellow (Y), cyan (C), and black (K). The control unit 14 controls each head group 8A to eject ink of multiple colors onto the printing paper P, thereby printing a color image on the printing paper P.

[0026] In order to treat the surface of the printing paper P, a coating agent may be ejected onto the printing paper P from the liquid ejection head 8 .

[0027] Furthermore, the number of liquid ejection heads 8 included in one head group 8A and the number of head groups 8A mounted on the printer 1 can be changed as appropriate depending on the object to be printed and the printing conditions. For example, if a single color is printed on the printing paper P and the printing range is to be printed with one liquid ejection head 8, the number of liquid ejection heads 8 mounted on the printer 1 may be one.

[0028] The printing paper P that has been printed inside the head case 5 is transported to the outside of the head case 5 by transport rollers 9 and passes through the inside of a dryer 10. The dryer 10 dries the printing paper P that has been printed. The printing paper P that has been dried in the dryer 10 is transported by transport rollers 11 and collected by a collection roller 13.

[0029] In the printer 1, by drying the printing paper P in the dryer 10, it is possible to reduce adhesion between overlapping printing paper P wound up on the recovery roller 13 and rubbing of undried liquid.

[0030] The sensor unit 12 is composed of a position sensor, a speed sensor, a temperature sensor, etc. The control unit 14 can determine the state of each part of the printer 1 based on information from the sensor unit 12 and control each part of the printer 1.

[0031] The printer 1 described so far has been shown to use printing paper P as the printing object (i.e., recording medium), but the printing object in printer 1 is not limited to printing paper P, and the printing object may also be a roll of cloth or the like.

[0032] Furthermore, the printer 1 may transport the printing paper P on a conveyor belt instead of directly transporting the printing paper P. By using a conveyor belt, the printer 1 can print on sheets of paper, cut pieces of cloth, wood, tiles, and the like.

[0033] The printer 1 may also print wiring patterns for electronic devices by ejecting liquid containing conductive particles from the liquid ejection head 8 .

[0034] The printer 1 may also produce chemicals by ejecting a predetermined amount of liquid chemicals or liquid containing chemicals from the liquid ejection head 8 toward a reaction vessel or the like.

[0035] The printer 1 may also include a cleaning unit that cleans the liquid ejection head 8. The cleaning unit cleans the liquid ejection head 8 by, for example, wiping or capping.

[0036] The wiping process is a process of removing liquid adhering to the liquid ejection head 8 by wiping the surface of the area where the liquid is ejected with a flexible wiper, for example.

[0037] The capping process is performed, for example, as follows: First, a cap is placed over the portion from which the liquid is ejected, for example, the second surface 21b (see FIG. 7) of the flow path member 21 (this process is called capping). As a result, a substantially sealed space is formed between the second surface 21b and the cap.

[0038] Next, the liquid is repeatedly discharged into this sealed space, thereby removing any liquid with a higher viscosity than the standard state or foreign matter that may have clogged the discharge hole 163 (see FIG. 7).

[0039] <Configuration of Liquid Ejection Head> Next, the configuration of the liquid ejection head 8 according to this embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is an exploded perspective view showing the schematic configuration of the liquid ejection head 8 according to this embodiment. Fig. 4 is a perspective view showing the configuration of the main part of the liquid ejection head 8 according to this embodiment.

[0040] The liquid ejection head 8 includes a head main body 20, a wiring section 40, and a support member 50. The head main body 20 includes a flow path member 21, a piezoelectric actuator substrate 22, and a reservoir 70. The wiring section 40 includes flexible substrates 41 and 42, and a drive IC 43.

[0041] For ease of understanding, FIGS. 3 and 4 illustrate a three-dimensional Cartesian coordinate system including a Z-axis, with the vertical downward direction being the positive direction and the vertical upward direction being the negative direction. This Cartesian coordinate system may also be shown in other drawings used in the following description. For convenience, in the following description, the direction in which the flow path member 21 of the head main body 20 in the liquid ejection head 8 is provided, i.e., the positive Z-axis direction, may be referred to as "down," and the direction in which the reservoir 70 is provided relative to the flow path member 21, i.e., the negative Z-axis direction, may be referred to as "up." In addition, in FIGS. 3 and 4, the shapes of the various components may be shown in simplified form.

[0042] The flow path member 21 has a generally flat plate shape and has a first surface 21a (see FIG. 7) which is one main surface, and a second surface 21b (see FIG. 7) located on the opposite side of the first surface 21a. The first surface 21a has an opening 161a (see FIG. 5), and liquid is supplied from the reservoir 70 to the inside of the flow path member 21 through the opening 161a.

[0043] The second surface 21b has a plurality of ejection holes 163 (see FIG. 5) that eject liquid onto the printing paper P. Inside the flow path member 21, a flow path is formed that allows the liquid to flow from the first surface 21a to the second surface 21b.

[0044] The piezoelectric actuator substrate 22 is located on the first surface 21a of the flow path member 21. The piezoelectric actuator substrate 22 has a plurality of displacement elements 170 (see FIG. 7). The displacement elements 170 are an example of a pressure applying section. The displacement elements 170 are located on the first surface 21a of the flow path member 21. The piezoelectric actuator substrate 22 will be described later with reference to FIG. 7.

[0045] Flexible substrates 41 and 42 are electrically connected to the piezoelectric actuator substrate 22. The flexible substrates 41 and 42 are flexible wiring substrates, and have the function of transmitting predetermined signals sent from the outside to the head main body 20. As shown in Fig. 3, the liquid ejection head 8 according to this embodiment has two flexible substrates 41 and 42. Note that the flexible substrates 41 and 42 are not shown in Fig. 4.

[0046] One end 41 a, 42 a (see FIG. 8 ) of the flexible substrates 41, 42 is located on the piezoelectric actuator substrate 22 of the head body 20. The one end 41 a, 42 a is electrically connected to the piezoelectric actuator substrate 22 of the head body 20. The other end of the flexible substrates 41, 42 is inserted into the slit portion 70 b of the reservoir 70, and is drawn out from the slit portion 70 b above the support member 50 (see FIG. 8 ), and is electrically connected to another wiring substrate (not shown). The flexible substrates 41, 42 have a connection surface that is connected to the piezoelectric actuator substrate 22 of the head body 20 and an opposite surface that is located opposite the connection surface.

[0047] The driving ICs 43 are mounted on the flexible substrates 41 and 42. The driving ICs 43 control the driving of the displacement elements 170 on the piezoelectric actuator substrate 22.

[0048] 3, two driving ICs 43 are provided on each of the flexible substrates 41 and 42. The number of driving ICs 43 provided on each of the flexible substrates 41 and 42 is not limited to two.

[0049] 3 and 4, such as a housing that houses the wiring portion 40. The support member 50 has a rectangular frame shape that extends in the longitudinal direction of the liquid ejection head 8, and is positioned on the reservoir 70 so as to surround a predetermined region that includes the slit portion 70b in a plan view.

[0050] The reservoir 70 is located on the first surface 21a side of the head main body 20 and is in contact with the first surface 21a other than the piezoelectric actuator substrate 22. The reservoir 70 has a flow path therein, and liquid is supplied from the outside through an opening 70a. The reservoir 70 has the function of supplying liquid to the flow path member 21 and the function of storing the supplied liquid.

[0051] The liquid ejection head 8 may further include components other than those shown in FIGS. 3 and 4, such as a housing that houses the wiring portion 40.

[0052] <Configuration of Head Main Body> Next, the configuration of the head main body 20 according to this embodiment will be described with reference to Figs. 5 to 7. Fig. 5 is an enlarged plan view of the head main body 20 according to this embodiment. Fig. 6 is an enlarged view of the area surrounded by the dashed line shown in Fig. 5. Fig. 7 is a cross-sectional view taken along line VII-VII shown in Fig. 5. Note that the right-hand area in Fig. 5 shows a transparent area.

[0053] 5, the head main body 20 has a flow path member 21 and a piezoelectric actuator substrate 22. The flow path member 21 has a supply manifold 161, a plurality of pressure chambers 162, and a plurality of ejection holes 163.

[0054] The plurality of pressurizing chambers 162 are connected to the supply manifold 161. The plurality of discharge holes 163 are connected to the plurality of pressurizing chambers 162, respectively.

[0055] The pressurizing chamber 162 is open to a first surface 21a (see FIG. 7) of the flow path member 21. The first surface 21a of the flow path member 21 has an opening 161a that is connected to the supply manifold 161. Liquid is supplied from the reservoir 70 (see FIG. 3) to the inside of the flow path member 21 through the opening 70a.

[0056] 5, the head main body 20 has four supply manifolds 161 inside the flow path member 21. The supply manifolds 161 have an elongated shape extending along the longitudinal direction of the flow path member 21, and openings 161a of the supply manifolds 161 are formed on the first surface 21a of the flow path member 21 at both ends thereof.

[0057] A plurality of pressure chambers 162 are formed in a two-dimensional manner in the flow path member 21. Each pressure chamber 162 is a hollow region having a generally diamond-shaped planar shape with rounded corners. The pressure chambers 162 open to the first surface 21 a of the flow path member 21 and are closed by bonding the piezoelectric actuator substrate 22 to the first surface 21 a.

[0058] The pressure chambers 162 form pressure chamber rows arranged in the longitudinal direction. The pressure chambers 162 in a pressure chamber row are arranged in a staggered pattern between two adjacent pressure chamber rows. Two pressure chamber rows connected to one supply manifold 161 form one pressure chamber group. In the example shown in FIG. 5 , the flow path member 21 has four pressure chamber groups.

[0059] The relative arrangement of the pressure chambers 162 within each pressure chamber group is the same, and the pressure chamber groups are positioned slightly offset from each other in the longitudinal direction.

[0060] The discharge holes 163 are arranged at positions that avoid an area of ​​the flow path member 21 that faces the supply manifold 161. In other words, when the flow path member 21 is seen through from the first surface 21 a side, the discharge holes 163 do not overlap with the supply manifold 161.

[0061] Furthermore, in plan view, the discharge holes 163 are positioned so as to fit within the mounting area of ​​the piezoelectric actuator substrate 22. Such discharge holes 163 occupy an area as a group that is approximately the same size and shape as the piezoelectric actuator substrate 22.

[0062] Then, by displacing the displacement element 170 (see FIG. 7), which is the pressure applying portion of the corresponding piezoelectric actuator substrate 22, droplets are ejected from the ejection hole 163.

[0063] 7, the flow path member 21 has a laminated structure in which a plurality of plates are stacked. These plates are, in order from the first surface 21a side of the flow path member 21, a cavity plate 21A, a base plate 21B, an aperture (restriction) plate 21C, a supply plate 21D, manifold plates 21E, 21F, and 21G, a cover plate 21H, and a nozzle plate 21I.

[0064] A large number of holes are formed in the plates that make up the flow path member 21. The thickness of each plate is approximately 10 μm to 300 μm. This allows for high accuracy in the hole formation. The plates are aligned and stacked so that these holes communicate with each other to form the individual flow paths 164 and the supply manifold 161.

[0065] In the flow path member 21, the supply manifold 161 and the discharge holes 163 are connected by individual flow paths 164. The supply manifold 161 is located on the second surface 21b side inside the flow path member 21, and the discharge holes 163 are located on the second surface 21b of the flow path member 21.

[0066] The individual flow path 164 has a pressurizing chamber 162 and an individual supply flow path 165. The pressurizing chamber 162 is located on the first surface 21a of the flow path member 21, and the individual supply flow path 165 is a flow path that connects the supply manifold 161 and the pressurizing chamber 162.

[0067] Furthermore, the individual supply flow path 165 includes a restriction 166 that is narrower than the other portions. The restriction 166 has a high flow path resistance because it is narrower than the other portions of the individual supply flow path 165. When the flow path resistance of the restriction 166 is high in this way, the pressure generated in the pressurizing chamber 162 is less likely to escape to the supply manifold 161.

[0068] The piezoelectric actuator substrate 22 includes piezoelectric ceramic layers 22A and 22B, a common electrode 171, individual electrodes 172, connection electrodes 173, dummy connection electrodes 174, and surface electrodes 175 (see FIG. 5).

[0069] The piezoelectric actuator substrate 22 has a piezoelectric ceramic layer 22B, a common electrode 171, a piezoelectric ceramic layer 22A, and an individual electrode 172 laminated in this order.

[0070] The piezoelectric ceramic layers 22A, 22B each have a thickness of about 20 μm. Each of the piezoelectric ceramic layers 22A, 22B extends so as to straddle the multiple pressure chambers 162. The piezoelectric ceramic layers 22A, 22B can be made of a ferroelectric ceramic material such as lead zirconate titanate (PZT).

[0071] The common electrode 171 is formed over substantially the entire surface in the plane direction in the region between the piezoelectric ceramic layer 22A and the piezoelectric ceramic layer 22B. In other words, the common electrode 171 overlaps with all of the pressure chambers 162 in the region facing the piezoelectric actuator substrate 22. The thickness of the common electrode 171 is approximately 2 μm. The common electrode 171 can be made of, for example, a metal material such as an Ag—Pd system.

[0072] The individual electrode 172 includes an individual electrode body 172a and an extraction electrode 172b. The individual electrode body 172a is located on the piezoelectric ceramic layer 22B in an area facing the pressure chamber 162. The individual electrode body 172a is slightly smaller than the pressure chamber 162 and has a shape that is approximately similar to that of the pressure chamber 162.

[0073] The extraction electrode 172b is extracted from the individual electrode body 172a. A connection electrode 173 is located at one end of the extraction electrode 172b, at a portion that is extracted outside the region facing the pressure chamber 162. The individual electrode 172 can be made of a metal material such as an Au-based material.

[0074] The connection electrode 173 is located on the extraction electrode 172b, has a thickness of about 15 μm, and is convex. The connection electrode 173 is electrically connected to electrodes provided on the flexible substrates 41 and 42 (see FIG. 3). The connection electrode 173 can be made of, for example, silver-palladium containing glass frit.

[0075] The dummy connection electrodes 174 are located on the piezoelectric ceramic layer 22A so as not to overlap with various electrodes such as the individual electrodes 172. The dummy connection electrodes 174 connect the piezoelectric actuator substrate 22 and the flexible substrates 41 and 42, thereby increasing the connection strength.

[0076] Furthermore, the dummy connection electrodes 174 stabilize the electrical connection by uniformly distributing the contact positions between the piezoelectric actuator substrates 22. The dummy connection electrodes 174 are preferably formed using the same material and process as the connection electrodes 173.

[0077] The surface electrode 175 is formed on the piezoelectric ceramic layer 22A at a position that avoids the individual electrodes 172. The surface electrode 175 is connected to the common electrode 171 through a via hole formed in the piezoelectric ceramic layer 22A. Therefore, the surface electrode 175 is grounded and maintained at ground potential. The surface electrode 175 is preferably formed using the same material and process as the individual electrodes 172.

[0078] In order to individually control the potential of the individual electrodes 172, each of them is electrically connected to the control unit 14 (see FIG. 1) via the flexible substrates 41, 42 and wiring. When the individual electrodes 172 and the common electrode 171 are set to different potentials and an electric field is applied in the polarization direction of the piezoelectric ceramic layer 22A, the portion of the piezoelectric ceramic layer 22A to which the electric field is applied operates as an active portion that is distorted by the piezoelectric effect.

[0079] That is, in the piezoelectric actuator substrate 22, the individual electrodes 172, the piezoelectric ceramic layer 22A, and the portions of the common electrode 171 that face the pressure chambers 162 function as displacement elements 170. When the displacement elements 170 undergo unimorph deformation, the pressure chambers 162 are pressed, and liquid is ejected from the ejection holes 163.

[0080] Next, a driving procedure for the liquid ejection head 8 according to this embodiment will be described. First, the individual electrodes 172 are set in advance to a higher potential (hereinafter referred to as a high potential) than the common electrode 171. Then, each time an ejection request is made, the individual electrodes 172 are temporarily set to the same potential as the common electrode 171 (hereinafter referred to as a low potential), and then are set to a high potential again at a predetermined timing.

[0081] As a result, when the individual electrode 172 becomes low potential, the piezoelectric ceramic layers 22A and 22B return to their original shapes, and the volume of the pressure chamber 162 increases compared to the initial state (when the potentials of both electrodes are different).

[0082] At this time, a negative pressure is applied to the pressurizing chamber 162, and the liquid is sucked into the pressurizing chamber 162 from the supply manifold 161 side. Thereafter, when the individual electrode 172 is again set to a high potential, the piezoelectric ceramic layers 22A and 22B deform so as to become convex toward the pressurizing chamber 162 side, and the pressure inside the pressurizing chamber 162 becomes positive due to the reduction in the volume of the pressurizing chamber 162.

[0083] As a result, the pressure applied to the liquid inside the pressure chamber 162 increases, and droplets are ejected. In other words, in order to eject droplets, a drive signal including a pulse based on a high potential is supplied to the individual electrode 172.

[0084] This pulse width may be set to AL (Acoustic Length), which is the length of time it takes for the pressure wave to propagate from the restrictor 166 to the discharge hole 163. In this way, when the inside of the pressure chamber 162 changes from a negative pressure state to a positive pressure state, the pressures of both sides are combined, and droplets can be discharged with stronger pressure.

[0085] In gradation printing, gradation is expressed by the number of droplets continuously ejected from the ejection holes 163, i.e., the droplet amount (volume) is adjusted by the number of droplet ejections. Therefore, droplets are continuously ejected the number of times corresponding to the specified gradation expression from the ejection holes 163 corresponding to the specified dot region.

[0086] Generally, when liquid is continuously ejected, the interval between pulses supplied to eject droplets may be set to AL. This causes the period of the residual pressure wave generated when ejecting the previously ejected droplet to match the period of the pressure wave generated when ejecting the next droplet. Therefore, the residual pressure wave and the pressure wave overlap, amplifying the pressure for ejecting the droplets. In this case, the speed of the droplets ejected later increases, and the impact points of multiple droplets become closer.

[0087] <Configuration of Main Parts of Liquid Ejection Head> Next, the configuration of main parts of the liquid ejection head 8 according to this embodiment will be described with reference to Fig. 8. Fig. 8 is an enlarged cross-sectional view taken along line VIII-VIII shown in Fig. 4.

[0088] As shown in FIG. 8, the reservoir 70 is located on the first surface 21a of the flow path member 21, and has a storage portion 70c and a slit portion 70b.

[0089] As described above, the piezoelectric actuator substrate 22 and the one ends 41 a, 42 a of the flexible substrates 41, 42 are located in this order on the first surface 21 a of the flow path member 21. The accommodation section 70 c is a space that accommodates the piezoelectric actuator substrate 22 and the one ends 41 a, 42 a of the flexible substrates 41, 42 between itself and the first surface 21 a.

[0090] The slit portion 70b is a groove-shaped gap that extends along the longitudinal direction (Y-axis direction) of the reservoir 70. The slit portion 70b is open on the top surface of the reservoir 70, and allows communication between the outside of the reservoir 70 and a storage portion 70c, which is a space formed inside the reservoir 70. The flexible substrates 41 and 42 connected to the piezoelectric actuator substrate 22 are inserted into the slit portion 70b and are drawn out to the outside of the reservoir 70 from the slit portion 70b.

[0091] The reservoir 70 also has a protective sheet 200 on one inner wall surface 70b1 of the slit portion 70b that faces the flexible substrates 41, 42 in the width direction of the slit portion 70b. The inner wall surface 70b1 of the slit portion 70b is located outside the short-side direction (X-axis direction) of the reservoir 70 and faces the connection surfaces of the flexible substrates 41, 42 that are inserted into the slit portion 70b. That is, the slit portion 70b has an inner wall surface that is located inside the short-side direction (X-axis direction) of the reservoir 70 and an inner wall surface 70b1 that is located outside the short-side direction (X-axis direction) of the reservoir 70. The protective sheet 200 is located between the outer inner wall surface 70b1 of the slit portion 70b and the flexible substrate 41, and between the outer inner wall surface 70b1 of the slit portion 70b and the flexible substrate 42.

[0092] In this way, by providing the protective sheet 200 on the inner wall surface 70b1 of the slit portion 70b of the reservoir 70, it is possible to prevent contact between the inner wall surface 70b1 and the flexible substrates 41 and 42 inserted into the slit portion 70b, thereby reducing the risk of damage to the flexible substrates 41 and 42.

[0093] Examples of materials that can be used for protective sheet 200 include polyethylene terephthalate and polycarbonate. Protective sheet 200 has higher rigidity than flexible substrates 41 and 42. Due to the high rigidity of protective sheet 200, protective sheet 200 can act as a guide for guiding flexible substrates 41 and 42 that are inserted into slit portion 70b, thereby improving work efficiency.

[0094] The protective sheet 200 also has a first surface and a second surface having a surface roughness greater than that of the first surface. For example, the ten-point mean surface roughness (Rz) of the first surface of the protective sheet 200 is approximately 5 μm, and the ten-point mean surface roughness (Rz) of the second surface of the protective sheet 200 is approximately 15 μm. The second surface of the protective sheet 200, which has a greater surface roughness, faces the flexible substrates 41 and 42. By facing the second surface of the protective sheet 200 toward the flexible substrates 41 and 42, the contact area between the protective sheet 200 and the flexible substrates 41 and 42 is reduced, making it easier to pull out the flexible substrates 41 and 42 from the slit portion 70b. Such a protective sheet 200 may be fabricated by stacking protective sheets having the above-described surface roughnesses, or by surface processing to achieve the above-described surface roughness.

[0095] The protective sheet 200 is also adhered to the inner wall surface 70b1 of the slit portion 70b via an adhesive member 300. The adhesive member 300 is, for example, double-sided tape. By adhering the protective sheet 200 to the inner wall surface 70b1 of the slit portion 70b, the position of the protective sheet 200 can be fixed relative to the inner wall surface 70b1 of the slit portion 70b. Furthermore, a gap is formed between the lower end of the protective sheet 200 and the piezoelectric actuator substrate 22. This makes it less likely that the lower end of the protective sheet 200 will come into contact with the piezoelectric actuator substrate 22, making the piezoelectric actuator substrate 22 less likely to be damaged.

[0096] As shown in FIG. 8 , the reservoir 70 has a laminated structure in which multiple plates are stacked. These multiple plates include, for example, plates 70A to 70E, positioned in order from the top surface of the reservoir 70. Numerous holes are formed in the multiple plates 70A to 70E that make up the reservoir 70. The multiple plates 70A to 70E are aligned and stacked so that the holes communicate with each other to form the storage section 70c and the slit section 70b. For example, the holes in plates 70A to 70C communicate with each other to form the slit section 70b, and the holes in plates 70D and 70E communicate with each other to form the storage section 70c. The protective sheet 200 is adhered via an adhesive member 300 to the inner wall surface 70b1 of the hole in at least the thickest plate of the plates 70A to 70C. 8, plate 70C is the thickest of plates 70A to 70C, and therefore protective sheet 200 is adhered to the inner wall surface 70b1 of the hole in plate 70C via adhesive member 300. By adhering protective sheet 200 to at least the inner wall surface 70b1 of the hole in the thickest plate, the adhesive strength between protective sheet 200 and the inner wall surface 70b1 of slit portion 70b can be maintained. Note that protective sheet 200 may also be adhered via adhesive member 300 to the inner wall surface 70b1 of the holes in plates 70B and 70D adjacent to plate 70C, in addition to the inner wall surface 70b1 of the hole in plate 70C.

[0097] Furthermore, the protective sheet 200 has a protruding portion 201 that protrudes from the slit portion 70b above the upper end of the support member 50. Therefore, the protective sheet 200 can serve as a guide that guides the placement of the support member 50 on the reservoir 70, and can accurately position the support member 50 on the reservoir 70. Furthermore, the protective sheet 200 can serve as a wall that shields the slit portion 70b from the interface between the reservoir 70 and the support member 50, and can reduce the risk of the adhesive 400 (described below) that bonds the reservoir 70 and the support member 50 together penetrating into the slit portion 70b.

[0098] Furthermore, protective sheet 200 contacts flexible substrates 41, 42, which are drawn out from slit portion 70b above the upper end of support member 50, at protruding portion 201. This makes it possible to avoid contact between the upper end of support member 50 and flexible substrates 41, 42, which are drawn out above the upper end of support member 50, thereby further reducing the risk of damage to flexible substrates 41, 42.

[0099] 9, the protective sheet 200 has chamfered portions 201a at the corners of the protruding portions 201. Fig. 9 is a side view of the protective sheet 200 as viewed from the negative direction of the X axis. By having the chamfered portions 201a at the corners of the protruding portions 201, the protective sheet 200 can reduce interference between the protective sheet 200 and the support member 50 when the support member 50 is placed on the reservoir 70 using the protective sheet 200 as a guide, thereby improving work efficiency.

[0100] Returning to the explanation of Figure 8, the protective sheet 200 has an end 202 that is not adhered to the inner wall surface 70b1 of the slit portion 70b. This end 202 is located close to the connection portion between the flexible substrates 41, 42 and the piezoelectric actuator substrate 22 (i.e., one end 41a, 42a of the flexible substrates 41, 42). Therefore, the end 202 of the protective sheet 200, whose movement is not restricted, can be located close to the connection portion between the flexible substrates 41, 42 and the piezoelectric actuator substrate 22, making it easier to pull out the flexible substrates 41, 42 from the slit portion 70b.

[0101] 8 , the support member 50 is adhered onto the reservoir 70 via an adhesive 400. A portion of the adhesive 400 seeps out from the interface between the support member 50 and the reservoir 70 and is positioned between the inner wall surface of the support member 50 and the protective sheet 200. With a portion of the adhesive 400 positioned between the inner wall surface of the support member 50 and the protective sheet 200, the protective sheet 200 is adhered to the inner wall surface 70b1 of the slit portion 70b via the adhesive member 300, and is also adhered to the inner wall surface of the support member 50 via the adhesive 400. This improves the adhesive strength of the protective sheet 200, reducing the possibility of the protective sheet 200 peeling off from the inner wall surface 70b1 of the slit portion 70b.

[0102] <Protective Sheet Adhesion Method> Next, a protective sheet 200 adhesion method will be described with reference to Fig. 10. Fig. 10 is an explanatory diagram for explaining an example of a protective sheet 200 adhesion method.

[0103] The method for adhering the protective sheet 200 uses a jig 500. The jig 500 has a plate-shaped base portion 501 and a pedestal portion 502 that rises from the base portion 501 and has a tapered surface 502a.

[0104] First, protective sheet 200 is placed on base 502 in a tilted state along tapered surface 502a, and is inserted together with base 502 into slit 70b of reservoir 70. In Fig. 10, protective sheet 200 placed on base 502 is shown by a dashed line. Adhesive member 300, which is double-sided tape, is attached to protective sheet 200 in advance.

[0105] Next, the protective sheet 200 is rotated on the base portion 502 in a direction away from the tapered surface 502a, so that the adhesive member 300 is attached to the inner wall surface 70b1 of the slit portion 70b. As a result, the protective sheet 200 is adhered to the inner wall surface 70b1 of the slit portion 70b via the adhesive member 300. Thereafter, the base portion 502 is pulled out from the slit portion 70b of the reservoir 70.

[0106] <Another embodiment> In the above embodiment, the protective sheet 200 has the protruding portion 201 that protrudes from the slit portion 70b above the upper end of the support member 50. However, it is also possible to adopt a configuration in which the protruding portion 201 is omitted. In other words, the protective sheet 200 may extend from the slit portion 70b to the upper end of the support member 50.

[0107] As described above, a liquid ejection head according to an embodiment (e.g., liquid ejection head 8) includes a flow path member (e.g., flow path member 21), a pressure applying unit (e.g., displacement element 170), a flexible substrate (e.g., flexible substrates 41, 42), and a reservoir (e.g., reservoir 70). The flow path member has a discharge hole (e.g., discharge hole 163) for discharging liquid. The pressure applying unit is located on the flow path member. The flexible substrate is electrically connected to the pressure applying unit. The reservoir has a slit portion (e.g., slit portion 70b) through which the flexible substrate is inserted and supplies liquid to the flow path member. The reservoir has a protective sheet (e.g., protective sheet 200) on one inner wall surface (e.g., inner wall surface 70b1) facing the flexible substrate in the width direction of the slit portion. This reduces the risk of damage to the flexible substrate according to the liquid ejection head according to an embodiment.

[0108] The liquid ejection head according to the embodiment may further include a frame-shaped support member (e.g., support member 50) positioned on the reservoir so as to surround a predetermined region including the slit portion in a plan view. The protective sheet may have a protrusion (e.g., protrusion 201) that protrudes from the slit portion above the upper end of the support member. This allows the liquid ejection head according to the embodiment to accurately position the support member on the reservoir. It also reduces the risk of the adhesive (e.g., adhesive 400) that bonds the reservoir and support member entering the slit portion.

[0109] Furthermore, the protective sheet may contact the protruding portion with the flexible substrate that is pulled out from the slit portion above the upper end of the support member, thereby further reducing the risk of damage to the flexible substrate according to the liquid ejection head of the embodiment.

[0110] The protective sheet may have chamfered corners on the protruding portions, which improves the workability of the liquid ejection head according to the embodiment when arranging the support member on the reservoir using the protective sheet as a guide.

[0111] The protective sheet may have a first surface and a second surface having a surface roughness greater than that of the first surface, and the second surface may be oriented toward the flexible substrate. This makes it possible to easily pull out the flexible substrate from the slit portion of the liquid ejection head according to the embodiment.

[0112] The protective sheet may have a higher rigidity than the flexible substrate, which improves the workability when inserting the flexible substrate into the slit portion in the liquid ejection head according to the embodiment.

[0113] The protective sheet may be adhered to one of the inner wall surfaces of the slit portion via an adhesive member (e.g., adhesive member 300). This allows the liquid ejection head according to the embodiment to fix the position of the protective sheet relative to one of the inner wall surfaces of the slit portion.

[0114] The reservoir may also have a laminated structure in which multiple plates (e.g., plates 70A-70E) are stacked. The multiple plates may include one or more plates (e.g., plates 70A-70C) having a hole that forms a slit portion. The protective sheet may be adhered via an adhesive member to one inner wall surface of the hole of at least the thickest plate (e.g., plate 70C) among the one or more plates. This allows the liquid ejection head according to the embodiment to maintain the adhesive strength between the protective sheet and one inner wall surface of the slit portion.

[0115] The protective sheet may also have an end portion (e.g., end portion 202) that is not adhered to one of the inner wall surfaces of the slit portion. The end portion may be located close to the connection portion between the flexible substrate and the pressure unit. This makes it possible to easily pull out the flexible substrate from the slit portion according to the liquid ejection head of the embodiment.

[0116] The support member may be adhered to the reservoir via an adhesive (e.g., adhesive 400). A portion of the adhesive may be located between the inner wall surface of the support member and the protective sheet. This reduces the possibility of the protective sheet and one of the inner wall surfaces of the slit portion peeling apart in the liquid ejection head according to the embodiment.

[0117] Further advantages and alternative embodiments may readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0118] REFERENCE SIGNS LIST 1 Printer 8 Liquid ejection head 20 Head body 21 Flow path member 41, 42 Flexible substrate 50 Support member 70 Reservoir 70A to 70E Plate 70b Slit portion 70b1 Inner wall surface 163 Ejection hole 170 Displacement element 200 Protective sheet 201 Protrusion 202 End 300 Adhesive member 400 Adhesive

Claims

1. a flow path member having a discharge hole for discharging a liquid; A pressurizing unit located on the flow path member; A flexible substrate electrically connected to the pressure unit; a reservoir having a slit portion through which the flexible substrate is inserted and a flow path that supplies liquid to the flow path member; a protective sheet positioned between the inner wall surface of the slit portion and the flexible substrate; A liquid ejection head comprising:

2. Further provided is a frame-shaped support member positioned on the reservoir so as to surround a predetermined area including the slit portion in a plan view, The liquid ejection head according to claim 1 , wherein the protective sheet has a protruding portion that protrudes from the slit portion above an upper end portion of the support member.

3. The liquid ejection head according to claim 2 , wherein the protective sheet contacts, at the protruding portion, the flexible substrate that is pulled out from the slit portion above an upper end portion of the support member.

4. The liquid ejection head according to claim 2 , wherein the protective sheet has chamfered corners of the protruding portion.

5. The liquid ejection head according to claim 1 , wherein the protective sheet has a first surface and a second surface having a surface roughness greater than that of the first surface, and the second surface faces the flexible substrate.

6. The liquid ejection head according to claim 1 , wherein the protective sheet has a higher rigidity than the flexible substrate.

7. The liquid ejection head according to claim 1 , wherein the protective sheet is adhered to the inner wall surface of the slit portion via an adhesive member.

8. The reservoir has a laminated structure in which a plurality of plates are laminated, the plurality of plates includes one or more plates having holes that form the slit portions, The liquid ejection head according to claim 7 , wherein the protective sheet is adhered via the adhesive member to the inner wall surface of the hole of at least the thickest plate among the one or more plates.

9. the protective sheet has an end portion that is not adhered to the inner wall surface of the slit portion, The liquid ejection head according to claim 7 , wherein the end portion is located in the vicinity of a connection portion between the flexible substrate and the pressure applying portion.

10. Further provided is a frame-shaped support member positioned on the reservoir so as to surround a predetermined area including the slit portion in a plan view, the protective sheet has a protruding portion protruding from the slit portion above an upper end portion of the support member, The support member is bonded onto the reservoir via an adhesive; The liquid ejection head according to claim 7 , wherein a portion of the adhesive is located between the inner wall surface of the support member and the protective sheet.

11. Further provided is a frame-shaped support member positioned on the reservoir so as to surround a predetermined area including the slit portion in a plan view, The liquid ejection head according to claim 1 , wherein the protective sheet extends from the slit portion to an upper end of the support member.

12. A recording apparatus comprising the liquid ejection head according to any one of claims 1 to 11.