JP2011031443A - Droplet ejection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a droplet ejection device which can reduce the variation of the impact position of a droplet occurring between an end side nozzle and a central side nozzle among a plurality of nozzles arranged in one direction. <P>SOLUTION: The end side nozzle 30a which is a nozzle out of a plurality of nozzles 30 arranged in one direction and is located on the end side in the arrangement direction has an ejection timing which is differentiated from the ejection timing of the central side nozzle 30b located closer to the central side than the end side nozzle 30a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a droplet ejecting apparatus that ejects droplets.

  In general, a liquid droplet ejecting apparatus used in various fields such as an ink jet printer for recording an image by landing ink droplets on a recording medium generally includes a plurality of nozzles arranged in one direction. And droplets are respectively ejected from the plurality of nozzles (see, for example, Patent Document 1).

JP 2009-149026 A

  By the way, the inventors of the present application, among the plurality of nozzles arranged in a row in the above-described droplet ejecting apparatus, have a nozzle located on the end side in the arrangement direction (hereinafter referred to as an end side nozzle) and a central side in the arrangement direction. It has been found that the velocity of the droplets ejected from each nozzle tends to be different between the nozzles positioned (hereinafter referred to as the center nozzle). The reason why the droplet velocity is different between the end-side nozzle and the center-side nozzle may be various factors due to the structure, the manufacturing process, and the like. Some of them are listed below.

1) If the manufacturing process of the droplet ejecting apparatus includes a process of heat-bonding different materials having different linear expansion coefficients, the above-described problem may occur. For example, the inkjet head of Patent Document 1 includes a flow path unit in which an ink flow path communicating with a nozzle is formed, and a piezoelectric layer made of a ferroelectric piezoelectric material joined to the flow path unit. A piezoelectric actuator that applies pressure to the ink using deformation (piezoelectric strain) generated in the ink. Patent Document 1 discloses that a metal channel unit and a piezoelectric layer are bonded with a thermosetting adhesive. In the bonding step using the adhesive, the channel unit and the piezoelectric layer are disclosed. It is necessary to heat the layer to the curing temperature of the thermosetting adhesive.

  As described above, when the metal channel unit having a different linear expansion coefficient and the piezoelectric layer are bonded in a heated state, the piezoelectric layer after the heat bonding has a residual due to the difference in the linear expansion coefficient with the metal. Stress is generated. Here, the constraint condition of the piezoelectric layer is substantially uniform and the residual stress of the piezoelectric layer is uniform at the central portion in the nozzle array direction, whereas the piezoelectric layer is at the end in the nozzle array direction (region close to the edge of the head). Therefore, the residual stress generated in the piezoelectric layer is likely to be different from that in the central portion. Furthermore, since the residual stress generated in the piezoelectric layer affects the deformation amount of the piezoelectric layer, if the deformation amount of the piezoelectric layer is different, the energy (droplet velocity) actually given to the liquid in the nozzle is different. It is also conceivable that slight warpage occurs in the entire head due to the difference in the linear expansion coefficient described above. In this case, since the end of the head in the nozzle arrangement direction is deformed so as to be slightly inclined with respect to the center, this can also be a factor that causes the droplet ejection characteristics of the end-side nozzle and the center-side nozzle to be different.

2) Further, the fact that the rigidity of the droplet ejection device is slightly different between the end portion and the center portion in the nozzle arrangement direction is considered to be one factor that the ejection characteristics of the end side nozzle and the center side nozzle are different. For example, in the ink jet head of Patent Document 1 described above, an ink flow path communicating with a plurality of nozzles is formed in the flow path unit. Here, in the central portion of the flow path unit in the nozzle arrangement direction where a large number of nozzles are densely arranged, the flow path structure corresponding to each of the large number of nozzles is arranged, so the rigidity of the flow path unit becomes lower. On the other hand, since there are few flow path structures arranged at the end in the arrangement direction, the rigidity of the flow path unit tends to increase. The rigidity of the flow path unit affects the application of pressure to the ink in the ink flow path, the pressure propagation in the ink flow path, etc. It is fully conceivable that the jet characteristics of the nozzle on the center side are different.

  As mentioned above, the end-side nozzle and the center-side nozzle are likely to have different conditions regarding droplet ejection, and for this reason, the velocity of the droplet ejected from each nozzle is likely to be different. In this way, if the droplet velocity is different between the end nozzle and the center nozzle, the landing position shift occurs when the droplets ejected from the nozzles land on the ejection target such as a recording medium. .

  An object of the present invention is to provide a droplet ejecting apparatus that can reduce a landing position deviation of droplets generated between an end-side nozzle and a center-side nozzle among a plurality of nozzles arranged in one direction.

  According to a first aspect of the invention, there is provided a droplet ejecting apparatus that controls a plurality of nozzles arranged along one direction, an energy applying unit that applies ejection energy to the liquid in the plurality of nozzles, and the energy applying unit. And an ejection control unit that ejects droplets from the plurality of nozzles, and the ejection control unit is an end-side nozzle that is located at least on one end side of both end sides in the arrangement direction of the plurality of nozzles. The injection timing is made different from the injection timing of the central nozzle located closer to the center than the end nozzle.

  According to the present invention, among the plurality of nozzles arranged along one direction, the injection timing of the end-side nozzle is made different from the injection timing of the central-side nozzle, whereby the end-side nozzle and the central-side nozzle are arranged. This makes it possible to reduce the landing position deviation caused by the difference in droplet velocity.

  In the droplet ejecting apparatus of the second invention, a plurality of nozzles arranged in order from the one end in the arrangement direction are set as the end side nozzles, and the ejection control means is arranged between the plurality of end side nozzles. Also, the injection timing is varied.

  Further, in the liquid droplet ejecting apparatus according to a third aspect, in the first aspect, the plurality of nozzles arranged in order from the one end in the arrangement direction are set as the end-side nozzle, The plurality of the end-side nozzles are divided into a plurality of nozzle groups according to the distance from the one end to the arrangement position of each nozzle, and the injection timing is varied among the plurality of nozzle groups. It is what.

  When a plurality of nozzles arranged in sequence from one end of the nozzle row are set as the end side nozzles, the nozzle closer to the center side nozzle has a smaller difference in droplet velocity from the center side nozzle, and the landing position deviation is also smaller. It will be smaller. Therefore, rather than making the injection timing the same for a plurality of end-side nozzles, the injection timing is individually set for each end-side nozzle or for each nozzle group into which the plurality of end-side nozzles are divided, and the respective injection timings are set. It is preferable to make them different.

  In the liquid droplet ejecting apparatus according to a fourth aspect of the present invention, in any one of the first to third aspects of the invention, the ejection control means is an end of each of the plurality of nozzles positioned on both ends in the arrangement direction. The nozzle injection timing is different from the injection timing of the central nozzle.

  According to the present invention, it is possible to reduce both the landing position deviations of the end side nozzles located on both ends in the arrangement direction with respect to the center side nozzle.

  According to a fifth aspect of the present invention, the liquid droplet ejecting apparatus according to the fourth aspect of the present invention has a liquid droplet ejecting surface in which the plurality of nozzles open, and is parallel to the liquid droplet ejecting surface and the arrangement direction of the plurality of nozzles. A liquid droplet ejecting head capable of reciprocating in an orthogonal scanning direction and an object to be ejected on which liquid droplets ejected from the plurality of nozzles are disposed are opposed to the liquid droplet ejecting surface. A transport unit that transports the head in a transport direction parallel to the arrangement direction, and the ejection control unit is configured so that each of the plurality of nozzles is in both the forward movement and the backward movement of the droplet ejection head. The droplets are ejected onto the ejected body, and the conveying means moves the ejected body relative to the droplet ejecting head between the forward and backward movements of the droplet ejecting head. Transport in the transport direction by the arrangement length of the plurality of nozzles. The one in which the features.

  In order to land droplets on a wide area of the ejected object, the forward and backward movements in the scanning direction of the droplet ejecting head are alternately repeated while ejecting the droplets from the nozzle, and during the reciprocating motion of the head. In addition, it is possible to adopt a method of conveying the ejected object by the length of the nozzle row. In this case, the droplet ejected from the nozzle on one end side in the arrangement direction during the forward movement of the droplet ejecting head and the droplet ejected from the nozzle on the opposite side (the other end side) in the backward movement in which the moving direction is opposite. The landing positions on the ejection target are adjacent to each other in the transport direction.

  Here, it is considered that the tendency (high or low) of the droplet velocity shift with respect to the central nozzle coincides between the nozzle located on one end side in the arrangement direction and the nozzle located on the other end side. When the droplet speed of the end nozzle is higher than that of the central nozzle, the landing position of the droplet ejected from the end nozzle is upstream of the moving direction of the head with respect to the landing position of the central nozzle. When the landing position is shifted and the droplet velocity is low, the landing position is shifted downstream in the moving direction of the head. Furthermore, since the head movement directions are opposite to each other during the forward movement and backward movement of the liquid droplet ejection head, the central nozzle of the liquid droplets ejected from the end side nozzle during forward movement and backward movement, respectively. The direction of landing position deviation with respect to is reversed. Accordingly, the landing position deviation between two droplets that are ejected at the time of forward movement and at the time of backward movement and land adjacent to each other in the transport direction on the ejection target is the landing between the end side nozzle and the center side nozzle. This is almost twice the displacement. Therefore, when such a droplet ejection method is employed, the present invention is very effective because the landing position of the end side nozzle can be brought close to the landing position of the central nozzle.

  In any one of the first to fifth inventions, the droplet ejection device according to a sixth aspect of the present invention is configured such that the ejection control unit supplies the energy applying unit with a drive signal corresponding to each nozzle, so that the energy is applied. The applying unit causes the droplets to be ejected from the nozzle corresponding to the driving signal, and the ejection control unit further supplies a timing of supplying the driving signal corresponding to the end-side nozzle to the energy applying unit. The timing is different from the supply timing of the drive signal corresponding to the central nozzle.

  According to the present invention, the supply timing of the drive signal corresponding to the end-side nozzle to the energy applying unit is different from the supply timing of the drive signal corresponding to the center-side nozzle, so that the end-side nozzle and the center-side nozzle The injection timing can be varied.

  In any one of the first to sixth inventions, the droplet ejecting apparatus according to a seventh aspect is the plurality of nozzles, the plurality of nozzles respectively communicating with the plurality of nozzles and arranged along the one direction. The piezoelectric actuator includes a flow path unit including a pressure chamber in which a liquid flow path is formed, and the energy applying unit includes a piezoelectric layer bonded to the flow path unit so as to cover the plurality of pressure chambers. It is characterized by this.

  As a flow path unit in which a liquid flow path is formed, a highly rigid material such as a metal material or silicon is generally used so that pressure can be effectively applied to the liquid and high liquid pressure can be endured. used. On the other hand, the piezoelectric layer bonded to the flow path unit is a layer made of a ferroelectric piezoelectric material. In this way, if the flow path unit and the piezoelectric layer made of different materials are heated when bonded using a thermosetting adhesive, residual stress is applied to the bonded piezoelectric layer due to the difference in thermal expansion coefficient. Occurs.

  Further, in the central region in the arrangement direction where the pressure chamber communicating with the central nozzle is disposed, the pressure condition communicating with the end nozzle is in contrast to the constraint conditions of the piezoelectric layer being almost uniform and the residual stress being uniform. In the arrangement direction end region where the chambers are arranged, the constraint condition of the piezoelectric layer tends to be different from that in the central portion, and therefore the residual stress in the piezoelectric layer tends to be different from that in the central portion. The difference in residual stress causes a difference in the deformation amount of the piezoelectric layer between the pressure chamber communicating with the end-side nozzle and the pressure chamber communicating with the center-side nozzle, and droplets are generated between the end-side nozzle and the center-side nozzle. The speed (landing position) will be different. Therefore, the present invention, which can bring the landing position of the end-side nozzle closer to the landing position of the central-side nozzle, is very effective for such a droplet ejecting apparatus.

  According to an eighth aspect of the present invention, there is provided a liquid droplet ejecting apparatus comprising: a plurality of nozzles arranged along one direction; an energy applying unit that applies ejection energy to the liquid in the nozzles; and the energy applying unit. And an ejection control unit that ejects droplets from the plurality of nozzles, and the ejection control unit is an end-side nozzle that is located at least on one end side of both end sides in the arrangement direction of the plurality of nozzles. On the other hand, the energy applied from the energy applying means is made different from the energy applied to the central nozzle located closer to the center than the end nozzle.

  According to the present invention, among the plurality of nozzles arranged along one direction, the energy applied to the end nozzle is made different from the energy applied to the center nozzle, whereby the end side Landing position deviation due to the difference in droplet velocity between the nozzle and the central nozzle can be reduced.

  According to the present invention, of a plurality of nozzles arranged in one direction, it is possible to reduce landing position deviation caused by a difference in droplet velocity between an end-side nozzle and a central-side nozzle. .

1 is a plan view illustrating a schematic configuration of a printer according to an embodiment. It is a top view of an inkjet head. FIG. 3 is a partially enlarged view of FIG. 2. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is a figure which shows the waveform of a drive signal, (a) shows a non-injection waveform, (b) shows an injection waveform, respectively. 4A and 4B are diagrams for explaining a landing position deviation of droplets, where FIG. 5A is a view of an inkjet head that is ejecting droplets as viewed from the downstream side in the conveyance direction of the recording paper, and FIG. It is a figure which shows the landing position on the recording paper of a droplet. It is a figure which shows the landing position of the droplet on the recording paper in bidirectional printing. FIG. 2 is a block diagram illustrating an electrical configuration of a printer. It is a figure which shows the landing position shift | offset | difference of the droplet each ejected from the some end side nozzle of the inkjet head in the modification. It is a figure which shows the example which divided the some end side nozzle into the nozzle group in another modification. It is a top view of the ink-jet head in another modification.

  Next, an embodiment of the present invention will be described. This embodiment is an example in which the present invention is applied to an inkjet printer including an inkjet head that ejects ink droplets onto a recording sheet.

  First, a schematic configuration of the ink jet printer 1 (droplet ejecting apparatus) of the present embodiment will be described. FIG. 1 is a schematic plan view of the ink jet printer of the present embodiment. As shown in FIG. 1, a printer 1 includes a carriage 2 configured to reciprocate along a predetermined scanning direction (left-right direction in FIG. 1), and an inkjet head 3 (droplet) mounted on the carriage 2. A recording sheet 100 (an ejected body) facing the droplet ejection surface 3a of the inkjet head 3 (the surface on the opposite side of the paper surface in FIG. 1) is parallel to the droplet ejection surface 3a and the scanning direction. A transport mechanism 4 (transport means) for transporting in the transport direction (downward in FIG. 1) orthogonal to each other is provided.

  The carriage 2 is configured to be able to reciprocate along two guide shafts 17 extending in parallel with the scanning direction (left-right direction in FIG. 1). An endless belt 18 is connected to the carriage 2. When the endless belt 18 is driven to travel by the carriage drive motor 19, the carriage 2 moves in the scanning direction as the endless belt 18 travels. It has become.

  An ink jet head 3 is mounted on the carriage 2. The ink-jet head 3 includes a plurality of nozzles 30 (see FIGS. 2 to 4) that open to the lower surface (the surface on the opposite side of FIG. 1: droplet ejection surface 3a). The inkjet head 3 is configured to eject ink supplied from an ink cartridge (not shown) from a plurality of nozzles 30 onto a recording paper 100 that is conveyed downward (conveying direction) in FIG. ing.

  The transport mechanism 4 includes a paper feed roller 12 disposed on the upstream side in the transport direction with respect to the ink jet head 3 and a paper discharge roller 13 disposed on the downstream side in the transport direction with respect to the ink jet head 3. The paper feed roller 12 and the paper discharge roller 13 are rotationally driven by a paper feed motor 14 and a paper discharge motor 15, respectively. The transport mechanism 4 transports the recording paper 100 from the upper side of FIG. 1 to the ink jet head 3 by the paper feed roller 12, and records the images, characters, etc. recorded by the ink jet head 3 by the paper discharge roller 13. The paper 100 is discharged downward in FIG.

  Next, the inkjet head 3 will be described. 2 is a plan view of the inkjet head, FIG. 3 is a partially enlarged view of FIG. 2, and FIG. 4 is a sectional view taken along line IV-IV of FIG. As shown in FIGS. 2 to 4, the inkjet head 3 includes a flow path unit 6 in which an ink flow path including a nozzle 30 and a pressure chamber 24 is formed, and a piezoelectric actuator 7 that applies pressure to the ink in the pressure chamber 24. And.

  First, the flow path unit 6 will be described. As shown in FIG. 4, the flow path unit 6 includes a cavity plate 20, a base plate 21, a manifold plate 22, and a nozzle plate 23, and these four plates 20 to 23 are joined in a laminated state. Among these, the cavity plate 20, the base plate 21, and the manifold plate 22 are substantially rectangular plates in plan view made of a metal material such as stainless steel. Therefore, ink flow paths such as a manifold 27 and a pressure chamber 24 described later can be easily formed on these three plates 20 to 22 by etching. Further, the nozzle plate 23 is formed of, for example, a polymer synthetic resin material such as polyimide, and is bonded to the lower surface of the manifold plate 22 with an adhesive.

  As shown in FIGS. 2 to 4, among the four plates 20 to 23, the uppermost cavity plate 20 has holes in which a plurality of pressure chambers 24 arranged along a plane penetrate the plate 20. It is formed by. The plurality of pressure chambers 24 are arranged in two rows in a staggered manner in the transport direction (the vertical direction in FIG. 2). Further, as shown in FIG. 4, the plurality of pressure chambers 24 are respectively covered with a diaphragm 40 and a base plate 21 described later from above and below. Furthermore, each pressure chamber 24 is formed in a substantially elliptical shape that is long in the scanning direction (left-right direction in FIG. 2) in plan view.

  As shown in FIGS. 3 and 4, communication holes 25 and 26 are respectively formed at positions where the base plate 21 overlaps both longitudinal ends of the pressure chamber 24 in plan view. The manifold plate 22 is formed with two manifolds 27 extending in the transport direction so as to overlap with the communication hole 25 side portions of the pressure chambers 24 arranged in two rows in a plan view. These two manifolds 27 communicate with an ink supply port 28 formed in a vibration plate 40 described later, and ink is supplied to the manifold 27 from an ink tank (not shown) via the ink supply port 28. Further, a plurality of communication holes 29 that are continuous with the plurality of communication holes 26 are formed at positions where the manifold plate 22 overlaps the ends of the plurality of pressure chambers 24 opposite to the manifolds 27 in plan view.

  Furthermore, a plurality of nozzles 30 are formed at positions where the nozzle plate 23 overlaps the plurality of communication holes 29 in plan view, and the lower surface of the nozzle plate 23 has droplets opened by the plurality of nozzles 30 respectively. It becomes the injection surface 3a. As shown in FIG. 2, the plurality of nozzles 30 are disposed so as to overlap with the end portions of the plurality of pressure chambers 24 arranged in two rows along the transport direction on the side opposite to the manifold 27. In other words, the plurality of nozzles 30 are arranged in a predetermined direction (here, the transport direction), and the plurality of pressure chambers 24 communicating with the plurality of nozzles 30 are also arranged along the arrangement direction of the nozzles 30. Are arranged.

  As shown in FIG. 4, the manifold 27 communicates with the pressure chamber 24 through the communication hole 25, and the pressure chamber 24 communicates with the nozzle 30 through the communication holes 26 and 29. As described above, a plurality of individual ink flow paths 31 from the manifold 27 to the nozzles 30 through the pressure chambers 24 are formed in the flow path unit 6.

  In FIG. 2, only one type of flow path structure (manifold 27, pressure chamber 24, nozzle 30, etc.) connected to one ink supply port 28 is shown for simplicity of explanation. The ink jet head 3 of the embodiment has a configuration in which a plurality of flow path structures shown in FIG. 2 are arranged in the scanning direction, and inks of a plurality of colors (for example, four colors of black, yellow, cyan, and magenta) are provided. Each is a color inkjet head that can be jetted.

  Next, the piezoelectric actuator 7 will be described. As shown in FIGS. 2 to 4, the piezoelectric actuator 7 includes a vibration plate 40 joined to the upper surface of the flow path unit 6 (cavity plate 20) so as to cover the plurality of pressure chambers 24, and the upper surface of the vibration plate 40. In addition, a piezoelectric layer 41 disposed to face the plurality of pressure chambers 24 and a plurality of individual electrodes 42 disposed on the upper surface of the piezoelectric layer 41 are provided.

  The diaphragm 40 is a substantially rectangular metal plate in plan view, and is made of, for example, an iron-based alloy such as stainless steel, a copper-based alloy, a nickel-based alloy, or a titanium-based alloy. The vibration plate 40 is joined to the cavity plate 20 in a state of being disposed on the upper surface of the cavity plate 20 so as to cover the plurality of pressure chambers 24. In addition, the upper surface of the conductive diaphragm 40 is disposed on the lower surface side of the piezoelectric layer 41, thereby generating an electric field in the thickness direction in the piezoelectric layer 41 with the plurality of individual electrodes 42 on the upper surface. Also serves as an electrode. The diaphragm 40 as the common electrode is connected to the ground wiring of the driver IC 47 that drives the piezoelectric actuator 7 and is always held at the ground potential.

  The piezoelectric layer 41 is made of a piezoelectric material mainly composed of lead zirconate titanate (PZT), which is a solid solution of lead titanate and lead zirconate and is a ferroelectric substance. As shown in FIG. 2, the piezoelectric layer 41 is continuously formed across the plurality of pressure chambers 24 on the upper surface of the vibration plate 40. The piezoelectric layer 41 is polarized in the thickness direction at least in a region facing the pressure chamber 24. In the present embodiment, the piezoelectric layer 41 is a piezoelectric sheet obtained by firing a green sheet, and is bonded by a thermosetting adhesive such as an epoxy adhesive. More specifically, the vibration plate 40 and the piezoelectric sheet are laminated with an adhesive interposed therebetween, and the piezoelectric layer 41 is pressed against the vibration plate 40 while the piezoelectric layer 41 and the vibration plate 40 are heated. The adhesive is cured and the two are joined.

  A plurality of individual electrodes 42 are respectively disposed in regions on the upper surface of the piezoelectric layer 41 facing the plurality of pressure chambers 24. Each individual electrode 42 has a substantially oval planar shape that is slightly smaller than the pressure chamber 24, and faces the central portion of the pressure chamber 24. Further, a plurality of contact portions 45 are drawn from the end portions of the plurality of individual electrodes 42 along the longitudinal direction of the individual electrodes 42.

  The plurality of contact portions 45 on the piezoelectric actuator 7 (piezoelectric layer 41) are electrically connected to the driver IC 47 by a wiring member (not shown). Then, the driver IC 47 switches the potential of the individual electrode 42 between a predetermined driving potential and a ground potential, and ejects ink droplets from the nozzle 30 corresponding to the individual electrode 42.

  Next, the operation of the piezoelectric actuator 7 during ink ejection will be described. When a predetermined drive potential is applied to a certain individual electrode 42 from the driver IC 47, between the individual electrode 42 to which this drive potential is applied and the diaphragm 40 as a common electrode held at the ground potential. A potential difference is generated, and an electric field in the thickness direction acts on the piezoelectric layer 41 sandwiched between the individual electrode 42 and the diaphragm 40. Since the direction of the electric field is parallel to the polarization direction of the piezoelectric layer 41, the piezoelectric layer 41 in the region (active region) facing the individual electrode 42 contracts in a plane direction perpendicular to the thickness direction. Here, since the lower vibration plate 40 of the piezoelectric layer 41 is fixed to the cavity plate 20, as the piezoelectric layer 41 positioned on the upper surface of the vibration plate 40 contracts in the surface direction, the vibration plate 40. The portion covering the pressure chamber 24 is deformed so as to protrude toward the pressure chamber 24 (unimorph deformation). At this time, since the volume in the pressure chamber 24 decreases, the ink pressure in the pressure chamber 24 rises, and ink is ejected from the nozzle 30 communicating with the pressure chamber 24.

  Furthermore, driving of the piezoelectric actuator 7 by the driver IC 47 will be described in detail. When the inkjet head 3 moves in the scanning direction together with the carriage 2, the driver IC 47 applies to each of the plurality of individual electrodes 42 of the piezoelectric actuator 7 in each predetermined time unit (hereinafter referred to as a driving cycle). Thus, the potential of the individual electrode 42 is switched by supplying a drive signal having a predetermined drive waveform.

  FIG. 5 shows two types of drive waveforms of the drive signal. The waveform shown in FIG. 5A is a non-ejection waveform with a constant potential (ground potential) that does not have the drive pulse P. In the drive cycle in which the drive signal having this non-ejection waveform is applied to the individual electrode 42 from the driver IC 47, the potential of the individual electrode 42 does not change from the ground potential, so no pressure is applied to the ink in the pressure chamber 24, No ink droplets are ejected from the nozzle 30. On the other hand, the waveform in FIG. 5B is an ejection waveform having a drive pulse P. In the drive cycle in which the drive signal having this ejection waveform is applied from the driver IC 47 to the individual electrode 42, the potential of the individual electrode 42 is switched between the ground potential and the drive potential by the drive pulse P. Pressure is applied to the ink, and ink droplets are ejected from the nozzle 30.

  By the way, as described above, as shown in FIG. 2, among the plurality of nozzles 30 arranged in one direction (a direction parallel to the transport direction in the present embodiment), nozzles located on the end side in the arrangement direction. The droplet ejection characteristics (droplet velocity) tend to be different between the nozzle 30 (hereinafter also referred to as the end-side nozzle 30a) and the nozzle 30 located on the center side in the arrangement direction with respect to the nozzle 30. In the inkjet head 3 of the present embodiment, the following factors 1) to 3) can be considered.

1) In the present embodiment, the metal cavity plate 10 and the piezoelectric layer 41 made of a piezoelectric material are joined with a thermosetting adhesive. In this case, the cavity plate 10 and the piezoelectric layer 41 are joined by heating to the curing temperature of the thermosetting adhesive. By the way, when the metal flow path unit having a different linear expansion coefficient and the piezoelectric layer 41 are heat-bonded, the residual stress resulting from the difference in the linear expansion coefficient is generated in the piezoelectric layer 41 after the heat-bonding.

  Here, the constraint condition of the piezoelectric layer 41 is substantially uniform and the residual stress of the piezoelectric layer 41 becomes uniform at the central portion in the nozzle arrangement direction, whereas the constraint condition of the piezoelectric layer 41 is central at the end portion in the nozzle arrangement direction. The residual stress generated in the piezoelectric layer 41 tends to be different from the central portion. As a specific example, the piezoelectric layer 41 at the end in the nozzle arrangement direction, that is, the portion of the piezoelectric layer 41 covering the pressure chamber 24 communicating with the end-side nozzle 30a is closer to the edge and therefore has a restraining force compared to the central portion. It is weak and some deformation is allowed. Therefore, the residual stress on the end side after heat bonding is smaller than that on the center side. This difference in residual stress affects the amount of deformation of the piezoelectric layer 41. If the amount of deformation of the piezoelectric layer 41 differs between the end portion and the central portion, the energy (droplet velocity) that is actually applied to the liquid in the nozzle 30. However, the end side nozzle 30a and the center side nozzle 30b are different.

  It is also conceivable that slight warpage occurs in the entire inkjet head 3 after heat bonding due to the difference in linear expansion coefficient described above. In this case, since the flow path unit 6 and the piezoelectric actuator 7 of the inkjet head 3 are deformed so that the end portions in the nozzle arrangement direction are slightly inclined with respect to the central portion, the end nozzle 30a and the central nozzle The droplet ejection characteristics of 30b can be a different factor.

2) When the piezoelectric actuator 7 is joined to the flow path unit 6, a plurality of pressure chambers 24 arranged in a line corresponding to the plurality of nozzles 30 on the flow path unit 6 side, and piezoelectrics corresponding thereto It is necessary to align the plurality of individual electrodes 42 on the actuator 7 side. Here, when alignment is performed with reference to one pressure chamber 24 located on the center side among the plurality of pressure chambers 24 arranged in a row, the pressure chambers 24 and individual chambers are arranged on the end side in the arrangement direction. The tolerances of the dimensions and positions of the electrodes 42 accumulate, and the positional relationship between the pressure chambers 24 and the individual electrodes 42 is slightly deviated from the normal positional relationship. As described above, if the pressure chamber 24 and the individual electrode 42 are misaligned on the end side, the energy (pressure) applied to the ink in the pressure chamber 24 deviates from the design value. The droplet speed is different between the central nozzle 30b. Further, when the piezoelectric actuator 7 is formed by laminating and firing a green sheet of piezoelectric material and an electrode material, the individual electrode 42 is likely to be displaced due to contraction when the green sheet is fired. In this case, when the piezoelectric actuator 7 is joined by aligning with respect to one pressure chamber 24 located on the center side among the plurality of pressure chambers 24 arranged in a row, The positional deviation between the pressure chamber 24 and the individual electrode 42 becomes more remarkable.

3) A large number of ink flow paths such as a plurality of pressure chambers 24 arranged in the nozzle arrangement direction are formed in the flow path unit 6. As shown in FIG. 2, in the central portion of the flow path unit 6 where the many nozzles 30 are densely packed, a large number of ink flow paths such as the pressure chambers 24 are densely arranged. While the rigidity of the channel unit 6 is low, the rigidity of the channel unit 6 tends to be high because there are few pressure chambers 24 and the like arranged at the end in the nozzle arrangement direction. And since the rigidity of the flow path unit 6 is different between the end portion in the nozzle arrangement direction and the central portion, the droplet ejection characteristics of the end-side nozzle 30a and the central-side nozzle 30b are different. For example, if the rigidity of the flow path unit 6 in the peripheral region of the pressure chambers 24 arranged at the nozzle array direction end is larger than that of the pressure chamber 24 at the center in the array direction, the end side is inside the pressure chamber 24. A large pressure is easily applied to the ink, and the droplet velocity of the end-side nozzle 30a communicating with the end-side pressure chamber 24 is increased.

4) The flow path unit 6 includes a cavity plate 20, a base plate 21, a manifold plate 22, and a nozzle plate 23, and these four plates 20 to 23 are joined in a stacked state. When these plates are stacked and joined, when alignment is performed with reference to one pressure chamber 24 located on the center side among the plurality of pressure chambers 24 arranged in a row, the end in the arrangement direction On the side, tolerances of dimensions and positions of the pressure chamber 24, the communication holes 25, 26, 29, and the nozzle 30 are stacked, and the positional relationship between the pressure chamber 24, the communication holes 25, 26, 29, and the nozzle 30 is a normal position. There will be some deviation from the relationship. As described above, if the pressure chamber 24, the communication holes 25, 26, 29, and the nozzle 30 are displaced on the end side, the flow path on the end side deviates from the design value. Even when the same pressure is applied, the droplet speed of the end-side nozzle 30a communicating with the end-side pressure chamber 24 is lower than that of the center-side nozzle 30b.

5) The inkjet head 3 cannot use all of the energy applied to eject the droplets for droplet ejection, and part of the energy is converted into thermal energy and stored in the inkjet head 3. . In the central part of the flow path unit 6 in the nozzle arrangement direction, many ink flow paths such as the pressure chambers 24 are densely arranged, whereas at the end part in the nozzle arrangement direction, there are few pressure chambers 24 and the like. For this reason, the heat radiation characteristics are different between the end-side nozzle 30a and the center-side nozzle 30b, and the droplet velocity is different between the end-side nozzle 30a and the center-side nozzle 30b.

  As mentioned above, the end-side nozzle 30a and the center-side nozzle 30b are likely to have different conditions regarding droplet ejection, and for this reason, the velocity of the droplet ejected from each nozzle 30 is likely to be different. As described above, when the droplet speeds are different between the end-side nozzle 30a and the center-side nozzle 30b, the landing positions on the recording paper 100 of the droplets ejected from the respective nozzles 30 are shifted. .

  6A and 6B are diagrams for explaining the displacement of the landing positions of the droplets on the recording paper 100. FIG. 6A is a diagram of the inkjet head 3 that is ejecting the droplets as viewed from the downstream side in the conveyance direction of the recording paper. ) Is a diagram showing the landing positions on the recording paper of the droplets ejected from a plurality of nozzles 30 arranged in a line. As shown in FIG. 6A, when the inkjet head 3 moves to the right in the drawing, the droplets D are ejected from the plurality of nozzles 30 arranged in a row toward the recording paper 100 at the same timing. Suppose that it was injected. Here, if the velocity of the droplet Da ejected from the end-side nozzle 30a is higher than the droplet Db ejected from the center-side nozzle 30b, the droplet Da from the end-side nozzle 30a It lands at a position shifted from the droplet Db to the upstream side in the moving direction of the inkjet head 3. In addition, the end-side nozzle 30a located on one end side in the nozzle arrangement direction and the end-side nozzle 30a located on the other end side have the same tendency (higher or lower) in the droplet velocity with respect to the central nozzle 30b. Conceivable. Accordingly, as shown in FIG. 6B, the droplets ejected from the plurality of nozzles 30 arranged in a line should draw a straight line, but in actuality, the head is moved at both ends. It will draw a curved line upstream in the direction.

  FIG. 6B described above shows the landing position of the droplet when the inkjet head 3 ejects the droplet while moving in one direction of the scanning direction (so-called one-way printing). However, in the case of so-called bi-directional printing in which droplets are ejected while reciprocating in both directions in the scanning direction, the impact of the landing position deviation described above on print quality is more serious.

  FIG. 7 is a diagram illustrating the landing positions of droplets on the recording paper 100 in bidirectional printing. Here, “bidirectional printing” refers to the following printing method. When the inkjet head 3 reciprocates in the scanning direction, both the movement in the scanning direction in one direction (forward movement) and the movement in the other direction in the scanning direction (reverse movement) cause the plurality of nozzles 30 to move to the recording paper 100. To eject droplets. Further, the recording paper 100 is transported in the transport direction by the arrangement length of the plurality of nozzles 30 by the transport mechanism 4 between the forward and backward movements of the inkjet head 3. At this time, as shown in FIG. 7, at the time of forward movement (when moving to the right in the figure), the landing of the droplet Da ejected from the end-side nozzle 30a located at one end (the lower end in the figure) of the nozzle row The position and the landing position of the droplet Da ′ ejected from the end-side nozzle 30a located at the other end (upper end in the figure) of the nozzle row during the backward movement (when moving to the left in the figure) are conveyed. Adjacent in terms of direction.

  In this bidirectional printing, the movement direction of the inkjet head 3 is opposite between the forward movement and the backward movement of the inkjet head 3, so that the liquid ejected from the end-side nozzle 30a during the forward movement and the backward movement respectively. The direction of the landing position deviation of the droplets Da and Da ′ with respect to the central nozzle 30b is reversed. Therefore, the landing position deviation between the two droplets Da and Da ′ ejected at the time of forward movement and at the time of backward movement and landed adjacent to each other in the transport direction on the recording paper 100 is the droplet Da of the end nozzle 30a. This is almost twice the landing position deviation between (Da ') and the droplet Db of the central nozzle 30b.

  Therefore, in the present embodiment, the landing timing of the liquid droplets ejected from the respective nozzles 30 is made different from the timing of ejecting the liquid droplets from the end-side nozzle 30a and the timing of ejecting the liquid droplets from the central-side nozzle 30b. The positional deviation can be reduced. This specific configuration will be described in detail later.

  Next, the electrical configuration of the printer 1 will be described with reference to the block diagram of FIG. As shown in FIG. 8, the control device 8 includes a central processing unit (CPU) 50, a read only memory (ROM) 51, a random access memory (RAM) 52, and a bus 53 connecting them. Having a microcomputer. The bus 53 also has an application specific integrated circuit (ASIC) 54 that controls a driver IC 47 of the inkjet head 3, a carriage drive motor 19 that drives the carriage 2, a paper feed motor 14 and a paper discharge motor 15 of the transport mechanism 4. Is connected. The ASIC 54 is connected to an external device PC (personal computer) 59 via an input / output interface (I / F) 58 so that data communication is possible.

  Further, the ASIC 54 has a head control circuit 61 for controlling the driver IC 47 and the carriage drive motor 19 of the inkjet head 3 based on the print data input from the PC 59, and the paper feed of the transport mechanism 4 based on the print data. A conveyance control circuit 62 and the like for controlling the motor 14 and the paper discharge motor 15 are incorporated.

  Next, the head control circuit 61 (ejection control means) will be described in detail. The head control circuit 61 controls the carriage drive motor 19 to reciprocate the ink jet head 3 in the scanning direction, and controls the driver IC 47 during the reciprocating movement to be conveyed from the nozzle 30 of the ink jet head 3 in the conveying direction. Ink droplets are ejected toward the recording paper 100 to be printed.

  Further, as shown in FIG. 8, the head control circuit 61 includes a drive waveform selection unit 63. The drive waveform selection unit 63 uses the two types of waveforms described above (non-injection waveform and injection waveform: see FIG. 5) for each of the drive periods that are temporally continuous based on the print data input from the PC 59. Either of these is selected and determined. Then, the head control circuit 61 transmits the drive waveform selected for each drive cycle to the driver IC 47, and causes the driver IC 47 to generate a drive signal having a predetermined voltage obtained by amplifying the drive waveform. By supplying this drive signal to the plurality of individual electrodes 42 of the piezoelectric actuator 7, ink is selectively ejected from the plurality of nozzles 30 corresponding to the plurality of individual electrodes 42 in each drive cycle of the inkjet head 3. The

  Further, as described above, among the plurality of nozzles 30 arranged in one row, the speed of the liquid droplets ejected from the end side nozzle 30a tends to be different from the speed of the liquid droplets ejected from the center side nozzle 30b. For this reason, if the ejection timings of the end-side nozzle 30a and the center-side nozzle 30b are the same, there is a problem that the landing positions on the recording paper 100 are shifted. Therefore, the head control circuit 61 includes a timing changing unit 64 that makes the ejection timing of the end-side nozzle 30a different from the ejection timing of the center-side nozzle 30b.

  The ROM 51 of the control device 8 holds information relating to the injection timing change executed by the timing change unit 64. Information stored in the ROM 51 includes, for example, information (for example, the number of the nozzle 30) for specifying which nozzle 30 is the end side nozzle 30a whose injection timing is to be changed, or the end side nozzle 30a. Information on how much the injection timing is shifted with respect to the other nozzles 30 (center side nozzle 30b) (amount of change in injection timing) is stored.

  The timing change amount of the end-side nozzle 30a is determined based on the droplet speed of the end-side nozzle 30a and the droplet speed of the center-side nozzle 30b, which are detected during the pre-shipment inspection. The determined information is stored in the ROM 51 of the control device 8.

  And the timing change part 64 makes the injection timing of the end side nozzle 30a differ from the injection timing of the center side nozzle 30b based on the information regarding the injection timing change memorize | stored in ROM51. Specifically, when the droplet speed of the end nozzle 30a is smaller than the central nozzle 30b, the ejection timing of the end nozzle 30a is advanced, and conversely when the droplet velocity is large, the ejection timing is set. Delay.

  Further, as a method of changing the injection timing, the timing at which the drive signal is supplied from the driver IC 47 to the piezoelectric actuator 7, that is, the above-described drive cycle (see FIG. 5) is timed between the end nozzle 30a and the center nozzle 30b. Can be adopted. The amount of time for which the drive period is shifted is determined according to the degree of deviation of the droplet velocity, and may be, for example, one drive period or two or more drive periods. It may be time. Alternatively, it may be shifted by a time less than one drive cycle (for example, a half cycle time).

  Alternatively, the application timing of the drive pulse P within one drive cycle of the ejection waveform shown in FIG. In other words, the position of the edge of the drive pulse P (the rising edge in FIG. 5B) may be different between the ejection waveform for the end-side nozzle 30a and the ejection waveform for the center-side nozzle 30b. .

  As described above, among the plurality of nozzles 30 arranged along one direction, the end-side nozzle 30a and the center-side nozzle are differentiated from the injection timing of the end-side nozzle 30a with the injection timing of the center-side nozzle 30b. It is possible to reduce landing position deviation caused by the difference in droplet velocity between 30b.

  In addition, by making the ejection timing of the end nozzles 30a located at both ends in the nozzle arrangement direction different from the ejection timing of the center nozzle 30b, the landing position deviation of the end nozzles 30a at both ends is reduced. be able to.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

1] In FIG. 6 of the above-described embodiment, it is assumed that the droplet velocities of the two end-side nozzles 30a located at both ends of the plurality of nozzles 30 arranged in one row are deviated from those of the center-side nozzle 30b. The injection timings of the two end side nozzles 30a are different from those of the center side nozzle 30b. However, in actuality, as shown in FIG. 9, not only the nozzle 30 located at the end, but also the nozzle 30 located at the center side, the droplet velocity is different from the center side nozzle 30b and the landing position. It is quite possible that a deviation will occur. In such a case, a plurality of nozzles 30 arranged in order from one end of the nozzle row are set as end-side nozzles 30a whose ejection timing should be changed.

  In addition, when a plurality of nozzles 30 are set as the end-side nozzles 30a, as shown in FIG. 9, among the plurality of end-side nozzles 30a, the nozzle 30 closer to the center-side nozzle 30b is closer to the center-side nozzle 30b. It is considered that the difference in droplet velocity is small and the landing position deviation is also small. Therefore, instead of uniformly determining the change amount of the injection timing for the plurality of end-side nozzles 30a to a certain value, the change amount of the injection timing is individually set for each of the end-side nozzles 30a, and the respective injection timings are set. It may be different.

  Alternatively, instead of setting the change amount of the injection timing for each of the plurality of nozzles 30 set as the end-side nozzles 30a, as shown in FIG. 10, the plurality of end-side nozzles 30a are moved from the end of the nozzle row. After dividing into a plurality of nozzle groups 31 (31 a to 30 c) according to the distance to the arrangement position of each nozzle 30, the amount of change in injection timing is individually set for each nozzle group 31, and between the nozzle groups 31. The injection timing may be different from each other. In FIG. 10, only some of the nozzles 30 arranged in a row are illustrated, and the remaining nozzles 30 are indicated by broken lines and are not illustrated. By dividing the plurality of end-side nozzles 30a into the nozzle group 31 in this way, it is necessary to individually set the injection timing for each of the many end-side nozzles 30a, particularly when the number of the end-side nozzles 30a is large. Thus, the amount of information to be stored in the ROM 51 regarding the change in the injection timing is small.

  In addition, among the plurality of nozzles 30 arranged in order from the end, to what range the nozzles 30 that actually cause a deviation in droplet velocity with respect to the central nozzle 30b are to be determined, inkjets having different structures Needless to say, even if the basic structure is the same among the heads 3, there may be differences among the individual ink-jet heads 3 due to differences in manufacturing conditions and material lots. Therefore, the following injection timing setting method is also possible.

  First, as the end-side nozzles 30a, a predetermined number of nozzles 30 arranged in order from the end are set regardless of whether or not the droplet velocity actually shifts. Then, the individual ink-jet heads 3 are inspected to determine to what extent the deviation of the droplet velocity actually occurs. In addition, the change amount of the ejection timing is set only for the nozzle 30 that is determined to have a drop in the droplet velocity among the plurality of nozzles 30 set as the end nozzle 30a. That is, when there is a nozzle 30 (or nozzle group 31) that is initially set as the end-side nozzle 30a but does not actually cause a deviation in droplet velocity, the nozzle 30 (nozzle group 31) is The injection timing is not changed, and the injection timing is the same as that of the central nozzle 30b. Thus, if the injection timing can be individually set for each end-side nozzle 30a or for each nozzle group 31 in which the plurality of end-side nozzles 30a are divided, it is optimal in the range where the deviation of the injection characteristics actually occurs. It is possible to determine a proper injection timing.

2] In the above embodiment, the injection timing of the end-side nozzles 30a located on both ends of the plurality of nozzles 30 arranged in one row is changed. However, the conditions affecting the droplet ejection characteristics may be different at both ends in the nozzle arrangement direction, and in this case, the droplet velocity may be different between the two types of end-side nozzles 30a positioned at both ends. For example, in FIG. 2 of the above embodiment, there is a distance from the lower end of the piezoelectric layer 41 in the drawing to the lower edge of the inkjet head 3 in order to secure the arrangement region of the ink supply port 28 on the lower side in the drawing. On the other hand, the upper end of the piezoelectric layer 41 in the figure overlaps with the upper edge of the inkjet head 3. For this reason, the conditions of the residual stress of the piezoelectric layer 41 and the like are different from each other at both ends in the nozzle arrangement direction, and there is a possibility that a difference in droplet velocity occurs between the nozzles 30 arranged at both ends. Therefore, among the end-side nozzles 30a disposed on both ends, only one end-side nozzle 30a that has a large deviation in droplet velocity with respect to the center-side nozzle 30b is made to have different ejection timing from the center-side nozzle 30b. May be.

3] In the above-described embodiment, the amount of change in the ejection timing of the end nozzle 30a is stored in advance in the ROM 51 as a value set based on the difference in droplet velocity obtained by inspection. However, the ROM 51 may store information on the droplet velocity of each nozzle 30, and the ejection timing change amount may be calculated from the droplet velocity information stored in the ROM 51 by calculation.

4] As shown in FIG. 11, when the inkjet head 3 has four or more nozzle rows 32 (32a to 32d) arranged in a direction orthogonal to the nozzle arrangement direction (here, the scanning direction), one row For the same reason as the difference in droplet velocity between the end-side nozzle 30a and the center-side nozzle 30b in the nozzle row 32, the nozzle rows 32b and 32c located on the center side with respect to the arrangement direction (scanning direction) of the nozzle row 32. It is conceivable that a difference in droplet speed also occurs between the nozzle rows 32a and 32d located on the end side. Therefore, in each nozzle row 32, the injection timing is made different between the end side nozzle 30a and the central side nozzle 30b, and further, the injection timing of the nozzle rows 32a and 32d located on the end side is located on the center side. The injection timing may be different between the nozzle rows 32b and 32c.

5] In the above-described embodiment and its modification, the timing change amount of the end-side nozzle 30a is determined by the droplet speed of the end-side nozzle 30a and the droplet of the center-side nozzle 30b detected at the time of inspection before shipment. Although the measurement is performed based on the velocity, for example, the capacitance that is a characteristic of the piezoelectric actuator 7, the actual dimensions of the individual electrodes 42, and the actual dimensions of the flow path such as the diameter of the nozzle 30 without measuring the droplet velocity. Alternatively, the droplet velocity may be calculated from the landing position deviation as a result of actual printing.

6] In the embodiment and the modified embodiment thereof, the deviation of the landing position due to the difference in droplet velocity is reduced by making the ejection timing different between the end-side nozzle 30a and the center-side nozzle 30b. The same effect can also be realized by making the amount of energy applied to the ink from the piezoelectric actuator 7 different between the end side nozzle 30a and the center side nozzle 30b.

  In order to make the ejection energy applied to the ink in the nozzle 30 from the piezoelectric actuator 7 different between the end-side nozzle 30a and the center-side nozzle 30b, for example, each nozzle 30 is transferred from the driver IC 47 to the piezoelectric actuator 7. The number of drive pulses P (see FIG. 5B) within one drive cycle of the drive signals supplied corresponding to can be changed between the end-side nozzle 30a and the center-side nozzle 30b. Or you may change the drive voltage V of a drive signal with the end side nozzle 30a and the center side nozzle 30b.

7] The energy applying means for applying the ejection energy to the ink in the nozzle 30 is not limited to the piezoelectric actuator 7 of the above embodiment. That is, even if the actuator model is different, the end side nozzle 30a and the center side nozzle are different because the density of the flow path structure is different between the end side and the center side in the nozzle arrangement direction (head rigidity varies). There may be a difference in droplet ejection characteristics from 30b.

8] In the ink jet printer 1 of the above embodiment, the ink jet head 3 reciprocates in the scanning direction, and the recording paper 100 is transported to the ink jet head 3 in a transporting direction perpendicular to the scanning direction. Although it is a so-called serial printer that performs printing, the position of the recording paper 100 during printing is fixed, and printing is performed on the recording paper 100 by moving an inkjet head having nozzles in two directions orthogonal to the recording paper 100. It may be what performs.

  Alternatively, a line-type inkjet head having a plurality of nozzles arranged along the width direction of the recording paper 100 and ejecting liquid droplets while being positioned and fixed at a predetermined position is provided. On the other hand, it may be a so-called line printer that performs printing by transporting the recording paper 100 in a direction orthogonal to the nozzle rows.

  The above-described embodiment and its modifications are examples in which the present invention is applied to an ink jet printer that forms an image or the like by ejecting ink droplets onto a recording sheet. It is not limited to printers. That is, as long as high landing accuracy is required, it can be applied to a droplet ejecting apparatus used in various technical fields other than a printer.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 3 Inkjet head 3a Droplet ejection surface 4 Conveyance mechanism 6 Flow path unit 7 Piezoelectric actuator 24 Pressure chamber 30 Nozzle 30a End side nozzle 30b Center side nozzle 31 Nozzle group 61 Head control circuit 100 Recording paper

Claims (8)

A plurality of nozzles arranged along one direction;
Energy applying means for applying spray energy to the liquid in the plurality of nozzles,
An ejection control unit that controls the energy applying unit to eject droplets from the plurality of nozzles;
The injection control means includes
Among the plurality of nozzles, the injection timing of the end nozzle located on at least one end side of the both end sides in the arrangement direction is different from the injection timing of the center nozzle located closer to the center than the end nozzle. A liquid droplet ejecting apparatus. A plurality of nozzles arranged in order from the one end in the arrangement direction is set as the end-side nozzle,
The injection control means includes
2. The droplet ejecting apparatus according to claim 1, wherein the ejection timing is different among the plurality of end-side nozzles. As the end side nozzle, a plurality of nozzles arranged in order from the one end in the arrangement direction is set,
The injection control means includes
The plurality of the end-side nozzles are divided into a plurality of nozzle groups according to the distance from the one end to the arrangement position of each nozzle, and the injection timing is made different among the plurality of nozzle groups. The droplet ejecting apparatus according to claim 1. The injection control means includes
The injection timing of the end side nozzles respectively positioned on both ends in the arrangement direction among the plurality of nozzles is different from the injection timing of the central side nozzle. The liquid droplet ejecting apparatus described. A liquid droplet ejecting head having a liquid droplet ejecting surface in which the plurality of nozzles are open, and capable of reciprocating in a scanning direction parallel to the liquid droplet ejecting surface and perpendicular to the arrangement direction of the plurality of nozzles;
An object to be ejected, which is disposed opposite to the droplet ejection surface and on which droplets ejected from the plurality of nozzles land, is conveyed in a conveyance direction parallel to the arrangement direction with respect to the droplet ejection head. A conveying means for
The ejection control unit ejects droplets from the plurality of nozzles to the ejected body at both the forward and backward movements of the droplet ejection head,
The transport means moves the ejected body in the transport direction by an arrangement length of the plurality of nozzles relative to the liquid droplet ejecting head during the forward and backward movements of the liquid droplet ejecting head. The droplet ejecting apparatus according to claim 4, wherein the droplet ejecting apparatus is transported. The injection control means includes
By supplying a driving signal corresponding to each nozzle to the energy applying unit, the energy applying unit causes the liquid droplets to be ejected from the nozzle corresponding to the driving signal,
Further, the injection control means includes
The supply timing of the drive signal corresponding to the end-side nozzle to the energy applying unit is made different from the supply timing of the drive signal corresponding to the center-side nozzle. Droplet ejector. A flow path unit in which a liquid flow path is formed, including the plurality of nozzles and a plurality of pressure chambers communicating with the plurality of nozzles and arranged along the one direction;
The liquid droplet according to claim 1, wherein the energy applying unit is a piezoelectric actuator including a piezoelectric layer bonded to the flow path unit so as to cover the plurality of pressure chambers. Injection device. A plurality of nozzles arranged along one direction;
Energy applying means for applying spray energy to the liquid in the plurality of nozzles,
An ejection control unit that controls the energy applying unit to eject droplets from the plurality of nozzles;
The injection control means includes
Among the plurality of nozzles, the energy applied from the energy applying means to the end-side nozzle located on at least one end side of the both end sides in the arrangement direction is positioned closer to the center than the end-side nozzle. A liquid droplet ejecting apparatus, wherein the energy is different from energy applied to a central nozzle.

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