JP2017154338A - Liquid jetting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jetting device that can suppress a decline in printing image quality.SOLUTION: The liquid jetting device includes: a liquid jetting head 3 including a nozzle face 23a opened with a nozzle and jetting a droplet toward a medium from the nozzle; a head movement mechanism for moving the liquid jetting head; and an angle adjustment mechanism 55 for adjusting an angle of the nozzle face relative to a medium. The liquid jetting device jets a droplet from the nozzle while adjusting the angle of the nozzle face relative to a medium in accordance with a movement speed of the liquid jetting head.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a liquid ejecting apparatus including a liquid ejecting head that ejects liquid while moving relative to a landing target.

  As a liquid ejecting apparatus equipped with a liquid ejecting head, for example, there is an image recording apparatus such as an ink jet printer or an ink jet plotter, but recently, a very small amount of liquid can be accurately landed on a predetermined position. It is also applied to various manufacturing equipments. For example, a display manufacturing apparatus for manufacturing a color filter such as a liquid crystal display, an electrode forming apparatus for forming an electrode such as an organic EL (Electro Luminescence) display or FED (surface emitting display), and a chip for manufacturing a biochip (biochemical element) Applied to manufacturing equipment. The recording head for the image recording apparatus ejects liquid ink, and the color material ejecting head for the display manufacturing apparatus ejects solutions of R (Red), G (Green), and B (Blue) color materials. The electrode material ejecting head for the electrode forming apparatus ejects a liquid electrode material, and the bioorganic matter ejecting head for the chip manufacturing apparatus ejects a bioorganic solution.

  Some liquid ejecting apparatuses as described above perform a recording operation (also referred to as a printing operation) by moving a liquid ejecting head in the width direction of a medium such as recording paper (that is, the main scanning direction). For example, the liquid ejecting head ejects liquid from a nozzle by applying a driving voltage to a piezoelectric element (a kind of actuator) and driving the piezoelectric element. When liquid is ejected by such a liquid ejecting head, satellite droplets (small droplets) smaller than the main droplet (main droplet) are generated. The main droplet and the satellite droplet ejected while the liquid ejecting head is moved are displaced in the landing position on the recording medium due to the difference in the drag received from the air during the flight. In order to eliminate such displacement of the landing position, in Patent Document 1, the flying direction of the main droplet and the satellite droplet is made different by making the shape of the nozzle asymmetric in the scanning direction of the liquid jet head.

JP 2000-203012 A

  By the way, in a configuration in which droplets are ejected from the nozzle even when the liquid ejecting head is being accelerated or decelerated (that is, when the speed of the liquid ejecting head has not reached a certain speed), the liquid ejecting head is accelerated. The amount of deviation of the landing positions of the main droplet and the satellite droplet is different between the accelerating section that is decelerating or the decelerating section that is decelerating, and the constant velocity section in which the liquid ejecting head is moving at a constant speed. This point will be described more specifically with reference to FIGS. FIG. 15 is a schematic diagram illustrating liquid ejection in a constant velocity section of the conventional liquid ejecting head 91. FIG. 16 is a schematic diagram illustrating the ejection of liquid in the acceleration section or the deceleration section of the conventional liquid jet head 91 (that is, the section moving at a lower speed than the constant speed section). FIG. 17 is a schematic diagram for explaining landing positions of liquids (main droplets and satellite droplets). In FIG. 15 and FIG. 16, “●” marks indicate the trajectory of the main droplet Md, and “x” marks indicate the trajectory of the satellite droplet Sd. 15 and 16 show a state in which the liquid ejecting head 91 ejects liquid droplets while moving to the right side, as indicated by arrows.

  For example, when the liquid ejecting head 91 moves in a range corresponding to an intermediate region in the width direction of the recording medium 93, the speed of the liquid ejecting head 91 is constant. As shown in FIG. 15, the main droplet Md and the satellite droplet Sd ejected from the nozzle 92 of the liquid ejecting head 91 in this constant velocity section fly obliquely due to inertia. Then, the landing positions of the main droplet Md and the satellite droplet Sd on the recording medium 93 are shifted by the distance D1 due to the difference in drag received from the air during the flight. On the other hand, for example, when the liquid ejecting head 91 is accelerating or decelerating a range corresponding to both ends in the width direction of the recording medium 93, the speed of the liquid ejecting head 91 is the speed of the liquid ejecting head 91 in the constant velocity section. Slower than speed. For this reason, as shown in FIG. 16, the main droplet Md and the satellite droplet Sd ejected from the nozzle 92 of the liquid ejecting head 91 in the acceleration section or the deceleration section are subjected to liquid ejection in the constant velocity section by the drag received from the air during the flight. It becomes smaller than the main droplet Md and satellite droplet Sd ejected from the head 91. As a result, the landing position shift amount D2 between the main droplet Md and the satellite droplet Sd ejected from the nozzle 92 of the liquid ejecting head 91 in the acceleration section or the deceleration section (specifically, the center of the area where the main droplet Md has landed) Between the main droplet Md ejected from the nozzle 92 of the liquid ejecting head 91 and the satellite droplet Sd in the constant velocity section is relatively greater than the distance D1 between the landing positions of the main droplet Md and the satellite droplet Sd. Becomes smaller.

  Thereby, for example, when a solid pattern or the like is printed, streaks and density unevenness may occur. Specifically, as shown in the schematic diagram of the landing position shown in FIG. 17, in the region corresponding to the constant velocity section of the liquid ejecting head 91 in the recording medium 93 (region A in FIG. 17), the main droplet Md and the satellite droplet. Since the landing position deviation amount D1 with Sd becomes relatively large, the amount of overlap between the main droplet Md and the satellite droplet Sd becomes small. That is, in this area, the ratio (in other words, density) occupied by the area (colored area) where the liquid has landed increases. On the other hand, in the region corresponding to the acceleration zone or the deceleration zone of the liquid jet head 91 in the recording medium 93 (region B in FIG. 17), the landing position deviation amount D2 between the main droplet Md and the satellite droplet Sd is relatively small. Therefore, the amount of overlap between the main droplet Md and the satellite droplet Sd increases. That is, in this region, the ratio (density) occupied by the region landed with the liquid is low. This difference in density appears as shading (so-called density unevenness), resulting in a decrease in print image quality. Even if the configuration disclosed in Patent Document 1 is adopted, the same problem occurs because the shape of the nozzle cannot be changed according to the speed of the liquid jet head. Further, the configuration disclosed in Patent Document 1 cannot cope with a case where the main droplet (and satellite droplet) ejection speed (that is, the initial velocity) changes or the distance between the nozzle and the recording medium changes. The amount of deviation between the droplet and the satellite droplet cannot be suppressed.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting apparatus capable of suppressing a decrease in print image quality.

A mounting apparatus according to the present invention has been proposed to achieve the above object, and includes a liquid jet head that includes a nozzle surface in which a nozzle is opened and ejects liquid droplets from the nozzle toward a medium.
A head moving mechanism for moving the liquid ejecting head;
An angle adjustment mechanism for adjusting an angle of the nozzle surface with respect to the medium,
A droplet is ejected from the nozzle while adjusting an angle of the nozzle surface with respect to the medium according to a moving speed of the liquid ejecting head.

  According to the present invention, it is possible to control the amount of deviation of the landing position between the main droplet and the satellite droplet. Thereby, even when the moving speed of the liquid ejecting head changes, it is possible to keep the amount of deviation of the landing positions of the main droplet and the satellite droplet within a certain range. As a result, the generation of streaks and density unevenness in the printed image can be suppressed, and the deterioration of image quality can be suppressed.

Further, in the above-described configuration, the storage device stores an angle adjustment table in which a correlation between a moving speed of the liquid jet head and an angle of the nozzle surface with respect to the medium is shown
It is desirable that the angle adjustment mechanism adopts a configuration that adjusts the angle of the nozzle surface based on information of the angle adjustment table stored in advance in the storage unit.

  According to this configuration, since the angle adjustment table is stored in advance, the processing speed is faster than when the angle of the nozzle surface is calculated for each printing operation. In addition, an angle adjustment table suitable for the characteristics of each liquid ejecting apparatus can be created in advance by printing a test pattern or the like.

  Further, in the above configuration, based on at least one piece of information among a size of a droplet ejected from the nozzle, an initial velocity of the droplet ejected from the nozzle, and a distance between the nozzle and the medium. It is desirable to employ a configuration for correcting the information in the angle adjustment table.

  According to this configuration, even when the moving speed of the liquid ejecting head changes, it is possible to make the amount of deviation of the landing positions of the main droplet and the satellite droplet within a certain range.

In the above configuration, the nozzle is formed for each type of liquid,
Based on the image data to be printed, the first nozzle that ejects the most used liquid among the plurality of types of liquid is determined,
A configuration in which the information in the angle adjustment table is corrected based on at least one information of the size of the droplet ejected from the first nozzle and the initial velocity of the droplet ejected from the first nozzle. It is desirable to adopt.

  According to this configuration, generation of streaks and density unevenness in the printed image can be further suppressed, and deterioration in image quality can be further suppressed.

Furthermore, in any one of the above configurations, a liquid supply source for supplying liquid to the nozzle is detachably provided,
When the liquid is first supplied from the liquid supply source to the nozzle, or when the liquid supply source is replaced, a mode for updating the information of the angle adjustment table stored in the storage unit is provided. It is desirable to adopt a configuration.

  According to this configuration, even if the ejection characteristics of the liquid ejected from the nozzle change due to the attachment / detachment of the liquid supply source, the deviation amount of the landing positions of the main droplet and the satellite droplet can be kept within a certain range.

FIG. 3 is a perspective view illustrating a configuration of a printer. 2 is a block diagram illustrating an electrical configuration of a printer. FIG. It is a schematic diagram explaining the structure of a carriage. FIG. 2 is an exploded perspective view illustrating a configuration of a recording head. It is sectional drawing of a unit head. 6 is a graph showing the relationship between the moving speed of a carriage and the amount of deviation of landing positions of main droplets and satellite droplets. FIG. 6 is a schematic diagram illustrating ink ejection in a constant velocity section of a recording head. FIG. 6 is a schematic diagram illustrating ink ejection in an acceleration section or a deceleration section of a recording head. It is a table | surface explaining an example of an angle adjustment table. It is a table | surface explaining the correction | amendment of an angle adjustment table. It is a table | surface explaining the correction | amendment of an angle adjustment table. It is a table | surface explaining the correction | amendment of an angle adjustment table. 3 is a flowchart illustrating a printing operation of a printer. It is a flowchart explaining the update operation | movement of an angle adjustment table. FIG. 10 is a schematic diagram illustrating liquid ejection in a constant velocity section of a conventional liquid ejection head. FIG. 10 is a schematic diagram illustrating liquid ejection in an acceleration section or a deceleration section of a conventional liquid ejecting head. It is a schematic diagram explaining the landing position of the liquid ejected from the conventional liquid ejecting head.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. Note that, in the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to this embodiment. In the following description, an ink jet printer (hereinafter referred to as a printer) 1 equipped with an ink jet recording head (hereinafter referred to as a recording head) 3 which is a kind of liquid ejecting head is taken as an example of the liquid ejecting apparatus of the present invention. Do it.

  FIG. 1 is a perspective view illustrating the internal configuration of the printer 1, and FIG. 2 is a block diagram illustrating the electrical configuration of the printer 1. FIG. 3 is a schematic diagram illustrating the configuration of the carriage 4. The external device 50 shown in FIG. 2 is an electronic device such as a computer, a digital camera, or a mobile phone. The external device 50 is electrically connected to the printer 1 wirelessly or in a wired manner, and instructs to record (print) an image or text on a recording medium 2 (corresponding to a medium in the present invention) made of paper, resin, or the like. In order to instruct, the image data corresponding to the image and the like is transmitted to the printer 1 together with the instruction / instruction.

  As shown in FIG. 1, the printer 1 in this embodiment includes a recording head 3, a carriage moving mechanism 5 (corresponding to the head moving mechanism in the present invention), a transport mechanism 6, a platen 11, and the like. The recording head 3 is an electronic device that is attached to the bottom side of the carriage 4 and ejects ink, which is a kind of liquid, toward the recording medium 2. The recording head 3 in the present embodiment is attached to the carriage 4 in a state in which the posture with respect to the recording medium 2 can be adjusted by a head angle adjustment mechanism 55 (described later) provided on the carriage 4. The carriage 4 is configured to reciprocate along the guide rod 10 by driving the carriage moving mechanism 5. For this reason, the recording head 3 is moved in the width direction (main scanning direction) of the recording medium 2 by the carriage moving mechanism 5. Further, an ink cartridge 7 as a kind of liquid supply source in which ink is stored is attached to the recording head 3 in a number corresponding to the color of ink to be ejected (in other words, the type of liquid). For example, ink cartridges 7 corresponding to black ink, cyan ink, magenta ink, and yellow ink are attached. Further, the ink cartridge 7 is configured to be detachable from the recording head 3, that is, replaceable. It is also possible to adopt a configuration in which the ink cartridge is arranged on the main body side of the printer, and the ink of the ink cartridge is sent to the recording head side through the supply tube.

  The transport mechanism 6 includes, for example, a roller and transports the recording medium 2 in the sub-scanning direction orthogonal to the main scanning direction. By driving the transport mechanism 6, the recording medium 2 is transported toward the discharge side through the platen 11. The platen 11 is a member that is long in the main scanning direction and is spaced from the nozzle surface 23a (see FIG. 5) of the recording head 3 when performing a recording operation (also referred to as a printing operation). On the surface of the platen 11, a plurality of support protrusions 11a are projected at predetermined intervals along the longitudinal direction. The upper surface of each support protrusion 11a serves as a contact surface that supports the recording medium 2, and partially supports the back surface (the surface opposite to the surface on which ink is landed) of the recording medium 2. In some cases, the transport mechanism is configured by an endless belt or a drum. In such a configuration, the belt or the drum serves as a support member that supports the recording medium. Further, as the support member, it is possible to adopt a structure in which the recording medium is adsorbed by an electrostatic force or a structure in which the recording medium is adsorbed by generating a negative pressure.

  A home position that is a standby position of the recording head 3 is set at a position deviated to one end side (right side in FIG. 1) in the main scanning direction with respect to the platen 11. The printer 1 is either in a forward movement in which the carriage 4 moves from the home position toward the opposite end or in a backward movement in which the carriage 4 returns from the opposite end to the home position. Alternatively, the printing operation can be performed both during the forward movement and during the backward movement. That is, the printer 1 sequentially transports the recording medium 2 onto the platen 11 by the transport mechanism 6, and ink droplets from the nozzles 24 (see FIG. 3) of the recording head 3 while relatively moving the recording head 3 in the main scanning direction. Are ejected (also referred to as ejection) and landed on the recording medium 2 to record an image or the like.

  As illustrated in FIG. 2, the printer 1 according to the present embodiment includes a printer controller 51 and a print engine 52. The printer controller 51 is a control unit that controls each unit in the printer 1. As shown in FIG. 2, the printer controller 51 in the present embodiment includes an interface (I / F) unit 58, a main control circuit 59, a storage unit 60 (corresponding to storage means in the present invention), and a drive signal generation circuit. 61. The interface unit 58 receives image data and a print command from the external device 50 to the printer 1 and outputs status information of the printer 1 to the external device 50 side. The storage unit 60 is an element that stores a program for the main control circuit 59 and data used for various controls, and includes a ROM, a RAM, and an NVRAM (nonvolatile storage element). The storage unit 60 stores an angle adjustment table described later.

  The main control circuit 59 controls each unit according to a program stored in the storage unit 60. In addition, the main control circuit 59 in the present embodiment generates ejection data indicating at which timing from which nozzle 24 ink is ejected during the printing operation based on the image data from the external device 50, and records the ejection data. It transmits to the head controller 65 of the head 3. Further, the main control circuit 59 in the present embodiment creates tilt data indicating how much the recording head 3 is tilted based on the angle adjustment table stored in the storage unit 60, and generates a drive signal corresponding to the tilt data. Transmit to the head angle adjustment mechanism 55. The main control circuit 59 also generates a timing pulse PTS from the encoder pulse output from the linear encoder 64. The main control circuit 59 controls transfer of image data, generation of a drive signal by the drive signal generation circuit 61, and the like in synchronization with the timing pulse PTS. Further, the main control circuit 59 generates a timing signal such as a latch signal LAT based on the timing pulse PTS and outputs it to the head controller 65 of the recording head 3.

  The head controller 65 selectively applies a drive signal to the piezoelectric element 32 based on the ejection data and the timing signal. As a result, the piezoelectric element 32 is driven, and ink (hereinafter also referred to as ink droplets) is ejected (ejected) from the nozzles 24, or a minute vibration operation is performed to the extent that ink is not ejected. The drive signal generation circuit 61 generates a drive signal including a drive pulse for recording an image or the like by ejecting ink onto the recording medium 2.

  Next, the print engine 52 will be described. As shown in FIG. 2, the print engine 52 includes a transport mechanism 6, a carriage moving mechanism 5, a linear encoder 64, a display device 53, an operation unit 54, a head angle adjustment mechanism 55, a recording head 3, and the like. . The carriage moving mechanism 5 includes a timing belt 8 and a pulse motor 9 such as a DC motor for driving the timing belt 8 (see FIG. 1). The carriage moving mechanism 5 moves the recording head 3 mounted on the carriage 4 in the main scanning direction. Further, the transport mechanism 6 sequentially sends the recording medium 2 onto the platen 11 and transports the recording medium 2 on the platen 11 in the sub scanning direction orthogonal to the main scanning direction. Further, the linear encoder 64 outputs an encoder pulse corresponding to the scanning position of the recording head 3 mounted on the carriage 4 to the printer controller 51 as position information in the main scanning direction. The main control circuit 59 of the printer controller 51 can grasp the scanning position (current position) of the recording head 3 based on the encoder pulse received from the linear encoder 64 side.

  The display device 53 includes, for example, a liquid crystal display panel, and displays various types of information such as error notifications and the current state of the printer 1 under the control of the main control circuit 59. The display device 53 displays a user interface for performing various settings of the printer 1. The operation unit 54 includes, for example, a button provided on the casing of the printer 1, a touch panel attached to the display device 53, and the like, and transmits a signal corresponding to the operation to the main control circuit 59. In addition, without providing the display device 53, notifications and various types of information can be displayed on a display unit provided in the external device 50 such as a computer. Further, a signal from an operation unit provided in the external device 50 may be received without providing the operation unit 54.

  The head angle adjusting mechanism 55 includes, for example, an eccentric cam 67, a drive motor 68, and an urging spring 69 as shown in FIG. 3 represents the moving direction of the recording head 3, that is, the main scanning direction. Also, the broken line in FIG. 3 represents the recording head 3 tilted by driving the head angle adjusting mechanism 55. The eccentric cam 67 is formed in a disc shape, and the drive shaft of the drive motor 68 is attached to a position off the center. The eccentric cam 67 is configured to be rotatable by driving a drive motor 68. The biasing spring 69 is attached to the opposite side of the eccentric cam 67 with the holder 12 of the recording head 3 interposed therebetween. Due to the urging force of the urging spring 69, one end (left side in FIG. 3) of the holder 12 in the main scanning direction is pressed against the eccentric cam 67 side. A rotation shaft 70 fixed to the carriage 4 is inserted through the center of the holder 12 in the main scanning direction. That is, the holder 12 is pivotally supported by the rotation shaft 70 and is configured to be rotatable about this. When the drive motor 68 is driven by the drive signal from the main control circuit 59, the eccentric cam 67 rotates to move the one end portion of the holder 12 away from or closer to the recording medium 2. Let Along with this, the posture of the holder 12 (that is, the recording head 3) changes around the rotation shaft 70, and the angle of the lower surface of the recording head 3 (in other words, the nozzle surface 23a) with respect to the recording medium 2 changes.

  Next, the configuration of the recording head 3 will be described. FIG. 4 is an exploded perspective view of the recording head 3. FIG. 5 is a cross-sectional view of the unit head 13 incorporated in the recording head 3. The recording head 3 is formed by stacking a holder 12, a plurality of unit heads 13, a fixed plate 14, and the like.

  The holder 12 is a synthetic resin member, and has a cartridge mounting portion 15 on the upper surface thereof. In the cartridge mounting portion 15, a plurality of ink introduction needles 16 corresponding to the ink cartridges 7 of the respective colors are provided side by side along the main scanning direction. The ink introduction needle 16 is a hollow needle-like member that is inserted into the ink cartridge 7. The ink stored in the ink cartridge 7 is introduced into a flow path (not shown) in the holder 12 through the ink introduction needle 16. The configuration for introducing the ink from the ink cartridge 7 into the holder 12 is not limited to the configuration using the ink introduction needle 16. For example, a porous member capable of absorbing ink is provided on each of the ink supply side and the reception side. It is also possible to employ a configuration in which ink is exchanged by providing and bringing the porous members into contact with each other.

  A plurality of unit heads 13 are attached below the holder 12. The unit heads 13 in the present embodiment are arranged in parallel along the main scanning direction (that is, the direction orthogonal to the nozzle row direction) with the longitudinal direction aligned in the direction orthogonal to the main scanning direction. In the present embodiment, four unit heads 13 are attached corresponding to the four colors of ink. The unit heads 13 are bonded and fixed to the fixing plate 14 in a state of being positioned with respect to each other. The fixed plate 14 is a plate material formed of, for example, stainless steel (SUS), and protects the lower surface and side surfaces of the unit head 13. As shown in FIG. 4, the fixing plate 14 in the present embodiment is configured so that the peripheral portion thereof is bent upward (that is, on the unit head 13 side) and along the side surface of the unit head 13. Further, four openings 14 a that expose the nozzles 24 (that is, the nozzle surface 23 a) of each unit head 13 are formed in the fixed plate 14 corresponding to each unit head 13. The number of unit heads 13 attached to the recording head 3 is not limited to four, and may be one or more. Further, the fixing plate 14 is not limited to one whose peripheral edge is bent upward, and a flat fixing plate can also be employed.

  Next, the configuration of the unit head 13 will be described. As shown in FIG. 5, the unit head 13 in this embodiment is attached to the head case 19 in a state where the actuator unit 17 and the flow path unit 18 are stacked. For convenience, the stacking direction of each member will be described as the vertical direction.

  The head case 19 in the present embodiment is a box-shaped member made of synthetic resin. As shown in FIG. 5, a housing space 20 and a penetrating space 22 that are long spaces along the nozzle row direction are formed in the central portion of the head case 19. The accommodation space 20 is a space in which the actuator unit 17 is accommodated, and is recessed from the lower surface of the head case 19 to the middle of the plate thickness direction (that is, the direction orthogonal to the lower surface) by the thickness of the actuator unit 17. Is formed. The through space 22 communicates with the ceiling surface on the upper surface side of the accommodation space 20 and is formed in a state of penetrating the head case 19 in the plate thickness direction. A flexible cable 35 (a type of wiring member) that supplies a drive signal to a piezoelectric element 32 (described later) is disposed in the through space 22 and the accommodation space 20. As shown in FIG. 4, the flexible cable 35 extends from the upper surface opening of the through space 22 to the outside of the unit head 13 and is connected to a head controller 65 provided in the holder 12. A liquid introduction path 21 through which ink flows is formed inside the head case 19. The liquid introduction path 21 is a flow path that connects a flow path in the holder 12 and a common liquid chamber 26 described later.

  A flow path unit 18 is connected to the lower surface of the head case 19. The flow path unit 18 is a long substrate along the nozzle row direction in which the communication substrate 25, the nozzle plate 23, and the compliance substrate 37 are laminated. The communication substrate 25 is a silicon plate material, and in this embodiment, is formed from a silicon single crystal substrate having a crystal plane orientation of the surface (upper surface and lower surface) as a (110) plane. As shown in FIG. 5, the communication substrate 25 communicates with the liquid introduction path 21, and stores a common liquid chamber 26 in which ink common to each pressure chamber 30 is stored, and introduces the liquid via the common liquid chamber 26. An individual communication path 27 that individually supplies ink from the passage 21 to each pressure chamber 30 and a nozzle communication path 28 that connects the pressure chamber 30 and the nozzle 24 are formed by anisotropic etching. A plurality of individual communication passages 27 are opened at positions corresponding to the pressure chambers 30 of the common liquid chamber 26. That is, a plurality of the individual communication paths 27 are formed along the direction in which the pressure chambers 30 are arranged in parallel (in other words, the nozzle row direction). Similarly, a plurality of nozzle communication paths 28 are also formed along the nozzle row direction.

  The nozzle plate 23 is a silicon substrate (for example, a silicon single crystal substrate) bonded to the lower surface of the communication substrate 25 (that is, the surface opposite to the pressure chamber forming substrate 29). The nozzle plate 23 of the present embodiment is joined to a region that is out of the compliance substrate 37 so as not to overlap the compliance substrate 37. In other words, the nozzle plate 23 is joined to a region outside the opening on the lower surface side of the common liquid chamber 26 of the communication substrate 25. A plurality of nozzles 24 (referred to as nozzle rows) are provided in a straight line shape (in other words, in a row shape) along the sub-scanning direction on the nozzle surface 23a which is the lower surface of the nozzle plate 23. The plurality of nozzles 24 (nozzle rows) arranged side by side are provided at equal intervals from the nozzle 24 on one end side to the nozzle 24 on the other end side at a pitch corresponding to the dot formation density.

  The compliance substrate 37 is a flexible substrate bonded to the lower surface of the communication substrate 25 and corresponding to the common liquid chamber 26. That is, the compliance substrate 37 is bonded to a region of the communication substrate 25 that is not covered with the nozzle plate 23. The compliance substrate 37 in the present embodiment is a plate material in which a sealing film 39 having low rigidity and flexibility is laminated on a fixed substrate 38 made of a hard material such as metal. A region of the fixed substrate 38 that faces the common liquid chamber 26 is an opening that is removed in the thickness direction. For this reason, the lower surface of the common liquid chamber 26 is sealed only with the sealing film 39 and functions as a compliance section that absorbs pressure fluctuations of the ink in the common liquid chamber 26.

  As shown in FIG. 5, the actuator unit 17 in the present embodiment includes a pressure chamber forming substrate 29, a vibration plate 31, a piezoelectric element 32, and a sealing plate 33, which are laminated and unitized. Is attached. The actuator unit 17 is formed in a size that can be accommodated in the accommodating space 20 of the head case 19, and is accommodated in the accommodating space 20.

  The pressure chamber forming substrate 29 is a hard plate made of silicon, and in the present embodiment, is produced from a silicon single crystal substrate having the crystal plane orientation of the surface (upper surface and lower surface) as the (110) plane. A part of the pressure chamber forming substrate 29 is completely removed in the plate thickness direction by anisotropic etching, and a plurality of spaces to be the pressure chambers 30 are arranged in parallel along the nozzle row direction. The space is partitioned by the communication substrate 25 on the lower side and partitioned by the diaphragm 31 to form the pressure chamber 30. Further, this space, that is, the pressure chamber 30 is formed long in a direction orthogonal to the nozzle row direction, and the individual communication path 27 communicates with one end portion in the longitudinal direction, and the nozzle is formed at the other end portion. The communication path 28 communicates.

  The diaphragm 31 is a thin film member having elasticity, and is laminated on the upper surface of the pressure chamber forming substrate 29 (that is, the surface opposite to the communication substrate 25 side). The diaphragm 31 seals the upper opening of the space to be the pressure chamber 30. In other words, the upper surface of the pressure chamber 30 is partitioned by the diaphragm 31. A portion of the diaphragm 31 corresponding to the pressure chamber 30 (specifically, an upper opening of the pressure chamber 30) functions as a displacement portion that displaces in a direction away from or close to the nozzle 24 as the piezoelectric element 32 is bent and deformed. To do. That is, a region corresponding to the upper opening of the pressure chamber 30 in the diaphragm 31 is a drive region where bending deformation is allowed. The volume of the pressure chamber 30 changes due to the deformation (displacement) of the drive region (displacement portion). On the other hand, a region of the diaphragm 31 that is out of the upper opening of the pressure chamber 30 is a non-driving region in which bending deformation is hindered.

The diaphragm 31 includes, for example, an elastic film made of silicon dioxide (SiO ₂ ) formed on the upper surface of the pressure chamber forming substrate 29, and an insulator film made of zirconium dioxide (ZrO ₂ ) formed on the elastic film. , Consisting of. And the piezoelectric element 32 is laminated | stacked on the area | region (namely, drive area | region) corresponding to each pressure chamber 30 on this insulating film (surface on the opposite side to the pressure chamber formation board | substrate 29 side of the diaphragm 31). It is also possible to adopt a configuration in which the pressure chamber forming substrate and the diaphragm are integrated. In other words, an etching process is performed from the lower surface side of the pressure chamber forming substrate, a pressure chamber is formed on the upper surface side leaving a thin portion with a thin plate thickness, and a configuration in which this thin portion functions as a diaphragm may be adopted. it can.

  The piezoelectric element 32 in the present embodiment is a so-called flexural mode piezoelectric element. A plurality of the piezoelectric elements 32 are arranged in parallel along the nozzle row direction corresponding to each nozzle 24. Each piezoelectric element 32 is formed by sequentially laminating, for example, a lower electrode layer serving as an individual electrode, a piezoelectric layer, and an upper electrode layer serving as a common electrode in order from the vibration plate 31. Note that the lower electrode layer can be a common electrode and the upper electrode layer can be an individual electrode depending on the convenience of the drive circuit and wiring. The piezoelectric element 32 configured as described above bends and deforms in a direction away from or close to the nozzle 24 when an electric field corresponding to the potential difference between both electrodes is applied between the lower electrode layer and the upper electrode layer.

  As shown in FIG. 5, the sealing plate 33 is a substrate on which a piezoelectric element accommodation space 34 that can accommodate the piezoelectric elements 32 is formed. The sealing plate 33 is joined to the vibration plate 31 in a state where the piezoelectric element 32 is accommodated in the piezoelectric element accommodation space 34. In addition, as a sealing plate, the flat member in which a piezoelectric element accommodation space is not formed is also employable. In this case, a space for accommodating the piezoelectric element is formed by increasing the thickness of the adhesive for joining the vibration plate and the sealing plate and surrounding the periphery of the piezoelectric element with this adhesive. Further, it is possible to adopt a configuration in which a circuit such as a drive circuit or wiring is formed on the sealing plate itself.

  The unit head 13 configured as described above operates as follows to eject ink droplets. That is, the drive signal from the head controller 65 is supplied to the piezoelectric element 32 in a state where the ink from the ink cartridge 7 is introduced into the pressure chamber 30 via the flow path (the liquid introduction path 21, the common liquid chamber 26, etc.). Then, the piezoelectric element 32 is deformed according to the drive signal, and causes a pressure fluctuation in the ink in the pressure chamber 30. Then, by utilizing this pressure fluctuation, ink droplets are ejected from the nozzle 24 communicating with the pressure chamber 30 toward the recording medium 2.

  By the way, the printer 1 in this embodiment adjusts the angle of the nozzle surface 23a with respect to the recording medium 2 according to the moving speed in the main scanning direction of the recording head 3 that moves in the main scanning direction by driving the carriage moving mechanism 5. However, the ink droplets are ejected from the nozzles 24. Specifically, the head angle is adjusted according to the moving speed of the recording head 3 in the main scanning direction so that the amount of deviation of the landing positions of the main droplet and satellite droplet ejected from the nozzle 24 is within a certain range. The angle of the nozzle surface 23 a is adjusted by driving the mechanism 55. This angle adjusting method will be described in detail below.

  FIG. 6 shows the moving speed of the carriage 4 (that is, the recording head 3) when the angle of the nozzle surface 23a with respect to the recording medium 2 (horizontal plane in this embodiment) is changed, and the landing positions of the main droplet and the satellite droplet. It is a graph showing the relationship with the deviation | shift amount. The horizontal axis represents the moving speed of the carriage 4 (recording head 3). In the present embodiment, character / second (cps) is used as an index representing the moving speed of the carriage 4. The vertical axis represents the amount of displacement of the landing position between the main droplet and the satellite droplet (more specifically, the distance (μm) between the center of the region where the main droplet landed and the center of the region where the satellite droplet landed). In this graph, the elevation angle with respect to the traveling direction of the recording head 3 (in other words, the elevation angle and the depression angle when facing the traveling direction from the recording head 3 (see angle θ in FIG. 8); hereinafter simply referred to as elevation angle). Is changed from θ1 to θ4. In the present embodiment, θ1 is a graph with an elevation angle of 2 °, θ2 is a graph with an elevation angle of 0 ° (that is, the nozzle surface 23a is not inclined), θ3 is a graph with an elevation angle of −2 ° (in other words, a depression angle of 2 °), θ4 is a graph with an elevation angle of −5 ° (in other words, a depression angle of 5 °).

  As can be seen from FIG. 6, in the state (θ2) in which the nozzle surface 23a is not inclined, the speed of the ejected ink droplets increases as the carriage 4 moves faster, and the ink droplets in flight accordingly. Since the drag received from the air also increases, the amount of shift in the landing position between the main droplet and the satellite droplet increases. For this reason, the deviation amount of the landing positions of the main droplets and satellite droplets ejected from the nozzles 24 in the acceleration section or the deceleration section of the carriage 4 (that is, the section in which the moving speed of the carriage 4 is slower than the constant speed section) This is relatively smaller than the amount of deviation of the landing positions of the main droplet and the satellite droplet ejected from the nozzle 24 in the constant velocity section 4. As a result, areas where ink droplets ejected from the nozzles 24 in the acceleration section or the deceleration section of the carriage 4 land (for example, both ends in the main scanning direction of the recording medium 2) and the nozzles 24 in the constant speed section of the carriage 4. The overlapping degree of the main droplet and the satellite droplet is different in a region where the ejected ink droplet is landed (for example, the central portion of the recording medium 2 in the main scanning direction). That is, the proportion (density) of the area where the ink has landed differs. This difference in density appears as shading (so-called density unevenness), resulting in a decrease in print image quality. As shown in FIG. 6, the nozzle surface 23a is also tilted due to the deviation of the landing positions of the main droplet and the satellite droplet when the nozzle surface 23a is tilted (the nozzle surface 23a is at the elevation angles θ1, θ3, θ4). This is the same tendency as the amount of deviation of the landing positions of the main droplet and the satellite droplet in a state where the main droplet and the satellite droplet are not in the state where the nozzle surface 23a is at the elevation angle θ2.

  On the other hand, as shown in FIG. 6, at the same moving speed of the carriage 4, as the inclination of the nozzle surface 23a changes from the elevation angle θ1 to the elevation angle θ4, that is, the inclination of the nozzle surface 23a increases in the minus direction of the elevation angle. It can be seen that the deviation amount of the landing positions of the main droplets and satellite droplets ejected from the nozzle 24 increases. In other words, as the inclination of the nozzle surface 23a increases in the positive direction of the elevation angle, the amount of shift in the landing position between the main droplet and satellite droplet ejected from the nozzle 24 decreases. That is, if the nozzle surface 23a is inclined so as to face in the direction opposite to the moving direction of the carriage 4, and ink droplets are ejected obliquely from the nozzle 24 in the direction opposite to the moving direction of the carriage 4 and downward, the nozzle surface The amount of deviation of the landing positions of the main droplet and the satellite droplet can be increased as compared with the state where 23a is not inclined (see FIG. 8). By utilizing this fact, it is possible to adjust the amount of deviation of the landing positions of the main droplet and the satellite droplet to be within a certain range. That is, when the moving speed of the carriage 4 is slow, as described above, the amount of deviation of the landing positions of the main droplet and the satellite droplet is smaller than when the moving speed of the carriage 4 is fast. Driven to increase the inclination of the nozzle surface 23a in the minus direction of the elevation angle. As a result, the shift amount of the landing position between the main droplet and the satellite droplet ejected from the recording head 3 moving slowly is changed to the shift amount of the landing position between the main droplet and the satellite droplet ejected from the recording head 3 moving fast. You can get closer.

  More specifically, as shown in FIG. 6, when the moving speed of the carriage 4 is 100 (cps), the elevation angle θ4 (−5 °) is selected as the inclination of the nozzle surface 23a. At this time, the amount of deviation between the landing positions of the main droplet and the satellite droplet is about 115 (μm). When the moving speed of the carriage 4 is 200 (cps), the elevation angle θ3 (−2 °) is selected as the inclination of the nozzle surface 23a. At this time, the amount of deviation between the landing positions of the main droplet and the satellite droplet is about 105 (μm). Further, when the moving speed of the carriage 4 is 300 (cps), the elevation angle θ2 (0 °) is selected as the inclination of the nozzle surface 23a. At this time, the deviation amount of the landing positions of the main droplet and the satellite droplet is about 110 (μm). In this way, by driving the head angle adjusting mechanism 55 according to the moving speed of the carriage 4 and changing the inclination of the nozzle surface 23a, the landing positions of the main droplets and the satellite droplets as shown by the broken lines in FIG. Can be made the same amount of deviation. In other words, even when the moving speed of the recording head 3 changes, the deviation amount of the landing positions of the main droplet and the satellite droplet is within a certain range (in the present embodiment, a range of about 100 (μm) to 120 (μm)). ). As a result, the occurrence of streaks and density unevenness in the printed image can be suppressed, and a decrease in print image quality can be suppressed. In short, when ink droplets are ejected when the moving speed of the recording head 3 changes between 50 (cps) and 300 (cps) in the acceleration section and the deceleration section of the carriage 4, the nozzle surface is adjusted accordingly. By gradually changing the inclination of 23a between the elevation angle θ4 (−5 °) and the elevation angle θ2 (0 °), the deviation amount of the landing position can be kept in the range of about 100 (μm) to 120 (μm). .

  FIG. 7 is a schematic diagram illustrating ink ejection in a constant velocity section of the carriage 4 (that is, the recording head 3) (for example, the moving speed of the carriage 4 is 300 (cps)). FIG. 8 is a schematic diagram showing ink ejection in the acceleration section or the deceleration section of the carriage 4 (recording head 3) (for example, the moving speed of the carriage 4 is 100 (cps)). In FIG. 7 and FIG. 8, “●” marks represent the trajectory of the main droplet Md, and “x” marks represent the trajectory of the satellite droplet Sd. 7 and 8, the recording head 3 ejects ink droplets while moving to the right as shown by the arrows. As shown in FIG. 7, in the constant velocity section of the carriage 4, the speed of the ink droplets ejected due to inertia becomes relatively high, so the drag that the ink droplets receive during flight increases, and the main droplet Md and the satellite droplet Sd. The displacement amount d1 of the landing position is relatively large. For this reason, the nozzle surface 23a is not inclined as in the conventional liquid jet head.

  On the other hand, in the acceleration section or the deceleration section of the carriage 4, the speed of the ejected ink droplet is relatively slow, so that the drag that the ink droplet receives during flight is small, and the landing position of the main droplet Md and the satellite droplet Sd is the same. The amount of deviation is relatively small. For this reason, as shown in FIG. 8, the nozzle surface 23a is tilted so as to face in the direction opposite to the moving direction of the carriage 4, and the ink droplets are slanted in the direction opposite to the moving direction of the carriage 4 and downward. By ejecting, the landing position shift amount d2 between the main droplet Md and the satellite droplet Sd is increased. As a result, the landing position deviation d2 between the main droplet Md and the satellite droplet Sd ejected from the nozzle 24 of the recording head 3 in the acceleration section or the deceleration section is ejected from the nozzle 24 of the recording head 3 in the constant speed section. The amount of landing position deviation d1 between the main droplet Md and the satellite droplet Sd can be approached. Note that if the ink droplets are ejected by tilting the nozzle surface 23a, the ink droplet ejection timing is changed according to the inclination because the ink droplets are displaced from the originally planned landing position. For example, the ejection timing of the ink droplet is delayed as the inclination of the nozzle surface 23a increases in the minus direction of the elevation angle. As a result, it is possible to change the amount of deviation of the landing position between the main droplet Md and the satellite droplet Sd without changing the landing position of the main droplet Md.

  In this embodiment, the amount of landing position deviation between the main droplet and the satellite droplet according to the moving speed of the carriage 4 is obtained in advance by calculation, experiment, or the like at the inclination angles of the plurality of nozzle surfaces 23a. The inclination angle of the nozzle surface 23a corresponding to the moving speed is obtained. This result is stored in the storage unit 60 as an angle adjustment table showing a correlation between the moving speed of the carriage 4 and the angle of the nozzle surface 23a with respect to the recording medium 2. That is, as shown in FIG. 9, the moving speed of the carriage 4 and the corresponding tilt angle of the nozzle surface 23a are stored in the storage unit 60 as an angle adjustment table. Then, the main control circuit 59 calculates the moving speed of the carriage 4 from the encoder pulse output from the linear encoder 64 and refers to the angle adjustment table stored in advance in the storage unit 60 to obtain the moving speed of the carriage 4. The inclination angle of the corresponding nozzle surface 23a is obtained. Thereafter, the main control circuit 59 transmits a drive signal to the head angle adjusting mechanism 55 based on the obtained tilt data of the tilt angle information of the nozzle surface 23a, and records it so as to obtain the determined tilt angle of the nozzle surface 23a. Control is performed to eject ink droplets from the nozzles 24 while changing the posture of the head 3. That is, the head angle adjustment mechanism 55 and the main control circuit 59 correspond to the angle adjustment mechanism in the present invention.

ここで、液滴に作用する抗力は以下の式で表される。

また、上式における抗力係数Ｃ_Ｄは、以下の式で表される。

さらに、レイノルズ数Ｒｅは、以下の式で表される。

なお、νは空気の動粘性係数である。 In the angle adjustment table in FIG. 9, the moving speed of the carriage 4 is divided into three stages, and the optimum inclination angle of the nozzle surface 23a is stored at each moving speed, but this is not restrictive. The relationship between the moving speed of the carriage 4 and the optimum inclination angle of the nozzle surface 23a may be obtained more finely. For example, the relationship between the moving speed of the carriage 4 and the amount of deviation of the landing position is obtained from the inclination angles of the plurality of nozzle surfaces 23a, and the carriage 4 is determined from the result so that the amount of deviation of the landing position falls within a certain range. The inclination angle of the nozzle surface 23a corresponding to the moving speed is obtained. In this case, the deviation amount of the landing positions of the main droplet and the satellite droplet according to the inclination angle of each nozzle surface 23a may be obtained by actually ejecting ink droplets, or may be obtained by calculation or simulation. When calculating | requiring by calculation, it can obtain | require from the following equation of motion of a droplet, for example.

Here, the drag acting on the droplet is expressed by the following equation.

Also, the drag coefficient C _D in the above formula can be expressed as the following formula.

Furthermore, the Reynolds number Re is expressed by the following equation.

Note that ν is the kinematic viscosity coefficient of air.

  As can be seen from the above formula, if the initial velocity of the ejected ink droplet, the size of the ejected ink droplet, or the distance between the nozzle 24 and the recording medium 2 changes, the landing of the ink droplet The position changes, and the amount of landing position deviation between the main droplet and the satellite droplet also changes. For this reason, it is desirable to correct the angle information of the angle adjustment table according to these changes. That is, at least one or more of the size of the ink droplet (main droplet) ejected from the nozzle 24, the initial speed of the ink droplet (main droplet) ejected from the nozzle 24, and the distance between the nozzle 24 and the recording medium 2 It is desirable to correct the angle information of the angle adjustment table based on this information. For example, the greater the remaining amount of ink in the in-cartridge 7, the higher the pressure in the pressure chamber 30 (hereinafter referred to as back pressure) communicating with the in-cartridge 7, and the initial velocity of ink droplets ejected from the nozzles 24 increases. There is a tendency. As the initial velocity of the ink droplet increases, the time until the ink droplet lands on the recording medium 2 is shortened, and the amount of deviation of the landing position between the main droplet and the satellite droplet is also decreased. For this reason, it correct | amends so that the inclination degree with respect to the recording medium 2 of the nozzle surface 23a may become small, so that the initial velocity of the ink droplet to eject becomes high. For example, as shown in FIG. 10, the absolute value of the angle information corresponding to the moving speed of each carriage 4 in the angle adjustment table is set to −30%, and the inclination of the nozzle surface 23a with respect to the recording medium 2 at the moving speed of each carriage 4 is set. To make it smaller. On the other hand, correction is performed so that the degree of inclination of the nozzle surface 23a with respect to the recording medium 2 increases as the initial velocity of the ejected ink droplets decreases. For example, as shown in FIG. 10, the absolute value of the angle information corresponding to the moving speed of each carriage 4 in the angle adjustment table is set to + 30%, and the inclination degree of the nozzle surface 23a with respect to the recording medium 2 at the moving speed of each carriage 4 is set. Make it bigger. As a result, even when the initial velocity of the ink droplet changes from the preset setting value, the deviation amount of the landing positions of the main droplet and the satellite droplet can be kept within a certain range. As a result, the generation of streaks and density unevenness in the printed image can be further suppressed, and the deterioration of the image quality can be further suppressed.

  Further, when the size (that is, the weight) of the ink droplet is increased by changing the driving waveform applied to the piezoelectric element 32, the amount of deviation of the landing position between the main droplet and the satellite droplet is decreased. For this reason, it correct | amends so that the inclination degree with respect to the recording medium 2 of the nozzle surface 23a may become small, so that the magnitude | size of the ink droplet to eject becomes large. For example, as shown in FIG. 11, the absolute value of the angle information corresponding to the moving speed of each carriage 4 in the angle adjustment table is set to −30%, and the inclination of the nozzle surface 23a relative to the recording medium 2 at the moving speed of each carriage 4 is set. To make it smaller. On the other hand, correction is performed so that the degree of inclination of the nozzle surface 23a with respect to the recording medium 2 increases as the size of the ejected ink droplet decreases. For example, as shown in FIG. 11, the absolute value of the angle information corresponding to the moving speed of each carriage 4 in the angle adjustment table is set to + 30%, and the inclination degree of the nozzle surface 23a with respect to the recording medium 2 at the moving speed of each carriage 4 is set. Make it bigger. As a result, even when the size of the ink droplet changes, the deviation amount of the landing positions of the main droplet and the satellite droplet can be kept within a certain range. As a result, the generation of streaks and density unevenness in the printed image can be further suppressed, and the deterioration of the image quality can be further suppressed.

  Further, for example, when the interval between the nozzle 24 and the recording medium 2 becomes narrow due to a change in the thickness of the recording medium 2 (that is, when the distance from the nozzle 24 to the recording medium 2 becomes short), the main The amount of deviation of the landing position between the droplet and the satellite droplet is small. For this reason, it correct | amends so that the inclination degree with respect to the recording medium 2 of the nozzle surface 23a may become small, so that the distance from the nozzle 24 to the recording medium 2 becomes short. For example, as shown in FIG. 12, the absolute value of the angle information corresponding to the moving speed of each carriage 4 in the angle adjustment table is set to −30%, and the inclination of the nozzle surface 23a with respect to the recording medium 2 at the moving speed of each carriage 4 is set. To make it smaller. On the other hand, as the distance from the nozzle 24 to the recording medium 2 increases, the inclination degree of the nozzle surface 23a with respect to the recording medium 2 is corrected so as to increase. For example, as shown in FIG. 12, the absolute value of the angle information corresponding to the moving speed of each carriage 4 in the angle adjustment table is set to + 30%, and the inclination degree of the nozzle surface 23a with respect to the recording medium 2 at the moving speed of each carriage 4 is set. Make it bigger. Thereby, even when the interval between the nozzle 24 and the recording medium 2 is changed, the deviation amount of the landing positions of the main droplet and the satellite droplet can be kept within a certain range. As a result, the generation of streaks and density unevenness in the printed image can be further suppressed, and the deterioration of the image quality can be further suppressed.

  Next, the printing operation of the printer 1 will be described with reference to the flowchart of FIG. The storage unit 60 of the printer 1 stores in advance an angle adjustment table corresponding to representative ink (for example, black ink). The angle adjustment table may be obtained by actually ejecting ink droplets when the printer 1 is manufactured, or may be obtained by calculation or simulation. Specifically, it can be obtained by printing a test pattern or the like, or can be obtained by a simulation or the like in consideration of the characteristics of the ink assumed to be used and the thickness of the recording medium.

  First, when image data is transmitted as print data from the external device 50 to the main control circuit 59, a print process is started. Based on the image data sent from the external device 50 and the thickness of the recording medium 2 to be printed, the main control circuit 59 determines whether it is necessary to perform a printing operation while tilting the recording head 3 (step S1). . For example, when printing a sentence or the like having a margin at the end of the recording medium 2, ink droplets may hardly be ejected in the acceleration section or the deceleration section of the carriage 4, and the ink density on the recording medium 2 is low. Therefore, density unevenness and the like are unlikely to occur. For this reason, in such a case, the main control circuit 59 determines that there is no need to tilt the recording head 3 (No in step S1). In addition, since the recording medium 2 is thick and the distance between the nozzle 24 and the recording medium 2 is narrow, the amount of deviation of the landing positions of the main droplet and the satellite droplet is reduced as a whole, and density unevenness is unlikely to occur. If it can be determined, the main control circuit 59 determines that there is no need to tilt the recording head 3 (No in step S1). Thus, when it is determined that there is no need to tilt the recording head 3, the angle of the recording head 3 is kept constant with respect to the recording medium 2 (for example, the nozzle surface 23 a is parallel to the recording medium 2. In this state, normal printing is performed in which ink is ejected from the nozzles 24 (step S6). When all the printing operations are completed, the printing process is completed.

  On the other hand, when printing a photograph or the like, the ink is landed at a high density up to the end of the recording medium 2, which may cause density unevenness. Therefore, in such a case, it is determined that the recording head 3 needs to be tilted (Yes in step S1). Next, the main control circuit 59 determines the first nozzle that ejects the most used ink among the inks of each color (in other words, a plurality of types of liquids) based on the image data to be printed (step S2). For example, when the magenta ink is most used by analyzing the image data, the nozzle 24 that ejects the magenta ink (in this embodiment, the nozzle row that ejects magenta ink) is determined as the first nozzle. The most used ink may be converted, for example, by the amount of ink consumed, or may be converted by the number of times the ink is ejected (that is, the number of dots). If the first nozzle is determined, the angle adjustment table stored in the storage unit 60 is referred to, the angle information in the angle adjustment table is corrected as appropriate, and the nozzle surface 23a is recorded according to the moving speed of the carriage 4. An inclination angle (simply referred to as angle information) with respect to the medium 2 is determined (step S3). Specifically, when the size and initial velocity of the ink droplets ejected from the first nozzle are changed from the initial settings (for example, when the remaining amount or viscosity of the ink cartridge 7 is changed as compared with the black ink state). The angle information in the angle adjustment table is corrected based on information on the size of the ink droplet ejected from the first nozzle, the initial velocity of the ink droplet ejected from the first nozzle, or both. Further, the angle information of the angle adjustment table is corrected according to the information on the thickness of the recording medium 2 (that is, the interval between the first nozzle and the recording medium 2). In this way, the main control circuit 59 creates tilt data composed of angle information corresponding to the moving speed of the carriage 4.

  When the tilt data is created, the carriage moving mechanism 5 is driven to start the movement of the carriage 4 (step S4). Then, the head angle adjusting mechanism 55 is driven to eject ink droplets from the nozzles 24 while changing the inclination angle of the nozzle surface 23a with respect to the recording medium 2 in accordance with the produced inclination data. That is, the printing operation is performed while changing the inclination angle of the nozzle surface 23a with respect to the recording medium 2 in accordance with the moving speed of the carriage 4 (step S5). When all the printing operations are completed, the printing process is completed. As described above, by performing the printing operation while adjusting the angle of the nozzle surface 23a in accordance with the moving speed of the carriage 4, it is possible to control the amount of landing position deviation between the main droplet and the satellite droplet. Thereby, the amount of deviation of the landing positions of the main droplet and the satellite droplet can be kept within a certain range, and the occurrence of streaks and density unevenness in the printed image can be suppressed. In particular, in the present embodiment, since the angle of the nozzle surface 23a is adjusted in accordance with the first nozzle that ejects the most used ink, the generation of streaks and density unevenness in the printed image can be further suppressed. As a result, deterioration in image quality can be further suppressed. Further, in the present embodiment, since the angle adjustment table is stored in the storage unit 60 in advance, the processing speed is faster than when the nozzle surface angle is calculated for each printing operation. In addition, an angle adjustment table suitable for the characteristics of each printer 1 can be created in advance by printing a test pattern or the like. Thereby, generation | occurrence | production of the stripe | line | muscle and density unevenness in a printed image can further be suppressed.

  In the above-described embodiment, the angle adjustment table is stored in advance in the storage unit 60 and is corrected according to the characteristics of the first nozzle. However, the present invention is not limited to this. For example, the storage unit 60 stores a calculation formula for obtaining an inclination angle of the nozzle surface 23 a with respect to the recording medium 2 according to the moving speed of the carriage 4, and the size and initial speed of the ink droplet ejected from the first nozzle, the recording medium 2 Based on information such as thickness, the inclination angle of the nozzle surface 23a with respect to the recording medium 2 according to the moving speed of the carriage 4 may be calculated for each printing process. Alternatively, an angle adjustment table may be created for each ink color (liquid type) and stored in the storage unit 60.

  By the way, it is desirable that the angle adjustment table stored in the storage unit 60 is updated when ink is first supplied from the ink cartridge 7 to the nozzle 24 or when the ink cartridge 7 is replaced. FIG. 14 is a flowchart for explaining the update operation of the angle adjustment table. First, the main control circuit 59 determines whether or not it is at the time of initial filling when ink is first supplied from the ink cartridge 7 to the nozzle 24, or when the ink cartridge 7 is replaced (step St1). . When it is determined by the main control circuit 59 that neither the initial filling nor the cartridge replacement is performed (No in step St1), the angle adjustment table updating operation is terminated. On the other hand, if it is determined by the main control circuit 59 that either the initial filling or the cartridge replacement has occurred (Yes in step St1), the display device 53 displays whether or not to update the angle adjustment table. (Step St2). The user views this display and operates the operation unit 54 to select whether or not to update the angle adjustment table. Based on the signal from the operation unit 54, the main control circuit 59 determines whether or not the user has selected to update the angle adjustment table (step St3). If the user selects not to update the angle adjustment table (No in step St3), the angle adjustment table update operation is terminated. On the other hand, when the user selects to update the angle adjustment table (Yes in step St3), a test pattern such as a solid pattern or a ruled line is printed (St4).

  Here, the test pattern is composed of a plurality of patterns (for example, five patterns) printed by changing the manner in which the angle of the nozzle surface 23 a changes with respect to the moving speed of the carriage 4. In the vicinity of each pattern, a corresponding number (for example, 1 to 5) is printed so that the user can confirm. The display device 53 displays a selection screen for allowing the user to select which number pattern has the best appearance. The user selects a number by operating the operation unit 54 in accordance with the guidance on the selection screen. The main control circuit 59 determines which number (that is, the pattern) is selected based on a signal from the operation unit 54 (step St5). If the user does not select a number corresponding to the pattern (No in step St5), the angle adjustment table update operation is terminated. On the other hand, when the user selects any number corresponding to the pattern (Yes in step St5), the main control circuit 59 sets the nozzle surface 23a that is performed along with the movement of the carriage 4 during printing of the pattern. The angle change is determined in the angle adjustment table (step St6). Then, the angle adjustment table is stored in the storage unit 60 (step St7), and the angle adjustment table update operation is terminated.

  As described above, by providing a mode for updating the information in the angle adjustment table, the back pressure changes due to the attachment / detachment of the ink cartridge 7, and the ejection characteristics of the ink ejected from the nozzles 24 change. Even if changes, the amount of landing position deviation between the main droplet and the satellite droplet can be kept within a certain range. That is, since the angle of the nozzle surface 23a can be changed according to the moving speed of the carriage 4 based on the latest state of the recording head 3 after the ink cartridge 7 is replaced, The occurrence of density unevenness can be further suppressed.

  In the above description, the nozzles 24 corresponding to a plurality of inks (four color inks) are provided, but the present invention is not limited to this. It is only necessary to have a nozzle corresponding to at least one ink. Further, the ink to be ejected is not limited to an achromatic or chromatic ink, and may be a transparent ink, a metallic ink containing metal particles, or the like. Further, the head angle adjusting mechanism 55 includes the eccentric cam 67, the drive motor 68, and the like, but is not limited thereto. In short, any configuration may be used as long as the posture of the recording head can be changed around a direction orthogonal to the traveling direction of the recording head.

  In the above description, the printer 1 including the ink jet recording head 3 is described as an example of the liquid ejecting apparatus. However, the present invention can also be applied to other liquid ejecting apparatuses. For example, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material ejecting head used for forming an electrode such as an organic EL (Electro Luminescence) display, FED (surface emitting display), a biochip (biochemical element) The present invention can also be applied to a liquid ejecting apparatus including a bio-organic matter ejecting head and the like used for manufacturing. In the color material ejecting head for the display manufacturing apparatus, a solution of each color material of R (Red), G (Green), and B (Blue) is ejected as a kind of liquid. Further, an electrode material ejecting head for an electrode forming apparatus ejects a liquid electrode material as a kind of liquid, and a bioorganic matter ejecting head for a chip manufacturing apparatus ejects a bioorganic solution as a kind of liquid.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Recording medium, 3 ... Recording head, 4 ... Carriage, 5 ... Carriage moving mechanism, 6 ... Conveyance mechanism, 7 ... Ink cartridge, 8 ... Timing belt, 9 ... Pulse motor, 10 ... Guide rod, 11 ... Platen, 11a ... Support projection, 12 ... Holder, 13 ... Unit head, 14 ... Fixing plate, 14a ... Opening, 15 ... Cartridge mounting part, 16 ... Ink introduction needle, 17 ... Actuator unit, 18 ... Flow path unit, 19 DESCRIPTION OF SYMBOLS ... Head case, 20 ... Storage space, 21 ... Liquid introduction path, 22 ... Through space, 23 ... Nozzle plate, 23a ... Nozzle surface, 24 ... Nozzle, 25 ... Communication board, 26 ... Common liquid chamber, 27 ... Individual communication passage 28 ... Nozzle communication path, 29 ... Pressure chamber forming substrate, 30 ... Pressure chamber, 31 ... Vibrating plate, 32 ... Piezoelectric element, 33 ... Sealing plate, 34 ... Piezoelectric element Accommodating space, 35 ... flexible cable, 37 ... compliance substrate, 38 ... fixed substrate, 39 ... sealing film, 50 ... external device, 51 ... printer controller, 52 ... print engine, 53 ... display device, 54 ... operation unit, 55 ... head angle adjusting mechanism, 58 ... interface unit, 59 ... main control circuit, 60 ... storage unit, 61 ... drive signal generation circuit, 64 ... linear encoder, 65 ... head controller, 67 ... eccentric cam, 68 ... drive motor, 69 ... Biasing spring, 70 ... Rotating shaft, 91 ... Liquid jet head, 92 ... Nozzle, 93 ... Recording medium

Claims (5)

A liquid ejecting head comprising a nozzle surface having a nozzle open, and ejecting liquid droplets from the nozzle toward a medium;
A head moving mechanism for moving the liquid ejecting head;
An angle adjustment mechanism for adjusting an angle of the nozzle surface with respect to the medium,
A liquid ejecting apparatus that ejects liquid droplets from the nozzle while adjusting an angle of the nozzle surface with respect to the medium according to a moving speed of the liquid ejecting head. Storage means for storing an angle adjustment table showing a correlation between a moving speed of the liquid jet head and an angle of the nozzle surface with respect to the medium;
2. The liquid ejecting apparatus according to claim 1, wherein the angle adjustment mechanism adjusts an angle of the nozzle surface based on information of the angle adjustment table stored in advance in the storage unit.   Information on the angle adjustment table based on at least one information among the size of the droplet ejected from the nozzle, the initial velocity of the droplet ejected from the nozzle, and the distance between the nozzle and the medium. The liquid ejecting apparatus according to claim 2, wherein: The nozzle is formed for each type of liquid,
Based on the image data to be printed, the first nozzle that ejects the most used liquid among the plurality of types of liquid is determined,
Correcting the information in the angle adjustment table based on at least one of the information on the size of the droplet ejected from the first nozzle and the initial velocity of the droplet ejected from the first nozzle. The liquid ejecting apparatus according to claim 3. A liquid supply source for supplying liquid to the nozzle is detachably provided,
When the liquid is first supplied from the liquid supply source to the nozzle, or when the liquid supply source is replaced, a mode for updating the information of the angle adjustment table stored in the storage unit is provided. The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is a liquid ejecting apparatus.

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