JP5040947B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid from a nozzle.

  In the ink jet printer described in Patent Literature 1, one end of a tube is connected to the left end of a buffer tank disposed on a carriage that reciprocates in the left-right direction (scanning direction) of the image recording unit. Cartridge mounting that extends to the left from the tank connection and bends approximately 180 ° to the right at some distance from the buffer tank connection, and the other end is mounted with an ink cartridge Connected to the department. In the ink jet printer, printing is performed on the recording paper P by ejecting ink from the nozzles of the image recording unit that reciprocates in the left-right direction onto the recording paper P conveyed forward.

JP 2009-39870 A

  In the ink jet printer described in Patent Document 1, when the carriage is accelerated by changing the moving direction, the ink in the tube tends to stay at the current position due to the law of inertia. For this reason, when the carriage moves to the right, the ink tends to flow in the direction of flowing out of the image recording unit, and the pressure in the image recording unit decreases. On the other hand, when the carriage moves to the left, the pressure in the image recording unit increases as ink tends to flow in the direction of flowing into the image recording unit. Therefore, when the image recording unit is moved to the right, the amount of ink supplied to the image recording unit is reduced. As a result, ink supply to the image recording unit is insufficient, and there is a possibility that ink cannot be normally ejected from the image recording unit.

  An object of the present invention is to provide a liquid ejection apparatus that is less likely to cause liquid ejection defects by suppressing insufficient supply of liquid to a liquid ejection head.

A liquid ejection apparatus according to a first aspect of the present invention is a liquid ejection head that ejects liquid from a plurality of nozzles, a moving unit that reciprocates the liquid ejection head in a predetermined scanning direction, and a device for supplying the liquid ejection head to the liquid ejection head A liquid tank in which liquid is stored, a tube having flexibility for connecting the liquid ejection head and the liquid tank, and transferring the liquid from the liquid tank to the liquid ejection head, and the liquid ejection head And a control means for controlling the operation of the moving means, and the tube has a portion arranged so as to extend from the connecting portion with the liquid ejection head to one side in the scanning direction, control means, said by the moving means is reciprocated with the liquid ejection head in the scanning direction, suited to the other side of the liquid ejecting head from said one side of the scanning direction When moving in the first direction, and, together with the ejected liquid from the plurality of nozzles in either the time of moving the liquid ejection head in the second direction toward the one side from the other side of the scanning direction, for moving the liquid discharge head prior Symbol first direction, the discharge amount of liquid from the liquid ejection head per unit time, is less than the time of moving the liquid discharge head before Symbol second direction Thus, the liquid ejection head and the moving means are controlled.

  According to this, the liquid supply amount to the liquid discharge head decreases, and the liquid discharge amount from the liquid discharge head per unit time when the liquid discharge head moves in the first direction moves in the second direction. Therefore, the shortage of liquid supply to the liquid discharge head can be suppressed, and the occurrence of liquid discharge failure in the liquid discharge head can be suppressed.

  A liquid ejection apparatus according to a second invention is the liquid ejection apparatus according to the first invention, wherein the control means ejects liquid from the plurality of nozzles at a predetermined drive frequency, and the liquid ejection head The liquid ejection head and the moving unit are controlled so that the driving frequency when moving in the first direction is lower than that when moving the liquid ejection head in the second direction. Is.

  According to this, the amount of liquid discharged from the liquid discharge head per unit time can be reduced by decreasing the drive frequency of the liquid discharge head.

A liquid ejection apparatus according to a third aspect is the liquid ejection apparatus according to the first aspect, wherein the control means ejects liquid at the same timing when moving the liquid ejection head in the first direction. The liquid ejection head and the moving unit are controlled so that the number of nozzles to be ejected is smaller than when the liquid ejection head is moved in the second direction.

According to this, the amount of liquid discharged from the liquid discharge head per unit time can be reduced by reducing the number of nozzles that discharge liquid at the same timing .

  A liquid discharge apparatus according to a fourth aspect of the present invention is the liquid discharge apparatus according to the first aspect of the present invention, wherein the control means moves liquid from the plurality of nozzles while moving the liquid discharge head in the first direction. The liquid ejection head and the moving means are controlled so that the total number of times of ejecting the liquid is less than during the movement of the liquid ejection head in the second direction.

  According to this, the amount of liquid discharged from the liquid discharge head per unit time can be reduced by reducing the total number of times the liquid is discharged from the nozzles.

  A liquid ejection apparatus according to a fifth aspect of the present invention is the liquid ejection apparatus according to the first aspect of the present invention, and is controlled by the control means for landing the liquid droplets ejected from the liquid ejection head. A transport unit that transports the target landing body in a direction orthogonal to the scanning direction, and the control unit performs the operation of causing the liquid to land on the target landing body. After the liquid is ejected from the plurality of nozzles while being moved in the first direction, the time before the liquid is ejected from the plurality of nozzles while being moved in the second direction is the liquid ejection head. After the liquid is ejected from the plurality of nozzles while moving the nozzle in the second direction, the liquid is then moved in the first direction so as to be longer than the time before the liquid is ejected from the plurality of nozzles. Yo To, and is characterized in that controlling the liquid ejection head and said moving means.

  When the liquid discharge head is moved in the first direction, the amount of liquid supplied to the liquid discharge head decreases. Therefore, when the liquid discharge amount from the liquid discharge head per unit time is the same when the liquid discharge head is moved in the first direction and when the liquid discharge head is moved in the second direction, the liquid discharge head is moved to the first direction. The amount of liquid in the liquid discharge head is smaller immediately after the movement in the direction is completed. Therefore, if the liquid is immediately moved next in the second direction to start discharging the liquid, there is a possibility that the liquid cannot be normally discharged from the liquid discharge head.

  However, in the present invention, after discharging the liquid from the plurality of nozzles while moving the liquid discharge head in the first direction, before discharging the liquid from the plurality of nozzles while moving in the second direction. After the liquid ejection head is moved in the second direction, the liquid is ejected from the plurality of nozzles, and then is moved in the first direction before the liquid is ejected from the plurality of nozzles. Therefore, after the liquid is discharged while moving the liquid discharge head in the first direction, the liquid is sufficiently supplied to the liquid discharge head and then moved in the second direction. Since the liquid is discharged, it is possible to suppress the occurrence of liquid discharge failure in the liquid discharge head.

  A liquid ejection apparatus according to a sixth invention is the liquid ejection apparatus according to any one of the first to fifth inventions, further comprising temperature detection means for detecting the temperature of the liquid, wherein the control means is The higher the temperature detected by the temperature detection means, the lower the liquid discharge amount from the liquid discharge head per unit time when the liquid discharge head is moved in the first direction. The ejection head and the moving means are controlled.

  When the temperature of the liquid supplied to the liquid discharge head increases, the viscosity of the liquid decreases, so that when the liquid discharge head moves in the first direction, the liquid discharge head easily flows away from the liquid discharge head. The amount of liquid supplied is particularly small.

  However, in the present invention, the higher the temperature of the liquid supplied to the liquid discharge head, the smaller the amount of liquid discharged from the liquid discharge head per unit time when the liquid discharge head is moved in the first direction. Therefore, the shortage of liquid supply to the liquid discharge head can be more reliably suppressed.

  Note that detecting the temperature of the liquid includes not only detecting the temperature of the liquid directly, but also detecting the temperature of another part having a certain relationship with the temperature of the liquid.

  According to the present invention, the liquid discharge amount from the liquid discharge head per unit time when the liquid discharge head is moved in the first direction when the liquid supply amount to the liquid discharge head is reduced is set to the second direction. Therefore, the shortage of liquid supply to the liquid discharge head can be suppressed, and the occurrence of liquid discharge failure in the liquid discharge head can be suppressed.

1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. It is a top view of the inkjet head of FIG. It is the III-III sectional view taken on the line of FIG. It is a block diagram of the control apparatus of FIG. It is a figure which shows the flow of an ink when the inkjet head is moving with a carriage. It is a figure which shows the position of the nozzle which discharges an ink in the modification 1 simultaneously. FIG. 10 is a diagram illustrating a landing position of an ink droplet in Modification 2. FIG. 10 is a diagram corresponding to FIG. FIG. 10 is a diagram corresponding to FIG. (A) is a figure which shows the space | interval of the nozzle of the modification 5, (b) is a figure which shows the landing position of the ink droplet in the modification 5. It is a figure which shows the connection position and bending direction of the tube in modification 6-8.

  Hereinafter, preferred embodiments of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a printer according to the present embodiment. As shown in FIG. 1, the printer 1 (liquid ejection device) has a carriage 2 (moving means), a sub tank 3, an ink jet head 4, a cartridge mounting portion 5, a tube 6, a transport roller 7, a temperature detection device 8, and the like. ing. The operation of the printer 1 is controlled by the control device 50. In FIG. 1, a nozzle 15 of an inkjet head 4 described later is shown in an enlarged manner.

  The carriage 2 reciprocates in the left-right direction (scanning direction) in FIG. The sub tank 3 is attached on the carriage 2. The ink jet head 4 is disposed on the lower surface of the sub tank 3 and is supplied with ink from the sub tank 3 and ejects ink from a plurality of nozzles 15 (see FIG. 2) formed on the lower surface. In the present embodiment, the combination of the sub tank 3 and the inkjet head 4 corresponds to the liquid discharge head according to the present invention.

  The cartridge mounting portion 5 is disposed at the lower right end portion of the printer 1 in FIG. 1 and includes four ink cartridges 20 (liquid tanks) filled with black, yellow, cyan, and magenta inks to be discharged from the inkjet head 4. ) Is removable.

  The tube 6 connects the sub tank 3 and the cartridge mounting portion 5. More specifically, one end of the tube 6 is connected to the left side surface of the lower end portion of the sub tank 3 in FIG. 1, and extends to the left (one side in the scanning direction) from the connecting portion with the sub tank 3. In addition, it is bent about 180 ° in the middle part of the connection part with the sub-tank 3 and extends to the right, and the other end is connected to the cartridge mounting part 5 (ink cartridge 20). Then, the ink in the ink cartridge 20 mounted on the cartridge mounting unit 5 is supplied to the inkjet head 4 via the tube 6 and the sub tank 3.

  The conveyance rollers 7 are respectively arranged above and below the carriage 2 in the vertical direction of FIG. 1 and convey the recording paper P downward (paper feeding direction) in FIG. The temperature detection device 8 is a sensor for detecting a temperature having a thermistor or the like, and detects the temperature inside the printer 1 and outputs the detection result to the control device 50 (see FIG. 4). Here, when a temperature change occurs in the printer 1, the temperature of the ink in the printer 1 also changes. That is, the temperature detection device 8 detects the temperature in the printer 1 that has a certain relationship with the temperature of the ink. The position at which the temperature detection device 8 is disposed is not limited to the position illustrated in FIG. 1, and is disposed at a position where the temperature of any part of the printer 1 that has a fixed relationship with the ink temperature can be detected. It only has to be. Alternatively, the temperature detection device 8 may directly detect the ink temperature.

  In the printer 1, recording is performed by ejecting ink from the inkjet head 4 that reciprocates in the scanning direction together with the carriage 2 onto the recording paper P that is transported in the paper feeding direction (downward in FIG. 1) by the transport roller 7. Printing is performed on the paper P.

  Next, the inkjet head 4 will be described. FIG. 2 is a plan view of the inkjet head 4 of FIG. 3 is a cross-sectional view taken along line III-III in FIG.

  As shown in FIGS. 2 and 3, the inkjet head 4 includes a flow path unit 31 in which an ink flow path including a pressure chamber 10 and a nozzle 15 is formed, and a piezoelectric for applying pressure to the ink in the pressure chamber 10. And an actuator 32.

  The flow path unit 31 is configured by stacking four plates of a cavity plate 21, a base plate 22, a manifold plate 23, and a nozzle plate 24. Of the four plates 21 to 24, the three plates 21 to 23 excluding the nozzle plate 24 are made of a metal material such as stainless steel, and the nozzle plate 24 is made of a synthetic resin material such as polyimide. Or the nozzle plate 24 may be comprised with the metal material similarly to the other three plates 21-23.

  The cavity plate 21 is formed with a plurality of pressure chambers 10 having a substantially elliptical planar shape with the scanning direction as the longitudinal direction. The plurality of pressure chambers 10 are arranged in the paper feed direction to form a row of one pressure chamber 10, and such rows of pressure chambers 10 are arranged in four rows in the scanning direction. In the base plate 22, a plurality of through holes 12 and 13 having a substantially circular planar shape are formed in portions facing both ends of the pressure chambers 10 in the longitudinal direction in plan view.

  A manifold channel 11 is formed in the manifold plate 23. The manifold channel 11 is provided corresponding to the row of the four pressure chambers 10, and each of the manifold channels 11 is paper in a portion facing the substantially right half of the plurality of pressure chambers 10 constituting each row of the pressure chambers 10. Extends in the feed direction. In addition, the manifold channel 11 is provided at a position facing the upper end portion in FIG. 2, and ink is supplied from four ink supply ports 9 connected to the sub tank 3. More specifically, black, yellow, cyan, and magenta inks are supplied from the four ink supply ports 9 in order from the one arranged on the left side of FIG.

  In the manifold plate 23, a plurality of through holes 14 having a substantially circular planar shape are formed at portions facing the plurality of through holes 13 in plan view. In the nozzle plate 24, a plurality of nozzles 15 are formed in a portion facing the through hole 14 in plan view. The plurality of nozzles 15 are arranged in the paper feed direction to form one nozzle row as in the pressure chamber 10, and such nozzle rows are arranged in four rows in the scanning direction. From the nozzles 15, black, yellow, cyan, and magenta inks are ejected in order from the nozzles on the left side of FIG. 2.

  In the flow path unit 31, the manifold flow path 11 communicates with the pressure chamber 10 through the through hole 12, and the pressure chamber 10 communicates with the nozzle 15 through the through holes 13 and 14. As described above, the flow path unit 31 is formed with a plurality of individual ink flow paths from the manifold flow path 11 to the nozzle 15 via the pressure chamber 10.

  The piezoelectric actuator 32 includes a vibration plate 41, a piezoelectric layer 42, and individual electrodes 43. The diaphragm 41 is made of a metal material such as stainless steel, and is joined to the upper surface of the flow path unit 31 so as to cover the plurality of pressure chambers 10. The conductive diaphragm 41 also serves as a common electrode for driving the piezoelectric actuator 32 as will be described later, and is always held at the ground potential.

  The piezoelectric layer 42 is made of a piezoelectric material mainly composed of lead zirconate titanate, which is a mixed crystal of lead titanate and lead zirconate, and continuously on the upper surface of the vibration plate 41 across the plurality of pressure chambers 10. Has been placed.

  The plurality of individual electrodes 43 have a substantially elliptical planar shape that is slightly smaller than the pressure chamber 10, and are arranged in portions on the upper surface of the piezoelectric layer 42 facing the substantially central portions of the plurality of pressure chambers 10. Has been. Further, the plurality of individual electrodes 43 extend to a portion where the end opposite to the nozzle 15 in the longitudinal direction does not face the pressure chamber 10, and the tip thereof serves as a connection terminal 43 a. The connection terminal 43a is connected to a driver IC 45 (see FIG. 4) via a flexible wiring member (FPC) (not shown), and a drive potential is individually applied to the plurality of individual electrodes 43 by the driver IC 45. More specifically, the driver IC 45 applies a drive pulse (drive potential) with a predetermined drive frequency to the plurality of individual electrodes 43 under the control of the print control unit 51 described later (drives the inkjet head 4 at the predetermined drive frequency). To do).

  Further, a portion of the piezoelectric layer 42 sandwiched between the plurality of individual electrodes 43 and the diaphragm 41 as a common electrode is polarized in the thickness direction.

  Here, a driving method of the piezoelectric actuator 32 will be described. In the piezoelectric actuator 32, the plurality of individual electrodes 43 are previously held at the ground potential by the driver IC 45. When a driving potential is applied to any one of the plurality of individual electrodes 43 by the driver IC 45, a potential difference is generated between the individual electrode 43 and the diaphragm 41 as a common electrode held at the ground potential. An electric field in the same thickness direction as the polarization direction is generated in a portion sandwiched between these electrodes. As a result, the portion of the piezoelectric layer 42 contracts in the horizontal direction perpendicular to the thickness direction, and as a result, the diaphragm 41 and the piezoelectric layer 42 are deformed so as to protrude toward the pressure chamber 10 as a whole. Due to this deformation, the volume of the pressure chamber 10 decreases, the pressure of the ink in the pressure chamber 10 increases, and ink is ejected from the nozzle 15 communicating with the pressure chamber 10.

  Next, the control device 50 that controls the operation of the printer 1 will be described. FIG. 5 is a block diagram of the control device 50. The control device 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and these operate as the print control unit 51 and the like. In addition to the print control unit 51, the control device 50 includes a part for controlling operations other than printing of the printer 1, and the illustration and description thereof are omitted here.

  The print control unit 51 includes a carriage 2 (specifically, a motor (not shown) for moving the carriage 2) for performing printing in the printer 1 in accordance with the temperature of the printer 1 detected by the temperature detection device 8. The operation of the transport roller 7 (specifically, a motor (not shown) that rotates the transport roller 7) and the driver IC 45 (inkjet head 4) is controlled.

  More specifically, as described above, the print control unit 51 moves the carriage 2 in the scanning direction while conveying the recording paper P in the paper feeding direction by the conveyance roller 7, thereby moving the inkjet head 4 in the scanning direction. Printing is performed on the recording paper P by moving and ejecting ink from the nozzles 15.

  At this time, as shown in FIG. 5A, when the carriage 2 is moved from the left side to the right side of the printer 1 to the right (first direction), the tube 6 is in the vicinity of the connection portion with the sub tank 3. Since the ink in the portion affected by the acceleration of the carriage 2 tries to stay at the current position by the law of inertia, the ink flows out from the sub tank 3 as indicated by an arrow in the tube 6 in FIG. Try to flow in the direction. Therefore, the pressure in the sub tank 3 and the ink jet head 4 decreases, and the amount of ink supplied from the tube 6 to the sub tank 3 and the ink jet head 4 decreases.

  On the other hand, as shown in FIG. 5B, when the carriage 2 is moved from the right side to the left side of the printer 1 to the left (second direction), contrary to the above, FIG. As indicated by the arrow in the tube 6), the ink in the tube 6 tends to flow in the direction of flowing into the sub tank 3, so that the pressure in the sub tank 3 and the ink jet head 4 rises, and the sub tank from the tube 6 rises. 3 and the ink supply amount to the inkjet head 4 are increased.

  Therefore, when the carriage 2 is moved to the right, the amount of ink supplied per unit time from the tube 6 to the sub tank 3 and the inkjet head 4 is smaller than when the carriage 2 is moved to the left. .

  For this reason, if the inkjet head 4 is driven at the same drive frequency as when the carriage 2 is moved to the right, the amount of ink supplied to the inkjet head 4 per unit time is unit time. There is a possibility that the amount of ink discharged from the hit inkjet head 4 will be smaller, that is, the supply of ink to the inkjet head 4 will be insufficient. If there is insufficient supply of ink to the inkjet head 4, there is a risk that ink cannot be ejected normally from the nozzles 15.

  Also, the higher the temperature, the lower the viscosity of the ink and the lower the flow resistance, so the ink in the tube 6 tends to flow. Therefore, when the temperature of the ink is high, the amount of ink supplied from the tube 6 to the sub tank 3 and the inkjet head 4 is particularly likely to decrease when the carriage 2 moves to the right.

  Here, the sub-tank 3 is provided with a damper (not shown) for suppressing ink pressure fluctuation. If the damper is intended to suppress ink pressure fluctuation due to acceleration of the carriage 2, the damper is large-sized. It is necessary to make it. Further, when the damper is increased in size, it is necessary to provide the printer 1 with a space in which the large damper can be moved together with the carriage 2, so that the printer 1 is also increased in size.

  Therefore, in the present embodiment, as shown in Table 1, when the inkjet head 4 is moved to the right by the carriage 2 under the control of the print control unit 51, the driving frequency is lower than that to the left. The inkjet head 4 is driven. More specifically, when the temperature detected by the temperature detection device 8 is 15 ° C. or higher, driving is performed at a driving frequency that is 20% lower, and when the temperature is lower than 15 ° C., driving is performed at a driving frequency that is 10% lower. That is, the higher the ink temperature, the lower the drive frequency of the inkjet head 4. Further, the moving speed of the carriage 2 is also changed in accordance with the drive frequency of the inkjet head 4.

  As a result, the amount of ink discharged from the inkjet head 4 per unit time when the inkjet head 4 is moved to the right is smaller than when the inkjet head 4 is moved to the left. The ink discharge amount does not become larger than the ink supply amount to the ink jet head 4 per unit time, and the above shortage of ink supply to the ink jet head 4 can be suppressed.

  Furthermore, when the ink temperature is high and the amount of ink supplied from the tube 6 to the sub tank 3 and the inkjet head 4 when the inkjet head 4 is moved to the right is smaller, the inkjet head 4 is moved to the right. Since the inkjet head 4 is driven at a low drive frequency, insufficient supply of ink to the inkjet head 4 can be more reliably suppressed.

  In Table 1, the temperature threshold for changing the drive frequency is 15 ° C., but the threshold can be changed as appropriate depending on the relationship between the temperature and the viscosity of the ink. Moreover, the drive frequency shown in Table 1 is an example, and the value is not limited to this.

  Next, modified examples in which various changes are made to the present embodiment will be described. However, components having the same configuration as in the present embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

  In the above-described embodiment, the drive frequency of the inkjet head 4 when moving the inkjet head 4 to the right is lower than that when moving the inkjet head 4 to the left, thereby moving the inkjet head 4 to the right. Although the amount of ink discharged from the inkjet head 4 per unit time is smaller than that when moving leftward, the present invention is not limited to this.

  For example, when moving the inkjet head 4 to the right, the number of nozzles 15 that simultaneously eject ink may be made smaller than when moving to the left.

  As an example of this case, in one modified example (modified example 1), when the inkjet head 4 is moved to the right, the black-filled nozzle 15 in FIG. 6A (from the top of FIG. 6A, When the ink is ejected from only the fourth and seventh nozzles 15) and the inkjet head 4 is moved to the left, the number of the black-filled nozzles 15 in FIG. Ink is ejected only from the second, third, fifth, sixth and eighth nozzles 15) from the top in FIG.

  In the first modification, the same nozzle 15 is used for each of the ink ejection timings determined by the drive frequency of the inkjet head 4 when the inkjet head 4 is moved to the right and to the left. Although it was made to discharge, it is not restricted to this. In another modified example (modified example 2), as in modified example 1, when the inkjet head 4 is moved to the right, the number of nozzles 15 that simultaneously eject ink is made smaller than when moved to the left. However, unlike the first modification, ink is ejected from different nozzles 15 at each ink ejection timing.

  Then, by ejecting ink from different nozzles 15 at each ink ejection timing, as shown in FIG. 7, the ink droplet I1 (filled black in the figure) is moved when the inkjet head 4 is moved to the right as shown in FIG. Ink droplets) are landed, and ink droplets I2 (ink droplets not painted in the drawing) are landed when moving to the left.

  Even in the case of these modified examples 1 and 2, the amount of ink discharged from the inkjet head 4 per unit time when the inkjet head 4 is moved to the right is smaller than that when the inkjet head 4 is moved to the left. As in the embodiment, insufficient supply of ink to the inkjet head 4 can be suppressed.

  Further, while moving the inkjet head 4 to the right from the left end to the right end of the moving range, the total number of times of ejecting ink from each nozzle 15 is greater than during moving to the left from the right end to the left end of the moving range. It may be reduced.

  As a specific example of this case, in another modified example (Modified Example 3), when the inkjet head 4 is moved to the right, as shown in FIG. Ink droplets I1 are landed by ejecting ink from the ink. On the other hand, when moving to the left, the ink droplet I2 is landed by ejecting ink from the nozzle 15 at 9 out of 15 ejection timings, which is greater than when moving to the right.

  Furthermore, in another modification (Modification 4), when the inkjet head 4 is moved to the right, ink is ejected from the first, third, fourth, sixth, and seventh nozzles 15 from the top of FIG. When the ink droplet I1 is landed and the ink jet head 4 is moved to the left, the ink droplet I2 is landed by ejecting ink from all the nozzles 15 of the ink jet head 4, and from the top of FIG. By ejecting ink only from the fifth and eighth nozzles 15, the ink droplet I3 is landed.

  That is, in this case, the total number of ink ejections from the nozzles 15 when the inkjet head 4 is moved to the right by the amount that ink is not ejected from the second, fifth, and eighth nozzles 15 from the top in FIG. , Less than when moving to the left.

  Furthermore, in another modification (Modification 5), as shown in FIG. 10A, the interval d of the nozzles 15 in the paper feed direction is approximately twice the interval of the nozzles 15 in the above-described embodiment. It has become. Then, after ejecting ink from the nozzle 15 while moving the inkjet head 4 to the right, the recording paper P is moved in the paper feeding direction by a distance half the interval d of the nozzle 15 by the transport roller 7, and then the inkjet Printing is performed by ejecting ink from the nozzles 15 while moving the head 4 to the left. As a result, printing can be performed with the same resolution as in the above-described embodiment with respect to the paper feed direction.

  When ink droplets are landed only on a predetermined ratio (about 5/6 in the figure) of the predetermined area A on the recording paper P using a printer having such an ink jet head, FIG. As shown in (b), when the inkjet head 4 is moved to the right, ink is ejected only at ejection timings less than the predetermined ratio (four times out of six consecutive ejection timings). Ink droplet I1 is landed. On the other hand, when the inkjet head 4 is moved to the left, the ink droplet I2 is landed by ejecting ink at all (greater than the predetermined ratio) ejection timings.

  Even in these modified examples 3 to 5, the amount of ink discharged per unit time in the inkjet head 4 when the inkjet head 4 is moved to the right is smaller than that when the inkjet head 4 is moved to the left. As in the case of the above, insufficient supply of ink to the inkjet head 4 can be prevented.

  In addition, when printing is performed by ejecting ink from the nozzle 15 while reciprocating the inkjet head 4 in the scanning direction by the carriage 2, after ejecting ink from the nozzle 15 while moving the inkjet head 4 to the right Next, the time until the ink is ejected from the nozzle 15 while moving to the left, the ink is ejected from the nozzle 15 while being moved to the left, and then the ink is ejected from the nozzle 15 while being moved to the right. You may make it longer than the time before discharging.

  Specifically, by changing the acceleration of the carriage 2, ink is ejected from the nozzle 15 while moving the inkjet head 4 to the right at a predetermined speed at a position facing the recording paper P, and then the recording paper P Deceleration time until the carriage 2 is stopped at a position that does not face, and then before ink is ejected from the nozzle 15 while moving the inkjet head 4 to the left at a predetermined speed at a position that faces the recording paper P. Ink from the nozzle 15 while moving the acceleration time for accelerating the carriage 2 stopped at a position not facing the recording paper P to a predetermined speed to the left at a position facing the recording paper P at a predetermined speed, respectively. After the ink is discharged, the speed is reduced until the carriage 2 is stopped at a position not facing the recording paper P. In the middle and the next position facing the recording paper P, the ink jet head 4 stops at a position not facing the recording paper P before ejecting ink from the nozzle 15 while moving the ink jet head 4 to the right at a predetermined speed. It is longer than the acceleration time for accelerating the carriage 2 to a predetermined speed.

  In addition, after completing the movement of the inkjet head 4 to the right, after a predetermined waiting time has elapsed, the next movement to the left is started and the movement to the left is completed. Immediately, the next rightward movement may be started.

  Alternatively, after completing the movement of the inkjet head 4 to the left and right, in each case, the next movement is started after the waiting time has elapsed, but the waiting after the completion of the movement to the right is started. The time is set longer than the waiting time after completion of the leftward movement.

  Further, after the ink is ejected from the nozzle 15 while moving the inkjet head 4 to the right, and before the ink is ejected from the nozzle 15 while being moved to the left, the above deceleration time, acceleration time, and The above-described deceleration time and acceleration time after discharging ink from the nozzle 15 while moving to the left for at least one of the waiting times and before discharging ink from the nozzle 15 while moving to the right And longer than the waiting time.

  As described above, when the inkjet head 4 is moved to the right, the amount of ink supplied to the inkjet head 4 decreases. Therefore, when the amount of ink discharged from the inkjet head 4 per unit time is the same when the inkjet head 4 is moved to the right and to the left, the inkjet head 4 is moved to the right. The amount of ink in the inkjet head 4 is smaller immediately after the movement is completed. For this reason, if ink is immediately ejected by starting to move to the left, ink may not be ejected normally from the inkjet head 4.

  However, in this case, after the ink is ejected from the nozzle 15 while moving the inkjet head 4 to the right, the time until the ink is ejected from the nozzle 15 while moving in the second direction is increased. Therefore, after the ink is ejected from the nozzle 15 while moving the inkjet head 4 to the right, the ink is sufficiently supplied to the inkjet head 4, and then the ink is ejected from the nozzle 15 while moving to the left. As a result, it is possible to suppress the occurrence of ink ejection failure in the inkjet head 4.

  In this case, the amount of ink discharged from the ink-jet head 4 per unit time is changed by the amount of time that elapses after the ink discharge from the ink-jet head 4 is completed until the next ink discharge is started. Will change.

  In the above-described embodiment, as the temperature of the ink is higher, the inkjet head 4 is driven at a lower drive frequency when the inkjet head 4 is moved to the right. The driving frequency for moving to the right may be constant regardless of the ink temperature as long as it is lower than that for moving to the left.

  Further, in the above-described embodiment, one end of the tube 6 is connected to the left side surface at the lower end portion of the sub tank 3 and extends leftward from the connection portion with the sub tank 3, but is not limited thereto. The tube 6 only needs to have a portion where the portion affected by the acceleration of the carriage 2 extends leftward from the connecting portion with the sub tank 3.

  As a specific example in this case, in one modified example (modified example 6), as shown in FIG. 11A, one end of the tube 6 is connected to the front surface of the sub tank 3 (the lower surface in FIG. 11). In addition, it is bent about 90 ° in the vicinity of the connecting portion with the sub tank 3 and extends to the left.

  In another modified example (modified example 7), as shown in FIG. 11B, one end of the tube 6 is connected to the right side of the lower end portion in FIG. Although it extends to the right, it is bent about 180 ° in the vicinity of the connecting portion with the sub tank 3 and extends to the left.

  In another modified example (modified example 8), as shown in FIG. 11C, one end of the tube 6 is connected to the front surface of the sub tank 3 in FIG. In the vicinity of the connection portion, it is bent by about 90 ° and once extends to the right, but in the vicinity of the connection portion with the sub tank 3, it is further bent by about 180 ° and extends to the left (Modification 8).

  In the case of these modified examples 6 to 8, as in the above-described embodiment, it is bent to about 180 ° and extends to the right at the middle part of the connection part with the sub tank 3 to the right, and the other end. Is connected to the cartridge mounting portion 5.

  In the case of the modified example 6, since the tube 6 extends to the left from the connection position with the sub tank 3, when the inkjet head 4 is moved to the right as in the above-described embodiment, the sub tank 3 and The amount of ink supplied to the inkjet head 4 is reduced.

  Further, in the modified examples 7 and 8, since the tube 6 extends once to the right from the connecting portion with the sub tank 3, when the ink jet head 4 moves to the right, the ink in this portion is transferred to the sub tank 3. It tries to flow in the direction of flowing into. However, in the modified examples 7 and 8, in the portion of the tube 6 affected by the acceleration of the carriage 2, the length of the portion extending to the left is longer than the length of the portion extending to the right. Therefore, when the inkjet head 4 moves to the right, the force that the ink in the portion extending to the left of the tube 6 flows in the direction of flowing out of the sub tank 3 is in the portion extending to the right. This is larger than the force that the ink tends to flow in the direction of flowing into the sub tank 3. Therefore, as a whole, the ink in the tube 6 tends to flow in the direction of flowing out from the sub tank 3 as in the above-described embodiment, and the amount of ink supplied to the sub tank 3 and the inkjet head 4 is reduced.

  Therefore, also in the case of the modified examples 6-8, the amount of ink discharged from the inkjet head 4 per unit time when the inkjet head 4 is moved to the right is made smaller than when the inkjet head 4 is moved to the left. Similarly to the above-described embodiment, insufficient supply of ink to the inkjet head 4 can be suppressed.

  Further, in the above description, the tube 6 is bent by about 180 ° and extends to the right at a part in the middle of the connection portion with the sub tank 3, and the other end is connected to the cartridge mounting portion 5. However, the present invention is not limited to this, and if the portion of the tube 6 that is affected by the acceleration of the carriage 2 extends at least to the left, how is the portion in the middle away from the connection with the sub tank 3 to some extent? It may be. In this case, the cartridge mounting unit 5 can be arranged at an arbitrary position in the printer 1.

  Furthermore, if the portion of the tube 6 that is affected by the acceleration of the carriage 2 that extends to the left is longer than the portion that extends to the right, when the inkjet head 4 is moved to the right, the ink to the inkjet head 4 Therefore, the length of the tube 6 is not limited to the above-described embodiment, and can be set to an arbitrary length. In this case, a so-called on-carriage structure in which the cartridge mounting portion 5 and the ink cartridge 20 are mounted on the carriage 2 and the ink cartridge 20 is moved by the movement of the carriage 2 may be employed.

  In the above description, the portion of the tube 6 that is affected by the acceleration of the carriage 2 extends to the left. However, the present invention is not limited to this, and the portion of the tube 6 that is affected by the acceleration of the carriage 2 is to the right. It may extend. In this case, the left side corresponds to the first direction according to the present invention, and the right side corresponds to the second direction according to the present invention.

  In this case, contrary to the above-described embodiment, when the ink jet head 4 is moved to the left, the pressure in the sub tank 3 and the ink jet head 4 is reduced, so that the carriage 2 is moved to the left. In addition, it is possible to suppress an insufficient supply of ink to the inkjet head 4 by reducing the amount of ink discharged from the inkjet head 4 per unit time as compared to when moving the ink to the right.

  In the above description, an example in which the present invention is applied to a printer that performs printing on the recording paper P by ejecting ink from the nozzles 15 has been described. However, the present invention is not limited to this, and liquid that ejects liquid other than ink from the nozzles. It is also possible to apply the present invention to a liquid ejection apparatus provided with an ejection head.

DESCRIPTION OF SYMBOLS 1 Printer 2 Carriage 3 Sub tank 4 Inkjet head 5 Cartridge mounting part 6 Tube 8 Temperature detection apparatus 15 Nozzle 20 Ink cartridge 50 Control apparatus

Claims (6)

A liquid discharge head for discharging liquid from a plurality of nozzles;
Moving means for reciprocating the liquid discharge head in a predetermined scanning direction;
A liquid tank storing liquid to be supplied to the liquid discharge head;
A tube having flexibility for connecting the liquid discharge head and the liquid tank and transferring the liquid from the liquid tank to the liquid discharge head;
Control means for controlling the operation of the liquid discharge head and the moving means,
The tube has a portion arranged to extend from the connection portion with the liquid ejection head to one side in the scanning direction,
The control means includes
The liquid ejecting head is reciprocated in the scanning direction by the moving means , and the liquid ejecting head is moved in the first direction from the one side to the other side in the scanning direction; and In any of the cases when moving in the second direction from the other side of the scanning direction toward the one side, the liquid is ejected from the plurality of nozzles,
For moving the liquid discharge head prior Symbol first direction, the discharge amount of liquid from the liquid ejection head per unit time, is less than the time of moving the liquid discharge head before Symbol second direction As described above, the liquid discharge apparatus controls the liquid discharge head and the moving means. The control means includes
While discharging liquid from the plurality of nozzles at a predetermined drive frequency,
The liquid ejection head and the moving unit are controlled so that the drive frequency when moving the liquid ejection head in the first direction is smaller than when moving the liquid ejection head in the second direction. The liquid ejection apparatus according to claim 1, wherein The control means includes
Wherein the liquid discharge head when moving in the first direction, the number of nozzles that out ejection of the liquid at the same timing, so as to less than when moving the liquid ejection head in the second direction, the liquid The liquid ejection apparatus according to claim 1, wherein the ejection head and the moving unit are controlled. The control means includes
While moving the liquid ejection head in the first direction, the total number of times that liquid is ejected from the plurality of nozzles is less than during moving the liquid ejection head in the second direction. The liquid ejection apparatus according to claim 1, wherein the liquid ejection head and the moving unit are controlled. Controlled by the control means,
A transport unit configured to transport a target to land a droplet discharged from the liquid discharge head in a direction perpendicular to the scanning direction;
The control means includes
When performing the operation of landing the liquid on the landing body,
The time until the liquid is ejected from the plurality of nozzles after the liquid is ejected from the plurality of nozzles while the liquid ejection head is moved in the first direction and then moved in the second direction. After discharging the liquid from the plurality of nozzles while moving the liquid discharge head in the second direction, until before discharging the liquid from the plurality of nozzles while moving in the first direction. The liquid discharge apparatus according to claim 1, wherein the liquid discharge head and the moving unit are controlled so as to be longer than a predetermined time. A temperature detecting means for detecting the temperature of the liquid;
The control means decreases the amount of liquid discharged from the liquid discharge head per unit time when the liquid discharge head is moved in the first direction as the temperature detected by the temperature detection means is higher. The liquid discharge apparatus according to claim 1, wherein the liquid discharge head and the moving unit are controlled as described above.

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