JP6609976B2 - Liquid ejection device - Google Patents

Description

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

  Patent Document 1 describes an ink jet recording apparatus that performs printing by discharging ink from a nozzle of an ink jet head onto a recording medium. In the ink jet recording apparatus of Patent Document 1, in order to prevent the ink in the nozzles from being thickened and the mass, speed, and direction of the ink droplets from the nozzles to change and the image quality to deteriorate, during printing, The ink meniscus of the idle nozzle is slightly vibrated.

JP 2007-185867 A

  Here, in Patent Document 1, when the ink ejected from the nozzle is an ink that tends to increase in viscosity, in order to eliminate the increase in the viscosity of the ink in the idle nozzle by slightly vibrating the meniscus of the ink in the idle nozzle, It is necessary to increase the vibration amount of the meniscus fine vibration of the ink of the rest nozzle to some extent. However, if the amount of vibration of the meniscus when the ink meniscus of the rest nozzle is slightly vibrated is too large, the ink may be ejected from the nozzle. In Patent Document 1, since the meniscus of the ink of the pause nozzle is slightly vibrated during printing, when the ink is ejected from the nozzle when the meniscus of the ink of the pause nozzle is slightly vibrated, the ejected ink lands on the recording medium. There is a risk of it. On the other hand, if the vibration amount of the meniscus when the ink meniscus of the rest nozzle is slightly vibrated is too small, the ink thickening may not be sufficiently eliminated.

  The object of the present invention is to reliably eliminate the increase in the viscosity of the liquid in the nozzle by vibrating the liquid meniscus in the nozzle, and to jump out of the nozzle when the liquid meniscus in the nozzle is vibrated. Another object of the present invention is to provide a liquid ejection device capable of preventing the liquid from landing on the recording medium.

  The liquid ejection apparatus according to the present invention is a positional relationship between a liquid ejection head having a nozzle and an actuator for applying energy to the liquid in the nozzle, and the ejection area where the liquid of the ejection target medium is ejected. And a control device that controls the operation of the actuator, the control device separating the nozzle and the discharge region from each other by a predetermined distance or more based on a signal from the position sensor. In the second state, the first vibration signal for vibrating the meniscus of the liquid in the nozzle is output to the actuator while the nozzle and the discharge region are closer to each other than the predetermined distance. The second vibration that causes the liquid meniscus in the nozzle to vibrate with an amount of vibration smaller than the amount of vibration of the meniscus by the first vibration signal. Outputs a signal to the actuator, and the nozzle and the discharge region, when in the third state in which overlap with each other, outputs an ejection signal for ejecting liquid from the nozzle to the actuator.

  In the present invention, the first vibration signal is output to the piezoelectric actuator when the nozzle and the discharge region are in the first state separated by a predetermined distance or more. Further, the second vibration signal is output when the nozzle and the discharge region are in the second state that is closer than a predetermined distance. Further, when the nozzle and the discharge area are in the third state facing each other, the discharge signal is output to the piezoelectric actuator. Thereby, in a state where the nozzle and the discharge area are largely separated, the liquid meniscus can be sufficiently vibrated to reliably eliminate the increase in the viscosity of the liquid. Further, it is possible to prevent the liquid from ejecting from the nozzle while applying vibration to the meniscus of the liquid in the nozzle in a state where the nozzle and the discharge area are not so far apart.

1 is a schematic configuration diagram of a printer according to a first embodiment. It is a top view of an inkjet head. It is the III-III sectional view taken on the line of FIG. FIG. 2 is a block diagram illustrating a hardware configuration of a printer. 4 is a flowchart illustrating a processing flow at the time of printing by the printer in the first embodiment. (A) is a figure which shows print data, (b) is a figure which shows the relationship between partial print data and partial print data, and each area | region. 6 is a flowchart illustrating how to output a drive signal for a black nozzle row in the printing process for one pass in FIG. 5. FIG. 6A is a diagram illustrating a state in which the black nozzle row is positioned upstream of the recording paper in the first embodiment, and FIG. 5B is a diagram illustrating a state in which the black nozzle row is a non-ejection region in the first embodiment. It is a figure which shows the state which has opposed, (c) is a figure which shows the state which the black nozzle row has opposed the discharge area | region in 1st Embodiment. (A) is a figure which shows the pulse which comprises a 1st vibration signal, (b) is a figure which shows the pulse which comprises a 2nd vibration signal, (c) is a figure which shows the pulse which comprises a discharge signal. is there. It is a schematic block diagram of the printer which concerns on 2nd Embodiment. It is a flowchart which shows the flow of the process at the time of printing with a printer in 2nd Embodiment. It is a figure which shows the relationship between the printing data in 2nd Embodiment, and printing data, and each area | region. 12 is a flowchart showing how to output a drive signal for a black head in the printing process of FIG. FIG. 9A is a diagram illustrating a state where a recording sheet is positioned upstream of a black nozzle row in the second embodiment, and FIG. 9B is a second embodiment in which a non-ejection area is a black nozzle row. (C) is a diagram showing a state in which the ejection region is opposed to a black nozzle row in the second embodiment. (A) is a block diagram corresponding to FIG. 4 of the first modification, and (b) is a flowchart showing processing for storing the first and second information in the RAM of the first modification. 10 is a flowchart corresponding to FIG. FIG. 15A is a block diagram corresponding to FIG. 4 of the second modification, and FIG. 15B is a flowchart corresponding to FIG. 15B of the second modification. (A) is a flowchart corresponding to FIG. 5 of Modification 3, and (b) is a flowchart of information writing processing for black in (a). 6 is a flowchart corresponding to FIG. 10 is a flowchart corresponding to FIG.

[First Embodiment]
Hereinafter, a preferred first embodiment of the present invention will be described.

  As shown in FIG. 1, the printer 1 according to the first embodiment includes a carriage 2, an inkjet head 3, transport rollers 4a and 4b, a platen 5, a linear encoder 6, and the like.

  The carriage 2 is supported by two guide rails 9a and 9b extending in the scanning direction so as to be movable in the scanning direction. The carriage 2 is connected to a carriage motor 61 (see FIG. 4) via a drive belt and pulleys (not shown). When the carriage motor 61 is driven, the carriage 2 moves in the scanning direction. In the following description, the right and left sides in the scanning direction are defined as shown in FIG.

  The inkjet head 3 is mounted on the carriage 2 and ejects ink from a plurality of nozzles 15 formed on the lower surface thereof. The plurality of nozzles 15 are arranged in the transport direction to form four nozzle rows 16K, 16Y, 16C, and 16M. These four nozzle rows 16K, 16Y, 16C, and 16M are arranged in the scanning direction. From the plurality of nozzles 15, black, yellow, cyan, and magenta inks are ejected in order from the nozzles 16K, 16Y, 16C, and 16M.

  The transport rollers 4a and 4b are respectively disposed on the upstream side and the downstream side of the carriage 2 in the transport direction, and transport the recording paper P in the transport direction. The platen 5 is disposed opposite the inkjet head 3 between the transport rollers 4a and 4b in the transport direction. The platen 5 supports the recording paper P conveyed to the conveyance rollers 4a and 4b from below.

  In the printer 1, printing is performed on the recording paper P by ejecting ink from the inkjet head 3 that moves in the scanning direction together with the carriage 2 while transporting the recording paper in the transport direction by the transport rollers 4 a and 4 b. However, in the first embodiment, for the sake of convenience, the description will be made on the assumption that ink is ejected from the plurality of nozzles 15 only when the carriage 2 that reciprocates in the scanning direction moves to the right side, so-called unidirectional printing is performed.

  The linear encoder 6 has an encoder film 7 and an encoder sensor 8. The encoder film 7 is provided on the guide rail 9a and extends in the scanning direction. The encoder film 7 is formed with a plurality of slits (not shown) along the scanning direction. The encoder sensor 8 is mounted on the carriage 2 and faces the encoder film 7 in the transport direction. The encoder sensor 8 counts the number of slits of the encoder film 7 when the carriage 2 moves, and detects the position of the carriage 2 in the scanning direction based on the counted number. Since the positional relationship between the carriage 2 and the nozzle rows 16K, 16Y, 16C, and 16M is constant, the positions of the nozzle rows 16K, 16Y, 16C, and 16M can be acquired from the detection result of the encoder sensor 8.

  Next, the inkjet head 3 will be described. As shown in FIGS. 2 and 3, the inkjet head 3 includes a flow path unit 21 and a piezoelectric actuator 22. The flow path unit 21 is formed by stacking four plates 31 to 34. The plates 31 to 33 are made of a metal material such as stainless steel. The plate 34 is made of a synthetic resin material such as polyimide or a metal material similar to the plates 31 to 33.

  The plurality of nozzles 15 are formed on the plate 34. A plurality of pressure chambers 10 are formed in the plate 31. The pressure chamber 10 has a substantially elliptical planar shape whose longitudinal direction is the scanning direction. The plurality of pressure chambers 10 are individually provided for the plurality of nozzles 15 and overlap the left end portion of the corresponding nozzle 15.

  A plurality of substantially circular through holes 12 and 13 are formed in the plate 32. The plurality of through holes 12 overlap the right end portions of the plurality of pressure chambers 10. The plurality of through holes 13 overlap the left end portions of the plurality of pressure chambers 10.

  Four manifold channels 11 are formed in the plate 33. The four manifold channels 11 correspond to the four nozzle rows 16K, 16Y, 16C, and 16M, extend in the transport direction, and are abbreviations of the plurality of pressure chambers 10 that correspond to the nozzle rows 16K, 16Y, 16C, and 16M. It overlaps with the right half. In addition, each manifold channel 11 is supplied with ink from an ink supply port 17 provided at the downstream end in the transport direction. The plate 33 is formed with a plurality of through holes 14 that overlap the plurality of through holes 13.

  The piezoelectric actuator 22 has two piezoelectric layers 41 and 42, a common electrode 43, and a plurality of individual electrodes 44. The piezoelectric layer 41 is made of a piezoelectric material mainly composed of lead zirconate titanate, and is disposed on the upper surface of the flow path unit 21 and continuously extends across the plurality of pressure chambers 10. The piezoelectric layer 42 is made of the same piezoelectric material as the piezoelectric layer 41 and is disposed on the upper surface of the piezoelectric layer 41.

  The common electrode 43 is disposed between the piezoelectric layer 41 and the piezoelectric layer 42 and extends continuously across the plurality of pressure chambers 10. The common electrode 43 is always held at the ground potential. The plurality of individual electrodes 44 are individually provided for the plurality of pressure chambers 10 on the upper surface of the piezoelectric layer 42. The individual electrode 44 has an elliptical shape that is slightly smaller than the pressure chamber 10, and is disposed so as to overlap the central portion of the corresponding pressure chamber 10. Further, the right end portion of the individual electrode 44 extends to a position where it does not overlap with the pressure chamber 10, and the tip end portion serves as a connection terminal 44 a for connecting to a wiring member (not shown). Corresponding to the arrangement of the common electrode 43 and the plurality of individual electrodes 44, the portion sandwiched between the common electrode 43 and each individual electrode 44 of the piezoelectric layer 42 is polarized in the thickness direction.

  Here, the operation of the piezoelectric actuator 22 will be described. In the piezoelectric actuator 22, the potentials of all the individual electrodes 44 are previously held at the ground potential. Each individual electrode 44 is switched from a ground potential to a predetermined drive potential of, for example, about 20 V when a pulse signal as described later is input. Then, an electric field parallel to the polarization direction is generated between the individual electrode 44 and the common electrode 43, and the piezoelectric layer 42 contracts in the plane direction by this electric field. Due to the contraction of the piezoelectric layer 42, the piezoelectric layers 41 and 42 are deformed so as to be convex toward the pressure chamber 10 as a whole, and the volume of the pressure chamber 10 is reduced. As a result, the pressure of the ink in the pressure chamber 10 increases, and the ink is ejected from the nozzle 15 or the meniscus of the ink in the nozzle 15 is slightly vibrated.

  Next, the control device 50 for controlling the operation of the printer 1 will be described. As shown in FIG. 4, the control device 50 includes a CPU (Central Processing Unit) 51, a ROM (Read Only Memory) 52, a RAM (Random Access Memory) 53, a nonvolatile memory 54, an ASIC (Application Specific Integrated Circuit) 55, and the like. Which cooperate to control the operation of the carriage motor 61, the piezoelectric actuator 22, and the transport motor 62. In addition, the control device 50 receives a signal from the encoder sensor 8.

  In FIG. 4, only one CPU 51 is illustrated, but the control device 50 may include only one CPU 51 or a plurality of CPUs 51. In FIG. 4, only one ASIC 55 is illustrated, but the control device 50 may include only one ASIC 55 or a plurality of ASICs 55. Further, the control device 50 may include only one of the CPU 51 and the ASIC 55.

  Next, a procedure for performing printing in the printer 1 will be described. In the printer 1, the control device 50 performs printing by executing processing according to the flowchart illustrated in FIG. 5. Here, the flowchart of FIG. 5 is started when a print command is input to the printer 1 by, for example, an operation unit (not shown) of the printer 1 or a PC (not shown) connected to the printer 1 by the user. The

  When printing is performed in the printer 1, as shown in FIG. 5, the control device 50 first acquires the size of the recording paper P from the size information of the recording paper P input from a PC or the like (S101). In addition, by performing halftone processing on image data indicating R, G, and B information at each dot of the image input from a PC or the like, print data 70K, 70Y, and K for each color of K, Y, C, and M 70C and 70M are acquired (S102).

  As shown in FIG. 6A, the print data 70K, 70Y, 70C, and 70M have a plurality of dot information 71 two-dimensionally in a first direction corresponding to the scanning direction and a second direction corresponding to the transport direction. It is the arranged data. Each dot information 71 is either ejection information 71a indicating that ink is ejected or non-ejection information 71b indicating that ink is not ejected. Here, in FIG. 6A, the dot information 71 with hatching indicates the ejection information 71a, and the dot information 71 without hatching indicates the non-ejection information 71b. In addition, here, for convenience, the discharge information 71a is described as one type of information, but the discharge information 71a may selectively take one of a plurality of types of information. For example, the discharge information 71a selectively takes one of information indicating that a small droplet is discharged, information indicating that a medium droplet is discharged, and information indicating that a large droplet is discharged. It may be.

  The print data 70K is composed of a plurality of partial print data 75K as shown in FIGS. 6 (a) and 6 (b). The partial print data 75K is a portion corresponding to one pass in the print data 70K. The partial print data 75K is obtained by arranging dot information rows 72 in which U pieces of dot information 71 are arranged in the first direction in V rows in the second direction. Here, U is the number of driving cycles of the piezoelectric actuator 22 in one pass. V is the number of nozzles 15 constituting the nozzle row 16K. Then, the v-th (v is a natural number equal to or less than V) dot information row 72 from the top in FIG. 6B in the second direction corresponds to the v-th nozzle 15 from the upstream side in the transport direction of the nozzle row 16K. . Further, in each dot information row 72, the u-th (u is a natural number equal to or less than U) dot information 71 from the left side in FIG. 6B in the first direction corresponds to the u-th driving cycle in one pass. .

  Similarly, the print data 70Y is composed of a plurality of partial print data 75Y. The print data 70C is composed of a plurality of partial print data 75C. The print data 70M is composed of a plurality of partial print data 75M.

  Next, for each of black, yellow, cyan, and magenta, drive signal determination processing for determining a drive signal is executed (S103 to S106).

  In the drive signal determination process for black in S103, as shown in FIG. 7, first, based on the size of the recording paper P and the partial print data 75K, the discharge area 81, the non-discharge area 82, and the outer area for black. The position in the scanning direction 83 is acquired (S201).

  Here, in the first embodiment, since the piezoelectric actuator 22 is driven only when the carriage 2 is moved to the right side, the nozzle row 16K is positioned on the right side in the scanning direction as the driving period after the piezoelectric actuator 22 increases. . That is, the number of drive cycles and the position of the nozzle row 16K in the scanning direction have a one-to-one correspondence. The nonvolatile memory 54 stores in advance the position of the end of the recording paper P in the scanning direction for each size of the recording paper P. In S201, discharge is performed as follows based on the position of the discharge information 71a in the partial print data 75K and the position of the end in the scanning direction of the recording paper P read from the nonvolatile memory 54 according to the size of the recording paper P. The positions in the scanning direction of the area 81, the non-ejection area 82, and the outer area 83 are acquired. That is, as shown in FIG. 6B, among the discharge information 71a included in the partial print data 75K, the position in the scanning direction corresponding to the rightmost discharge information 71a in the first direction and the leftmost discharge information 71a. The position between the positions in the scanning direction corresponding to is acquired as the position of the ejection region 81. Further, the position between the left edge E1 of the recording paper P and the ejection area 81 in the scanning direction is acquired as the position of the non-ejection area 82. Further, the position on the left side of the recording paper P in the scanning direction is acquired as the position of the outer region 83. Note that the position of the left end of the outer region 83 is the position of the nozzle row 16 in the scanning direction in the first drive cycle. That is, the position of the left end of the outer region 83 is the position of the nozzle row 16 in the scanning direction when output of drive signals to the plurality of individual electrodes 44 corresponding to the nozzle row 16K of the piezoelectric actuator 22 is started in one pass. is there.

  Subsequently, the value of the variable u is set to 1 (S202). Next, in the u-th driving cycle, as shown in FIG. 8A, it is determined whether the nozzle row 16K is positioned in the outer region 83 (S203). As described above, since there is a one-to-one relationship between the drive cycle and the position of the nozzle row 16K in the scanning direction, the nozzle row 116K is located in the scan direction in the u-th drive cycle. I understand. In S203, the nozzle row 16K is positioned in the outer region 83 depending on whether or not the position in the scanning direction of the nozzle row 16K in the u-th driving cycle is included in the position of the outer region 83 acquired in S201. It is determined whether or not to do.

  If the nozzle row 16K is positioned in the outer region 83 in the u th drive cycle (S203: YES), the drive signal is sent to all the individual electrodes 44 corresponding to the nozzle row 16K in the u th drive cycle. Information indicating that the first vibration signal G1 is output is stored in the RAM 53 (S204). The first vibration signal G <b> 1 is a signal for vibrating the ink meniscus in the nozzle 15.

  On the other hand, if the nozzle row 16K is not positioned in the outer region 83 in the u th drive cycle (S203: NO), as shown in FIG. 8B, the nozzle row 16K is not in the u th drive cycle. It is determined whether or not it faces the ejection region 82 (S205). In S205, the nozzle row 16K faces the non-ejection region 82 depending on whether or not the position of the nozzle row 16K in the u-th driving cycle is included in the position of the non-ejection region 82 acquired in S201 in the scanning direction. It is determined whether or not.

  When the nozzle row 16K faces the non-ejection region 82 (S205: YES), the second vibration signal G2 is supplied as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 16K in the u-th drive cycle. Is stored in the RAM 53 (S206). The second vibration signal G2 is a signal for causing the ink meniscus in the nozzle 15 to vibrate with a smaller vibration amount than when the first vibration signal G1 is output.

  On the other hand, when the nozzle row 16K does not face the non-ejection region 82 in the u-th driving cycle (S205: NO), as shown in FIG. It is determined whether or not it faces the discharge area 81 (S207). In S207, whether or not the nozzle row 16K faces the ejection region 81 in the scanning direction depends on whether or not the position of the nozzle row 16K in the u-th driving cycle is included in the position of the ejection region 81 acquired in S201. Determine whether.

  If the nozzle row 16K faces the ejection region 81 (S207: YES), V dot information arranged in the u-th second direction from the left in FIG. 6B in the u-th driving cycle. 71, information indicating that the ejection signal G3 is output as a drive signal is stored in the RAM 53 in the individual electrode 44 corresponding to the dot information 71 that is the ejection information 71a. The ejection signal G3 is a signal for ejecting ink from the nozzle 15.

  Then, after any of S204, S206, and S208, if the value of the variable u is smaller than U (S209: NO), the value of u is incremented by 1 (S210), and the process returns to S203. On the other hand, when the value of the variable u is equal to U (S209: YES), the process ends.

  Here, the first drive signal G1 is a signal including a pulse having a pulse width W1 and not including a pulse having a pulse width larger than W1, as shown in FIG. The pulse width W1 is not less than 0.14 times and not more than 0.2 times the pressure reversal period AL when the pressure is applied to the ink in the pressure chamber 10. The second vibration signal G2 includes a pulse having a pulse width W2 as illustrated in FIG. 9B and does not include a pulse having a pulse width larger than W2. The pulse width W2 is smaller than the pulse width W1 and is less than 0.14 times the inversion period AL. The ejection signal is a signal including a pulse having a pulse width W3 as shown in FIG. The pulse width W3 is larger than the pulse widths W1 and W2, and is not less than 0.6 times the inversion period AL. In addition, the first vibration signal G1, the second vibration signal G2, and the ejection signal G3 have the same pulse height H.

  In the drive signal determination process for yellow in S104, the drive signal determination process for cyan in S105, and the drive signal determination process for magenta in S106, similarly to the drive signal determination process for black in S103, the processes in S201 to S210 are performed. Determine the drive signal. And the drive signal output to each individual electrode 44 in all the drive cycles of 1 path | pass is determined by the drive signal home processing of S103-S106.

  Next, printing processing for one pass is executed (S107). In S107, the information stored in the RAM 53 in any of S204, S206, and S208 and the encoder sensor 8 for each drive cycle of the nozzle rows 16K, 16Y, 16C, and 16M while moving the carriage 2 to the right in the scanning direction. The first vibration signal G1, the second vibration signal G2, and the ejection signal G3 are selectively output to each individual electrode 44 in each drive cycle of the piezoelectric actuator 22 in accordance with the signal from

  Accordingly, as shown in FIG. 8A, when the nozzle row 16K is positioned in the outer region 83, the ink meniscus in all the nozzles 15 constituting the nozzle row 16K is vibrated. In this state, the distance D11 between the nozzle row 16K and the ejection region 81 in the scanning direction is equal to or greater than the predetermined distance Dm. Further, as shown in FIG. 8B, even when the nozzle row 16K is opposed to the non-ejection region 82, the ink meniscus in all the nozzles 15 constituting the nozzle row 16K is vibrated. However, when the nozzle row 16K faces the non-ejection region 82, the amount of ink meniscus vibration is smaller than when the nozzle row 16K is positioned in the outer region 83. In this state, the distance D12 between the nozzle row 16K and the ejection region 81 in the scanning direction is less than the predetermined distance Dm. Further, as shown in FIG. 8C, when the nozzle row 16K is opposed to the discharge region 81, ink is ejected from the plurality of nozzles 15 constituting the nozzle row 16K according to the print data. .

  Also for the nozzle rows 16Y, 16C, and 16M, as in the nozzle row 16K, the ink meniscus in the nozzle 15 is vibrated depending on the position in the scanning direction, or ink is ejected from the nozzle 15 according to the print data. Is done.

  After the printing process for one pass in S107, if unprocessed print data that has not been processed in S103 to S107 remains (S108: YES), the process returns to S103, and the unprocessed print data is returned. Is not left (S108: NO), the process is terminated.

  In the first embodiment described above, when the nozzle row 16K does not face the recording paper P, the first vibration signal G1 is output to the plurality of individual electrodes 44 corresponding to the nozzle row 16K. The ink meniscus 15 is vibrated with a larger vibration amount than when the second vibration signal G2 is output. Thereby, the viscosity increase of the ink in the nozzle 15 can be reliably eliminated. At this time, ink may eject from the nozzle 15, but the ejected ink does not land on the recording paper P. The ejected ink lands on the platen 5 and flows into a waste liquid tank (not shown) by flowing along a groove (not shown) formed on the platen 5, for example. The same applies to the nozzle rows 16Y, 16C, and 16M.

  In the first embodiment, when the nozzle row 16K is opposed to the non-ejection area 82 of the recording paper P, the second vibration signal G2 is output to the plurality of individual electrodes 44 corresponding to the nozzle row 16K. Thus, the ink meniscus in the nozzle 15 is vibrated with a smaller vibration amount than when the first vibration signal G1 is output. Accordingly, it is possible to prevent ink from ejecting from the nozzle 15 and landing on the non-ejection area 82 while vibrating the ink meniscus in the nozzle 15. The same applies to the nozzle rows 16Y, 16C, and 16M.

  In the first embodiment, the inkjet head 3 corresponds to the liquid ejection apparatus of the present invention. The linear encoder 6 corresponds to the position sensor of the present invention. Further, the state where the nozzle rows 16K, 16Y, 16C, and 16M are located on the left side of the recording paper P in the scanning direction corresponds to the first state of the present invention. Further, the state where the nozzle rows 16K, 16Y, 16C, and 16M face the non-ejection region 82 corresponds to the second state of the present invention. Further, the state in which the nozzle rows 16K, 16Y, 16C, and 16M face the ejection region 81 corresponds to the third state of the present invention. An operation performed by the printing process for one pass corresponds to a unit operation of the present invention.

[Second Embodiment]
Next, a preferred second embodiment of the present invention will be described. As shown in FIG. 10, the printer 100 according to the second embodiment includes four inkjet heads 101 </ b> K, 101 </ b> Y, 101 </ b> C, and 101 instead of the carriage 2 and the inkjet head 3 in the printer 1 according to the first embodiment. . The printer 100 includes a rotary encoder 102.

  The four inkjet heads 101K, 101Y, 101C, and 101M are so-called line heads that extend in the scanning direction over the entire length of the recording paper P, and are arranged in the transport direction. The ink jet heads 101K, 101Y, 101C, and 101M eject ink from a plurality of nozzles 115 formed on the lower surface thereof. The plurality of nozzles 115 of the ink jet head 101K form a nozzle row 116K by being arranged in the scanning direction, and eject black ink.

  Similarly, the plurality of nozzles 115 of the inkjet head 101Y form a nozzle row 116Y, and discharge yellow ink. The plurality of nozzles 115 of the ink jet head 101C form a nozzle row 116C and discharge cyan ink. The plurality of nozzles 115 of the ink jet head 101M form a nozzle row 116M, and eject magenta ink.

  Here, the inkjet heads 101 </ b> K, 101 </ b> Y, 101 </ b> C, and 101 </ b> M also have the flow path unit 21 and the piezoelectric actuator 22 as in the inkjet head 3. However, in the inkjet heads 101K, 101Y, 101C, and 101M, the arrangement and size of the ink flow paths such as the pressure chambers 10 and the manifold flow paths 11 according to the arrangement of the plurality of nozzles 115, the piezoelectric layers 41 and 42, and the common electrode 43. The arrangement and size of the individual electrodes 44 are different from those of the inkjet head 3.

  The rotary encoder 102 includes an encoder disk 103 and an encoder sensor 104. The encoder disk 103 is a disk-shaped member, and a plurality of slits (not shown) are formed along the circumferential direction. The encoder disk 103 is attached to the transport roller 4a and rotates together with the transport roller 4a. The encoder sensor 104 faces the encoder disk 103 in the scanning direction, and counts the number of slits of the encoder disk 103 that pass when the transport roller 4a rotates. Then, the rotation amount of the transport roller 4a is detected based on the count number. Thereby, the conveyance amount of the recording paper P can be detected from the detection result of the encoder sensor 104.

  The printer 100 prints on the recording paper P by ejecting ink from the inkjet heads 101K, 101Y, 101C, and 101M while transporting the recording paper P in the transport direction by the transport rollers 4a and 4b.

  Printing in the printer 100 will be described in more detail. When printing is performed in the printer 100, the control device 50 first determines the size of the recording paper P from the size information of the R, G, B recording paper P input from a PC or the like, as shown in FIG. Obtain (S301). Next, the print data 120K, 120Y for each color of K, Y, C, M is obtained by performing halftone processing on the image data indicating R, G, B information at each dot of the image input from a PC or the like. , 120C, 120M are acquired (S202).

  The print data 120K, 120Y, 120C, and 120M are data in which a plurality of dot information 121 is two-dimensionally arranged in a first direction corresponding to the transport direction and a second direction corresponding to the scan direction, as shown in FIG. It is. The dot information 121 is either ejection information 121a indicating that ink is ejected or non-ejection information 121b indicating that ink is not ejected. Here, in FIG. 12, dot information 121 with hatching indicates ejection information 121a, and dot information 121 without hatching indicates non-ejection information 121b. In addition, here, for the sake of convenience, the description will be made assuming that the ejection information 121a is one type of information, but the ejection information 121a may selectively take one of a plurality of types of information. For example, the discharge information 121a selectively takes one of information indicating that a small droplet is discharged, information indicating that a medium droplet is discharged, and information indicating that a large droplet is discharged. It may be.

  The print data 120K is obtained by arranging dot information columns 122 in which U pieces of dot information 121 are arranged in the first direction into V rows in the second direction. Here, U is the number of driving cycles of the piezoelectric actuator 22 during printing on the recording paper P. V is the number of nozzles 115 constituting the nozzle row 116K. The v-th (v is a natural number equal to or less than V) dot information sequence 122 from the left in FIG. 12 in the second direction corresponds to the v-th nozzle 115 from the left in the scanning direction of the inkjet head 101K. Further, the u-th (u is a natural number equal to or less than U) dot information 121 from the lower side of FIG. 12 in the first direction of each dot information row 122 corresponds to the u-th driving cycle. Similarly to the print data 120K, the print data 120Y, 120C, and 120M are dot information columns 122 in which U dot information 121 is arranged in the first direction, and are arranged in V columns in the second direction.

  Next, for each of black, yellow, cyan, and magenta, drive signal determination processing for determining a drive signal is executed (S303 to S306).

  In the drive signal determination process for black in S303, as shown in FIG. 13, first, based on the size of the recording paper P and the print data 120K, the ejection area 131 and non-ejection on the recording paper P for black. The position of the area 132 is acquired (S401).

  Here, in the second embodiment, as described above, the recording paper P is transported in the transport direction by the transport rollers 4a and 4b, and ink is ejected from the inkjet heads 101K, 101Y, 101C, and 101M, thereby recording paper. Print on P. Accordingly, there is a one-to-one relationship between each area on the recording paper P and the number of drive cycles at which the area of the recording paper P is ejected. The nonvolatile memory 54 stores information about the number of driving cycles of the recording paper P, for each size of the recording paper P, the position of the end of the recording paper P in the transport direction. Yes. In S401, based on the position of the ejection information 121a in the print data 120K and the information read from the nonvolatile memory 54 according to the size of the recording paper P, the ejection area 131 on the recording paper P is as follows. In addition, the position of the non-ejection region 132 is acquired. That is, as shown in FIG. 12, among the discharge information 121a included in the print data 120K on the recording paper P, the position of the region corresponding to the uppermost discharge information 121a in the first direction and the lowermost discharge A position between the position corresponding to the area position corresponding to the information 121 a is acquired as the position of the ejection area 131. Further, the position between the discharge area 131 and the edge E <b> 2 downstream of the recording sheet P in the transport direction on the recording sheet P is acquired as the position of the non-ejection area 132.

  Subsequently, the value of the variable u is set to 1 (S402). Next, in the u-th driving cycle, as shown in FIG. 14A, it is determined whether or not the recording paper P is positioned on the upstream side in the transport direction from the nozzle row 116K (S403). Here, the position of the edge E2 of the recording paper P in the transport direction is determined by the size of the recording paper P and the number of driving cycles as described above. In S403, depending on whether or not the position of the edge E2 of the recording paper P in the u-th driving cycle is positioned upstream of the nozzle row 116K, the recording paper P is upstream of the nozzle row 116K in the transport direction. It is determined whether or not it is located.

  When the recording paper P is positioned upstream of the nozzle row 116K in the transport direction in the u-th driving cycle (S403: YES), all of the recording paper P corresponding to the nozzle row 116K in the u-th driving cycle. Information indicating that the first vibration signal G1 is output as a drive signal to the individual electrode 44 is stored in the RAM 53 (S404).

  On the other hand, when the recording paper P is not positioned upstream of the nozzle row 116K in the transport direction in the u-th driving cycle (S403: NO), as shown in FIG. 14B in the u-th driving cycle. Next, it is determined whether or not the non-ejection area 132 of the recording paper P faces the nozzle row 116K (S405). Here, the position of the non-ejection area 132 in the transport direction is determined by the position of the non-ejection area 132 on the recording paper P acquired in S401 and the number of drive cycles. In S405, the non-ejection area 132 of the recording paper P faces the nozzle row 116K depending on whether or not the position of the non-ejection area 132 in the u-th driving cycle overlaps the position of the nozzle row 116K in the transport direction. It is determined whether or not. When the non-ejection area 132 of the recording paper P faces the nozzle row 116K in the u-th driving cycle (S405: YES), all the individual corresponding to the nozzle row 116K in the u-th driving cycle. Information indicating that the second vibration signal G2 is output as the drive signal is stored in the RAM 53 in the RAM 53 (S406).

  On the other hand, when the non-ejection area 132 of the recording paper P does not face the nozzle row 116K in the u-th driving cycle (S405: NO), as shown in FIG. 14C in the u-th driving cycle. Then, it is determined whether or not the ejection area 131 of the recording paper P faces the nozzle row 116K (S407). Here, the position of the ejection region 131 in the transport direction is determined by the position of the ejection region 131 on the recording paper P acquired in S401 and the number of drive cycles. In S407, whether or not the ejection region 131 of the recording paper P faces the nozzle row 116K depending on whether or not the position of the one ejection region 131 in the u-th driving cycle overlaps the position of the nozzle row 116K in the transport direction. Determine whether or not. When the ejection area 131 of the recording paper P faces the nozzle row 116K in the u-th driving cycle (S407: YES), the u-th second data from the lower side of FIG. Of the V pieces of dot information 121 arranged in the direction, information indicating that the ejection signal G3 is output as a drive signal is stored in the RAM 53 in the individual electrode 44 corresponding to the dot information 121 that is the ejection information 121a ( S408),

  Then, after any of S404, S406, and S408, if the value of the variable u is smaller than U (S409: NO), the value of u is incremented by 1 (S410), and the process returns to S403. On the other hand, when the value of the variable u is equal to U (S409: YES), the process ends.

  In the drive signal determination process for yellow in S304, the drive signal determination process for cyan in S305, and the drive signal determination process for magenta in S306, as in the drive signal determination process for black in S303, the processes in S401 to S410 are performed. Determine the drive signal. Then, the drive signals to be output to the individual electrodes 44 of the ink jet heads 101K, 101Y, 101C, and 101M in all the drive cycles are determined by the drive signal determination process of S303 to S306.

  Next, a printing process is executed (S307). In S307, the recording paper P is conveyed in the conveyance direction by the conveyance rollers 4a and 4b, and the information stored in the RAM 53 in any of S404, S406, and S408 for each drive cycle of the nozzle rows 116K, 116Y, 116C, and 116M. In addition, according to the signal from the encoder sensor 104, any one of the first vibration signal G1, the second vibration signal G2, and the discharge signal G3 is selectively applied to each individual electrode 44 in each drive cycle of the piezoelectric actuator 22. Output.

  As a result, as shown in FIG. 14A, when the recording paper P is located on the upstream side in the transport direction from the nozzle row 116K, the ink in all the nozzles 115 constituting the nozzle row 116K. The meniscus is vibrated. In this state, the interval D21 between the nozzle row 116K and the ejection region 131 in the transport direction is equal to or greater than the predetermined distance Dm. As shown in FIG. 14B, even when the non-ejection region 132 faces the nozzle row 16K, the ink meniscus in all the nozzles 115 constituting the nozzle row 116K is vibrated. However, when the non-ejection area 132 is opposed to the nozzle row 116K, the amount of vibration of the ink meniscus is smaller than when the recording paper P is positioned upstream of the nozzle row 116K in the transport direction. In this state, the interval D22 between the nozzle 116K and the ejection region 131 in the transport direction is less than the predetermined distance Dm. Further, as shown in FIG. 14C, when the nozzle row 116K faces the ejection region 131, ink is ejected from the plurality of nozzles 115 constituting the nozzle row 116K according to the print data. .

  As for the nozzle rows 116Y, 116C, and 116M, similarly to the nozzle row 116K, the ink meniscus in the nozzle 115 is vibrated depending on the position of the recording paper P, or ink is ejected from the nozzle 115 according to the print data. The

  Here, in the second embodiment, for the sake of convenience, it has been described that the print signal is determined after determining drive signals for all the drive cycles in S303 to S306, but the present invention is not limited to this. For example, in the drive signal determination process of S303 to S306, when the drive signal for a part of the drive cycle is determined, the print process of S307 is started, and the drive after the part of the drive period is performed during the print process. You may make it determine the drive signal in a period.

  In the second embodiment described above, when the recording paper P is located upstream of the nozzle row 116K in the transport direction, the first vibration signal G1 is applied to all the individual electrodes 44 of the inkjet head 101K. Then, the ink meniscus in the plurality of nozzles 115 constituting the nozzle row 116K is vibrated with a larger vibration amount than when the second vibration signal G2 is output. Thereby, the viscosity increase of the ink in the plurality of nozzles 115 of the inkjet head 101 can be surely eliminated. At this time, ink may eject from the nozzle 115 of the inkjet head 101K, but the ejected ink does not land on the recording paper P. The same applies to the inkjet heads 101Y, 101C, and 101M.

  In the second embodiment, when the non-ejection area 132 of the recording paper P faces the nozzle row 116K, the second vibration signal G2 is output to all the individual electrodes 44 of the inkjet head 101K. The ink meniscus in the plurality of nozzles 115 constituting the nozzle row 116K is vibrated with a smaller amount of vibration than when the first vibration signal G1 is output. As a result, while the meniscus of the ink in the plurality of nozzles 115 constituting the nozzle row 116K is vibrated, the ink is ejected from the plurality of nozzles 115 constituting the nozzle row 116K, and the ink lands on the recording paper P. Can be prevented. The same applies to the inkjet heads 101Y, 101C, and 101M.

  In the second embodiment, the ink jet heads 101K, 101Y, 101C, and 101M correspond to the liquid discharge head of the present invention. The rotary encoder 102 corresponds to the position sensor of the present invention. Further, the state in which the recording paper P is positioned upstream of the nozzle rows 116K, 116Y, 116C, and 116M in the transport direction corresponds to the first state of the present invention. The state where the non-ejection region 132 faces the nozzle rows 116K, 116Y, 116C, and 116M corresponds to the second state of the present invention. Further, the state in which the ejection region 131 faces the nozzle rows 116K, 116Y, 116C, and 116M corresponds to the third state of the present invention.

  Next, modified examples in which various changes are made to the first and second embodiments will be described.

  In the first embodiment, when the nozzle row 16K is positioned in the outer region 83 in the u-th drive cycle, the drive signal is always applied to all the individual electrodes 44 corresponding to the nozzle row 16K in the u-th drive cycle. The information indicating that the first vibration signal G1 is output is stored in the RAM 53, but is not limited thereto.

(Modification 1)
In the first modification, the printer 1 further includes a temperature sensor 151 as shown in FIG. The temperature sensor 151 detects a temperature corresponding to the temperature of the ink in the nozzle 15, such as the temperature around the inkjet head 3. Then, as shown in FIG. 15B, during the operation of the printer 1, the control device 50 always determines whether the temperature of the ink in the nozzle 15 is equal to or higher than the predetermined temperature based on the signal from the temperature sensor 151. Is determined (S501). If the temperature is equal to or higher than the predetermined temperature Tm (S501: YES), the first information is stored in the RAM 53 (S502). If the temperature is lower than the predetermined temperature Tm (S501: NO), the second information is stored in the RAM 53. Is stored (S503).

  In the first modification, in the black drive signal determination process, as shown in FIG. 16, the nozzle row 16K is positioned in the outer region 83 in the u-th drive cycle (S301: YES), and the first is stored in the RAM 53. When the information is stored (S601: YES), the RAM 53 stores information indicating that the first vibration signal G1 is output as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 16K in the u-th drive cycle. (S602). On the other hand, even when the nozzle row 16K is located in the outer region 83 in the u th drive cycle (S301: YES), if the second information is stored in the RAM 53 (S601: NO), the u th drive cycle In addition, information indicating that the second vibration signal G2 is output as a drive signal is stored in the RAM 53 in all the individual electrodes 44 corresponding to the nozzle row 16K (S603). The same applies to the drive signal determination processing for yellow, cyan, and magenta.

  The higher the temperature of the ink in the nozzle 15, the easier the water in the ink evaporates and the more easily the ink in the nozzle 15 thickens. Therefore, in the first modification, when the temperature of the ink in the nozzle 15 is equal to or higher than the predetermined temperature Tm, the nozzle row 16K is located upstream of the recording paper P in the moving direction of the carriage 2 as in the first embodiment. When positioned, the first vibration signal G1 is output to all the individual electrodes 44 corresponding to the nozzle row 16K, and the meniscus of the ink in the nozzle 15 is vibrated. Thereby, the viscosity increase of the ink in the nozzle 15 can be reliably eliminated. The same applies to the nozzle rows 16Y, 16C, and 16M.

  On the other hand, when the temperature of the ink in the nozzle 15 is lower than the predetermined temperature Tm, unlike the first embodiment, the nozzle row 16K is positioned upstream of the recording paper P in the movement direction of the carriage 2. Also, the second vibration signal G2 is output to all the individual electrodes 44 corresponding to the nozzle row 16K, and the meniscus of the ink in the nozzle 15 is vibrated. As a result, it is possible to prevent the ink meniscus in the nozzle 15 from vibrating more than necessary and, on the contrary, to promote the thickening of the ink in the nozzle 15. The same applies to the nozzle rows 16Y, 16C, and 16M.

(Modification 2)
In the first modification, the control device 50 selectively stores either the first information or the second information in the RAM 53 based on the signal from the temperature sensor 151. However, the present invention is not limited to this. In the second modification, as shown in FIG. 17A, in the first modification, the temperature sensor 151 is not provided and the humidity sensor 161 is further provided. The humidity sensor 161 detects the humidity corresponding to the humidity around the nozzle 15, such as the humidity around the inkjet head 3. Then, as shown in FIG. 17B, during the operation of the printer 1, the control device 50 always determines whether or not the humidity around the nozzle 15 is equal to or higher than the predetermined humidity Um based on a signal from the humidity sensor 161. Is determined (S701). If the humidity is equal to or higher than the predetermined humidity Um (S701: YES), the second information is stored in the RAM 53 (S702). If the humidity is lower than the predetermined humidity Um (S701: NO), the first information is stored in the RAM 53. Store (S703).

  The lower the humidity around the nozzle 15, the more easily the water in the ink evaporates, and the ink in the nozzle 15 tends to thicken. Therefore, in the second modification, when the humidity around the nozzle 15 is less than the predetermined humidity Um, the nozzle row 16K is positioned upstream of the recording paper P in the movement direction of the carriage 2 as in the first embodiment. The first vibration signal G1 is output to all the individual electrodes 44 corresponding to the nozzle row 16K, and the ink meniscus in the nozzle 15 is vibrated. Thereby, the viscosity increase of the ink in the nozzle 15 can be reliably eliminated. The same applies to the nozzle rows 16Y, 16C, and 16M.

  On the other hand, when the humidity around the nozzle 15 is equal to or higher than the predetermined humidity Um, unlike the first embodiment, the nozzle row 16K may be positioned upstream of the recording paper P in the movement direction of the carriage 2. The second vibration signal G2 is output to the plurality of individual electrodes 44 corresponding to the nozzle row 16K, and the meniscus of the ink in the nozzle 15 is vibrated. As a result, it is possible to prevent the ink meniscus in the nozzle 15 from vibrating more than necessary and promote the increase in the viscosity of the ink in the nozzle. The same applies to the nozzle rows 16Y, 16C, and 16M.

(Modification 3)
In the third modification, as shown in FIG. 18A, when the unprocessed print data 70K remains after the printing process for one pass in S107 (S105: YES), the control device 50 causes the black color to be black. , Yellow, cyan, and magenta, information writing processing for writing either the first information or the second information to the RAM 53 is executed (S801 to S804). Then, after the information writing process for each color in S801 to S804 is completed, the process returns to S103.

  In the information writing process for black ink in S801, first, as shown in FIG. 18B, the black ink ejection amount in the printing process in S107 is calculated from the partial print data 75K (S901). In S901, for example, based on the number of ejection information 71a included in the partial print data 75K, the ejection amount of black ink in the printing process in S107 is calculated. If the calculated discharge amount of black ink is equal to or greater than the predetermined amount Vm (S902: YES), the second information is written in the RAM 53 (S903), and the process is terminated. On the other hand, when the calculated ink discharge amount is less than the predetermined amount Vm (S902: NO), the first information is written in the RAM 53 (S904), and the process is terminated.

  The information writing process for yellow ink in S802, the information writing process for cyan ink in S803, and the information writing process for magenta ink in S804 are the same as the information writing process for black ink in S801. , S901 to S904 are executed.

  The smaller the amount of ink ejected from the nozzle 15 in a pass, the greater the degree of thickening of the ink in the nozzle 15 in the next pass. Therefore, in Modification 3, when the amount of ink discharged from the nozzles 15 in the immediately preceding head driving process is less than the predetermined amount Vm, the nozzle row 16K performs recording in the movement direction of the carriage 2 as in the first embodiment. When positioned upstream of the paper P, the first vibration signal G1 is output to the plurality of individual electrodes 44 corresponding to the nozzle row 16K, and the ink meniscus in the nozzle 15 is vibrated. Thereby, the viscosity increase of the ink in the nozzle 15 can be reliably eliminated. The same applies to the nozzle rows 16Y, 16C, and 16M.

  On the other hand, when the amount of ink discharged from the nozzles 15 in the immediately preceding head driving process is less than the predetermined amount Vm, unlike the first embodiment, the nozzle row 16K is more than the recording paper P in the movement direction of the carriage 2. Even if it is located upstream, the second vibration signal G2 is output to the plurality of individual electrodes 44 corresponding to the nozzle row 16K, and the meniscus of the ink in the nozzle 15 is vibrated. As a result, it is possible to prevent the ink meniscus in the nozzle 15 from vibrating more than necessary and promote the increase in the viscosity of the ink in the nozzle. The same applies to the nozzle rows 16Y, 16C, and 16M.

  Also in the second embodiment, similarly to the first to third modifications, either the first information or the second information may be selectively stored in the RAM 53. In this case, in the u-th driving cycle, when the recording paper P is positioned upstream of the nozzle row 116K in the transport direction and the first information is stored in the RAM 53, the u-th driving cycle. The RAM 53 stores information indicating that the first vibration signal G1 is output as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 116K. Further, in the u-th driving cycle, even if the recording paper P is positioned upstream of the nozzle row 116K in the transport direction, if the second information is stored in the RAM 53, the u-th driving cycle The RAM 53 stores information indicating that the second vibration signal G2 is output as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 116K. The same applies to the nozzle rows 16Y, 16C, and 16M.

(Modification 4)
In the fourth modification, when the control device 50 moves the carriage 2 to the right side or the left side, bidirectional printing in which printing is performed by ejecting ink from the nozzles 15 and the carriage 2 is set to either the right side or the left side. Only when it is moved to, one of the unidirectional printing in which printing is performed by ejecting ink from the nozzle 15 is selectively performed. Whether the control device 50 performs bidirectional printing or unidirectional printing depends on the type of image to be printed, the image quality selected by the user by operating the printer 1 or a PC (not shown) connected to the printer 1, and the like. It depends on. For example, when speed is required rather than image quality, such as document printing, bidirectional printing is performed. On the other hand, in the case where image quality is required rather than speed, such as when printing a photograph, unidirectional printing is performed.

  And in the modification 4, as shown in FIG. 19, before S101, the control apparatus 50 memorize | stores 2nd information in RAM53, when bi-directional printing is performed (S1001: NO) (S1002). When one-way printing is performed (S1001: YES), the first information is stored in the RAM 53 (S1003).

  In unidirectional printing, the period during which ink is not ejected from the nozzles 15 is longer than in bidirectional printing, and the ink in the nozzles 15 tends to thicken. Therefore, in the fourth modification, when unidirectional printing is performed, as in the first embodiment, when the nozzle row 16K is positioned upstream of the recording paper P in the movement direction of the carriage 2, The first vibration signal G1 is output to the plurality of individual electrodes 44 corresponding to the nozzle row 16K, and the meniscus of the ink in the nozzle 15 is vibrated. Thereby, the viscosity increase of the ink in the nozzle 15 can be reliably eliminated. The same applies to the nozzle rows 16Y, 16C, and 16M.

  On the other hand, when performing bidirectional printing, unlike the first embodiment, the nozzle row 16K corresponds to the nozzle row 16K even if the nozzle row 16K is positioned upstream of the recording paper P in the movement direction of the carriage 2. The second vibration signal G2 is output to the plurality of individual electrodes 44 to vibrate the ink meniscus in the nozzle 15. As a result, it is possible to prevent the ink meniscus in the nozzle 15 from vibrating more than necessary and, on the contrary, to promote the thickening of the ink in the nozzle 15. The same applies to the nozzle rows 16Y, 16C, and 16M.

  Further, in a printer capable of performing unidirectional printing as in Modification 4, the nozzle array formed by the nozzles 15 that eject ink that tends to increase in viscosity is used when the inkjet head 3 is driven in unidirectional printing. The nozzle rows 16K, 16Y, 16C, and 16M are preferably arranged so as to be positioned on the upstream side in the movement direction of the carriage 2. In this case, as the nozzle row is formed by the nozzles 15 that eject ink that tends to thicken, the period of time in the outer region 83 is longer in the one-pass printing process of S107. As a result, the nozzle 15 that ejects ink that tends to thicken has a longer period during which the first drive signal G1 is input to the individual electrode 44 and the ink meniscus is vibrated, and the ink meniscus in the nozzle 15 is efficiently removed. Can be vibrated.

  From the same point of view, in a printer in which a plurality of line heads are arranged in the transport direction, such as the printer 100 of the second embodiment, the line head having nozzles that eject ink that tends to thicken is more downstream in the transport direction. It is preferable to arrange.

  In the first to fourth modifications, the RAM 53 that selectively stores either the first information or the second information corresponds to the storage unit of the present invention. In addition, the condition regarding which of the first information and the second information is stored in the RAM 53 by the control device 50 may be different from the conditions described in the first to fourth modifications.

(Modification 5)
In the so-called serial type printer in which printing is performed by ejecting ink from the inkjet head 3 while moving the carriage 2 in the scanning direction as in the first embodiment, the carriage 2 is usually set to 1 in S107. In the printing process for the pass, acceleration or deceleration is performed in the regions at both ends of the moving range, and the region moves between them at a constant speed. On the other hand, in the first embodiment, the drive signal is determined in S103 to S106 without considering whether the carriage 2 is moving at a constant speed or is accelerated or decelerated. Is not limited.

  In the fifth modification, the nonvolatile memory 54 stores information about a constant speed position where the carriage 2 moves at a constant speed and an acceleration / deceleration position where the carriage accelerates or decelerates in the scanning direction. In the drive signal determination process for black in S103, as shown in FIG. 20, in the u-th drive cycle, the nozzle row 16K is positioned in the outer region 83 (S301: YES), and the carriage 2 is at a constant speed. When located at the position (S1101: NO), information indicating that the first vibration signal G1 is output as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 16K in the u-th drive cycle is stored in the RAM 53. (S1102). On the other hand, when the carriage 2 is located at the acceleration / deceleration position (S1101: YES), the second vibration signal G2 is output as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 16K in the u-th drive cycle. The information shown is stored in the RAM 53 (S1103). The same applies to the drive signal determination processing for yellow, cyan, and magenta in S104 to S106.

  When the carriage 2 is accelerated or decelerated, the ink pressure in the inkjet head 3 becomes unstable. Therefore, when the carriage 2 is accelerating or decelerating, if the first vibration signal G1 is output to the plurality of individual electrodes 44 to vibrate the ink meniscus in the nozzle 15, the ink may be ejected from the nozzle 15. Increases nature. Here, as described above, the ink ejected from the nozzle 15 located in the outer region 83 lands on the platen 5 and flows into a waste liquid tank (not shown) through a groove (not shown) formed in the platen 5. However, if the amount of ink ejected from the nozzle 15 becomes too large, the ink remains on the platen 5 and the ink on the platen 5 may adhere to the recording paper P.

  Therefore, in the fifth modification, even if the nozzle row 16K is located upstream of the recording paper P in the movement direction of the carriage 2, the nozzle row 16K is located in the acceleration / deceleration position. The second vibration signal G2 is output to all the individual electrodes 44 corresponding to 16K. Thereby, when the meniscus of the ink in the nozzle 15 which comprises the nozzle row 16K is vibrated, it can prevent that an ink jumps out from the nozzle 15. FIG. The same applies to the nozzle rows 16Y, 16C, and 16M.

  In the first embodiment, when the nozzle row 16K does not face the ejection region 81 in the u-th driving cycle, depending on whether the nozzle row 16K is located in the outer region 83 or the non-ejection region 82. , Outputting the first vibration signal G1 as the drive signal and the second vibration signal G2 to all the individual electrodes 44 corresponding to the nozzle row 16K in the u-th drive cycle. Of the information shown, any information is selectively stored in the RAM 53, but the present invention is not limited to this. Regardless of the position of the edge E1, in the u-th driving cycle, when the distance between the nozzle row 16K and the ejection region 81 in the scanning direction is equal to or greater than the predetermined distance Dm, the nozzle row 16K is moved to the u-th driving cycle. Information indicating that the first vibration signal G <b> 1 is output as a drive signal to all the corresponding individual electrodes 44 may be stored in the RAM 53. Further, when the distance is less than the predetermined distance Dm, information indicating that the second vibration signal G2 is output as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 116K in the u-th drive cycle is stored in the RAM 53. It may be memorized. Similarly, in the second embodiment, regardless of the position of the edge E2, when the distance between the nozzle row 116K and the ejection region 131 in the transport direction is equal to or greater than the predetermined distance Dm in the u-th driving cycle, Information indicating that the first vibration signal G1 is output as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 116K may be stored in the RAM 53 in the drive cycle. Further, when the distance is less than the predetermined distance Dm, information indicating that the first vibration signal G1 is output as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 116K in the u-th drive cycle is stored in the RAM 53. It may be memorized. The same applies to the nozzle rows 16Y, 16C, and 16M.

  In the printer 100 of the second embodiment, the present invention can also be applied to printing on roll paper conveyed in the conveyance direction. When printing on roll paper by the printer 100, for example, in the u-th drive cycle, an area that is separated and discarded after printing out of areas located in two ejection areas arranged in the roll paper conveyance direction. When facing the nozzle row 116K, information indicating that the first vibration signal G1 is output as a drive signal to all the individual electrodes 44 corresponding to the nozzle row 116K is stored in the RAM 53 in the u-th drive cycle. On the other hand, in the u-th drive cycle, when the region remaining together with the discharge region among the two discharge regions aligned in the roll paper conveyance direction faces the nozzle row 116K, the u-th drive cycle, the nozzle row Information indicating that the second vibration signal G2 is output as a drive signal to all the individual electrodes 44 corresponding to 116K is stored in the RAM 53. The same applies to the nozzle rows 16Y, 16C, and 16M.

  In the first and second embodiments, the second vibration signal G2 is configured such that the pulse width W1 of the pulse configuring the first vibration signal G1 is 0.14 to 0.2 times the inversion period AL. The pulse width W2 of the pulse is less than 0.14 times the inversion cycle AL, and the pulse width W3 of the pulse constituting the ejection signal G3 is 0.6 times or more of the inversion cycle AL. I can't. If the magnitude relationship of the pulse widths W1 to W3 does not change, the range of the pulse widths W1 to W3 with respect to the inversion period AL may be out of the above range.

  In the first and second embodiments, the first vibration signal G1, the second vibration signal G2, and the ejection signal G3 have different pulse widths, but the present invention is not limited to this. For example, the first vibration signal G1, the second vibration signal G2, and the discharge signal G3 are signals including pulses having the same pulse width, and the height of the pulse that forms the first vibration signal G1 forms the discharge signal G3. The height of the pulse constituting the second vibration signal G2 may be lower than the height of the pulse constituting the first vibration signal G1.

  In the first embodiment, the size of the recording paper P is acquired from the size information of the recording paper P input together with the print data. However, the present invention is not limited to this. For example, a media sensor for detecting the presence or absence of the recording paper P may be provided in the carriage 2, and the size of the recording paper P may be acquired based on a signal from the media sensor.

  In the first embodiment, the positions of the ejection region 81, the non-ejection region 82, and the outer region 83 are acquired for each pass, but the present invention is not limited to this. For example, the positions of the ejection region 81, the non-ejection region 82, and the outer region 83 that are common to all paths may be specified. In this case, for example, among the ejection information 71a included in the print data 70K, the position in the scanning direction corresponding to the position of the leftmost ejection information 71a in the first direction and the scanning direction corresponding to the rightmost ejection information 71a. A position between the positions is acquired as the position of the ejection region 81 common to all passes. Further, the position between the left edge E1 in the scanning direction of the recording paper P and the ejection area 81 is acquired as the position of the non-ejection area 82 common to all passes. Further, the position on the left side of the recording paper P in the scanning direction is acquired as the position of the outer region 83 common to all paths. The same applies to the print data 70Y, 70C, and 70M.

  In the first and second embodiments, the position of the ejection region 81 is acquired from the print data, but the present invention is not limited to this. For example, when acquiring image data from a PC or the like, the position information of the ejection region 81 may be acquired as meta information of the image data. Alternatively, when the position of the ejection region 81 is always the same depending on the size of the recording paper P, the position of the ejection region 81 may be acquired based on the size of the recording paper P acquired in S101 and S401. Good.

  In the first and second embodiments, the inkjet heads 3, 101K, 101Y, 10C, and 101M are provided with piezoelectric actuators, but the present invention is not limited to this. The inkjet heads 3, 101K, 101Y, 10C, and 101M are, for example, so-called thermal type actuators that discharge ink from the nozzles 15 and 115 by heating the ink in the flow path and generating bubbles in the flow path. In addition, an actuator other than the piezoelectric actuator may be provided.

  In the above, an example in which the present invention is applied to a printer that performs printing by ejecting ink from nozzles has been described. However, the present invention is not limited thereto. The present invention can also be applied to a liquid ejection apparatus other than a printer that ejects liquid other than ink from nozzles.

DESCRIPTION OF SYMBOLS 1,100 Printer 3, 101K, 101Y, 101C, 101M Inkjet head 6 Linear encoder 15, 115 Nozzle 16K, 16Y, 16C, 16M, 116K, 116Y, 116C, 116M Nozzle row 22 Piezoelectric actuator 50 Control device 102 Rotary encoder 151 Temperature Sensor 161 Humidity sensor

Claims (11)

A liquid ejection head having a nozzle and an actuator for applying energy to the liquid in the nozzle;
A position sensor for detecting a positional relationship between the nozzle and a discharge region where the liquid of the discharge target medium is discharged;
A control device for controlling the operation of the actuator;
A carriage mounted with the liquid ejection head and configured to be movable in the scanning direction;
A carriage motor controlled by the control device and driving the carriage ,
The position sensor includes an encoder that detects a position of the carriage in the scanning direction;
The control device is based on a signal from the position sensor,
When the nozzle and the discharge area are in a first state separated from each other by a predetermined distance or more, a first vibration signal for vibrating a meniscus of liquid in the nozzle is output to the actuator,
When the nozzle and the discharge region are in a second state that is closer to the predetermined distance than each other, the meniscus of the liquid in the nozzle is reduced by a vibration amount smaller than the vibration amount of the meniscus by the first vibration signal. Outputting a second vibration signal to vibrate to the actuator;
When the nozzle and the discharge region are in a third state where they overlap each other, a discharge signal for discharging the liquid from the nozzle is output to the actuator ,
further,
The controller is
Based on the signal from the encoder,
When the nozzle does not overlap the medium to be ejected, the first vibration signal is output to the actuator,
The second vibration signal is output to the actuator when the nozzle overlaps a non-ejection area located between the edge of the medium to be ejected and the ejection area in the scanning direction. a liquid ejection apparatus. A liquid ejection head having a nozzle and an actuator for applying energy to the liquid in the nozzle;
A position sensor for detecting a positional relationship between the nozzle and a discharge region where the liquid of the discharge target medium is discharged;
A control device for controlling the operation of the actuator;
A carriage mounted with the liquid ejection head and configured to be movable in the scanning direction;
A carriage motor controlled by the control device and driving the carriage ,
The position sensor includes an encoder that detects a position of the carriage in the scanning direction;
The control device is based on a signal from the position sensor,
When the nozzle and the discharge area are in a first state separated from each other by a predetermined distance or more, a first vibration signal for vibrating a meniscus of liquid in the nozzle is output to the actuator,
When the nozzle and the discharge region are in a second state that is closer to the predetermined distance than each other, the meniscus of the liquid in the nozzle is reduced by a vibration amount smaller than the vibration amount of the meniscus by the first vibration signal. Outputting a second vibration signal to vibrate to the actuator;
When the nozzle and the discharge region are in a third state where they overlap each other, a discharge signal for discharging the liquid from the nozzle is output to the actuator ,
Further, the control device controls the carriage motor to reciprocate the carriage in the scanning direction, and drives the actuator only when moving the carriage to one side,
The liquid ejection head has a plurality of nozzle rows each formed by arranging the plurality of nozzles in a direction orthogonal to the scanning direction;
Different types of liquid are discharged from the plurality of nozzles forming each nozzle row,
The plurality of nozzle rows are arranged on the upstream side in the carriage movement direction when the actuator is driven, as nozzle rows formed by nozzles that are arranged in the scanning direction and discharge liquid that tends to thicken. A liquid discharge apparatus characterized by comprising: A liquid ejection head having a nozzle and an actuator for applying energy to the liquid in the nozzle;
A position sensor for detecting a positional relationship between the nozzle and a discharge region where the liquid of the discharge target medium is discharged;
A control device for controlling the operation of the actuator;
A carriage mounted with the liquid ejection head and configured to be movable in the scanning direction;
A carriage motor controlled by the control device to drive the carriage;
A storage unit ,
The position sensor includes an encoder that detects a position of the carriage in the scanning direction;
The control device is based on a signal from the position sensor,
When the nozzle and the discharge area are in a first state separated from each other by a predetermined distance or more, a first vibration signal for vibrating a meniscus of liquid in the nozzle is output to the actuator,
When the nozzle and the discharge region are in a second state that is closer to the predetermined distance than each other, the meniscus of the liquid in the nozzle is reduced by a vibration amount smaller than the vibration amount of the meniscus by the first vibration signal. Outputting a second vibration signal to vibrate to the actuator;
When the nozzle and the discharge region are in a third state where they overlap each other, a discharge signal for discharging the liquid from the nozzle is output to the actuator ,
Further, the control device includes:
When the first information is stored in the storage unit, the first vibration signal is output to the actuator when in the first state,
When the second information is stored in the storage unit, the second vibration signal is output to the actuator instead of the first vibration signal when the second information is in the first state . The controller is
A unit operation for driving the actuator while repeatedly moving the carriage in the scanning direction by controlling the carriage motor;
If the discharge amount of the liquid from the nozzle in a unit operation of the immediately preceding is less than Tokoro quantitative, stores the first information in the storage unit,
4. The liquid ejection apparatus according to claim 3 , wherein the second information is stored in the storage unit when a liquid ejection amount from the nozzle in the immediately preceding unit operation is equal to or greater than the predetermined amount. The controller is
A bidirectional driving operation for controlling the carriage motor to reciprocate the carriage in the scanning direction and drive the actuator regardless of the carriage moving direction;
Controlling the carriage motor to reciprocate the carriage in the scanning direction, and selectively performing one-way driving operation for driving the actuator only when the carriage is moved to one side;
When the one-way drive operation is performed, the storage unit stores the first information,
The liquid ejection apparatus according to claim 3 , wherein the second information is stored in the storage unit when the bidirectional driving operation is performed. A temperature sensor for detecting temperature information related to the temperature of the liquid in the nozzle;
The control device is based on a signal from the temperature sensor,
When the temperature in the nozzle is equal to or higher than a predetermined temperature , the storage unit stores the first information,
The liquid ejection apparatus according to claim 3 , wherein when the temperature in the nozzle is lower than the predetermined temperature, the second information is stored in the storage unit. A humidity sensor for detecting humidity information related to the humidity around the nozzle;
The control device is based on a signal from the humidity sensor,
When the humidity around the nozzle is less than a predetermined humidity, the storage unit stores the first information,
The liquid ejecting apparatus according to claim 3 , wherein when the humidity around the nozzle is equal to or higher than a predetermined humidity, the storage unit stores the second information. A liquid ejection head having a nozzle and an actuator for applying energy to the liquid in the nozzle;
A position sensor for detecting a positional relationship between the nozzle and a discharge region where the liquid of the discharge target medium is discharged;
A control device for controlling the operation of the actuator;
A carriage mounted with the liquid ejection head and configured to be movable in the scanning direction;
A carriage motor controlled by the control device to drive the carriage;
A constant speed position for moving the carriage at a constant speed in the scanning direction; and an acceleration / deceleration data storage unit for storing acceleration / deceleration data relating to an acceleration / deceleration position for accelerating or decelerating the carriage ,
The position sensor includes an encoder that detects a position of the carriage in the scanning direction;
The control device is based on a signal from the position sensor,
When the nozzle and the discharge area are in a first state separated from each other by a predetermined distance or more, a first vibration signal for vibrating a meniscus of liquid in the nozzle is output to the actuator,
When the nozzle and the discharge region are in a second state where the nozzle and the discharge region are closer to each other than the predetermined distance, the liquid meniscus in the nozzle is reduced with a vibration amount smaller than the vibration amount of the meniscus by the first vibration signal. Outputting a second vibration signal to vibrate to the actuator;
When the nozzle and the discharge region are in a third state where they overlap each other, a discharge signal for discharging the liquid from the nozzle is output to the actuator ,
Further, the control device, based on the acceleration / deceleration data,
Outputting the first vibration signal to the actuator when the carriage is positioned at the constant speed position and the nozzle and the discharge region are in the first state;
When the carriage is located at the acceleration / deceleration position and the nozzle and the discharge region are in the first state, the second vibration signal is output to the actuator instead of the first vibration signal. A liquid discharge apparatus characterized by that . A liquid ejection head having a nozzle and an actuator for applying energy to the liquid in the nozzle;
A position sensor for detecting a positional relationship between the nozzle and a discharge region where the liquid of the discharge target medium is discharged;
A control device for controlling the operation of the actuator,
The liquid ejection head has a plurality of the nozzles forming a nozzle row extending in a first direction,
A transport device that transports the medium to be ejected in a second direction orthogonal to the first direction;
The position sensor has an encoder that detects a conveyance amount of the discharged medium by the conveyance device;
The control device is based on a signal from the position sensor,
When the nozzle and the discharge area are in a first state separated from each other by a predetermined distance or more, a first vibration signal for vibrating a meniscus of liquid in the nozzle is output to the actuator,
When the nozzle and the discharge region are in a second state where the nozzle and the discharge region are closer to each other than the predetermined distance, the liquid meniscus in the nozzle is reduced with a vibration amount smaller than the vibration amount of the meniscus by the first vibration signal. Outputting a second vibration signal to vibrate to the actuator;
When the nozzle and the discharge region are in a third state where they overlap each other, a discharge signal for discharging the liquid from the nozzle is output to the actuator ,
Further, the control device includes:
Based on the signal from the encoder,
When the nozzle does not overlap the medium to be ejected, the first vibration signal is output to the actuator,
The second vibration signal is output to the actuator when the nozzle overlaps a non-ejection area located between the edge of the medium to be ejected and the ejection area in the second direction. A liquid ejection device. A liquid ejection head having a nozzle and an actuator for applying energy to the liquid in the nozzle;
A position sensor for detecting a positional relationship between the nozzle and a discharge region where the liquid of the discharge target medium is discharged;
A control device for controlling the operation of the actuator,
The liquid ejection head has a plurality of the nozzles forming a nozzle row extending in a first direction,
A transport device that transports the medium to be ejected in a second direction orthogonal to the first direction;
The position sensor has an encoder that detects a conveyance amount of the discharged medium by the conveyance device;
The control device is based on a signal from the position sensor,
When the nozzle and the discharge area are in a first state separated from each other by a predetermined distance or more, a first vibration signal for vibrating a meniscus of liquid in the nozzle is output to the actuator,
When the nozzle and the discharge region are in a second state that is closer to the predetermined distance than each other, the meniscus of the liquid in the nozzle is reduced by a vibration amount smaller than the vibration amount of the meniscus by the first vibration signal. Outputting a second vibration signal to vibrate to the actuator;
When the nozzle and the discharge region are in a third state where they overlap each other, a discharge signal for discharging the liquid from the nozzle is output to the actuator ,
The liquid discharge head has a plurality of the nozzle rows,
Different types of liquids are discharged from the nozzles forming each nozzle row,
The plurality of nozzle rows are arranged in the second direction, and the nozzle rows that form nozzles that discharge ink that tends to increase in viscosity are arranged on the downstream side in the second direction. apparatus. A liquid ejection head having a nozzle and an actuator for applying energy to the liquid in the nozzle;
A position sensor for detecting a positional relationship between the nozzle and a discharge region where the liquid of the discharge target medium is discharged;
A control device for controlling the operation of the actuator;
A storage unit ,
The liquid ejection head has a plurality of the nozzles forming a nozzle row extending in a first direction,
A transport device that transports the medium to be ejected in a second direction orthogonal to the first direction;
The position sensor has an encoder that detects a conveyance amount of the discharged medium by the conveyance device;
The control device is based on a signal from the position sensor,
When the nozzle and the discharge area are in a first state separated from each other by a predetermined distance or more, a first vibration signal for vibrating a meniscus of liquid in the nozzle is output to the actuator,
When the nozzle and the discharge region are in a second state where the nozzle and the discharge region are closer to each other than the predetermined distance, the liquid meniscus in the nozzle is reduced with a vibration amount smaller than the vibration amount of the meniscus by the first vibration signal. Outputting a second vibration signal to vibrate to the actuator;
When the nozzle and the discharge region are in a third state where they overlap each other, a discharge signal for discharging the liquid from the nozzle is output to the actuator ,
Further, the control device includes:
When the first information is stored in the storage unit, the first vibration signal is output to the actuator when the nozzle and the ejection target medium are in the first state,
When the second information is stored in the storage unit, the second vibration signal is output to the actuator instead of the first vibration signal when the second information is in the first state .

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