JP2011031441A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize the degradation of print quality resulting from the effect of crosstalk in a shear mode inkjet head by simple voltage control. <P>SOLUTION: When at least one of two adjacent ink chambers 6A1 and 6A3 in the same group as the ink chamber 6A2 which is not driven to eject ink is driven to eject ink, a dummy pulse is applied to the electrode 11A2 of the ink chamber 6A2 which is not driven to eject ink after the ending application of an ejection driving pulse to the ink chamber which is driven to eject ink, thereby reducing the volume of the ink chamber 6A2 which is not driven to eject ink. The dummy pulse has a voltage substantially equal to the voltage of the ejection driving pulse being applied to the ink chamber which is driven to eject ink, and an application time shorter than that of the ejection driving pulse. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an inkjet recording apparatus that records on a recording medium by ejecting ink from nozzles of an inkjet head.

  Conventionally, a share mode type ink jet head is known as one of ink jet head systems. The share mode type ink jet head has a plurality of ink chambers arranged in parallel, and nozzles communicate with each ink chamber. The ink chambers are separated by a partition made of two piezoelectric members having different polarization directions, and electrodes are provided on the surfaces of the partitions. When the pulse voltage is applied to the electrode and the partition wall is deformed, the volume and pressure in the ink chamber change, and the ink in the ink chamber is ejected from the nozzle.

  In such a share mode type ink jet head, the plurality of arranged ink chambers are usually divided into three groups so that every two ink chambers belong to the same group. Then, the ink chambers are sequentially driven for each group, and ink is ejected from the nozzles. The driving of the three groups is set as one cycle, and the driving is controlled to repeat this.

  In the share mode type ink jet head, a so-called crosstalk in which the pressure state in the ink chamber other than the ink chamber to be ejected changes due to the deformation of the partition wall during ejection driving of the ink chamber.

  In the case of performing the divided drive control as described above, the influence of crosstalk is caused depending on whether the adjacent ink chambers in the same group of the ink chambers to be ejected are ejected within the same cycle or not ejected. As a result, the flying speed and ejection volume of ink ejected from the ink chamber to be ejected are different, which may lead to a decrease in print quality.

  Therefore, a dummy pulse having a voltage approximately half the pulse voltage applied to the electrode of the ink chamber to be ejected is applied to the electrode of the ink chamber that is not the object of ejection driving near the ink chamber to be ejected. Patent Document 1 discloses a technique for increasing the flying speed of ink ejected from an ink chamber to be ejected using crosstalk caused by deformation of a partition wall.

JP 2000-255055 A

  In Patent Document 1, since a dummy pulse having a voltage different from the pulse voltage applied to the electrode of the ink chamber to be ejected is used, there is a problem that voltage control becomes complicated.

  The present invention has been made in view of the above, and it is an object of the present invention to provide an ink jet recording apparatus capable of suppressing a decrease in print quality due to the influence of crosstalk in a share mode ink jet head by simple voltage control. Objective.

  In order to achieve the above object, an ink jet recording apparatus according to claim 1 includes a plurality of juxtaposed ink chambers, a plurality of nozzles communicating with the ink chambers and ejecting ink, and the adjacent ink chambers. An inkjet head having a plurality of variable means for deforming the partition, and applying the ejection drive pulse to each of the variable means to change the volume of the ink chamber to be ejected and then returning it to the original volume The head driving means for increasing the pressure in the ink chamber to be ejected and ejecting ink from the nozzles, and the plurality of ink chambers are the same every n (n = 2, 3,...). The ink chambers are divided into n + 1 groups so as to belong to the group, and the ink chambers that are to be driven for ejection are ejected in units of groups, and the ink chambers that are to be ejected for all groups are ejected in one cycle. Control means for controlling the head drive means, wherein the control means is for at least one of the ink chambers adjacent to each other in the same group with respect to an ink chamber that is not ejected and driven within the period in each period. When one of them is driven to discharge within the period, the variable means corresponding to the ink chamber that is not driven to discharge is supplied with a voltage that is substantially the same as the voltage of the discharge driving pulse applied to the ink chamber that is to be driven to discharge. Applying a dummy pulse having an application time shorter than the ejection drive pulse after the application of the ejection drive pulse to the ink chambers to be ejected in the adjacent ink chambers is completed, and the partition walls on both sides of the ink chamber not ejected The head driving means is controlled to deform the head.

  An ink jet recording apparatus according to a second aspect is the ink jet recording apparatus according to the first aspect, wherein the control means is configured such that, in each period, both of the ink chambers adjacent to the ink chambers that are not ejected in the period are in the period. The number of dummy pulses equal to the larger one of the number of ink drops, which is the number of times of ejection driving in the cycle of the adjacent ink chambers, is set to the variable corresponding to the ink chamber not ejected. The head driving means is controlled to be applied to the means.

  An ink jet recording apparatus according to a third aspect is the ink jet recording apparatus according to the first aspect, wherein the control means is configured such that, in each period, both of the ink chambers adjacent to the ink chambers that are not driven to discharge within the period are in the period. The number of the dummy pulses equal to the maximum number of ink drops in one preset period is applied to the variable means corresponding to the ink chamber that is not ejected. It is characterized by controlling.

  An ink jet recording apparatus according to a fourth aspect of the present invention is the ink jet recording apparatus according to any one of the first to third aspects, wherein the control means is arranged so that each of the adjacent ink chambers that are not driven to be driven within the period in each period. When any one of the ink chambers is driven to be ejected within the period, the same number of the dummy pulses as the number of ink drops that is the number of times of ejection driving in the period of the ink chamber to be ejected are ejected. The head driving means is controlled to apply to the variable means corresponding to the ink chamber that is not.

  According to the ink jet recording apparatus of the present invention, it is possible to suppress a decrease in print quality due to the influence of crosstalk in a share mode type ink jet head by simple voltage control.

1 is a perspective view showing a schematic cross-sectional view of an inkjet head in an inkjet recording apparatus according to an embodiment of the present invention. It is sectional drawing along the AA line of the state provided with the ink supply part in the inkjet head shown in FIG. It is sectional drawing along the BB line in FIG. It is a block diagram which shows the function structure of the inkjet recording device which concerns on this Embodiment. It is a figure which shows the basic operation | movement of ink discharge. It is a wave form diagram of the voltage applied to an electrode in order to discharge 1 drop of ink. It is sectional drawing which shows an example of a structure of an inkjet head. It is a figure which shows an example of the timing chart of the ejection drive of each ink chamber in the case of time-division drive of the inkjet head shown in FIG. It is a wave form diagram of the voltage applied to the electrode of each ink chamber at the time division drive in this embodiment. It is a figure which shows operation | movement of the inkjet head at the time-division drive in this Embodiment. It is a figure which shows an example of the experimental result which shows the relationship between the application time of a dummy pulse, and the flying speed of an ink. It is a table | surface figure which shows the result of having determined the suppression effect of the flying speed of the ink by a dummy pulse for every length of application time. 4 is a flowchart showing an operation during recording in the ink jet recording apparatus according to the present embodiment. It is a figure which shows an example of the voltage waveform applied to the electrode of the ink chamber which is not discharge-driven, and the electrode of the ink chamber of the both sides. It is a figure which shows the other example of the voltage waveform applied to the electrode of the ink chamber which is not discharge-driven, and the electrode of the ink chamber of the both sides. FIG. 10 is a diagram illustrating still another example of a voltage waveform applied to an electrode of an ink chamber that is not ejected and an electrode of an ink chamber adjacent to the electrode.

  Embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals, and the description thereof is omitted or simplified.

  FIG. 1 is a perspective view showing a schematic configuration of a shear mode type ink jet head in an ink jet recording apparatus according to an embodiment of the present invention in a partial cross section, and FIG. 2 includes an ink supply unit in the ink jet head shown in FIG. FIG. 3 is a sectional view taken along the line BB in FIG. 1.

  In the present embodiment, since the configuration related to the ink chambers described later is common to all the ink chambers, subscripts such as alphabets or the like indicating individual ink chambers may be omitted and collectively described.

As shown in FIGS. 1 to 3, in the inkjet head 1, a plurality of partition walls 4 made of two piezoelectric members 4 a and 4 b are disposed between a substrate 2 made of ceramic or the like and a cover plate 3. The piezoelectric members 4a and 4b are made of a known piezoelectric material such as PZT (PbZrO ₃ —PbTiO ₃ ), for example, and are polarized in different directions as indicated by arrows in FIG.

  A nozzle plate 5 is fixed to the tips of the substrate 2, the cover plate 3, and the partition wall 4. As a result, the plurality of ink chambers 6 surrounded by the substrate 2, the cover plate 3, the partition wall 4, and the nozzle plate 5 are formed to be aligned. The nozzle plate 5 is provided with a plurality of nozzles 7, and one end side of the ink chamber 6 communicates with the nozzles 7. The other end of the ink chamber 6 is connected to an ink tank (not shown) by an ink tube 10 through an ink inlet 8 and an ink supply port 9 communicating with all the ink chambers 6. The ink inlet 8, the ink supply port 9, and the ink tube 10 constitute an ink supply unit.

  Electrodes (variable means) 11 are formed in close contact with the surfaces of the partition walls 4 constituting the side surfaces of the ink chamber 6 and the substrate 2 constituting the bottom surface. The electrode 11 in the ink chamber 6 extends to the rear side surface of the piezoelectric member 4a. A flexible cable 12 is connected to each electrode 11 via an anisotropic conductive film (not shown) on the rear side surface, and a pulse voltage is applied to the electrode 11 via the flexible cable 12. It has become.

  When a pulse voltage is applied to the electrode 11, the volume of the ink chamber 6 and the pressure in the ink chamber 6 are changed by shearing the partition 4. Thereby, the ink in the ink chamber 6 is ejected from the nozzle 7.

  FIG. 4 is a block diagram showing a functional configuration of the ink jet recording apparatus according to the present embodiment. As shown in FIG. 4, the ink jet recording apparatus according to the present embodiment includes a head drive unit 21 that drives the ink jet head 1, a control unit 22, and a drive waveform storage unit 23.

  The head drive unit 21 applies a pulse voltage to the electrode 11 of the inkjet head 1 through the flexible cable 12 to deform the partition wall 4 to change the volume of the ink chamber 6 and the pressure in the ink chamber 6, and the nozzle 7 is a discharge drive for discharging ink.

  The control unit 22 controls driving of the inkjet head 1 by the head driving unit 21 based on image data input from an image processing unit (not shown) or the like.

  The drive waveform storage unit 23 stores voltage waveform data for driving the inkjet head 1.

  Next, the basic operation of ink ejection will be described.

  As shown in FIG. 5, the case where ink is ejected from the ink chamber 6B among the three ink chambers 6A to 6C separated by the partition walls 4A to 4D including the piezoelectric members 4a and 4b will be described. FIG. 6 is a waveform diagram of a voltage applied to the electrode 11B of the ink chamber 6B in order to discharge one drop of ink.

From the steady state shown in FIG. 5 (a), at time t1 in FIG. 6, the ink chambers 6A, 6C electrode 11A, while grounded 11C, the driving pulse of the negative voltage -V _A to the electrode 11B in the ink chamber 6B (discharge When the drive pulse P1 is applied, an electric field in a direction perpendicular to the polarization direction of the piezoelectric members 4a and 4b constituting the partition walls 4B and 4C is generated. As a result, the joint surface of the piezoelectric members 4a and 4b is deformed, and as shown in FIG. 5B, the partition walls 4B and 4C are deformed away from each other, and the volume of the ink chamber 6B is increased. As a result, a negative pressure is generated in the ink in the ink chamber 6B, and the ink flows from the ink inlet 8 into the ink chamber 6B.

  The application time of the drive pulse P1 is 1AL from time t1 to time t2. AL (Acoustic Length) is the time from when the pressure wave caused by the ink flowing into the ink chamber 6 whose volume has expanded to reach the nozzle 7 through the entire area of the ink chamber 6. It depends on the density of the ink and the like.

  When the voltage applied to the electrode 11B of the ink chamber 6B is returned to the ground potential at the time t2 in FIG. 6 from the state of FIG. 5B, the partition walls 4B and 4C are in the neutral position shown in FIG. Return. As a result, the ink in the ink chamber 6 </ b> B is rapidly pressurized, and the ink is ejected from the corresponding nozzle 7.

When 1AL elapses after the voltage applied to the electrode 11B of the ink chamber 6B is returned to the ground potential, the drive pulse P2 of the positive voltage _VA is applied to the electrode 11B of the ink chamber 6B for a period of 1AL from time t3 to time t4. To do. As a result, as shown in FIG. 5C, the partition walls 4B and 4C are deformed so as to approach each other, and the volume of the ink chamber 6B is reduced.

  Ink is ejected when the pressure in the ink chamber 6B reaches a peak immediately after time t2. After the pressure reaches a peak, a negative pressure is generated in the ink chamber 6B. By applying the drive pulse P2 to reduce the volume in the ink chamber 6B to generate a pressurizing force, the negative pressure in the ink chamber 6B after ink ejection is suppressed, and the residual vibration of the ink in the ink chamber 6B occurs. It is suppressed. Thereby, the next discharge operation can be performed stably.

  After application of the drive pulse P2, the voltage applied to the electrode 11B of the ink chamber 6B between time t4 and time t5 is set to the ground potential, and the state shown in FIG.

  The drive waveform storage unit 23 stores waveform data indicating the voltage waveform of FIG. The control unit 22 controls the head drive unit 21 based on the waveform data indicating the voltage waveform of FIG. 6 read from the drive waveform storage unit 23, thereby causing the ejection operation as described above to be performed.

  Next, time-division driving of the inkjet head 1 will be described.

  In the share mode type ink jet head 1, ink is ejected by utilizing the deformation of the partition wall 4 as described above, and therefore, the adjacent ink chambers 6 cannot be ejected simultaneously. For this reason, the control unit 22 divides all the ink chambers 6 included in the inkjet head 1 into a plurality of groups including ink chambers 6 that are not adjacent to each other, and drives the ink chambers 6 to be ejected in units of groups.

  That is, in the ink jet recording apparatus of the present embodiment, the plurality of ink chambers 6 of the ink jet head 1 are divided into n + 1 groups so as to belong to the same group every n (n = 2, 3,...). In turn, the ink chambers 6 to be driven for ejection in the group are ejected, and the ink chambers 6 to be ejected in all groups are ejected and driven in one cycle. By repeating this cycle, an image is recorded on a recording medium such as paper conveyed below the nozzle 7 of the inkjet head 1.

  For example, every two ink chambers 6 are divided into three groups so that they belong to the same group. As shown in FIG. 7, when the ink-jet head 1 has nine ink chambers 6A1, 6B1, 6C1, 6A2, 6B2, 6C2, 6A3, 6B3, and 6C3, these include group A and ink chambers including ink chambers 6A1 to 6A3. It is divided into a group B including the chambers 6B1 to 6B3 and a group C including the ink chambers 6C1 to 6C3.

  FIG. 8 shows a timing chart of ejection driving of each ink chamber in this case. As shown in FIG. 8, in the first driving period, the ink chambers 6A1 to 6A3 of the group A are driven, then the ink chambers 6B1 to 6B3 of the group B are driven, and then the ink chambers 6C1 to 6C3 of the group C are driven, This constitutes one period T. One line of the image is printed every period T.

  In each ink chamber, ejection driving is performed a number of times corresponding to the number of ink drops for each pixel set in the image data for each cycle T (for each driving period). The maximum number of ink drops ejected in one drive period (for example, 5 drops) is set in advance, and ink equal to or less than the maximum ink drop number is ejected in each drive period. Of course, ink may not be ejected within the driving period (the number of ink drops is 0).

  When the time-sharing drive as described above is performed, in the ink chamber 6 in which the ejection drive is performed, when the adjacent ink chamber 6 in the same group is also ejected, the adjacent ink chamber 6 is affected by the crosstalk. The pressure in the ink chamber 6 during the ejection driving is lower than when the ejection driving is not performed. For this reason, in the ink chamber 6 in which the ejection drive is performed, the flying speed and the ejection volume of the ejected ink differ depending on whether or not the ejection drive of the adjacent ink chambers 6 in the same group is performed. May be reduced.

  In order to eliminate such an inconvenience, in the present embodiment, when ejection drive of a certain ink chamber 6 is not performed in a certain period T, the ink chamber 6 of both adjacent ink chambers 6 in the same group as that ink chamber 6 is used. At least one of them, if ejection driving is performed within the same period T, a dummy pulse is applied to the electrode 11 of the ink chamber 6 where ejection driving is not performed at a predetermined timing.

  The operation of the inkjet head 1 when applying this dummy pulse will be described.

  In the inkjet head 1 having nine ink chambers 6A1 to 6A3, 6B1 to 6B3, 6C1 to 6C3 as shown in FIG. 7, the ink chamber 6A2 is not ejected in a certain cycle, and the ink chambers in the group A A case where the ink chambers 6A1 and 6A3 adjacent to 6A2 are driven to discharge will be described.

  FIG. 9A is a waveform diagram of a voltage applied to the electrodes 11A1 and 11A3 of the ink chambers 6A1 and 6A3, and FIG. 9B is a waveform diagram of a dummy pulse applied to the electrode 11A2 of the ink chamber 6A2. .

  The waveform diagram of FIG. 9A is the same as the waveform diagram of FIG. FIG. 9A shows two drops.

  When the drive pulse P1 is applied to the electrodes 11A1 and 11A3 of the ink chambers 6A1 and 6A3 from the steady state of FIG. 7, as shown in FIG. 10A, the partition walls 4A1 and 4B1 on both sides of the ink chamber 6A1 and the ink chamber 6A3. The partition walls 4A3 and 4B3 on the both sides are deformed in directions away from each other, and ink flows into the ink chambers 6A1 and 6A3.

  Thereafter, the voltage applied to the electrodes 11A1 and 11A3 of the ink chambers 6A1 and 6A3 is returned to the ground potential, and at the same time, the dummy pulse P3 shown in FIG. 9B is applied to the electrode 11A2 of the ink chamber 6A2.

  As a result, as shown in FIG. 10B, the partition walls 4A1 and 4B1 and the partition walls 4A3 and 4B3 return to the neutral position, and the partition walls 4A2 and 4B2 on both sides of the ink chamber 6A2 are deformed so as to approach each other.

  As a result, the ink in the ink chambers 6A1 and 6A3 is pressurized, and the ink is ejected from the nozzles 7 corresponding to the ink chambers 6A1 and 6A3. On the other hand, the partition walls 4A2 and 4B2 on both sides of the ink chamber 6A2 are deformed so as to approach each other, thereby generating a negative pressure in the ink chambers 6C1 and 6B2. This is applied to the ink chambers 6A1 and 6A3 via the ink chambers 6B1 and 6C2. It is transmitted. As a result, the pressure increase in the ink chambers 6A1 and 6A3 is suppressed to the same extent as when the ink chamber 6A2 is also driven to discharge.

Voltage of the dummy pulse P3 is a drive pulse P1, P2 voltage as large as the positive voltage _{V A} of the application time _{T D} of the dummy pulse P3 is shorter than 1AL, preferably AL / 12~AL / 3, Particularly, AL / 6 to AL / 4 are preferable.

After application time _{T D} of the dummy pulse P3, when the voltage applied to the electrode 11A2 of the ink chamber 6A2 returned to the ground potential, the partition wall 4A2,4B2 returns to the neutral position, the inkjet head 1 returns to the state of FIG.

  Thereafter, when 1AL has elapsed since the voltage applied to the electrodes 11A1 and 11A3 of the ink chambers 6A1 and 6A3 is returned to the ground potential, the drive pulse P2 is applied to the electrodes 11A1 and 11A3. As a result, as shown in FIG. 10C, the partition walls 4A1 and 4B1 and the partition walls 4A3 and 4B3 are deformed so as to approach each other, and the ink in the ink chambers 6A1 and 6A3 is pressurized, and after the ink discharge Residual vibration is suppressed.

As described above, after the drive pulse P1 is applied, the voltage applied to the electrodes 11A1 and 11A3 of the ink chambers 6A1 and 6A3 is returned to the ground potential, and then the pressure in the ink chambers 6A1 and 6A3 increases, thereby the ink chamber 6A1. , 6A3 ejects ink. For example, when AL = 2400 ns, the pressure in the ink chambers 6A1, 6A3 peaks after about 300 to 700 ns after the voltage applied to the electrodes 11A1, 11A3 is returned to the ground potential. Therefore, by application time _{T D} is applied to the electrodes of the ink chambers 6A2 not ejection driving the AL / 12~AL / 3 about the dummy pulse P3, effective pressure increase in the ink chamber 6A1,6A3 which discharge driven Can be suppressed.

Figure 11 is a diagram showing an example of experimental results showing the relationship between the application time T _D and the ink of the flying speed of the dummy pulse P3. FIG. 11 shows the experimental results when AL = 2400 ns and the dummy pulse P3 is applied to the electrode 11 of the ink chamber 6 that is not ejected and is adjacent to each other in the same group of the ink chamber 6 that is ejected.

In FIG. 11, the flying speed of about 9.8 m / s when the dummy pulse P3 is applied is T _D = 0 ns. This is the ink flying speed when P3 is not applied. Compared to this case, when the dummy pulse P3 is applied to the electrodes 11 of the adjacent ink chambers 6 in the same group (when T _D = 0 ns), the flying speed of the ink from the ink chamber 6 that is driven to discharge is set. It is understood that is suppressed.

On the other hand, when the ink chambers 6 adjacent to each other in the same group of the ink chambers 6 that are driven to discharge are also driven to discharge (solid printing), the experimental result that the flying speed of the ink is about 4.7 m / s was obtained. . According to FIG. 11, when the dummy pulse P3 is applied to the adjacent ink chambers 6 in the same group that are not driven to discharge, particularly when the application time T _D = 400 to 600 ns, the adjacent ink chambers in the same group. 6 also has a flying speed of about 4.7 m / s, which is the same as that in the case of ejection driving (solid printing).

From such experimental results, showing the results of determining the inhibitory effect of the flying speed of the ink by the dummy pulse P3 for each length of application time T _D in FIG. As described above, T _D = AL / 12 to AL / 3 (200 to 800 ns) is preferable, and in particular, T _D = AL / 6 to AL / 4 (400 to obtain a flying speed equivalent to that for solid printing). 600 ns) is preferred.

If the application time T _D is outside the above range, it decreases the inhibitory effect of the flying speed of the ink. Further, when the application time T _D is longer than AL / 3 is adjacent to the ink chamber 6 to the dummy pulse P3 is applied, there is a possibility that ink is ejected from the ink chamber 6 of the different groups. For example, in the example of FIG. 10, if the application time of the dummy pulse P3 applied to the electrode 11A2 of the ink chamber 6A2 is too long, ink is transferred to the ink chambers 6C1 and 6B2 adjacent to the ink chamber 6A2 due to deformation of the partition walls 4A2 and 4B2. When the partition walls 4A2 and 4B2 return to the neutral position after the application of the dummy pulse P3, the ink in the ink chambers 6C1 and 6B2 may be pressurized and the ink may be ejected.

  The waveform data indicating the dummy pulse P3 in FIG. 9B is stored in the drive waveform storage unit 23, similarly to the waveform data indicating the voltage waveform in FIG.

Note that the application start point of the dummy pulse P3 is not limited to the end point of application of the drive pulse P1 (the start point of application of the ground potential), but may be delayed. Also, the application time T _D may be adjusted by the temperature of the ink.

  Next, an operation during recording in the ink jet recording apparatus according to the present embodiment will be described with reference to a flowchart shown in FIG.

  During the recording operation, the control unit 22 performs each ink of the inkjet head 1 according to the flowchart shown in FIG. 13 in order for each group of the ink chambers 6 within the period T based on the input image data. The drive of the chamber 6 is controlled.

  First, in step S <b> 10, the control unit 22 determines whether each ink chamber 6 is an ink chamber that should be driven to discharge in the period T based on the image data. Here, when the number of ink drops set in the pixel corresponding to the ink chamber 6 in the period T is other than 0 in the image data, the control unit 22 determines that the ink chamber is to be ejected, When the number of ink drops is 0, it is determined that the ink chamber is not to be ejected. If the ink chamber is to be driven for ejection (step S10: YES), the process proceeds to step S20. If the ink chamber is not to be ejected (step S10: NO), the process proceeds to step S30.

  In step S20, the control unit 22 reads out waveform data indicating the voltage waveform of FIG. 6 from the drive waveform storage unit 23, and controls the head drive unit 21 based on the waveform data, so that description will be given with reference to FIG. The ink chamber 6 is caused to perform the ejecting operation. The ejection operation is repeated for the number of ink drops in the period T of the ink chamber 6 set by the image data.

  In step S30, the control unit 22 determines that at least one of the two adjacent ink chambers 6 in the same group of the ink chambers 6 is an ink chamber to be ejected in the cycle T based on the image data. Determine whether or not. If at least one of the adjacent ink chambers 6 in the group is an ink chamber to be ejected (step S30: YES), the process proceeds to step S40, and both the adjacent ink chambers 6 in the group eject both. If the ink chamber is not to be driven (step S30: NO), the process is terminated.

  In step S <b> 40, the control unit 22 determines whether or not both of the adjacent ink chambers 6 in the same group of the ink chambers 6 are ink chambers that should be ejected in the cycle T. When both the adjacent ink chambers 6 in the same group are ink chambers to be ejected (step S40: YES), the process proceeds to step S50, and either one of the adjacent ink chambers 6 in the same group ejects. If the ink chamber is to be driven (step S40: NO), the process proceeds to step S60.

  In step S50, the control unit 22 reads the waveform data of the dummy pulse P3 from the drive waveform storage unit 23, and the same number as the larger number of ink drops in the period T of the adjacent ink chambers 6 in the group. The head driving unit 21 is controlled so that the dummy pulse P3 is applied to the electrode 11 of the ink chamber 6.

  For example, in the inkjet head 1 shown in FIG. 7, when the ink chamber 6A2 is not driven to be ejected and the adjacent ink chambers 6A1 and 6A3 in the group A are ejected, the ink chambers 6A1 and 6A3 in the cycle T. Assuming that the number of ink drops is 5 and 3, respectively, as shown in FIG. 14, in the driving period of group A within the period T, dummy pulses P3 are applied to the ink chamber 6A2 in accordance with the ejection driving of the ink chamber 6A1. Applied 5 times.

  In step S60, the control unit 22 applies the same number of ink drops to the electrodes 11 of the ink chamber 6 as the number of ink drops in the cycle T of the ink chamber 6 that is driven to discharge among the adjacent ink chambers 6 in the group. The head drive unit 21 is controlled to apply the dummy pulse P3.

  For example, in the inkjet head 1 shown in FIG. 7, the ink chamber 6A2 is not driven to be ejected, and the ink chamber 6A1 of the adjacent ink chambers 6A1 and 6A3 in the group A is ejected and ejected. If the number is 4 and the ink chamber 6A3 is not ejected, the dummy pulse P3 is applied four times to the ink chamber 6A2 in accordance with the ejection driving of the ink chamber 6A1, as shown in FIG.

  By such processing, as described above, even when the ink chamber 6 adjacent to the ink chamber 6 to be ejected is not ejected in the same group, the pressure increase in the ink chamber 6 to be ejected is adjacent. The ink chamber 6 is also suppressed to the same extent as when it is driven to discharge. Thereby, it is possible to reduce a decrease in print quality due to a difference in the flying speed and discharge volume of the ink in the ink chamber 6 that is driven to discharge depending on whether or not the adjacent ink chamber 6 is driven in the same group.

  In the flowchart of FIG. 13 described above, the number of dummy pulses P3 to be applied to the electrode 11 of the ink chamber 6 is determined according to the number of ink drops in the adjacent ink chamber 6, but the number of dummy pulses P3. May be fixed at the maximum number of ink drops.

  For example, when the ink chamber 6A2 is not driven for ejection and the adjacent ink chambers 6A1 and 6A3 in the group A are ejected, the number of ink drops in the period T of the ink chambers 6A1 and 6A3 is 4 and 3, respectively. If there is, the dummy pulse P3 is applied four times to the ink chamber 6A2 according to the flow chart of FIG. 13, but as shown in FIG. 16, it depends on the number of ink drops in the ink chambers 6A1 and 6A3. Instead, the dummy pulse P3 may be applied five times, which is the maximum number of ink drops.

  As described above, according to the present embodiment, when at least one of the two adjacent ink chambers 6 in the same group of ink chambers 6 that are not driven to discharge is driven to discharge, By applying the dummy pulse P3 and deforming the partition walls 4 on both sides thereof, the pressure rise in the ink chamber 6 that is driven to discharge is about the same as when the ink chambers 6 on both sides in the same group are also driven to discharge. Can be suppressed. As a result, it is possible to prevent the flying speed and discharge volume of the ink in the ink chamber 6 that is driven to discharge due to the influence of crosstalk depending on whether or not the adjacent ink chambers 6 are driven in the same group. Can be reduced. In the present embodiment, since the dummy pulse P3 having the same voltage as the drive pulses P1 and P2 is used, the voltage control is simple.

DESCRIPTION OF SYMBOLS 1 Inkjet head 4 Partition 6 Ink chamber 11 Electrode 21 Head drive part 22 Control part 23 Drive waveform storage part

Claims (4)

An ink-jet head having a plurality of juxtaposed ink chambers, a plurality of nozzles communicating with the ink chambers and ejecting ink, and a plurality of variable means for deforming partition walls between the adjacent ink chambers;
By applying an ejection drive pulse to each of the variable means and changing the volume of the ink chamber to be ejected, the partition is deformed so as to return to the original volume, whereby the pressure in the ink chamber to be ejected is changed. A head driving means for raising the nozzle and discharging ink from the nozzle;
The plurality of ink chambers are divided into n + 1 groups so as to belong to the same group every n (n = 2, 3,...), And the ink chambers to be ejected in units of groups are ejected and driven in one cycle. Control means for controlling the head drive means so as to drive the ink chambers to be driven for ejection of all groups,
The control means does not perform the ejection driving when at least one of the two adjacent ink chambers in the same group is driven to be ejected within the period for the ink chamber that is not ejected within the period in each period. A dummy pulse having a voltage substantially the same as the voltage of the ejection driving pulse applied to the ink chamber to be ejected and having a shorter application time than the ejection driving pulse is applied to the variable means corresponding to the ink chamber. The head driving means is controlled to deform the partition walls on both sides of the ink chamber that is not ejected and applied after the application of the ejection driving pulse to the ink chamber to be ejected in the chamber. Inkjet recording apparatus.   In each cycle, when both of the ink chambers on both sides of the ink chamber that are not driven for ejection within the cycle are ejected within the cycle, the control unit determines the number of times of ejection driving in the cycle of the adjacent ink chamber. 2. The head driving unit is controlled to apply the same number of the dummy pulses as a larger one of a certain number of ink drops to the variable unit corresponding to the ink chamber that is not driven to be ejected. 2. An ink jet recording apparatus according to 1.   In each cycle, the control means is equal to the preset maximum number of ink drops in one cycle when both of the ink chambers adjacent to the ink chambers that are not driven in the cycle are ejected in the cycle. 2. The ink jet recording apparatus according to claim 1, wherein the head driving unit is controlled to apply a number of the dummy pulses to the variable unit corresponding to the ink chamber that is not ejected.   In each cycle, when one of the ink chambers on both sides of the ink chamber that is not driven to discharge in the cycle is driven to discharge in the cycle, the control means The head driving unit is controlled to apply the same number of the dummy pulses as the number of ink drops, which is the number of ejection drivings in a cycle, to the variable unit corresponding to the ink chamber not ejected. The inkjet recording apparatus according to any one of 1 to 3.

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