JP2009248340A - Liquid ejection device and liquid ejection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the arrangement of liquid droplets landing on a medium almost equal, even when a driving pulse is not applied at a uniform interval. <P>SOLUTION: A liquid ejection device includes: a head for ejecting the liquid droplets by applying the driving pulse to a driving element (A); a driving signal generating part for repeatedly generating a driving signal including the first driving pulse and the driving pulse on and after the second which is a plurality of driving pulses on and after the second following after the first driving pulse and having a predetermined wavelength and whose wavelength is different from that of the first driving pulse (B); and a controller for causing the head to eject the liquid droplets by applying the driving pulse of the driving signal to the driving element (C). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejection apparatus and a liquid ejection method.

  2. Description of the Related Art Many printing apparatuses are used that form an image on a medium such as paper by ejecting ink droplets from a nozzle of a head by applying a drive signal to a drive element. The drive signal includes a plurality of drive pulses. Each time this drive pulse is applied, ink droplets are ejected from the nozzles of the head. In such a printing apparatus, an image is formed in a wide area of the medium by ejecting ink droplets while moving the head at a constant speed in the moving direction of the head.

By the way, the drive signal is not only a drive pulse for ejecting ink droplets but also a drive pulse (fine vibration pulse) for vibrating the ink surface (meniscus) in the nozzle to prevent ink thickening. There is. In the drive signal, the drive pulses for ejecting ink droplets are continuously arranged, but the drive signal also includes a fine vibration pulse. In recent years, since the frequency between drive pulses tends to be high, when fine vibration pulses are sandwiched, drive pulses for ejecting ink droplets may not be continuously applied to the drive elements at equal intervals. Also, for other reasons, there may be a case where drive pulses for ejecting ink droplets cannot be continuously applied to the drive elements at equal intervals.
Japanese Patent No. 31855981

  As described above, if the drive pulses for ejecting the ink droplets cannot be continuously applied to the drive element at the same interval, the ink droplet ejection interval does not become the same interval. Then, since the ink droplets are ejected while the head is moved, the ink droplets that land on the paper are not arranged at equal intervals unless the ink droplet ejection intervals are equal. In recent years, since the beauty of an image to be formed is more demanded, it is desirable not to make it conspicuous that liquid droplets such as ink droplets landed on a medium are not arranged at equal intervals.

  The present invention has been made in view of such circumstances, and even when drive pulses cannot be applied to the drive elements at equal intervals, liquid droplets that have landed on the medium may not line up at equal intervals. The purpose is to make it inconspicuous.

The main invention for achieving the above object is:
(A) a head that ejects a liquid droplet by applying a driving pulse to the driving element;
(B) a first drive pulse and a plurality of second and subsequent drive pulses having a predetermined waveform following the first drive pulse and having a waveform different from that of the first drive pulse. A drive signal generation unit that repeatedly generates a drive signal including the second and subsequent drive pulses;
(C) a controller that applies a driving pulse of the driving signal to the driving element to discharge the liquid droplet from the head;
It is a liquid discharge apparatus provided with.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

(A) a head that ejects a liquid droplet by applying a driving pulse to the driving element;
(B) a first drive pulse and a plurality of second and subsequent drive pulses having a predetermined waveform following the first drive pulse and having a waveform different from that of the first drive pulse. A drive signal generation unit that repeatedly generates a drive signal including the second and subsequent drive pulses;
(C) a controller that applies a driving pulse of the driving signal to the driving element to discharge the liquid droplet from the head;
A liquid ejection apparatus comprising:
In this way, even when drive pulses cannot be applied to the drive elements at even intervals, it can be made inconspicuous that the liquid droplets that have landed on the medium are not arranged at equal intervals.

In this liquid ejection apparatus, it is preferable that the first drive pulse is a drive pulse having a liquid droplet ejection speed higher than that of the second drive pulse. In addition, it is desirable that the ejection amount of the liquid droplets ejected by each driving pulse is equal in the first driving pulse and the second and subsequent driving pulses. In addition, it is desirable that the voltage change rate of the portion that ejects the liquid droplet in the first drive pulse is larger than the voltage change rate of the portion that ejects the liquid droplet in the second drive pulse. . Further, the drive signal is a drive signal including a drive pulse that does not eject the liquid droplet, and the first drive pulse is a drive pulse that does not eject the liquid droplet when the drive signal is repeatedly generated. A subsequent drive pulse is desirable.
In this way, even when drive pulses cannot be applied to the drive elements at even intervals, it can be made inconspicuous that the liquid droplets that have landed on the medium are not arranged at equal intervals.

Generating a first drive pulse, applying the first drive pulse to the drive element to eject a liquid drop;
A plurality of second and subsequent drive pulses having a predetermined waveform following the first drive pulse, the second and subsequent drive pulses having a waveform different from that of the first drive pulse; Applying a second and subsequent drive pulses to the drive element to eject liquid droplets;
A liquid ejection method comprising:
By doing so, even when the drive pulses cannot be applied to the drive elements at equal intervals, it is possible to make it inconspicuous that the liquid droplets that have landed on the medium are not arranged at equal intervals.

(A) a head that ejects a liquid droplet by applying a driving pulse to the driving element;
(B) A drive signal including at least three drive pulses having a predetermined waveform, and an interval between the first drive pulse and the second drive pulse is an interval between the second and subsequent drive pulses. A drive signal generator for repeatedly generating different drive signals;
(C) a controller that applies a driving pulse of the driving signal to the driving element to discharge the liquid droplet from the head;
A liquid ejection apparatus comprising:
In this liquid ejection apparatus, the drive signal is generated such that an interval between the first drive pulse and the second drive pulse is longer than an interval between the second and subsequent drive pulses. It is desirable that Further, the drive signal is a drive signal including a drive pulse that does not eject the liquid droplet, and the first drive pulse is a drive pulse that does not eject the liquid droplet when the drive signal is repeatedly generated. A subsequent drive pulse is desirable.
In this way, even when drive pulses cannot be applied to the drive elements at even intervals, it can be made inconspicuous that the liquid droplets that have landed on the medium are not arranged at equal intervals.

=== First Embodiment ===
FIG. 1A is an external perspective view of the printer 1, and FIG. 1B is an internal perspective view of the printer 1. FIG. 2 is a block diagram of the printer 1. Hereinafter, the configuration of the printer 1 will be described with reference to these drawings.

  The printer 1 includes a paper transport mechanism 20, a carriage movement mechanism 30, a head unit 40, a detector group 50, a controller 60, and a drive signal generation circuit 70. The printer 1 acquires print data from the computer 110 via the interface 61 in the controller 60, and prints an image on a sheet based on the print data.

  The controller 60 includes a processing device such as a CPU 62 and a storage device such as a memory 63. A program for causing the printer 1 to perform a desired operation is stored in the storage device. The processing device executes this program. The controller 60 controls the paper transport mechanism 20, the carriage movement mechanism 30, the head unit 40, and the drive signal generation circuit 70 in the printer 1.

  Under the control of the controller 60, the paper transport mechanism 20 sends the paper to a printable position or transports the paper in the transport direction by a predetermined transport amount. Under the control of the controller 60, the carriage moving mechanism 30 moves the carriage CR to which the head unit 40 is attached in the carriage moving direction using the carriage CR moving belt 31 and the carriage motor 32.

  The head unit 40 includes a head 41 and a head control circuit (not shown). The head 41 includes a plurality of nozzles that eject ink droplets and a plurality of piezoelectric elements 417 for ejecting ink droplets. The head control circuit has a function of controlling ejection of ink droplets from the head 41. Under the control of the head control circuit, a drive pulse of the drive signal COM is applied to each piezoelectric element 417 at an appropriate timing.

  The detector group 50 is a plurality of various sensors attached to each part of the printer 1, and sends detection results to the controller 60.

  The drive signal generation circuit 70 generates a drive signal COM to be applied to the piezoelectric element 417. The drive signal generation circuit 70 includes a DAC for generating an analog waveform and a transistor for power amplification. Then, a signal representing the waveform of the drive signal is generated by the DAC, and this is power-amplified by the transistor, thereby generating the drive signal COM. The drive signal COM will be described later.

  FIG. 3 is a view of the head 41 as viewed from below. In the figure, nozzles 439 of each nozzle row are shown. A black ink nozzle row Nk for ejecting black K ink droplets, a cyan ink nozzle row Nc for ejecting cyan C ink droplets, and magenta M. A magenta ink nozzle row Nm for discharging the ink droplets and a yellow ink nozzle row Ny for discharging the yellow Y ink are shown. Each nozzle row has 90 nozzles. The direction of each nozzle row coincides with the paper transport direction.

  FIG. 4A is a plan view showing the structure of one pressure chamber 435 in the head 41. 4B is a cross-sectional view of the head 41 taken along the line AA. As shown in the sectional view, the head 41 includes a nozzle plate 411 made of a metal plate (for example, made of stainless steel), a spacer member 412, an ink supply member 413, and a lid member 414 made of a ceramic plate (for example, zirconia plate). The spacer member 415 and the diaphragm 416 are integrally laminated by an adhesive, welding, or the like.

  A piezoelectric element 417 for applying pressure to the ink in the pressure chamber 435 is attached to the surface of the vibration plate 416 as illustrated. The piezoelectric element 417 is made of a thin plate of piezoelectric material such as a piezoelectric element having a shape narrower than the pressure chamber 435 and having a shape elongated in the longitudinal direction of the pressure chamber 435, and is configured to bend in the width direction when a voltage is applied. Has been. Then, an electrode (not shown) is connected to the piezoelectric element 417, and a predetermined drive signal is applied to the electrode, so that the piezoelectric element 417 is bent, thereby deforming the diaphragm 416 and pressurizing the ink in the pressure chamber 435.

  The ink supplied from the ink cartridge and guided to the reservoir 432 first passes through the first through hole 433 perforated in the ink supply member 413 and then passes through the second through hole 434 perforated in the lid member 414. Into the pressure chamber 435.

  The pressure chamber 435 is formed by covering a horizontally long through hole provided in the spacer member 415 with a lid member 414 and a vibration plate 416, and the ink flowing into the pressure chamber 435 is accompanied by driving of the piezoelectric element 417. The diaphragm 416 is deformed and pressed.

  The pressurized ink flows into the third through hole 436 similarly formed in the lid member 414, passes through the fourth through hole 437 formed in the ink supply member 413, and is formed in the spacer member 412. It flows into the fifth through hole 438. Then, an amount of ink corresponding to the pressurized pressure is ejected as ink droplets from the nozzle 439 perforated in the nozzle plate 411 which is the end of the ink flow path.

  FIG. 5 is a detailed diagram of the drive signal COM of the reference example. As described above, the drive signal COM is applied to the piezoelectric element 417 for ejecting ink droplets. The drive signal COM is repeatedly generated every repetition period T.

  The repetition period T of the drive signal COM is equal to the period for forming one pixel on the paper. That is, the period T that is a repetition period corresponds to a period during which the nozzle moves by one pixel. For example, when the print resolution is 720 dpi, the period T corresponds to a period for the nozzle to move 1/720 inch. Then, by applying the drive pulses PS1 to PS5 of each section included in the period T to the piezoelectric element 417, several ink droplets are ejected into one pixel, and a plurality of gradations can be expressed.

  In the figure, the intermediate voltage is indicated by a dotted line near the center of the amplitude of the drive pulse. The intermediate voltage is a reference voltage for causing the displacement of the piezoelectric element 417 to be a reference displacement. Then, by changing the voltage in the plus direction or the minus direction with respect to the intermediate voltage, the piezoelectric element 417 is displaced and ink droplets are ejected.

  The drive signal COM includes a first drive pulse PS1 generated in the section T1 of the repetition period T, a second drive pulse PS2 generated in the section T2, a third drive pulse PS3 generated in the section T3, and a section T4. And the fifth drive pulse PS5 generated in the section T5.

  The drive signal COM starts from the intermediate voltage in the first interval Pini, and then the first drive pulse PS1 is generated. The first drive pulse is a voltage change in the sections Pwd1, Pwh1, Pwc1, Pwh2, and Pwd2. Further, the second drive pulse PS2 to the fourth drive pulse PS4 have waveforms having the same voltage change as the first drive pulse PS1. The first drive pulse PS1 to the fourth drive pulse PS4 are connected with an intermediate voltage in the section Pdis.

  In the present embodiment, the piezoelectric element 417 is driven so as to draw the meniscus toward the inner side of the head (the direction away from the paper) when the voltage of the drive pulse becomes lower than the intermediate voltage. On the other hand, the piezoelectric element 417 is driven so as to push out the meniscus toward the outside of the head (the direction toward the paper) when the voltage of the drive pulse becomes higher than the intermediate voltage. Here, the meniscus is the liquid surface in the nozzle.

  First, in the section Pwd1, the voltage starts decreasing in a direction in which the voltage becomes lower than the intermediate voltage. Then, along with that, the meniscus is also drawn in the minus direction (inward direction of the head). When the voltage is maintained at a predetermined voltage in the section Pwh1, the meniscus is slightly pulled in the minus direction due to the inertia of the ink, but the meniscus displacement turns in the plus direction so as to freely oscillate.

  Next, in the section Pwc1, the voltage starts increasing in the direction of returning to the intermediate voltage. Then, the meniscus is displaced so as to go in the plus direction (outward direction of the head). In the section Pwh2, the voltage is maintained at a predetermined voltage. In this way, after driving the piezoelectric element 417 to push it out of the head, if the voltage is maintained at a predetermined voltage, a force is applied to stop the displacement of the meniscus. However, due to the inertia of the ink, the meniscus is pushed out of the head. The inertia of the ink exceeds the surface tension of the meniscus, and the ink is ejected as ink droplets so that the ink is torn off from the nozzle.

  Thereafter, in the section Pwd2, the voltage starts to decrease in the direction of returning to the intermediate voltage. Then, the meniscus is also displaced in the direction returning to the nozzle surface.

  In such a drive pulse, when the voltage change rate in the section Pwc1 is large, the piezoelectric element 417 is also displaced with a large acceleration. Then, the speed of the ink droplet ejected in this section Pwc1 can be increased by increasing the voltage change rate.

  By the way, the fifth drive pulse is a voltage change in BSD1, BSD2, and BSD3. The fourth drive pulse PS4 and the fifth drive pulse PS5 are connected by an intermediate voltage in the section BSD0. Since the amplitude of the voltage change of the fifth drive pulse PS is not large, ink droplets are not ejected even when this is applied to the piezoelectric element 417. When the fifth drive pulse PS5 is applied to the piezoelectric element 417, the ink surface (meniscus) in the nozzle is slightly vibrated. This prevents the ink from thickening. Such a drive pulse is referred to herein as a fine vibration pulse.

  This fine vibration pulse is applied to the piezoelectric element 417 when ink droplets are not ejected during one cycle of the drive signal. That is, when an ink droplet is ejected during one cycle of this drive signal, this fine vibration pulse is not applied to the piezoelectric element 417. At this time, the potential of the piezoelectric element 417 is maintained at an intermediate potential. However, in the case of ejecting ink droplets during one cycle of the drive signal, in addition to the drive pulses for ejecting ink droplets (first drive pulse PS1 to fourth drive pulse PS4), the fine vibration pulse (fifth drive pulse PS5). ) May also be applied to the piezoelectric element 417.

  FIG. 6 is a diagram for explaining the arrangement of ink droplets that land on a sheet by the drive signal COM of the reference example. In the figure, the arrangement of ink droplets on the paper when all the drive pulses of the first drive pulse PS1 to the fifth drive pulse PS5 of the drive signal COM (FIG. 5) of the reference example are continuously applied is shown. Yes. In the figure, the ink droplet D1 is the ink droplet ejected by applying the first drive pulse PS1 to the piezoelectric element 417 on the paper. The ink droplet D2 is an ink droplet ejected by applying the second drive pulse PS2 to the piezoelectric element 417 on the paper. In addition, an ink droplet D3 is an ink droplet ejected by applying the third drive pulse PS3 to the piezoelectric element 417 on the paper. Further, an ink droplet D4 is an ink droplet ejected by applying the fourth drive pulse PS4 to the piezoelectric element 417 on the paper.

  The drive signal COM is repeatedly generated. Accordingly, the ink droplets D1 to D4 repeatedly land in the carriage movement direction. The fifth drive pulse PS5 is a drive pulse that does not eject ink droplets. Therefore, when the first drive pulse PS1 is applied to the piezoelectric element 417 at the position where the ink droplet ejected when the fourth drive pulse PS4 is applied to the piezoelectric element 417 and the period of the next drive signal are applied. The gap between the positions where the ejected ink droplets land is wider than the interval between the landing positions of the other ink droplets.

  As described above, the shape of each of the first drive pulse PS1 to the fourth drive pulse PS4 is the same. The intervals between these drive pulses are also equal. Therefore, the ink droplets ejected by the first drive pulse PS1 to the fourth drive pulse PS4 land on the paper at equal intervals. However, as described above, the landing positions of the ink droplets ejected by the fourth driving pulse PS4 and the landing positions of the ink droplets ejected by the first driving pulse PS1 are the first driving pulse PS1 to the fourth driving pulse PS4. The distance between the landing positions of the ink droplets by the respective driving pulses is wider than that. That is, when the drive signal COM is continuously applied to the piezoelectric element 417, the drive pulse capable of ejecting ink droplets may not be applied to the piezoelectric element 417 at equal time intervals.

  However, even in such a case, it is desirable not to make it conspicuous that the ink droplets that have landed on the paper are not arranged at equal intervals. In the embodiment described below, it is not noticeable that the ink droplets that have landed on the paper are not arranged at equal intervals even when drive pulses capable of ejecting ink droplets cannot be applied to the piezoelectric elements 417 at equal intervals. I am doing so.

  FIG. 7 is a diagram for explaining the drive signal COM ′ in the first embodiment. In the figure, the first drive pulses PS1 to PS5 in the repetition period T are shown. The drive signal COM ′ in the first embodiment is different from the drive signal COM in the reference example only in the first drive pulse PS1 in the section T1. The remaining second drive pulse PS2 to fifth drive pulse PS5 and the intermediate voltage interval Pdis connecting them are the same voltage changes as those in the intervals T2 to T5 in the reference example.

  In the section T1, sections Pwd1, Pwh1, Pwc1, Pwh2, Pwh2, and Pwd2 for defining the first drive pulse PS1 and a section Pini for defining the drive pulse application timing are shown. A section Pdis is shown over the section T2. Note that the minimum voltage and the maximum voltage of the drive pulse PS1 of the first embodiment are the same as those of the reference example. Therefore, a drive pulse different from the first drive pulse PS1 of the reference example can be defined by making the lengths of the sections Pwd1, Pwh1, Pwc1, Pwh2, and Pwd2 for defining the first drive pulse PS1 different. .

  In the first embodiment, the length of the section Pwh1 is shorter than that of the reference example. The length of the section Pwc1 is also shorter than that of the reference example. Further, the length of the section Pwh2 is made longer than that of the reference example by the amount that the sections Pwh1 and Pwc1 are shortened.

  By doing so, the voltage change rate in the section Pwc1 of the first drive pulse PS1 becomes larger than that of the reference example. When the voltage change rate in the section Pwc1 is large, the acceleration of the ejected ink also increases. That is, the ink droplet ejection speed can be increased. Further, if the length of the section Pwh1 is shortened, the section Pwc1 for ejecting ink droplets is reached earlier. Therefore, the timing for ejecting ink droplets can be advanced.

  FIG. 8 is a diagram for explaining the arrangement of ink droplets that land on a sheet by the drive signal COM ′ according to the first embodiment. In the drawing, the arrangement of the ink droplets on the paper when all the drive pulses of the first drive pulse PS1 to the fifth drive pulse PS5 of the drive signal COM ′ in the first embodiment are continuously applied is shown. . Also here, the ink droplet D1 is the ink droplet ejected by applying the first drive pulse PS1 to the piezoelectric element 417 on the paper. The ink droplet D2 is an ink droplet ejected by applying the second drive pulse PS2 to the piezoelectric element 417 on the paper. In addition, an ink droplet D3 is an ink droplet ejected by applying the third drive pulse PS3 to the piezoelectric element 417 on the paper. Further, an ink droplet D4 is an ink droplet ejected by applying the fourth drive pulse PS4 to the piezoelectric element 417 on the paper.

  In the drive signal COM ′ in the first embodiment, the timing of ejecting ink droplets by the first drive pulse PS1 is earlier than that of the reference example. In addition, the ink droplet ejection speed by the first drive pulse PS1 is higher than the ink droplet ejection speed by the first drive pulse PS1 of the reference example. By doing so, the ink droplets ejected by the first drive pulse PS1 land on the paper earlier than that of the reference example.

  Therefore, as shown in the figure, the ink droplet D1 ejected by the first drive pulse PS1 has landed so as to approach the landing position of the ink droplet D4 ejected by the preceding fourth drive pulse PS4. Further, the ink droplet D1 ejected by the first driving pulse PS1 is landed so as to be away from the landing position of the ink droplet D2 ejected by the subsequent second driving pulse PS2.

  In the reference example, a space in which no ink droplets have landed occurs between the landing position of the ink droplet D4 ejected by the fourth driving pulse PS4 and the landing position of the ink droplet D1 ejected by the first driving pulse PS1. It was. In the first embodiment, the ink droplet D1 ejected by the first driving pulse PS1 is the landing position of the ink droplet D4 ejected by the fourth driving pulse PS4 and the ink droplet D2 ejected by the second driving pulse PS2. Landing to fill the gap between the landing positions. Then, it can be made inconspicuous that the ink droplets that have landed on the paper are not arranged at equal intervals.

=== Second Embodiment ===
FIG. 9 is a diagram for explaining the drive signal COM ″ in the second embodiment. In the figure, the first drive pulse PS1 to the fifth drive pulse PS5 in the repetition period T are shown. The length of the repetition period T is the same as the repetition period T in the reference example described above. In the drive signal COM ″ in the second embodiment, the only difference from the drive signal COM in the reference example is the application timing of the first drive pulse PS1 in the section T1.

  In the section T1, each section (Pwd1, Pwh1, Pwc1, Pwh2, Pwd2) for defining the first drive pulse PS1 and a section Pini for defining the drive pulse application timing are shown. Further, a section Pdis in which the first drive pulse PS1 and the second drive pulse PS2 are connected with an intermediate voltage is shown. Note that the minimum voltage and the maximum voltage of the drive pulse PS1 of the first embodiment are the same as those of the above-described reference example. Further, the length of each section (Pwd1, Pwh1, Pwc1, Pwh2, Pwd2) for defining the first drive pulse PS1 is the same as that of the reference example.

  In the second embodiment, the interval Pini that defines the application timing of the first drive pulse PS1 is shorter than that of the reference example. In the second embodiment, the interval Pdis from the application of the first drive pulse PS1 to the start of the application of the second drive pulse PS2 is increased by the amount of the interval Pini.

  The section Pdis between the second drive pulse PS2 and the third drive pulse PS3 is the same as that of the reference example. The section Pdis between the third drive pulse PS3 and the fourth drive pulse PS4 is also the same as that of the reference example. The lengths of the sections BSD0, BSD1, BSD2, and BSD3 are the same as those in the reference example.

  Thus, if the section Pini is shortened, the section Pwc1 for ejecting ink droplets is reached earlier in the first drive pulse PS1. Therefore, the timing for ejecting ink droplets by the first drive pulse PS1 can be advanced. Also in this case, as shown in FIG. 8, the ink droplet D1 ejected by the first drive pulse P1 is landed on the ink droplet D4 ejected by the fourth drive pulse PS4, and the second drive pulse PS2 Is landed so as to fill the space between the landed positions of the ink droplets D2 ejected by the above. Then, it can be made inconspicuous that the ink droplets that have landed on the paper are not arranged at equal intervals.

  In addition, the application timing of the first drive pulse PS1 of the first embodiment described above may be advanced as in the second embodiment. By appropriately combining these embodiments, it is possible to prevent the ink droplets that have landed on the paper from being arranged at equal intervals.

=== Third Embodiment ===
FIG. 10 is a diagram for explaining the drive signal COM ′ ″ in the third embodiment. The repetition period T ′ includes a section T1 ′ and a section T2 ′. The section T1 ′ and the section T2 ′ each correspond to a period during which the nozzle moves by one pixel. That is, the repetition period T ′ corresponds to a period during which the nozzle moves by two pixels.

  The drive signal COM "" in the third embodiment has nine drive pulses of the first drive pulse PS1 to the ninth drive pulse PS9. Among them, the fifth drive pulse PS5 is a drive pulse for finely vibrating the meniscus without ejecting ink droplets. The other drive pulses are drive pulses for ejecting ink droplets. Further, there is no drive pulse in the section T25, and the voltage is an intermediate voltage.

  Under such circumstances, ink droplets cannot be ejected in the sections T15 and T25. Then, no special countermeasure is taken because the ink droplet does not land between the landing position of the ink droplet ejected by the fourth driving pulse PS4 and the landing position of the ink droplet ejected by the sixth driving pulse PS6. In this case, the gap is larger than the interval between the landing positions of the other ink droplets. In addition, no special measures are taken because the ink droplet does not land between the landing position of the ink droplet ejected by the ninth drive pulse PS9 and the landing position of the ink droplet ejected by the first drive pulse PS1. In this case, the gap is larger than the interval between the landing positions of the other ink droplets.

  In the third embodiment, even in such a case, by applying the first drive pulse PS1 in the first embodiment to the first drive pulse PS1 and the sixth drive pulse PS6, the ink droplets that have landed on the protons are even. It is made inconspicuous not to line up at intervals.

  FIG. 11 is a diagram for explaining the arrangement of inks that land on a sheet by a drive signal COM ″ ″ according to the third embodiment. In the drawing, the arrangement of ink droplets on the paper when all the drive pulses of the first drive pulse PS1 to the ninth drive pulse PS9 of the drive signal COM ′ ″ in the third embodiment are continuously applied is shown. ing. Also here, the ink droplet D1 is the ink droplet ejected by applying the first drive pulse PS1 to the piezoelectric element 417 on the paper. The ink droplet D2 is an ink droplet ejected by applying the second drive pulse PS2 to the piezoelectric element 417 on the paper. In addition, an ink droplet D3 is an ink droplet ejected by applying the third drive pulse PS3 to the piezoelectric element 417 on the paper. Further, an ink droplet D4 is an ink droplet ejected by applying the fourth drive pulse PS4 to the piezoelectric element 417 on the paper.

  Further, an ink droplet D6 is an ink droplet ejected by applying the sixth drive pulse PS6 to the piezoelectric element 417 on the paper. Further, an ink droplet D7 is an ink droplet ejected by applying the seventh drive pulse PS7 to the piezoelectric element 417 on the paper. In addition, an ink droplet D8 is an ink droplet ejected by applying the eighth drive pulse PS8 to the piezoelectric element 417 on the paper. Further, an ink droplet D9 is an ink droplet ejected by applying the ninth drive pulse PS9 to the piezoelectric element 417 on the paper.

  Thus, when the first drive pulse PS1 in the first embodiment is applied to the first drive pulse PS1 in the third embodiment, the ink droplet D1 ejected by the first drive pulse PS1 is ejected by the seventh drive pulse. The ink droplet D7 is landed so as to fill a space between the ink droplet D2 ejected by the second drive pulse PS2. Further, when the first drive pulse PS1 in the first embodiment is applied to the first drive pulse PS1 in the third embodiment, the ink droplet D6 ejected by the sixth drive pulse PS6 is ejected by the fifth drive pulse PS5. Landing is performed so as to fill the gap between the ink droplet D5 and the landing position of the ink droplet D7 ejected by the seventh drive pulse PS7. Then, it can be made inconspicuous that the ink droplets that have landed on the paper are not arranged at equal intervals.

  Further, the application timing of the first drive pulse PS1 may be advanced as in the second embodiment. Even in this case, the ink droplet D1 ejected by the first drive pulse PS1 is composed of the ink droplet D7 ejected by the seventh drive pulse and the ink droplet D2 ejected by the second drive pulse PS2. Landing to fill the gap between the landing positions. Then, it can be made inconspicuous that the ink droplets that have landed on the paper are not arranged at equal intervals.

  In the third embodiment, the first drive pulse PS1 corresponds to the first drive pulse, and the second drive pulse PS2 to the fourth drive pulse PS4 correspond to drive pulses after the second drive pulse. Further, the sixth drive pulse PS6 corresponds to the first drive pulse, and the seventh drive pulse PS7 to the ninth drive pulse PS9 correspond to drive pulses after the second drive pulse.

=== Other Embodiments ===
The drive pulse in the section T5 where the fine vibration pulse (fifth drive pulse PS5) of the first embodiment and the second embodiment described above is present may be a constant intermediate voltage. That is, it may be the same as the constant intermediate voltage in the section T25 (FIG. 10) of the third embodiment. As described above, the driving pulse that does not eject the liquid droplet includes the one having such a constant intermediate voltage.

  Further, in the first to third embodiments, the driving pulse that does not eject the liquid droplet is provided at the tail of the repetition period T, but may be located at a place other than the tail. In this case as well, in the repeatedly generated drive signal, the drive pulse that follows the drive pulse that does not eject the liquid droplet is taken as the first drive pulse.

  In the first to third embodiments, the start / end timing of each pulse element of the first drive pulse (first drive pulse PS1, sixth drive pulse PS6) is set to the second and subsequent drive pulses ( The second drive pulse PS2 to the fourth drive pulse PS4 and the seventh drive pulse PS7 to the ninth drive pulse PS9) are different. On the other hand, each voltage value (intermediate voltage, highest voltage, lowest voltage, etc.) of the first drive pulse is the same as the second and subsequent drive pulses, but the amount of ink droplets ejected by each drive pulse is constant. It is good also as changing each voltage value so that it may become.

  In the above-described embodiment, the printer 1 has been described as the liquid ejecting apparatus. However, the present invention is not limited to this, and other fluids (liquid, liquids in which particles of functional materials are dispersed, gels, and the like) are not limited thereto. Such a fluid can also be embodied in a liquid ejection device that ejects or ejects the fluid. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, gas vaporizer, organic EL manufacturing apparatus (especially polymer EL manufacturing apparatus), display manufacturing apparatus, film formation You may apply the technique similar to the above-mentioned embodiment to the various apparatuses which applied inkjet technology, such as an apparatus and a DNA chip manufacturing apparatus. These methods and manufacturing methods are also within the scope of application.

  The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

<About line head printer>
In the above-described embodiment, the case of ejecting ink droplets while moving the head has been described. However, in the liquid ejection device of the type that ejects ink droplets while moving the paper relative to the head while fixing the head. There may be. For example, a line head printer that performs printing by ejecting ink droplets while moving the paper in a direction orthogonal to the nozzle array direction of the head may be used.

<About the head>
In the above-described embodiment, ink is ejected using the piezoelectric element 417. However, the method for discharging the liquid is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

FIG. 1A is an external perspective view of the printer 1, and FIG. 1B is an internal perspective view of the printer 1. 2 is a block diagram of the printer 1. FIG. It is the figure which looked at the head 41 from the bottom. 4A is a plan view showing the structure of one pressure chamber 435 in the head 41, and FIG. 4B is a cross-sectional view of the head 41 taken along the line AA. It is a detailed view of a drive signal COM of a reference example. It is a figure for demonstrating the arrangement | sequence of the ink droplet which lands on the paper with the drive signal COM of a reference example. It is a figure for demonstrating the drive signal COM 'in 1st Embodiment. FIG. 6 is a diagram for explaining the arrangement of ink droplets that land on a sheet by a drive signal COM ′ according to the first embodiment. It is a figure for demonstrating the drive signal COM '' in 2nd Embodiment. It is a figure for demonstrating the drive signal COM "" in 3rd Embodiment. FIG. 10 is a diagram for explaining an arrangement of ink droplets that land on a sheet by a drive signal COM ′ ″ according to a third embodiment.

Explanation of symbols

1 printer,
20 paper transport mechanism, 30 carriage movement mechanism,
40 head units, 41 heads,
60 controller, 70 drive signal generation circuit,
411 Nozzle plate, 412 Spacer member, 413 Ink supply member,
414 Lid member, 415 Spacer member, 416 Diaphragm, 417 Piezoelectric element,
432 reservoir, 433 first through hole, 434 second through hole, 435 pressure chamber,
436 3rd hole, 437 4th hole, 438 5th hole, 439 Nozzle PS1 1st drive pulse, PS2 2nd drive pulse, PS3 3rd drive pulse,
PS4 4th drive pulse, PS5 5th drive pulse, PS6 6th drive pulse,
PS7 7th drive pulse, PS8 8th drive pulse, PS9 9th drive pulse

Claims (9)

(A) a head that ejects a liquid droplet by applying a driving pulse to the driving element;
(B) a first drive pulse and a plurality of second and subsequent drive pulses having a predetermined waveform following the first drive pulse and having a waveform different from that of the first drive pulse. A drive signal generation unit that repeatedly generates a drive signal including the second and subsequent drive pulses;
(C) a controller that applies a driving pulse of the driving signal to the driving element to discharge the liquid droplet from the head;
A liquid ejection apparatus comprising:   2. The liquid ejection apparatus according to claim 1, wherein the first drive pulse is a drive pulse having a liquid droplet ejection speed faster than the second drive pulse.   3. The liquid ejection apparatus according to claim 1, wherein in the first driving pulse and the second and subsequent driving pulses, the ejection amount of the liquid droplets ejected by each driving pulse is equal.   The rate of change in voltage of the portion that ejects the liquid droplet in the first drive pulse is greater than the rate of change in voltage of the portion that ejects the liquid droplet in the second drive pulse. 4. The liquid ejection device according to any one of 3.   The drive signal is a drive signal including a drive pulse that does not cause the liquid droplet to be ejected, and the first drive pulse follows the drive pulse that does not cause the liquid droplet to be ejected when the drive signal is repeatedly generated. The liquid ejection device according to claim 1, wherein the liquid ejection device is a drive pulse. Generating a first drive pulse, applying the first drive pulse to the drive element to eject a liquid drop;
A plurality of second and subsequent drive pulses having a predetermined waveform following the first drive pulse, the second and subsequent drive pulses having a waveform different from that of the first drive pulse; Applying a second and subsequent drive pulses to the drive element to eject liquid droplets;
A liquid ejection method comprising: (A) a head that ejects a liquid droplet by applying a driving pulse to the driving element;
(B) A drive signal including at least three drive pulses having a predetermined waveform, and an interval between the first drive pulse and the second drive pulse is an interval between the second and subsequent drive pulses. A drive signal generator for repeatedly generating different drive signals;
(C) a controller that applies a driving pulse of the driving signal to the driving element to discharge the liquid droplet from the head;
A liquid ejection apparatus comprising:   The drive signal is generated according to claim 7, wherein an interval between the first drive pulse and the second drive pulse is longer than an interval between the second and subsequent drive pulses. Liquid discharge device.   The drive signal is a drive signal including a drive pulse that does not cause the liquid droplet to be ejected, and the first drive pulse follows the drive pulse that does not cause the liquid droplet to be ejected when the drive signal is repeatedly generated. The liquid ejection apparatus according to claim 7, wherein the liquid ejection apparatus is a drive pulse.

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