JP7078824B2 - Liquid injection head, liquid injection recording device, liquid injection head drive method and liquid injection head drive program - Google Patents

Description

The present disclosure relates to a liquid injection head, a liquid injection recording device, a method for driving the liquid injection head, and a drive program for the liquid injection head.

A liquid injection recording device equipped with a liquid injection head is used in various fields. In the liquid injection head, the volume of the pressure chamber is changed by applying a pulse signal to the piezoelectric actuator, so that the liquid filled in the pressure chamber is ejected from the nozzle. When one drop of liquid is discharged from the nozzle, a pulse signal with the pulse width of the on-pulse peak (AP) that maximizes the discharge speed as one pulse is used, and the discharge amount corresponding to this pulse width is the minimum. It becomes. For example, in Patent Document 1, a pulse signal of one pulse is continuously applied to one pixel a plurality of times in succession, and a plurality of droplets are ejected from a nozzle to increase the size of the droplets, resulting in gradation and height. Techniques for forming density pixels are described.

Japanese Unexamined Patent Publication No. 2007-210348

In such a liquid injection head, it is generally required to improve the image quality. It is desirable to provide a liquid injection head, a liquid injection recording device, a method for driving the liquid injection head, and a drive program for the liquid injection head, which can improve the image quality.

The liquid injection head according to the embodiment of the present disclosure has a nozzle for injecting a liquid, a pressure chamber communicating with the nozzle and being filled with a liquid, and a piezoelectric actuator for changing the volume of the pressure chamber, and a piezoelectric actuator. By applying a pulse signal to the pressure chamber, the volume of the pressure chamber is expanded and contracted, and a control unit for injecting the liquid filled in the pressure chamber is provided. When one drop of liquid is injected, the control unit uses the first pulse signal, which has a pulse width less than the width of the on-pulse peak, and the pulse signal, which expands the volume in the pressure chamber, to be less than twice the width of the on-pulse peak. A predetermined time interval is applied so as to include a second pulse signal provided apart from the first pulse signal. The predetermined time interval is 0.61 times or more and 1.08 times or less the width of the on-pulse peak. Further, the first pulse signal is a pulse signal for injecting a droplet, and the second pulse signal is an auxiliary pulse signal for pulling back a part of the droplet ejected by the first pulse signal. At the same time, it is the last pulse when one drop of liquid is ejected. The term "single drop injection" as used herein means a state in which one drop of liquid is finally ejected from the nozzle to the outside regardless of the number of the pulse signals applied by the control unit. The same applies to the following.

The liquid injection recording device according to the embodiment of the present disclosure includes the liquid injection head according to the embodiment of the present disclosure.

The method for driving the liquid injection head according to the embodiment of the present disclosure expands and contracts the volume of the pressure chamber by applying a pulse signal to the piezoelectric actuator that changes the volume of the pressure chamber communicating with the nozzle. Therefore, when one drop of the liquid filled in the pressure chamber is ejected from the nozzle, applying a pulse signal that expands the volume of the pressure chamber produces a first pulse signal having a pulse width smaller than the width of the on-pulse peak. It includes the application and the application of a second pulse signal provided at a predetermined time interval equal to or less than twice the width of the on-pulse peak from the first pulse signal. The predetermined time interval is 0.61 times or more and 1.08 times or less the width of the on-pulse peak. Further, the first pulse signal is a pulse signal for injecting a droplet, and the second pulse signal is an auxiliary pulse signal for pulling back a part of the droplet ejected by the first pulse signal. At the same time, it is the last pulse when one drop of liquid is ejected.

The drive program of the liquid injection head according to the embodiment of the present disclosure expands and contracts the volume of the pressure chamber by applying a pulse signal to the piezoelectric actuator that changes the volume of the pressure chamber communicating with the nozzle. Therefore, when one drop of the liquid filled in the pressure chamber is ejected from the nozzle, applying a pulse signal that expands the volume of the pressure chamber produces a first pulse signal having a pulse width smaller than the width of the on-pulse peak. To have the computer perform the application to include applying and applying a second pulse signal provided at a predetermined time interval equal to or less than twice the width of the on-pulse peak from the first pulse signal. It is the one that was made. The predetermined time interval is 0.61 times or more and 1.08 times or less the width of the on-pulse peak. Further, the first pulse signal is a pulse signal for injecting a droplet, and the second pulse signal is an auxiliary pulse signal for pulling back a part of the droplet ejected by the first pulse signal. At the same time, it is the last pulse when one drop of liquid is ejected.

According to the liquid injection head, the liquid injection recording device, the driving method of the liquid injection head, and the driving program of the liquid injection head of the present disclosure, it is possible to improve the image quality.

It is a perspective view which shows the structure of the liquid injection recording apparatus in 1st Embodiment of this disclosure. It is a perspective view of the liquid injection head in 1st Embodiment of this disclosure. It is a perspective view of the head tip in 1st Embodiment of this disclosure. It is an exploded perspective view of the head tip in 1st Embodiment of this disclosure. It is a schematic block diagram which shows an example of the control part in 1st Embodiment of this disclosure. It is explanatory drawing of the control to miniaturize the droplet at the time of one drop ejection in the 1st Embodiment of this disclosure. It is a figure which shows an example of the drive waveform which concerns on the comparative example. It is a table which shows the 1st example of the experimental result when the width of "ON1" of a main pulse signal was changed by the control which concerns on a comparative example. It is a table which shows the 2nd example of the experimental result when the width of "ON1" of a main pulse signal was changed by the control which concerns on a comparative example. It is a figure which graphed the experimental result in the control which concerns on the comparative example shown in FIG. 8 and FIG. It is a figure which shows an example of the drive waveform in 1st Embodiment of this disclosure. It is a table which shows the 1st example of the experimental result at the time of changing the width of "ON1" of the main pulse signal in 1st Embodiment of this disclosure. It is a table which shows the 2nd example of the experimental result at the time of changing the width of "ON1" of the main pulse signal in 1st Embodiment of this disclosure. 12 is a graph showing the experimental results shown in FIGS. 12 and 13. It is a table which shows the 1st example of the experimental result when the width of "OFF" in the 2nd Embodiment of this disclosure was changed. It is a table which shows the 2nd example of the experimental result when the width of "OFF" in the 2nd Embodiment of this disclosure was changed. It is a figure which graphed the experimental result shown in FIGS. 15 and 16. It is a table which shows the 1st example of the experimental result when the width of "ON2" in the 3rd Embodiment of this disclosure was changed. It is a table which shows the 2nd example of the experimental result when the width of "ON2" in the 3rd Embodiment of this disclosure was changed. It is a figure which graphed the experimental result shown in FIGS. 18 and 19. It is a figure which shows an example of the drive waveform in 4th Embodiment of this disclosure. It is a table which shows an example of the experimental result when the width of "ON12" in the 4th Embodiment of this disclosure was changed. It is a figure which graphed the experimental result shown in FIG. 22.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The explanation will be given in the following order.
1. 1. 1st Embodiment (Example when the width of "ON1" as a 1st pulse signal is changed)
2. 2. Second embodiment (example when the width of "OFF" as a predetermined time interval is changed)
3. 3. Third embodiment (example when the width of "ON2" as the second pulse signal is changed)
4. Fourth Embodiment (Example in the case where a plurality of pulse signals are provided before the second pulse signal)
5. Modification example

<1. First Embodiment>
First, the first embodiment will be described.

(Liquid injection recording device)
The schematic configuration of the liquid injection recording apparatus 1 according to the first embodiment will be described. Since the method for driving the liquid injection head according to the first embodiment is embodied in the liquid injection recording device 1 according to the first embodiment, the method will be described below.

FIG. 1 is a perspective view showing the configuration of the liquid injection recording device 1. In the figure below, the scale of each member is changed as appropriate to make the explanation easier to understand.

As shown in FIG. 1, the liquid injection recording device 1 includes a pair of conveying means 2 and 3 for conveying a recording medium S such as recording paper, and a liquid injection head 4 for injecting ink (not shown) onto the recording medium S. The ink supply means 5 for supplying ink to the liquid injection head 4 and the scanning means 6 for scanning the liquid injection head 4 in the scanning direction X orthogonal to the transport direction Y of the recording medium S are provided.

In the first embodiment, the direction orthogonal to the two directions of the transport direction Y and the scanning direction X is the vertical direction Z. Further, the above-mentioned ink corresponds to a specific example of "liquid" in the present disclosure.

The pair of transport means 2 and 3 are arranged at intervals in the transport direction Y, one transport means 2 is located on the upstream side of the transport direction Y, and the other transport means 3 is located on the downstream side of the transport direction Y. Is located in. These transport means 2 and 3 are arranged parallel to the grit rollers 2a and 3a extending in the scanning direction X and the grit rollers 2a and 3a, and are recorded between the grit rollers 2a and 3a. Each of the pinch rollers 2b and 3b that sandwiches the medium S and a drive mechanism (not shown) such as a motor that rotates the grit rollers 2a and 3a around the axis thereof are provided. Then, by rotating the grit rollers 2a and 3a of the pair of transport means 2 and 3, it is possible to transport the recorded medium S in the arrow B direction along the transport direction Y.

The ink supply means 5 includes an ink tank 10 containing ink and an ink pipe 11 connecting the ink tank 10 and the liquid injection head 4.

In the illustrated example, the ink tank 10 carries ink tanks 10Y, 10M, 10C, and 10K containing four colors of ink, yellow (Y), magenta (M), cyan (C), and black (K), respectively. They are arranged side by side in the direction Y. The ink pipe 11 is, for example, a flexible hose having flexibility, and is capable of following the operation (movement) of the carriage 16 that supports the liquid injection head 4.

The scanning means 6 includes a pair of guide rails 15 extending in the scanning direction X and arranged in parallel with each other at intervals in the transport direction Y, and a carriage 16 movably arranged along the pair of guide rails 15. A drive mechanism 17 for moving the carriage 16 in the scanning direction X is provided.

The drive mechanism 17 is arranged between the pair of guide rails 15, and is wound between the pair of pulleys 18 arranged at intervals in the scanning direction X and the pair of pulleys 18 to move in the scanning direction X. An endless belt 19 and a drive motor 20 for rotationally driving one of the pulleys 18 are provided.

The carriage 16 is connected to the endless belt 19, and is movable in the scanning direction X as the endless belt 19 is moved by the rotational drive of one of the pulleys 18. Further, the carriage 16 is mounted with a plurality of liquid injection heads 4 arranged side by side in the scanning direction X.

In the illustrated example, four liquid injection heads 4, that are, liquid injection heads 4Y, 4M, 4C, and 4K, which inject yellow (Y), magenta (M), cyan (C), and black (K) inks, respectively. It is installed.

(Liquid injection head)
Next, the liquid injection head 4 will be described in detail.

FIG. 2 is a perspective view of the liquid injection head 4. As shown in FIG. 2, the liquid injection head 4 heads a fixed plate 25 fixed to the carriage 16, a head tip 26 fixed on the fixed plate 25, and ink supplied from the ink supply means 5. It includes an ink supply unit 27 that further supplies ink to the ink introduction hole 41a described later of the chip 26, and a control unit 28 that applies a drive voltage to the head chip 26.

When a driving voltage is applied, the liquid injection head 4 ejects ink of each color at a predetermined ejection amount. At this time, by moving the liquid injection head 4 in the scanning direction X by the scanning means 6, recording can be performed in a predetermined range in the recording medium S. By repeating this scanning while transporting the recorded medium S in the transport direction Y by the transport means 2 and 3, recording can be performed on the entire recorded medium S.

A metal base plate 30 such as aluminum is fixed to the fixed plate 25 in an upright state along the vertical direction Z, and a flow path member 31 that supplies ink to the ink introduction hole 41a described later of the head tip 26. Is fixed. Above the flow path member 31, a pressure shock absorber 32 having a storage chamber for storing ink is arranged in a state of being supported by the base plate 30. The flow path member 31 and the pressure shock absorber 32 are connected to each other via the ink connecting pipe 33, and the ink pipe 11 is connected to the pressure shock absorber 32.

Under such a configuration, when ink is supplied from the pressure shock absorber 32 through the ink pipe 11, the ink is temporarily stored in the internal storage chamber, and then a predetermined amount of ink is applied to the ink connecting pipe 33 and the ink connecting pipe 33. It is supplied to the ink introduction hole 41a via the flow path member 31.

The flow path member 31, the pressure shock absorber 32, and the ink connecting pipe 33 function as the ink supply unit 27.

Further, an IC board 36 on which a control circuit 35 such as an integrated circuit for driving the head chip 26 is mounted is attached to the fixed plate 25. The control circuit 35 and the common electrodes (drive electrodes) and individual electrodes (none of which are shown) described later of the head chip 26 are electrically connected via a flexible substrate 37 on which a wiring pattern (not shown) is printed and wired. As a result, the control circuit 35 can apply a drive voltage between the common electrode and the individual electrode via the flexible substrate 37.

The IC board 36 on which these control circuits 35 are mounted and the flexible board 37 function as the control unit 28.

(Head tip)
Subsequently, the head chip 26 will be described in detail.

FIG. 3 is a perspective view of the head tip 26, and FIG. 4 is an exploded perspective view of the head tip 26. As shown in FIGS. 3 and 4, the head tip 26 includes an actuator plate 40, a cover plate 41, a support plate 42, and a nozzle plate 60 provided on the side surface of the actuator plate 40.

The head tip 26 is a so-called edge shoot type that ejects ink from a nozzle hole 43a facing the end in the longitudinal direction of the liquid ejection channel 45A, which will be described later.

The actuator plate 40 is a so-called laminated plate in which two plates of the first actuator plate 40A and the second actuator plate 40B are laminated. The actuator plate 40 is not limited to the laminated plate, and may be composed of one plate. Further, the actuator plate 40 corresponds to a specific example of the "piezoelectric actuator" in the present disclosure.

The first actuator plate 40A and the second actuator plate 40B are both a piezoelectric substrate that has been polarized in the thickness direction, for example, a PZT (lead zirconate titanate) ceramic substrate, and the polarization directions of the first actuator plate 40A and the second actuator plate 40B are opposite to each other. It is joined. The actuator plate 40 has a substantially rectangular shape in a plan view, which is long in the first direction (arrangement direction) L2 orthogonal to the thickness direction L1 and short in the second direction L3 orthogonal to the thickness direction L1 and the first direction L2. Is formed in.

Since the head tip 26 of the first embodiment is an edge shoot type, the thickness direction L1 coincides with the scanning direction X in the liquid injection recording device 1, and the first direction L2 is the transport direction Y and the second direction. L3 coincides with the vertical direction Z. That is, for example, of the side surfaces of the actuator plate 40, the side surface facing the nozzle plate 60 (the side surface on the side where ink is ejected) is the lower end surface 40a, which is located on the opposite side of the second direction L3 from the lower end surface 40a. The side surface is the upper end surface 40b. In the following description, in accordance with this vertical direction, the description may be simply referred to as a lower side or an upper side. However, it goes without saying that the vertical direction usually changes depending on the installation angle of the liquid injection recording device 1.

On one main surface (the surface on which the cover plate 41 overlaps) 40c of the actuator plate 40, a plurality of channels 45 arranged at a predetermined interval in the first direction L2 are formed. These plurality of channels 45 are grooves that extend linearly along the second direction L3 in a state of being open to one main surface 40c side, and one side in the longitudinal direction is open to the lower end surface 40a side of the actuator plate 40. There is. A drive wall (piezoelectric partition wall) 46 having a substantially rectangular cross section and extending in the second direction L3 is formed between the plurality of channels 45. Each channel 45 is divided by the drive wall 46.

Further, the plurality of channels 45 are roughly classified into a liquid ejection channel 45A filled with ink and a non-ejection channel 45B not filled with ink. The liquid discharge channels 45A and the non-discharge channels 45B are alternately arranged side by side in the first direction L2. The liquid discharge channel 45A corresponds to a specific example of the "pressure chamber" in the present disclosure.

Of these, the liquid discharge channel 45A is formed in a state of being opened only on the lower end surface 40a side without opening on the upper end surface 40b side of the actuator plate 40. On the other hand, the non-discharge channel 45B is formed so as to open not only on the lower end surface 40a side of the actuator plate 40 but also on the upper end surface 40b side.

A common electrode (not shown) is formed on the inner wall surface of the liquid discharge channel 45A, that is, the pair of side wall surfaces and the bottom wall surface facing the first direction L2. This common electrode extends in the second direction L3 along the liquid discharge channel 45A and conducts to a common terminal 51 formed on one main surface 40c of the actuator plate 40.

On the other hand, on the inner wall surface of the non-discharge channel 45B, a pair of side wall surfaces facing the first direction L2 are formed with individual electrodes (not shown). These individual electrodes extend in the second direction L3 along the non-discharge channel 45B and conduct to the individual terminals 53 formed on one main surface 40c of the actuator plate 40.

The individual terminal 53 is formed on the upper end surface 40b side of the common terminal 51 on one main surface 40c of the actuator plate 40. The individual electrodes located on both sides of the liquid discharge channel 45A are connected to each other (individual electrodes formed in different non-discharge channels 45B).

Under such a configuration, when the control circuit 35 applies a drive voltage between the common electrode and the individual electrode through the flexible substrate 37 and further through the common terminal 51 and the individual terminal 53, the drive wall 46 is deformed. .. Then, the pressure of the ink filled in the liquid ejection channel 45A fluctuates. As a result, the ink in the liquid ejection channel 45A can be ejected from the nozzle hole 43a, and various information such as characters and figures can be recorded on the recording medium S.

A cover plate 41 is superposed on one main surface 40c of the actuator plate 40. In the cover plate 41, the ink introduction holes 41a are formed in a substantially rectangular shape in a long plan view in the first direction L2.

In the ink introduction hole 41a, a plurality of slits 55a are formed to introduce the ink supplied through the flow path member 31 into the liquid ejection channel 45A and to restrict the introduction into the non-ejection channel 45B. The ink introduction plate 55 is formed. That is, the plurality of slits 55a are formed at positions corresponding to the liquid ejection channels 45A, and ink can be filled only in each liquid ejection channel 45A.

The cover plate 41 is formed of, for example, the same PZT ceramic substrate as the actuator plate 40, and is subjected to the same thermal expansion as the actuator plate 40 to suppress warpage and deformation due to temperature changes. However, the present invention is not limited to this case, and the cover plate 41 may be formed of a material different from that of the actuator plate 40. In this case, it is preferable to use a material having a coefficient of thermal expansion close to that of the actuator plate 40 as the material of the cover plate 41.

The support plate 42 supports the overlapped actuator plate 40 and the cover plate 41, and also supports the nozzle plate 60 at the same time. The support plate 42 is a substantially rectangular plate material long formed in the first direction L2 so as to correspond to the actuator plate 40, and a fitting hole 42a penetrating in the thickness direction is formed in most of the center. There is. The fitting hole 42a is formed in a substantially rectangular shape along the first direction L2, and supports the superimposed actuator plate 40 and the cover plate 41 in a state of being fitted into the fitting hole 42a. ..

Further, the support plate 42 is formed in a stepped plate shape so that its outer shape becomes smaller due to a step toward the lower end in the thickness direction. That is, the support plate 42 has a base portion 42A located on the upper end side in the thickness direction and a step portion 42B arranged on the lower end surface of the base portion 42A and having an outer shape smaller than that of the base portion 42A. , Is integrally molded. The support plate 42 is combined so that the end surface of the step portion 42B is flush with the lower end surface 40a of the actuator plate 40. Further, the nozzle plate 60 is fixed to the end surface of the step portion 42B by, for example, adhesion or the like.

(Control unit)
Subsequently, the control unit 28 will be described in detail.

FIG. 5 is a schematic block diagram showing an example of the control unit 28. As shown in FIG. 5, in the control unit 28, the control circuit 35 mounted on the IC board 36 passes through the flexible board 37 and further through the common terminal 51 and the individual terminal 53 of the actuator plate 40 to the common electrode and the individual electrode, respectively. It is electrically connected.

The control circuit 35 applies a drive voltage (pulse signal) between the common electrode and the individual electrode of the actuator plate 40. As a result, the drive wall 46 is deformed, the volume in the liquid discharge channel 45A (pressure chamber) expands and contracts, and the ink (liquid) filled in the liquid discharge channel 45A is ejected from the nozzle hole 43a.

Specifically, the control circuit 35 applies a pulse signal having a positive drive voltage between the common electrode and the individual electrode, for example, in the liquid discharge channel 45A during the period when the pulse signal is high. When the volume expands and the high period of the pulse signal ends (at the low period), the volume in the expanded liquid discharge channel 45A contracts to return, thereby causing the liquid discharge channel. The pressure of the ink filled in 45A rises, and the ink is ejected (sprayed) from the nozzle hole 43a.

Further, the control circuit 35 turns on, for example, the pulse width (width of the high period) of the pulse signal so that the ejection speed becomes the maximum when ejecting a normal one drop of ink (one drop ejection). The width of the pulse peak (pulse width). The on-pulse peak (hereinafter referred to as AP) is a liquid ejection channel 45A for accommodating ink, a nozzle hole 43a that communicates with the liquid ejection channel 45A and ejects ink from the liquid ejection channel 45A, and a volume of the liquid ejection channel 45A. For the liquid injection head 4 having the actuator plate 40 for expanding or contracting the ink, 1/2 of the natural vibration cycle of the ink in the liquid ejection channel 45A is set to 1 AP.

Further, the control circuit 35 makes the pulse width of the pulse signal less than the width of 1 AP or the width of 1 AP, and adds an auxiliary pulse signal after that to reduce the size of the droplet at the time of ejecting one droplet. Can be done. That is, in the liquid injection head 4 of the first embodiment, it is possible to control the amount of droplets to be ejected at the time of ejection of one droplet (discharge amount: Drop Blume) to be small without changing the head structure.

FIG. 6 is an explanatory diagram of control for reducing the size of a droplet when one drop is discharged. In this figure, the horizontal axis is time t. The drive waveform P1 shows the waveform of the drive voltage applied between the common electrode and the individual electrode. In the drive waveform P1, the pulse signal that becomes high during the period from time t1 to time t2 is a pulse signal for ejecting a droplet, and is also referred to as a main pulse signal below. Further, the pulse signal that becomes high during the period from time t3 to time t4 is an auxiliary pulse signal for pulling back a part of the droplet ejected by the main pulse signal. In this figure, "ON1" indicates a high period of the main pulse signal, and "ON2" indicates a high period of the auxiliary pulse signal. Further, "OFF" indicates a period between the main pulse signal and the auxiliary pulse signal (that is, a period from time t2 to time t3).

Here, in the present embodiment (and the second and third embodiments described later), the above-mentioned main pulse signal (pulse signal having a pulse width of "ON1") is the "first pulse signal" in the present disclosure. Corresponds to one specific example. Further, the above-mentioned auxiliary pulse signal (pulse signal having a pulse width of "ON2") corresponds to a specific example of the "second pulse signal" in the present disclosure.

Further, the pressure change waveform P2 shows the pressure change in the liquid discharge channel 45A. Further, the ink volume change waveform P3 shows the volume change of the meniscus of the ink (liquid) in the liquid ejection channel 45A. During the "ON1" period from time t1 to time t2, the volume of the liquid ejection channel 45A expands, the internal pressure decreases, and the volume of ink also decreases due to the application of the main pulse signal. The "ON1" of the main pulse signal at this time is equal to or less than the width of 1 AP. Next, when the "OFF" period is entered at time t2, the volume of the liquid discharge channel 45A begins to contract to return to its original state, and the internal pressure increases. As a result, when the volume of the ink increases and exceeds the threshold value E, the ink starts to be ejected. Here, during the "ON2" period from time t3 to time t4, the volume of the liquid discharge channel 45A expands again and the internal pressure drops due to the application of the auxiliary pulse signal. As a result, a part of the discharged droplets is pulled back into the liquid discharge channel 45A, and the discharge amount for one drop is reduced.

As described above, in the first embodiment, by adding an auxiliary pulse signal after the main pulse signal, a part of the discharged droplets is controlled to be pulled back into the liquid discharge channel 45A. As a result, the droplets at the time of ejecting one droplet can be miniaturized, and the minimum ejection amount can be reduced without changing the structure of the head. By setting the "ON1" of the main pulse signal to less than the width of 1 AP, the ejection amount is further reduced from that of a normal one drop, and a part of the droplet ejected by adding the auxiliary pulse signal. May be controlled to be pulled back into the liquid discharge channel 45A. When "ON1" of the main pulse signal is less than 1AP width, the droplet can be made smaller and the head structure is changed compared to the case where "ON1" is 1AP width. The minimum discharge amount can be reduced without any problem.

Next, with reference to FIGS. 7 to 14, a control method for reducing the size of the droplet when the control circuit 35 ejects one droplet will be described in detail. In addition, in FIGS. 8 to 10 and 13 to 14, the experimental results under the condition of using the liquid injection head of the standard droplet (the droplet size of one drop ejection is standard) with the solvent-based ink and the water-based ink are shown. Shows the experimental results under the condition of using a liquid injection head of a large droplet (the droplet size of one droplet is larger than the standard droplet). Here, in the experiment under the condition of using the liquid injection head of the standard droplet with the solvent-based ink, when "ON1" is set to the width of 1 AP in the drive waveform shown in FIG. 7 described as a comparative example below, A liquid injection head having a discharge rate of 5 m / s (meters per second), a voltage (peak value) of 24.4 V, and a discharge amount of 8.3 pL (picolitre) is used. On the other hand, in the experiment under the condition of using the liquid injection head of large droplets with the water-based ink, the ejection speed is 5 m / s when "ON1" is set to the width of 1 AP in the drive waveform shown in FIG. A liquid injection head (IRH2513 series manufactured by SII Printec) having a voltage (peak value) of 22.1 V and a discharge rate of 14.7 pL is used.

[Comparison example]
First, as a comparative example, an example of a control method that does not add an auxiliary pulse signal will be described.

FIG. 7 is a diagram showing an example of a drive waveform according to a comparative example. In FIG. 7, the horizontal axis is time. Further, the example shown in FIG. 7 is an example in which only the main pulse signal is applied at the time of discharging one drop. 8 and 9 are tables showing experimental results when the width of the main pulse signal “ON1” is changed by the control according to the comparative example. FIG. 8 shows the experimental results under the condition of using a liquid injection head of standard droplets with a solvent-based ink. On the other hand, FIG. 9 shows the experimental results under the condition of using a liquid injection head with a large droplet of water-based ink.

In FIGS. 8 and 9, the voltage (peak value) at which the discharge speed becomes 5 m / s (meters per second) when the width of “ON1” of the main pulse signal is changed, and the discharge amount at that voltage are measured. The result is shown. Here, the discharge speed of 5 m / s is a target reference speed (for example, the maximum speed). The voltage (peak value) and discharge amount at 5 m / s shown in the figure are relative values (ratio: unit is%) with each of them as 100% when "ON1" is the width of the on-pulse peak (1.00 AP). ).

Further, FIG. 10 is a graph showing the experimental results shown in FIGS. 8 and 9, showing the change in the discharge amount when the width of “ON1” is changed. The horizontal axis is the width of "ON1", and the vertical axis is the discharge amount at the voltage (peak value) which is the reference speed. Further, the solid line 101 shows the change in the discharge amount under the condition of the standard droplet, and the broken line 102 shows the change in the discharge amount under the condition of the large droplet.

As shown in FIGS. 8 to 10, in the control method according to the comparative example not using the auxiliary pulse signal, the discharge amount is most reduced when the width of “ON1” of the main pulse signal is changed (shortened). This is when "ON1" is 0.65 AP under the standard droplet condition and 0.37 AP is "ON1" under the large droplet condition. However, the minimum ejection amount is 95.2% under the standard droplet condition and 92.5% under the large droplet condition, and the decrease in the ejection amount is less than 8%. Further, the voltage (peak value) at which the discharge speed is 5 m / s when the minimum discharge amount is 92.5% under the condition of large droplets is 162.0%, and "ON1" is the on-pulse peak. It is 1.6 times or more the width (1.00 AP). Therefore, considering the power consumption, it is conceivable that the minimum discharge amount is 95.9% under the condition of large droplets, and in that case, the reduction of the discharge amount is less than 5%.

In this way, in the control method according to the comparative example that does not use the auxiliary pulse signal, it becomes difficult to reduce the size of the droplet when ejecting one droplet, and as a result, it becomes difficult to improve the image quality. ..

[Miniaturization of droplets]
Next, a control method for reducing the size of the droplet at the time of discharging one droplet according to the first embodiment will be described.

FIG. 11 is a diagram showing an example of a drive waveform for miniaturizing a droplet according to the first embodiment. In FIG. 11, the horizontal axis is time. Further, in the example shown in FIG. 11, an auxiliary pulse signal having a width of "ON2" is applied at a predetermined time interval ("OFF" period) after the main pulse signal having a width of "ON1". That is, in the present embodiment (and the second and third embodiments described later), this "OFF" period corresponds to a specific example of the "predetermined time interval" in the present disclosure.

12 and 13 are tables showing experimental results when the width of the main pulse signal “ON1” is changed in the drive waveform shown in FIG. FIG. 12 shows the experimental results under the condition of using the liquid injection head of the standard droplet with the solvent-based ink as in FIG. On the other hand, FIG. 13 is an experimental result under the condition of using a liquid injection head of a large droplet with a water-based ink as in FIG. 9. Here, "OFF" is fixed at 0.85 AP and "ON2" is fixed at 0.31 AP. Further, regarding the voltage (peak value) and the discharge amount of 5 m / s (reference voltage) shown in the figure, "ON1" is the width of the on-pulse peak (1.00 AP) in the control according to the comparative example in which the auxiliary pulse signal is not added. It is a relative value (ratio: unit is%) with each of the times as 100%.

Further, FIG. 14 is a graph showing the experimental results shown in FIGS. 12 and 13, showing the change in the discharge amount when the width of “ON1” is changed. The horizontal axis is the width of "ON1", and the vertical axis is the discharge amount at the voltage (peak value) which is the reference speed. Further, the solid line 201 shows the change in the discharge amount under the condition of the standard droplet, and the broken line 202 shows the change in the discharge amount under the condition of the large droplet.

As shown in FIGS. 12 to 14, in the control method to which the auxiliary pulse signal is added, the “ON1” of the main pulse signal is set to the width of the on-pulse peak (1.00 AP) or less (more effectively, the width of the on-pulse peak). By shortening to less than), the droplets can be miniaturized. For example, in the illustrated experimental results, under the standard droplet conditions, the discharge amount when "ON1" is 1.00 AP is 88.0%, and the discharge amount when "ON1" is 0.77 AP is 74.7%. , The discharge amount decreases as the width of "ON1" becomes shorter than the width of the on-pulse peak, such that the discharge amount when "ON1" is 0.65 AP is 66.3%. When "ON1" is 0.42AP, the discharge amount can be halved to 49.4%.

Further, in the illustrated experimental results, under the condition of large droplets, the discharge amount when "ON1" is 1.00 AP is 93.9%, and the discharge amount when "ON1" is 0.84 AP is 86.4%. , The discharge amount decreases as the width of "ON1" becomes shorter than the width of the on-pulse peak, such that the discharge amount when "ON1" is 0.68 AP is 78.9%. When "ON1" is 0.37AP, the discharge amount is 49.0%, which is a maximum reduction of 51%. However, when "ON1" is 0.42AP under the standard droplet condition and when "ON1" is 0.37AP under the large droplet condition, the voltage (peak value) is 148.0% and 158.4, respectively. Since it has increased by about 50% to%, the range of use may be, for example, up to 0.54 AP when considering the power consumption. When "ON1" was 0.29 AP, the pulse width was too short (that is, the time for expanding the actuator plate 40 was too short), so that the liquid was not discharged.

As described above, the liquid injection head 4 included in the liquid injection recording device 1 according to the first embodiment individually communicates with the plurality of nozzle holes 43a for ejecting ink (liquid) and the plurality of nozzle holes 43a. An actuator plate 40 having a plurality of liquid discharge channels 45A filled with ink and changing the volume in the liquid discharge channel 45A, and a volume in the liquid discharge channel 45A by applying a pulse signal to the actuator plate 40. The control circuit 35 is provided with a control circuit 35 that expands and contracts the liquid to eject the ink filled in the liquid ejection channel 45A. Then, the control circuit 35 has a pulse width equal to or less than the width of the on-pulse peak (width of "ON1" shown in FIG. 11) as a pulse signal that expands the volume in the liquid discharge channel 45A when one drop of ink is ejected. (1st pulse signal) and an auxiliary pulse signal (2nd pulse signal) provided at a predetermined time interval (“OFF” shown in FIG. 11) from the main pulse signal. Apply to. Specifically, in the present embodiment (and the second and third embodiments described later), the control circuit 35 is a pulse that expands the volume in the liquid ejection channel 45A when one drop of ink is ejected. As the signal, the above-mentioned main pulse signal and auxiliary pulse signal are applied, respectively.

As a result, the droplets at the time of ejecting one droplet can be miniaturized without changing the structure of the liquid injection head 4, and for example, the minimum ejection amount is reduced by about 51% at the maximum as compared with the above comparative example. be able to. Therefore, according to the first embodiment, it is possible to easily reduce the size of the droplet when ejecting one droplet, and it is possible to improve the image quality.

When the width of "ON1" of the main pulse signal is smaller than the width of the on-pulse peak, the volume of one drop of ink (liquid) before being pulled back by the auxiliary pulse signal is reduced, and the width of the on-pulse peak is used. In contrast to the case, the droplet at the time of ejecting one droplet can be made smaller.

Further, by changing the width of the main pulse signal "ON1" to be equal to or less than the width of the on-pulse peak, the minimum discharge amount at the time of one drop discharge can be changed.

<2. Second embodiment>
Subsequently, the second embodiment will be described. Since the configuration of the liquid injection recording device 1 in the second embodiment is the same as that in the first embodiment, the description thereof will be omitted. Since the method for driving the liquid injection head according to the second embodiment is embodied in the liquid injection recording device 1 according to the second embodiment, the method will be described below.

In the first embodiment, in the control method to which the auxiliary pulse signal is added, the case where the width of "OFF" and "ON2" is fixed and the width of "ON1" is changed has been described, but the second embodiment has been described. Then, the case where the width of "ON1" and "ON2" is fixed and the width of "OFF" is changed will be described. The drive waveform is the waveform shown in FIG. 11, and the liquid injection head used in each experiment of the standard droplet condition and the large droplet condition is the same as that of the first embodiment.

15 and 16 are tables showing experimental results when the width of "OFF" between the main pulse signal and the auxiliary pulse signal is changed in the drive waveform shown in FIG. FIG. 15 shows the experimental results under the condition of using a liquid injection head of standard droplets with a solvent-based ink as in FIG. On the other hand, FIG. 16 shows the experimental results under the condition of using the liquid injection head of large droplets with the water-based ink as in FIG. 9. The width of "ON1" is fixed to a value of 1 AP or less based on the experimental results of the first embodiment. Here, the width of "ON1" is 0.65 AP under the standard droplet condition and 0.53 AP under the large droplet condition as a value in which the voltage (peak value) does not increase so much and the discharge amount can be expected to decrease. It is fixed to. The width of "ON2" is the same as that of the first embodiment.

Further, FIG. 17 is a graph showing the experimental results shown in FIGS. 15 and 16, showing the change in the discharge amount when the width of “OFF” is changed. The horizontal axis is the width of "OFF", and the vertical axis is the discharge amount at the voltage (peak value) which is the reference speed. Further, the solid line 301 shows the change in the discharge amount under the condition of the standard droplet, and the broken line 302 shows the change in the discharge amount under the condition of the large droplet.

As shown in FIGS. 15 to 17, the width of "ON1" of the main pulse signal is 1 AP or less, and the width of "OFF" between the main pulse signal and the auxiliary pulse signal is twice the width of "ON1". By doing the following, the droplets can be miniaturized. For example, in the illustrated experimental results, under the standard droplet conditions, "ON1" is 0.65 AP, whereas "OFF" is 1.12 AP, and the discharge amount is 90.4%, "OFF". When is 1.00 AP, the discharge amount is 81.9%, and when "OFF" is 0.88 AP, the discharge amount is 71.1%. According to the experimental results, when "OFF" is 0.77 AP or less, droplet splitting may occur in the ejected droplets.

Further, in the illustrated experimental results, under the condition of large droplets, "ON1" is 0.53 AP, whereas "OFF" is 0.92 AP, and the discharge amount is 76.2%, "OFF". When 0.76AP, the discharge amount is 60.5%, and when "OFF" is 0.68AP, the discharge amount is 5.
When 2.4% and "OFF" is 0.61 AP, the discharge amount is 46.9%. Further, even when "OFF" is 1.08 AP, the discharge amount is 87.1%, and the droplet is reduced in size by about 13%. According to the experimental results, when "OFF" is 0.45 AP or less, droplet splitting may occur in the ejected droplets.

As described above, the predetermined time interval (“OFF” shown in FIG. 11) from the main pulse signal (first pulse signal) to the auxiliary pulse signal (second pulse signal) is twice the width of the on-pulse peak. The following is preferable because the droplets can be miniaturized. The pulse width (width of "ON1" shown in FIG. 11) of the main pulse signal (first pulse signal) at this time is equal to or less than the width of the on-pulse peak (or on-pulse) as in the first embodiment. Less than the width of the peak).

As described above, in the second embodiment, the condition of "ON1" of the main pulse signal in the first embodiment is added to the condition of "OFF" from the main pulse signal to the auxiliary pulse signal. The droplets at the time of ejecting one drop can be miniaturized and can be miniaturized more stably without changing the structure of the liquid injection head 4 as in the embodiment.

For example, as the width of "OFF" becomes longer, the rise time t3 of "ON2" shown in FIG. 6 is delayed, and theoretically, the amount of the discharged droplets that are pulled back into the liquid discharge channel 45A decreases. Therefore, the discharge amount tends to increase. Further, according to the experimental results shown in FIGS. 15 and 16, if the width of "OFF" is longer than twice the width of the on-pulse peak, droplet splitting may occur. Therefore, for example, by setting the width of "OFF" to twice or less the width of the on-pulse peak, the droplet can be miniaturized more stably.

Further, as shown in FIGS. 15 and 16, when the width of "OFF" is shorter than the width of "ON1", the liquid may not be discharged (liquid non-discharge) or the discharge amount may increase. Therefore, the predetermined time interval (“OFF” shown in FIG. 11) from the main pulse signal (first pulse signal) to the auxiliary pulse signal (second pulse signal) is the pulse width of the main pulse signal (“OFF” shown in FIG. 11). It may be more than the width of "ON1").

<3. Third Embodiment>
Subsequently, the third embodiment will be described. Since the configuration of the liquid injection recording device 1 in the third embodiment is the same as that in the first embodiment, the description thereof will be omitted. Since the method for driving the liquid injection head according to the third embodiment is embodied in the liquid injection recording device 1 according to the third embodiment, the method will be described below.

In the first embodiment, in the control method to which the auxiliary pulse signal is added, the widths of "OFF" and "ON2" are fixed and the width of "ON1" is changed, and in the second embodiment, "ON1" and "ON1" and The case where the width of "ON2" is fixed and the width of "OFF" is changed has been described. In the third embodiment, a case where the widths of "ON1" and "OFF" are fixed and the width of "ON2" is changed will be described. The drive waveform is the waveform shown in FIG. 11, and the liquid injection heads used in the experiments under the standard droplet condition and the large droplet condition are the same as those in the first and second embodiments.

18 and 19 are tables showing experimental results when the width of the auxiliary pulse signal “ON2” is changed in the drive waveform shown in FIG. FIG. 18 is an experimental result under the condition of using a liquid injection head of a standard droplet with a solvent-based ink as in FIG. On the other hand, FIG. 19 shows the experimental results under the condition of using the liquid injection head of large droplets with the water-based ink as in FIG. 9. The width of "ON1" is fixed at 0.65 AP under the standard droplet condition and 0.53 AP under the large droplet condition as a value of 1 AP or less as in the second embodiment. Further, the width of "OFF" is fixed to twice or less of "ON1" based on the experimental result of the second embodiment. Here, the width of "OFF" is 0.88 AP under the standard droplet condition, as a value in which the increase in voltage (peak value) is not so large, the discharge amount is expected to decrease, and droplet splitting does not occur. It is fixed at 0.76 AP under the condition of large droplets.

Further, FIG. 20 is a graph showing the experimental results shown in FIGS. 18 and 19, showing the change in the discharge amount when the width of “ON2” is changed. The horizontal axis is the width of "ON2", and the vertical axis is the discharge amount at the voltage (peak value) which is the reference speed. Further, the solid line 401 shows the change in the discharge amount under the condition of the standard droplet, and the broken line 402 shows the change in the discharge amount under the condition of the large droplet.

As shown in FIGS. 18 to 20, the width of "ON1" is 1 AP or less, the width of "OFF" is twice or less the width of "ON1", and the width of "ON2" is less than the width of "ON1". Thereby, the droplet can be miniaturized. For example, in the illustrated experimental results, under the standard droplet conditions, "ON1" is 0.65 AP, whereas "ON2" is 0.58 AP to 0.12 AP, and the discharge amount is 79.5%. It is ~ 68.7%, and the droplets are miniaturized. Further, under the condition of a large droplet, "ON1" is 0.53AP, whereas the discharge amount when "ON2" is 0.45AP to 0.12AP is 57.1% to 70.1%. Yes, the droplets are miniaturized.

As described above, in the liquid injection head 4 included in the liquid injection recording device 1 according to the third embodiment, the pulse width (width of "ON2" shown in FIG. 11) of the auxiliary pulse signal (second pulse signal) is , It is preferable that the pulse width of the main pulse signal (first pulse signal) is smaller than the pulse width (width of “ON1” shown in FIG. 11) because the droplets can be miniaturized. In the third embodiment, the pulse width of the main pulse signal (the width of “ON1” shown in FIG. 11) is equal to or less than the width of the on-pulse peak (or the width of the on-pulse peak) as in the first embodiment. Less than width). Further, the predetermined time interval (“OFF” shown in FIG. 11) from the main pulse signal to the auxiliary pulse signal is not more than twice the width of the on-pulse peak.

As described above, in the third embodiment, the condition of "ON1" of the main pulse signal in the first embodiment and the condition of "OFF" from the main pulse signal to the auxiliary pulse signal in the second embodiment are set. By adding the condition of "ON2" of the auxiliary pulse signal, the droplet at the time of ejecting one droplet can be miniaturized without changing the structure of the liquid injection head 4 as in the first and second embodiments. , It can be further stably miniaturized.

For example, if the width of "ON2" is increased, the fall time t4 of "ON2" shown in FIG. 6 is delayed and increases after the volume of ink (liquid) in the liquid ejection channel 45A starts to increase. It is possible that the ink (liquid) that has been added is added and the volume of the liquid ejection channel 45A begins to shrink in an attempt to return to the original volume, so that the ink is ejected. Therefore, the discharge amount tends to increase or the seat split tends to occur. Therefore, for example, by setting the width of "ON2" to be less than the width of "ON1", the droplet can be further stably miniaturized. More specifically, for example, under the condition of a standard droplet, "ON2" is 0.58 AP or less, and the droplet can be stably miniaturized. Further, for example, under the condition of a large droplet, "ON2" is 0.45 AP or less, and the droplet can be stably miniaturized. Further, the voltage (peak value) as the reference speed at this time is about 110 to 120% under the condition of the standard droplet and about 130 to 136% under the condition of the large droplet.

In this way, for example, the width of "ON1" is less than or equal to the width of the on-pulse peak (or less than the width of the on-pulse peak), the width of "OFF" is less than twice the width of the on-pulse peak, and the width of "ON2" is set. By setting the width to less than the width of "ON1", as shown in FIGS. 18 to 20, it is possible to stably realize the miniaturization of the droplet while suppressing the increase in the voltage (peak value).

<4. Fourth Embodiment>
Subsequently, the fourth embodiment will be described. Since the configuration of the liquid injection recording device 1 in the fourth embodiment is the same as that in the first embodiment, the description thereof will be omitted. Since the method for driving the liquid injection head according to the fourth embodiment is embodied in the liquid injection recording device 1 according to the fourth embodiment, the method will be described below.

In the first embodiment, in the control method to which the auxiliary pulse signal is added, the widths of "OFF" and "ON2" are fixed and the width of "ON1" is changed, and in the second embodiment, "ON1" and "ON1" and The case where the width of "ON2" is fixed and the width of "OFF" is changed has been described. Further, in the third embodiment, the case where the width of "ON1" and "OFF" is fixed and the width of "ON2" is changed has been described.

In each of these first to third embodiments, the main pulse signal (pulse signal having the pulse width of "ON1") and the auxiliary pulse signal (pulse signal having the pulse width of "ON2") are simple. It is composed of one (one) pulse signal. In other words, in each of the first to third embodiments, only one pulse signal applied before the auxiliary pulse signal is provided, that is, only the main pulse signal applied immediately before the auxiliary pulse signal. Has been done.

On the other hand, in the fourth embodiment, as described in detail below, the auxiliary pulse signal (pulse signal having a pulse width of "ON2") is composed of one pulse signal, while the main pulse. The signal is composed of a plurality of (two or more) pulse signals. In other words, in the fourth embodiment, unlike the first to third embodiments, a plurality of pulse signals (main pulse signals) applied before the auxiliary pulse signal are provided. The so-called "multi-pulse method" driving method has come to be used.

FIG. 21 shows an example of the drive waveform in the fourth embodiment. In the example shown in FIG. 21, as described above, a pulse having a pulse width of “ON11” is applied as a main pulse signal applied before the auxiliary pulse signal (a pulse signal having a pulse width of “ON2”). Two are provided, a signal and a pulse signal having a pulse width of "ON12".

Further, in the fourth embodiment, an "OFF1" period, which is a predetermined time interval, is provided between the pulse signal having the pulse width of "ON11" and the pulse signal having the pulse width of "ON12". Has been done. Similarly, an "OFF2" period, which is a predetermined time interval, is provided between the pulse signal having the pulse width of "ON12" and the auxiliary pulse signal (the pulse signal having the pulse width of "ON2"). ..

Then, the control circuit 35 in the fourth embodiment has a pulse width (“ON12”” equal to or less than the width of the on-pulse peak as a pulse signal that expands the volume in the liquid discharge channel 45A when one drop of ink is jetted. A main pulse signal having a width) and an auxiliary pulse signal provided at a predetermined time interval (“OFF2”) from the main pulse signal are applied so as to be included. Specifically, in the present embodiment, the control circuit 35 has the above-mentioned two main pulse signals (“ON11”” as pulse signals that expand the volume in the liquid ejection channel 45A when one drop of ink is ejected. , Two pulse signals having a pulse width of "ON12") and one auxiliary pulse signal are applied, respectively.

Here, in the present embodiment, unlike the first to third embodiments described so far, of the above two main pulse signals, the pulse signal having the pulse width of "ON12" is the present. Corresponds to a specific example of the "first pulse signal" in the disclosure. That is, of the plurality of main pulse signals, only the main pulse signal applied immediately before the auxiliary pulse signal corresponds to a specific example of the "first pulse signal" in the present disclosure. Further, in the present embodiment, unlike the first to third embodiments described so far, only the "OFF2" period among the above-mentioned "OFF1" period and "OFF2" period is described in the present disclosure. Corresponds to a specific example of "predetermined time interval".

Therefore, also in the present embodiment, the pulse width of "ON12", the pulse width of "ON2", and the length of the "OFF2" period are the same as in the first to third embodiments described so far. Etc. may be set respectively.

FIG. 22 is a table showing the experimental results when the width of “ON12” in the main pulse signal is changed in the drive waveform shown in FIG. 21, and is a large droplet of water-based ink as in FIG. It is an experimental result under the condition using the liquid injection head of. The width of "ON11" is fixed to 0.58AP, and the width of "ON2" is fixed to 0.31AP as a value of 1AP or less as in the first and second embodiments. The widths of "OFF1" and "OFF2" are fixed at 1.42AP and 0.46AP, respectively.

The voltage (peak value) and discharge amount of 6 m / s (reference voltage) shown in the figure are set to "ON12" in the control when the auxiliary pulse signal is not added (when only the above two main pulse signals are applied). Is a relative value (ratio: unit is%) with each as 100% when the width of the on-pulse peak (1.00 AP).

Further, FIG. 23 is a graph showing the experimental results shown in FIG. 22 and shows the change in the discharge amount when the width of “ON12” is changed (see the solid line 501). The horizontal axis is the width of "ON12", and the vertical axis is the discharge amount at the voltage (peak value) which is the reference speed.

As shown in FIGS. 22 and 23, even in the driving method of the present embodiment (driving method of the “multi-pulse method”), the droplets are the same as those of the first to third embodiments described so far. Can be miniaturized. Specifically, in this experimental result, the discharge amount is 87.6% to 98.7% except for some conditions, and the droplet is miniaturized. That is, even in the case of the multi-pulse method, by adding an auxiliary pulse signal (a pulse signal having a pulse width of "ON2"), the ejection amount when ejecting one drop of ink becomes small (one drop becomes small). ) The phenomenon is shown.

In this embodiment, as described above, the widths of "ON11", "ON2", "OFF1", and "OFF2" are fixed and the width of "ON12" is changed. Is not limited. That is, in the case of the multi-pulse method as in the present embodiment, for example, by changing the width of "ON11" and "ON2" and the width of "OFF1" and "OFF2", the present embodiment can be used. Similarly, the ejection amount can be changed while reducing the size of the droplet.

In this way, in the present embodiment, when one drop of ink is ejected, a pulse width (width of "ON12") equal to or less than the width of the on-pulse peak is used as a pulse signal for expanding the volume in the liquid ejection channel 45A. It is applied so as to include a main pulse signal having the main pulse signal and an auxiliary pulse signal (pulse signal having a pulse width of “ON2”) provided at a predetermined time interval (“OFF2”) from the main pulse signal.

As a result, the droplets at the time of ejecting one droplet can be miniaturized without changing the structure of the liquid injection head 4, and the minimum ejection amount can be reduced. Therefore, also in the fourth embodiment, as in the first to third embodiments, it is possible to easily reduce the size of the droplet when ejecting one drop, and to improve the image quality. can.

Further, in the present embodiment, as described above, since the auxiliary pulse signal is added in the case of the multi-pulse method, for example, the following effects can be obtained. That is, in this multi-pulse method, generally, the ejection amount when ejecting one drop of ink is a discrete value (discrete value) according to the number of pulse signals and the pulse width, but an auxiliary pulse signal is added. It is possible to specify the discharge value that fills the gap between such discrete values. Therefore, the number of ink ejection values that can be set can be increased, and the convenience can be improved.

In the present embodiment, the control circuit 35 has the above-mentioned two main pulse signals and one auxiliary pulse signal as pulse signals that expand the volume in the liquid ejection channel 45A when one drop of ink is ejected. Are applied respectively. That is, in the present embodiment, the case of the so-called "two-drop waveform" in the case of the multi-pulse method has been described as an example. However, the present invention is not limited to this example, and the auxiliary pulse signal may be additionally applied in the case of the “waveform of 3 drops or more” in the same manner as in the present embodiment. That is, the control circuit 35 applies three or more main pulse signals and one auxiliary pulse signal as pulse signals that expand the volume in the liquid ejection channel 45A when injecting one drop of ink. You may do it. Even in this case, of the three or more main pulse signals, only the main pulse signal applied immediately before the auxiliary pulse signal corresponds to a specific example of the "first pulse signal" in the present disclosure. ..

As described above, as described with respect to the first to fourth embodiments, even if any of the control methods of the first to fourth embodiments is used, the droplets at the time of ejecting one droplet without changing the head structure are used. Can be miniaturized, which makes it possible to change the minimum discharge amount when one drop is discharged. Further, as can be seen from the experimental results of the first to fourth embodiments, any of the control methods of the first to fourth embodiments is applied regardless of the type of ink (solvent-based ink, water-based ink, etc.). be able to.

<5. Modification example>
Although the present disclosure has been described with reference to some embodiments, the present disclosure is not limited to these embodiments and various modifications are possible.

For example, in the above-described embodiment, the case where the head tip 26 is a so-called edge shoot type in which ink is ejected from the nozzle hole 43a facing the longitudinal end of the liquid ejection channel 45A has been described. However, the present invention is not limited to this, and the configuration of the above-described embodiment can also be adopted for a so-called side chute type head tip that ejects ink from a nozzle hole facing the center in the longitudinal direction of the liquid ejection channel 45A. Is. Further, the liquid injection head 4 may be a circulation type liquid injection head that recirculates the ink supplied to each liquid discharge channel 45A to the storage chamber of the pressure shock absorber 32, or may be a non-circulation type liquid injection head. There may be.

Further, in the above-described embodiment, the pair of transport means 2 and 3 for transporting the recorded medium S such as recording paper and the liquid injection head 4 are scanned in the scanning direction X orthogonal to the transport direction Y of the recorded medium S. The liquid injection recording device 1 for recording by moving the scanning means 6 has been described. Instead, the scanning means 6 is fixed and the moving mechanism moves the recording medium two-dimensionally for recording. It may be a recording device. That is, the moving mechanism may be any one that relatively moves the liquid injection head and the recording medium.

Further, in the above-described embodiment, the case where the pulse signal that expands the volume in the liquid discharge channel 45A is a pulse signal (positive pulse signal) that expands during the high period has been described, but in this case, Not limited. That is, not only in the case of a pulse signal that expands in the high period and contracts in the low period, but conversely, as a pulse signal (negative pulse signal) that expands in the low period and contracts in the high period. May be good.

Further, for example, a signal for assisting the ejection of the droplet may be additionally applied immediately after the “ON” period and during the “OFF” period. Examples of the signal for assisting the ejection of the droplet include a pulse signal for contracting the volume in the liquid ejection channel 45A (the expanded volume is contracted once and then further contracted). Even if a signal for assisting the ejection of such droplets is added, it does not affect the contents (driving method, etc.) of the present disclosure described so far.

It should be noted that all or a part of the functions of each part of the control circuit 35 in the above-described embodiment are recorded on a computer-readable recording medium by recording a program for realizing these functions on the recording medium. It may be realized by loading the program into a computer system and executing it. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. Further, such a "program" corresponds to a specific example of the "drive program of the liquid injection head" in the present disclosure.

Further, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, or a storage unit such as a hard disk built in a computer system. Further, a "computer-readable recording medium" is a communication line for transmitting a program via a network such as the Internet or a communication line such as a telephone line, and dynamically holds the program for a short period of time. It may also include a program that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or a client in that case. Further, the above-mentioned program may be for realizing a part of the above-mentioned functions, and may be further realized for realizing the above-mentioned functions in combination with a program already recorded in the computer system.

Further, the control circuit 35 in the above-described embodiment may be realized as an integrated circuit such as an LSI (Large Scale Integration). Further, for example, the control circuit 35 may be integrated into a processor. Further, the method of making an integrated circuit is not limited to the LSI, and may be realized by a dedicated circuit or a general-purpose processor. Further, when an integrated circuit technology that replaces an LSI appears due to advances in semiconductor technology, an integrated circuit based on this technology may be used.

Further, various examples described so far may be applied in any combination.

It should be noted that the effects described in the present specification are merely examples and are not limited, and other effects may be obtained.

In addition, the present disclosure may have the following structure.
(1)
A nozzle that sprays liquid and
A piezoelectric actuator that has a pressure chamber that communicates with the nozzle and is filled with the liquid and that changes the volume of the pressure chamber.
A control unit that expands and contracts the volume of the pressure chamber by applying a pulse signal to the piezoelectric actuator and injects the liquid filled in the pressure chamber.
Equipped with
The control unit
As the pulse signal that expands the volume in the pressure chamber when one drop of the liquid is injected, a first pulse signal having a pulse width equal to or less than the width of the on-pulse peak and a predetermined time interval from the first pulse signal. A liquid injection head that is applied so as to include a second pulse signal provided at intervals.
(2)
The first pulse signal is the pulse signal applied immediately before the second pulse signal.
The liquid injection head according to (1) above, wherein the pulse width of the second pulse signal is smaller than the pulse width of the first pulse signal.
(3)
The liquid injection head according to (2) above, wherein the predetermined time interval is not more than twice the width of the on-pulse peak.
(4)
The first pulse signal is the pulse signal applied immediately before the second pulse signal.
The liquid injection head according to any one of (1) to (3) above, wherein the predetermined time interval is equal to or larger than the pulse width of the first pulse signal.
(5)
The first pulse signal is the pulse signal applied immediately before the second pulse signal.
The liquid injection head according to any one of (1) to (4) above, wherein the pulse width of the first pulse signal is less than the width of the on-pulse peak.
(6)
The liquid injection head according to any one of (1) to (5) above, wherein the pulse width of the second pulse signal is 0.58 times or less the width of the on-pulse peak.
(7)
When the control unit injects a drop of the liquid, the control unit
The pulse signal applied before the second pulse signal includes the first pulse signal applied immediately before the second pulse signal, and a plurality of the pulse signals are provided from (1) to (6). ) The liquid injection head according to any one of.
(8)
A liquid injection recording device provided with the liquid injection head according to any one of (1) to (7) above.
(9)
By applying a pulse signal to the piezoelectric actuator that changes the volume of the pressure chamber communicating with the nozzle, the volume of the pressure chamber is expanded and contracted, and one drop of the liquid filled in the pressure chamber is dropped from the nozzle. When spraying
Applying the pulse signal to expand the volume in the pressure chamber
Applying a first pulse signal with a pulse width equal to or less than the width of the on-pulse peak,
Applying a second pulse signal provided at a predetermined time interval from the first pulse signal, and
How to drive the liquid injection head, including.
(10)
By applying a pulse signal to the piezoelectric actuator that changes the volume of the pressure chamber communicating with the nozzle, the volume of the pressure chamber is expanded and contracted, and one drop of the liquid filled in the pressure chamber is dropped from the nozzle. When spraying
Applying the pulse signal to expand the volume in the pressure chamber
Applying a first pulse signal with a pulse width equal to or less than the width of the on-pulse peak,
Applying a second pulse signal provided at a predetermined time interval from the first pulse signal, and
A liquid injection head drive program that causes the computer to run to include.

1 ... Liquid injection recording device, 4 ... Liquid injection head, 28 ... Control unit, 35 ... Control circuit, 36 ... IC board, 37 ... Flexible board, 40 ... Actuator plate, 43a ... Nozzle hole, 45 ... Channel, 45A ... Liquid Discharge channel, 51 ... common terminal, 53 ... individual terminal.

Claims (9)

A nozzle that sprays liquid and
A piezoelectric actuator that has a pressure chamber that communicates with the nozzle and is filled with the liquid and that changes the volume of the pressure chamber.
A control unit that expands and contracts the volume of the pressure chamber by applying a pulse signal to the piezoelectric actuator and injects the liquid filled in the pressure chamber.
Equipped with
The control unit
As the pulse signal that expands the volume in the pressure chamber when one drop of the liquid is injected, the first pulse signal having a pulse width less than the width of the on-pulse peak and twice or less the width of the on-pulse peak. A predetermined time interval is applied so as to include a second pulse signal provided apart from the first pulse signal .
The predetermined time interval is 0.61 times or more and 1.08 times or less the width of the on-pulse peak.
The first pulse signal is a pulse signal for injecting a droplet, and is a pulse signal.
The second pulse signal is an auxiliary pulse signal for pulling back a part of the droplet ejected by the first pulse signal, and is the last pulse when ejecting one drop of the liquid.
Liquid injection head. The first pulse signal is the pulse signal applied immediately before the second pulse signal.
The liquid injection head according to claim 1, wherein the pulse width of the second pulse signal is smaller than the pulse width of the first pulse signal. The first pulse signal is the pulse signal applied immediately before the second pulse signal.
The liquid injection head according to claim 1 or 2, wherein the predetermined time interval is equal to or larger than the pulse width of the first pulse signal. The liquid injection head according to any one of claims 1 to 3, wherein the pulse width of the second pulse signal is 0.58 times or less the width of the on-pulse peak. The liquid injection head according to any one of claims 1 to 4, wherein the predetermined time interval is 0.76 times or more and 1.08 times or less the width of the on-pulse peak. When the control unit injects a drop of the liquid, the control unit
Claims 1 to 5 so that the pulse signal applied before the second pulse signal includes the first pulse signal applied immediately before the second pulse signal and is provided in a plurality thereof. The liquid injection head according to any one of the above items. A liquid injection recording device including the liquid injection head according to any one of claims 1 to 6 . By applying a pulse signal to the piezoelectric actuator that changes the volume of the pressure chamber communicating with the nozzle, the volume of the pressure chamber is expanded and contracted, and one drop of the liquid filled in the pressure chamber is dropped from the nozzle. When spraying
Applying the pulse signal to expand the volume in the pressure chamber
Applying a first pulse signal with a pulse width less than the width of the on-pulse peak,
Applying a second pulse signal provided at a predetermined time interval equal to or less than twice the width of the on-pulse peak from the first pulse signal, and
Includes
The predetermined time interval is 0.61 times or more and 1.08 times or less the width of the on-pulse peak.
The first pulse signal is a pulse signal for injecting a droplet, and is a pulse signal.
The second pulse signal is an auxiliary pulse signal for pulling back a part of the droplet ejected by the first pulse signal, and is the last pulse when ejecting one drop of the liquid.
How to drive the liquid injection head. By applying a pulse signal to the piezoelectric actuator that changes the volume of the pressure chamber communicating with the nozzle, the volume of the pressure chamber is expanded and contracted, and one drop of the liquid filled in the pressure chamber is dropped from the nozzle. When spraying
Applying the pulse signal to expand the volume in the pressure chamber
Applying a first pulse signal with a pulse width less than the width of the on-pulse peak,
Applying a second pulse signal provided at a predetermined time interval equal to or less than twice the width of the on-pulse peak from the first pulse signal, and
Let the computer run to include
The predetermined time interval is 0.61 times or more and 1.08 times or less the width of the on-pulse peak.
The first pulse signal is a pulse signal for injecting a droplet, and is a pulse signal.
The second pulse signal is an auxiliary pulse signal for pulling back a part of the droplet ejected by the first pulse signal, and is the last pulse when ejecting one drop of the liquid.
Drive program for the liquid injection head.

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