JP4853219B2 - Droplet ejector - Google Patents

Description

  The present invention relates to a droplet ejecting apparatus.

  2. Description of the Related Art Conventionally, ink jet recording apparatuses that eject ink droplets from a plurality of nozzles and perform printing on a recording medium such as paper have various advantages such as small size, low cost, and quietness, and are widely marketed. In particular, a piezo ink jet recording apparatus that ejects ink droplets by changing the pressure in a pressure chamber using a piezoelectric element has many advantages such as high-speed printing and high resolution.

  In such an ink jet recording apparatus, it is known to perform wiping in order to remove contaminants such as ink and paper dust adhering to the nozzle surface of the droplet ejection head. At this time, in order to prevent the wiper blade from deteriorating due to friction with the nozzle surface or to improve the wiping ability by dissolving the ink solidified on the nozzle surface, the nozzle surface or the wiper blade is wiped in a wet state. A technique (referred to as wet wipe) is also known.

  As a method for realizing this wet wipe, a method of performing a wiping operation while causing ink to overflow from the nozzle by pressurizing the ink supplied to the head (see, for example, Patent Document 1), and overflowing ink from the nozzle opening. A method of performing a wiping operation by applying a signal different from that at the time of printing in order to make it appear (see, for example, Patent Document 2), and a dedicated opening having a larger opening than the nozzle for jetting in order to overflow the cleaning liquid in the head A method of performing a wiping operation by providing a nozzle and applying a voltage lower than that during jetting (for example, see Patent Document 3) is known.

  As a method other than these, a driving waveform dedicated for wiping the nozzle surface (hereinafter referred to as “ink overflow waveform”) different from the driving waveform during ejection (hereinafter referred to as “ejection waveform”) is applied during wiping. And a method of performing wiping in a state where ink is overflowed from the nozzle opening to the head surface (referred to as “FaceFlood”).

In this method, when the ejection characteristics vary between nozzles, nozzle groups, or between heads due to variations in head manufacturing, etc., the ejection waveform is adjusted in the voltage direction so that the ejection characteristics fall within a certain range. It is known to do. Also in the ink overflow waveform, it is necessary to adjust the ink overflow waveform in the voltage direction in order to keep the ink overflow characteristic within a certain range in the same manner as the ejection waveform.
Japanese Patent Laid-Open No. 3-99857 JP-A-7-96604 JP 2002-166562 A

  However, the ejection waveform can be adjusted by analyzing the printed test pattern, but it is difficult to quantitatively measure the wetting caused by ink overflow. For this reason, it is not easy to adjust the waveform as in the case of the ejection waveform, and there is a problem that a new waveform adjustment method is required in the case of the ink overflow waveform.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a droplet ejecting apparatus that wipes the nozzle surface by optimizing the amount of droplets on the nozzle surface of the droplet ejecting head. .

In order to solve the above-mentioned object, a droplet ejecting apparatus according to claim 1 includes a droplet ejecting head that ejects droplets from a plurality of nozzles by applying a pressure wave to a liquid in a pressure chamber by a driving element, and a nozzle surface. of the time wiping without ejecting droplets from the nozzle, and as the liquid overflows on the nozzle surface, wherein a maximum flow rate of the liquid at the opening of the nozzle is 1.0 to 3.0 m / s A correction magnification within a certain range centered on the optimum range of the correction magnification of the ejection waveform for generating droplets from the nozzle while generating the ink overflow waveform when wiping the nozzle surface Driving waveform generating means for correcting the nozzle surface, and wiping means for wiping the nozzle surface of the droplet ejecting head in a state where the liquid overflows the nozzle surface when wiping the nozzle surface, and the driving waveform generating means ,consumption When it is desired to suppress the force, the correction ratio of the ink overflow waveform is set to a small value within a certain range centered on the optimum range of the correction ratio of the ejection waveform, and the environment in which the liquid is easily solidified or the When the liquid has physical properties that tend to solidify, the correction factor of the ink overflow waveform is set to a large value within a certain range centered on the optimum range of the correction factor of the ejection waveform. And

According to a second aspect of the present invention, in the liquid droplet ejecting apparatus according to the first aspect, the driving waveform generating unit is any one of the liquid droplet ejecting head unit, the nozzle unit, and a plurality of nozzle units . When the voltage of the ejection waveform is corrected by the correction magnification in units, the voltage of the ink overflow waveform is corrected in a certain range around the optimum range of the correction magnification in any one of the units.

According to a third aspect of the present invention, in the liquid droplet ejecting apparatus according to the second aspect, the drive waveform generating means sets the voltage of the ink overflow waveform to 0.85 to 1.15 times the predetermined magnification. Correct with magnification.

According to a fourth aspect of the present invention, in the liquid droplet ejecting apparatus according to the second aspect, the drive waveform generating unit corrects the voltage of the ink overflow waveform at the same magnification as the predetermined magnification.

  According to the first aspect of the present invention, there is obtained an effect that the nozzle surface can be wiped off with an appropriate amount of ink overflow without ink flying or bubble entrainment.

  Further, according to the second to fourth aspects of the invention, even when the ejection waveform is corrected at a predetermined magnification, the nozzle surface is wiped off with an appropriate amount of ink overflow without ink flying or bubble entrainment. The effect of being able to be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an ink jet recording apparatus 10 including a liquid droplet ejecting apparatus according to this embodiment of the present invention.

  As shown in FIG. 1, the ink jet recording apparatus 10 is capable of transporting paper P as a recording medium. A droplet ejecting head (hereinafter referred to as “recording head”) 12 having a width wider than the maximum width of the paper P is provided above the transport path of the paper P. The recording head 12 includes a plurality of unit heads 14A and 14B, and is arranged in a staggered manner on the upstream side and the downstream side of the paper P to be conveyed.

  As shown in FIGS. 2 and 3, a plurality of nozzles 16 are formed on the bottom surfaces (surfaces facing the paper) of the unit heads 14 </ b> A and 14 </ b> B, and ink droplets corresponding to image information are generated from these nozzles 16. Discharged. Therefore, as shown in FIG. 1, on the paper P on which image recording has been completed, an area recorded by the unit head 14A located on the upstream side of the recording head 12, and a unit head 14B located on the downstream side of the recording head 12. The areas recorded by the above are alternately arranged along the width direction of the paper P.

  Here, in the unit heads 14A and 14B adjacent in the width direction of the conveyed paper P, the end portions of the unit heads 14A and 14B are arranged so as to overlap each other, and there is an area that cannot be printed in the print area. It does not occur.

  In this way, by arranging the unit heads 14A and 14B along the width direction of the paper P to form a print area, the recording head 12 does not need to move along the width direction of the paper P, and the movement of the paper P As a result, an image is formed on the entire surface of the paper P, so that high productivity can be obtained.

  As shown in FIG. 1, a rubber wiper blade 18 for wiping the nozzle surface 17 (see FIGS. 2 and 3) of the unit head 14 is disposed below the recording head 12. The wiper blade 18 is housed in a box-like wiper holder 20 with the tip end surface being horizontal and the tip end exposed.

  Support pieces 20 </ b> A and 20 </ b> B project from the bottom surfaces on both sides of the wiper holder 20 along the width direction of the recording head 12, and the tip portions are fixed to the belts 22 and 24. The belt 22 is arranged in parallel with the transport direction of the paper P while being wound around the pulleys 26 and 28. The belt 24 is arranged in parallel with the conveyance direction of the paper P in a state of being wound around a pulley (not shown) and the pulley 30. The pulley 26 and the pulley 30 are connected by a shaft 32, and the pulley 28 and a pulley (not shown) are connected by a shaft 34.

  A gear 36 is connected to the pulley 28. The gear 36 meshes with a gear 40 connected to a motor 38, and when the motor 38 is driven, a driving force is transmitted to the pulley 28 via the gears 40 and 36. When the pulley 28 is rotated by this driving force, a pulley (not shown) is rotated via the shaft 34, and the pulleys 26 and 30 are rotated via the belts 22 and 24. At this time, since the belts 22 and 24 move in parallel with the moving direction of the paper P, the wiper blade 18 can move along the arrow A direction via the support pieces 20A and 20B and the wiper holder 20.

  As shown in FIG. 3, the unit head 14 has a flow path forming plate 52, a communication hole plate 54, a pressure chamber plate 56, and a vibration plate 58 above the nozzle plate 50 in which the plurality of nozzles 16 are formed. Are aligned and laminated, and are bonded by a bonding means such as an adhesive.

  A plurality of communication holes 62 communicating with the nozzles 16 are formed in the flow path forming plate 52, and a plurality of communication holes 64 are formed in the communication hole plate 54. The nozzle 16, the communication hole 62, and the communication hole 64 communicate with each other and are connected to a pressure chamber 66 formed in the pressure chamber plate 56.

  On the other hand, a plurality of ink pools 68 are formed in the flow path forming plate 52, and ink is supplied from an ink supply port (not shown). The communication hole plate 54 is formed with a plurality of supply holes 70 so as to be connected to the ink pool 68. The ink pool 68, the supply hole 70, and the pressure chamber 66 communicate with each other in a state where the flow path forming plate 52, the communication hole plate 54, and the pressure chamber plate 56 are laminated.

  In addition, a piezoelectric element 60 is attached to the upper part of the vibration plate 58 above each pressure chamber 66. A drive waveform is applied to the piezoelectric element 60.

  In such a recording head 12, as shown in FIG. 3, a continuous ink passage is formed from the ink pool 68 to the supply hole 70, the pressure chamber 66, the communication hole 64, the communication hole 62, and the nozzle 16. The ink stored in the ink pool 68 is filled into the pressure chamber 66 through the supply hole 70. When a driving waveform is applied from the circuit board to each piezoelectric element 60, the diaphragm 58 is bent and deformed together with the piezoelectric element 60 to expand or compress the pressure chamber 66. As a result, when a volume change occurs in the pressure chamber 66, a pressure wave is generated in the pressure chamber 66. The ink moves by the action of the pressure wave, and ink droplets are ejected from the nozzle 16 to the outside.

  In the ink jet recording apparatus 10, when wiping is performed without sucking ink from the nozzle 16, ink does not discharge from the circuit board to each piezoelectric element 60 before wiping starts, and ink overflows the nozzle surface 17. A drive voltage having such a voltage waveform (ink overflow waveform) is applied. Thereafter, the drive unit 72 (see FIG. 2) rotates the motor 38 shown in FIG. 1, moves the wiper blade 18 in the direction of arrow A, and wipes the nozzle surface 17.

  FIG. 4 is a block diagram showing a configuration for driving the piezoelectric element 60. As shown in the figure, the head drive control circuit 82 generates a nozzle selection signal for selecting a nozzle for ejecting ink droplets in accordance with an instruction of a head drive signal from the controller 80, and transmits it to the drive unit 72. Further, the head drive control circuit 82 generates waveform information indicating a waveform generated from an ejection waveform or an ink overflow waveform corresponding to the size of the ink droplet to be ejected, and correction magnification information for correcting the waveform. Transmit to the waveform generation circuit 84.

  The waveform generation circuit 84 generates an ejection waveform or an ink overflow waveform based on the waveform information received from the head drive control circuit 82, and when there is correction magnification information to the drive unit 72, an ejection waveform or ink overflow based on the waveform information. The waveform is corrected with the correction magnification and transmitted to the drive unit 72.

  The drive unit 72 selects the nozzle 16 based on the received nozzle selection information, and applies a drive waveform to the piezoelectric element 60 corresponding to the selected nozzle 16. The piezoelectric element 60 changes its shape by applying a drive waveform, and applies pressure to the pressure chamber 66 shown in FIG. 3 using this change in shape, and ejects ink droplets from the nozzle 16 according to the drive waveform, or The ink liquid overflows the nozzle surface 17 for wiping.

  FIG. 5 shows an example of an ink overflow waveform applied to the piezoelectric element 60 during wiping. As shown in FIG. 5, the ink overflow waveform is a triangular waveform, and the voltage is increased in the direction in which the pressure chamber 66 is contracted, and then the voltage is decreased in the direction in which the pressure chamber 66 is expanded. By applying such a triangular waveform at 18 kHz, which is the same as the ejection frequency, it is possible to form a state in which ink overflows the nozzle surface 17. The waveform is not limited to a triangular waveform, and may be a square waveform or a trapezoidal waveform.

  Next, the operation of the ink jet recording apparatus 10 when the ink overflow waveform shown in FIG. 5 is applied, and the wiping operation of the nozzle surface 17 of the present embodiment will be described. In FIG. 6, the behavior of the ink near the nozzle opening 19 when this ink overflow waveform is applied is shown in order from (a) to (d).

  In this wiping method, the nozzle surface 17 is wiped without sucking ink from the nozzles 16. As shown in FIG. 6A, in the initial state where ink is not sucked and the nozzle surface 17 is dry, the nozzle surface 17 is contaminated with ink mist. Before starting wiping, the ink overflow waveform shown in FIG. 5 is applied to each piezoelectric element 60 (see FIG. 3). This ink overflow waveform is set to such a voltage waveform that ink droplets are not ejected from the nozzles 16 and the ink overflows. As a result, as shown in FIG. 6B, ink overflow (ink overflow) 90 occurs on the nozzle surface 17 in the vicinity of the nozzle opening 19. Immediately after applying the ink overflow waveform, as shown in FIG. 6C, the motor 38 (see FIG. 1) is rotated to move the wiper blade 18 in the direction of the arrow, and the nozzle surface 17 is wiped.

  By this wiping, as shown in FIG. 6D, the ink overflow (ink overflow) 90 is wiped off by the wiper blade 18, and the ink is collected at the tip of the wiper blade 18. For this reason, the contact portion between the wiper blade 18 and the nozzle surface 17 becomes wet immediately after the start of wiping.

Here, by applying the ink overflow waveform, the ink overflows from the nozzle opening 19 as shown in FIG. 6, and the following conditions must be satisfied in order to realize an appropriate wet wipe.
(1) Ink does not fly due to an ink overflow waveform (upper limit of applied power 1).
(2) No bubbles are trapped inside the nozzle due to the ink overflow waveform (upper limit of applied power 2).
(3) A necessary amount of ink is overflowed by the ink overflow waveform (lower limit of applied power).

  In other words, it is necessary to correct the waveform by adjusting the applied power so as to satisfy the conditions (1) to (3).

  FIG. 7 is a graph of experimental results on the relationship between the maximum ink flow rate at the nozzle opening 19 and the ink overflow. In FIGS. 7A and 7B, the optimum range A of the maximum ink flow rate in which sufficient ink overflow occurs and neither ink flying nor bubble entrainment occurs is 1.0 m / s to 3.0 m / s. In the range satisfying the above (1) to (3), the lower limit is expanded to a state where ink overflow has occurred but is somewhat insufficient, and ink will fly with some nozzles but no bubble entrainment will occur. When the upper limit is widened, the appropriate range B of the maximum ink flow rate is 0.5 m / s to 4.0 m / s. In the appropriate range B, the ink flying rate is very small, and no fatal device contamination (for example, damage to the sensor or electric system or subsequent paper smearing) does not occur.

  Although the unit is not described in the ink overflow amount on the vertical axis in FIG. 7B, it is very difficult to define and measure the ink overflow amount itself, and it is unclear how much the numerical value is meaningful. Because. However, the relative amount is described as a relative amount because it is considered meaningful.

  Table 1 summarizes the relationship between the maximum ink flow velocity at the nozzle opening 19 and the amount of ink overflow, the state of bubble entrainment, and the state of ink flight from the experimental results of FIG. In Table 1, “◯” indicates that it is suitable for performing wet wipe. As shown in Table 1, from the viewpoint of ink overflow, bubble entrainment, and ink flying, it is understood that the range suitable for performing wet wipe is a range painted in gray, and the nozzle opening 19 at that time It was revealed that the maximum flow rate of the ink at 1.0 m / s to 3.0 m / s. Therefore, it is necessary to correct the ink overflow waveform so as to satisfy this condition.

  Here, regarding the magnification when correcting the ink overflow waveform in the voltage direction, unlike the case of the ejection waveform, it is difficult to determine the correction magnification by directly inspecting the phenomenon of ink overflow. When correcting the waveform during mass production of droplet ejection devices, the ejection characteristics can be easily known by measuring the landing position, dot shape, dot diameter, patch density, etc. on the paper surface by printing a test pattern. However, it is very difficult to measure the ink flow rate at the nozzle opening and the amount of ink overflow from the nozzle opening in the ink overflow waveform. That is, in the case of the ejection waveform, it can be confirmed from the print result, but in the case of the ink overflow waveform, there is no way to confirm from the result.

  Further, since the phenomenon differs between ejection and ink overflow, the optimum range differs between the correction of the ejection waveform and the correction of the ink overflow waveform, and it is considered that the correction magnifications of the two do not match.

  As described above, since it is difficult to directly determine the correction ratio of the ink overflow waveform during mass production of the droplet ejecting apparatus, the relationship between the correction ratio of the ejection waveform and the correction ratio of the ink overflow waveform can be obtained by experiments in advance. For example, at the time of mass production, the correction magnification of the ink waveform can be calculated based on the correction magnification of the ejection waveform by obtaining the correction magnification of the ejection waveform by printing a test pattern or the like.

  FIG. 8 and FIG. 9 are graphs of the results of experiments conducted to compare the correction magnification of the ejection waveform and the correction magnification of the ink overflow waveform. In this experiment, printing or wet wiping was performed on several recording heads with different characteristics by multiplying the ejection waveform and ink overflow waveform by 0.7 to 1.6 times in the voltage direction, respectively, and the print quality and wiping effect I investigated.

  FIG. 8 shows the experimental results regarding the recording head A. FIG. In FIGS. 8A and 8B, the range satisfying the conditions (1) to (3) for realizing the appropriate wet wipe described above, that is, sufficient ink overflow occurs, and ink flying is also involved in bubbles. The optimum range of the correction magnification that does not occur is A (0.8 to 1.0 times). Furthermore, in the range satisfying the above (1) to (3), the lower limit is extended to a state where ink overflow has occurred but is slightly insufficient, and some of the nozzles will cause ink to fly but bubble entrainment will occur. The appropriate range of the correction magnification with the upper limit extended to the state where it is not performed is B (0.75 to 1.1 times).

  FIG. 9 shows the experimental results relating to the recording head B. The optimum range A of the correction magnification is 1.0 to 1.3 times, and the appropriate range B is 0.95 to 1.4 times.

  Table 2 summarizes the experimental results of FIGS. In Table 2, “◯” indicates the optimum range of the correction magnification of the ejection waveform or the correction magnification of the ink overflow waveform. As shown in Table 2, the recording head A has an optimum ejection waveform corrected 0.9 times with respect to the standard head, and the recording head B has an optimum ejection waveform corrected 1.15 times. is there. Since the ejection waveform needs to eject a desired droplet volume (image density), the optimum range of the correction magnification is very narrow. Taking the recording head A as an example, the optimum correction magnification is 0.9 times, and if it is 0.8 to 1.0 times, it is ejected normally but deviates from the target droplet volume (image density). Further, when the correction magnification is shifted up and down, landing positions and mist are generated, and further, ink droplet floating due to bubble entrainment and insufficient droplet speed (state in which the droplet speed decreases due to air resistance and does not reach the sheet) occurs.

  On the other hand, in the ink overflow waveform, even if there is a slight difference in the amount of ink overflow, there is no significant difference in the performance of wet wipes, so it can be seen that the optimum range of the correction magnification is wider than the ejection waveform. In addition, when comparing the correction magnification of the ejection waveform and the ink overflow waveform, there are conditions that do not cause landing position deviation or mist in the ejection waveform (range of experimental results of insufficient density or excessive density), and conditions that allow normal wet wipe. It can be seen that they are almost equal.

  Accordingly, the correction ratio of the ink overflow waveform is a fixed range centered on the optimum range of the correction ratio of the ejection waveform, and the range of the optimum correction magnification of the ejection waveform and the optimum correction ratio of the ink overflow waveform (in the gray portion of Table 2). From the ratio of the upper limit value and the lower limit value, it was found from the above experiment that the ratio was 0.85 to 1.15 times the correction magnification of the injection waveform.

  Further, when the correction unit is a nozzle group or a print head (that is, a set of a plurality of nozzles), the ink overflow correction magnification is within the above range (ejection waveform) considering that there are variations in characteristics among them. It was found that it is desirable to make the same as the median value of 0.85 to 1.15 times the correction magnification of the injection waveform, that is, the correction magnification of the injection waveform.

  On the other hand, when it is desired to reduce the power consumption due to waveform application as much as possible, it is desirable to make the correction ratio of the ink overflow waveform as small as possible (for example, 0.85 times the ejection waveform), and conversely, it is very easy to solidify. For the environment and ink physical properties, the ink overflow waveform correction magnification should be increased as much as possible (for example, 1.15 times the ejection waveform), and the amount of ink overflow should be increased. It became clear that it was possible.

  From the above results, it has been clarified that it is possible to derive from the correction magnification of the ejection waveform instead of directly obtaining the correction magnification of the ink overflow waveform at the time of mass production of the product. Therefore, the inkjet recording apparatus 10 according to the present embodiment has a correction magnification of 0.85 to 1.15 times the correction magnification of the ejection waveform, and more preferably the ejection waveform of each nozzle (piezoelectric element) of the recording head. The ink overflow waveform is corrected at the same correction magnification as the correction magnification. Thereby, the inkjet recording apparatus 10 can perform an appropriate wet wipe by keeping the maximum value of the ink flow velocity at the nozzle opening 19 within the optimum range of 1.0 to 3.0 m / s.

  In addition, the inkjet recording apparatus 10 may have another form that realizes wiping due to ink overflow, such as a method of causing ink to overflow more easily by controlling back pressure simultaneously with application of ink overflow waveform, or application of ink overflow waveform. At the same time, the present invention can be applied to a waveform used in a system for preventing the overflowed ink from being drawn back into the nozzle by opening and closing the valve of the flow path.

  Further, in this embodiment, the correction of the ink overflow waveform is performed in units of nozzles, but the present invention is not limited to this, and can be applied in units of a plurality of nozzles or recording heads.

1 is a partial perspective view illustrating an ink jet recording apparatus according to an embodiment. FIG. 2 is a partial configuration diagram illustrating a recording head and a wiper blade of the ink jet recording apparatus illustrated in FIG. 1. It is a fragmentary sectional view which shows the recording head of the inkjet recording device shown in FIG. It is a block diagram which shows the structure which drives a piezoelectric element. It is a figure which shows the voltage waveform (ink overflow waveform) of the drive voltage applied to a piezoelectric element at the time of wiping. It is a figure explaining operation | movement of the inkjet recording device at the time of wiping. It is a graph which shows the relationship between the maximum ink speed and ink overflow in a nozzle opening part. 6 is a graph showing a comparison between a correction magnification of an ejection waveform and a correction magnification of an ink overflow waveform (an example of a recording head A). 6 is a graph showing a comparison between a correction magnification of an ejection waveform and a correction magnification of an ink overflow waveform (an example of a recording head B).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet recording device 12 Recording head 16 Nozzle 17 Nozzle surface 18 Wiper blade 19 Nozzle opening 60 Piezoelectric element 72 Drive unit 80 Controller 82 Head control circuit 84 Waveform generation circuit 90 Ink overflow

Claims (4)

A liquid droplet ejecting head that ejects liquid droplets from a plurality of nozzles by applying a pressure wave to the liquid in the pressure chamber by a driving element;
When wiping the nozzle surface, the maximum flow velocity of the liquid at the nozzle opening is 1.0 to 3.0 m / s so that no liquid is ejected from the nozzle and the liquid overflows the nozzle surface. An ink overflow waveform at the time of wiping the nozzle surface, and the voltage of the ink overflow waveform is within a certain range centered on the optimum range of the correction magnification of the ejection waveform for ejecting droplets from the nozzle. Drive waveform generation means for correcting with the correction magnification ;
Wiping means for wiping the nozzle surface of the droplet ejection head in a state where liquid overflows the nozzle surface at the time of wiping the nozzle surface , and
The drive waveform generation means sets the correction ratio of the ink overflow waveform to a small value within a certain range centered on the optimum range of the correction ratio of the ejection waveform when it is desired to suppress power consumption, In the case where the environment in which the liquid is easily solidified or the physical property in which the liquid is easily solidified, the correction magnification of the ink overflow waveform is within a certain range centered on the optimum range of the correction magnification of the ejection waveform. A droplet ejecting apparatus characterized by being set to a large value . The drive waveform generating unit, the droplet ejection head unit, the nozzle unit, and either one unit of the plurality of nozzles unit, when correcting the voltage of the ejection waveform by the correction factor, the one of 2. The droplet ejecting apparatus according to claim 1, wherein the voltage of the ink overflow waveform is corrected in a certain range centered on the optimum range of the correction magnification. The droplet ejecting apparatus according to claim 2, wherein the drive waveform generating unit corrects the voltage of the ink overflow waveform at a magnification of 0.85 to 1.15 times the predetermined magnification. The droplet ejection apparatus according to claim 3, wherein the drive waveform generation unit corrects the voltage of the ink overflow waveform at the same magnification as the predetermined magnification.