JP2010143065A - Liquid discharge method and liquid discharge device - Google Patents

Abstract

Disclosed is a discharge port for discharging a liquid, an individual liquid chamber communicating with the discharge port, a diaphragm forming a part of an inner surface of the individual liquid chamber, and a volume of the individual liquid chamber by deforming the diaphragm. In a liquid discharge method for discharging liquid by inputting a drive signal for expanding, contracting, re-expanding, and re-contracting an individual liquid chamber to the actuator, a meniscus after completion of input of the drive signal is provided. The overshooting of the liquid is prevented, and the deflection of the liquid ejection direction due to the bending of the protruding liquid column is suppressed.
With respect to the minimal displacement of the diaphragm that appears after the completion of the drive signal input, the displacement of the diaphragm from the appearance until the time when the liquid column cutting portion is observed on the discharge port side does not fall below the minimal displacement. In addition, an auxiliary drive signal including a waveform portion for expanding the individual liquid chamber and a waveform portion for returning the individual liquid chamber to the initial volume is input to the actuator.
[Selection] Figure 7

Description

  The present invention relates to a liquid ejection method and a liquid ejection apparatus. In particular, the present invention provides a liquid discharge device that includes a discharge port for discharging a liquid and an individual liquid chamber that communicates with the discharge port, and discharges liquid by deforming a diaphragm that forms a part of the individual liquid chamber by an actuator. The present invention relates to a method and a liquid ejection apparatus. The present invention is not only a device for recording on a recording medium such as paper, cloth, leather, nonwoven fabric, and OHP plastic film, but also an apparatus for patterning and processing by attaching a liquid to a substrate, a plate material, a solid material, etc. Furthermore, it can also be applied to a coating apparatus or the like.

  2. Description of the Related Art Conventionally, a liquid discharge head that discharges liquid (such as ink) using a piezoelectric element that is deformed by application of a voltage pulse is known. Such a liquid discharge head includes a discharge port for discharging a liquid and an individual liquid chamber communicating with the discharge port, and a diaphragm is disposed on a part of the side surface of the individual liquid chamber. Then, the diaphragm is deformed by the deformation of the piezoelectric element, and the liquid is discharged by causing a change (expansion or contraction, etc.) of the internal volume of the individual liquid chamber. As a method using deformation of a piezoelectric element, there are a type using longitudinal vibration that causes expansion / contraction in the axial direction of the piezoelectric element, and a type using bending of the piezoelectric element (hereinafter referred to as a vendor type) ( For example, see Patent Document 1).

Japanese Patent No. 3425113 (page 5, FIG. 2, FIG. 3)

  One of the typical methods for ejecting liquid droplets using a liquid ejection head using a piezoelectric element is to change the volume of individual liquid chambers in the order of “expansion-contraction-reexpansion-recontraction”. is there. The liquid ejected from the liquid ejection head due to such a volume change is divided in the middle after extending in a columnar shape, whereby the separated liquid droplets reach a receiver such as a recording medium. Patent Document 1 discloses that the time at which the liquid (liquid column) extending in a columnar shape is divided and the droplet is broken is in the process of “re-expansion”.

  However, when the present inventor conducted an ink ejection experiment with a drive signal shown in FIG. 6A described later using the same vendor-type liquid ejection head (inkjet head) as in Patent Literature 1, A phenomenon different from the disclosure was confirmed. That is, as a result of observing in detail that the liquid column is separated from the meniscus in the vicinity of the discharge port and flies, the separation actually occurs after the input of the drive signal causing the change is completed, that is, “re-contraction It was confirmed after the process.

  The present inventor who has confirmed this phenomenon has intensively studied and found that the discharge form that causes the liquid column division after the "reshrinking" process is effective in the sense that the droplet amount can be controlled reliably. Obtained knowledge. This is because the liquid column is not divided at the time of the “re-expansion” process, so the control amount in “re-expansion” can be transmitted to the liquid column, and the control amount can be changed appropriately. This is because the droplet amount can be adjusted.

  However, in the discharge mode in which the liquid column is divided after the "reshrinking" process according to the study of the present inventors, if an overshoot occurs in which the meniscus rises outside the discharge port before the division, the root of the liquid column is bent. A problem has been found that the droplet discharge direction is deflected.

  The object of the present invention is to prevent meniscus overshoot and to bend the protruding liquid column while ensuring the controllability of the droplet amount in the second expansion (reexpansion) process of the volume of the individual liquid chamber. The purpose is to realize high-quality printing by eliminating the deflection in the ejection direction as a factor.

For this purpose, the present invention provides a discharge port for discharging a liquid, an individual liquid chamber communicating with the discharge port, a diaphragm forming a part of the inner surface of the individual liquid chamber, and deforming the diaphragm. An actuator for changing the volume of the individual liquid chamber, and a liquid discharge method for discharging liquid by changing the volume of the individual liquid chamber.
A corrugated portion for expanding the individual liquid chamber, a corrugated portion for contracting the individual liquid chamber, and a corrugated portion for re-expanding the individual liquid chamber in order to cause the liquid to be discharged; A main drive signal including a waveform portion for contracting the individual liquid chamber is input to the actuator;
With respect to the minimum displacement point δ _L of the diaphragm that appears after the completion of the input of the main drive signal, the diaphragm displacement until the time t _B when the liquid column division is observed on the discharge port side after the appearance is minimal displacement. inputting a waveform portion for inflating the individual liquid chamber so as not to fall below the point [delta] _L, an auxiliary drive signal including a waveform portion for the return to contract the volume of the individual liquid chamber initial state to the actuator ,
It is characterized by that.

Further, the present invention provides a discharge port for discharging a liquid, an individual liquid chamber communicating with the discharge port, a diaphragm forming a part of an inner surface of the individual liquid chamber, and deforming the diaphragm to In a liquid ejecting apparatus that ejects liquid by changing the volume of the individual liquid chamber, using a liquid ejecting head including an actuator that changes the volume of the individual liquid chamber,
A main drive signal is input to the actuator, and a controller that inputs an auxiliary drive signal after the input is provided.
The main drive signal includes a waveform portion for expanding the individual liquid chamber, a waveform portion for contracting the individual liquid chamber, and a re-expansion of the individual liquid chamber in order to cause the liquid to be discharged. And a corrugated portion for contracting the individual liquid chamber,
Said auxiliary drive signal to the minimum displacement point [delta] _L of the diaphragm appearing after completion of input of the main drive signal, after the occurrence of at the discharge port side to the time t _B that the liquid column interrupted is observed including a corrugated portion for inflating the individual liquid chamber so that the vibration plate displacement does not fall below the minimum displacement point [delta] _L, and a waveform portion for the contract the volume of the individual liquid chamber back into an initial state,
It is characterized by that.

  According to the present invention, by inputting the auxiliary drive signal after inputting the main drive signal for discharging the liquid, the liquid column protruding from the discharge port is caused to be bent before the liquid column protrudes from the discharge port. It has become possible to prevent meniscus overshoot. For this reason, high-quality printing can be realized without deflection in the ejection direction. The liquid discharge head is applied not only to the recording apparatus but also to various fields such as a patterning apparatus and a coating apparatus, and liquids having various physical properties and various head structures are used. Therefore, the present invention is preferable in providing an appropriate and universal guide for driving control of the liquid discharge head and expanding the application field.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

1. FIG. 1 is a schematic perspective view showing an ink jet recording apparatus as an example of a liquid discharge apparatus to which the present invention can be applied. The recording medium P inserted into the liquid ejection device is conveyed to the recordable area of the liquid ejection head unit 100 by the feed rollers 107, 108, 109, and 110. The liquid discharge head unit 100 is supported by a guide shaft 102 so as to be movable along the extending direction thereof. As the motor 103 is driven, the belt 104 laid around the pulleys 105 and 106 moves, and the liquid discharge head unit 100 reciprocates in the recording area in the A direction. Liquid discharge can be performed in the course of the movement. In the figure, the direction indicated by the arrow B is the conveyance direction of the recording medium P.

  The liquid discharge head unit 100 includes a liquid discharge head 103 in the form of an ink jet head for discharging a plurality of colors of ink, and an ink tank 101 for supplying ink to each liquid discharge head 103. The inks of a plurality of colors in the liquid ejection device of this example are four colors of black (Bk), cyan (C), magenta (M), and yellow (Y). The position of each color is not particularly limited, and the type and number of color tones (color and density) to be used are not limited.

  In the case of this example, the ink tanks of the respective color inks (Bk, C, M, Y) of black, cyan, magenta, and yellow are all replaceable independently. The liquid ejection head unit 100 includes a group of liquid ejection heads that eject liquid droplets of Bk, C, M, and Y, an ink tank for Bk 101B, an ink tank for C 101C, an ink tank for M, and ink for Y. A tank 101Y is mounted. Each ink tank is connected to a corresponding liquid discharge head, and supplies ink into an individual liquid chamber communicating with the discharge port of the liquid discharge head. In addition to this example, for example, an ink tank for each color and a liquid discharge head may be integrated so as not to be separated. Alternatively, only the liquid discharge head may be mounted on the liquid discharge head unit, and ink may be supplied from an ink tank provided at a fixed portion of the apparatus via a flexible tube or the like. In addition to these examples, for example, the ink tanks for the respective colors may be combined into an integral structure in any combination.

  A recovery system unit 112 is disposed below one end (right end in the figure) of the main scanning region where the liquid discharge head unit 100 can move. The recovery system unit 112 caps the discharge port forming surface of the liquid discharge head, and wipes off the cap or the discharge port forming surface for protecting or performing suction recovery during non-recording operations. It can have a wiper blade or the like.

2. Liquid Discharge Head FIGS. 2 and 3 are configuration examples of a liquid discharge head applicable to the present invention, and show a schematic front view and a cross-sectional view taken along the line C-C as viewed from the discharge port forming surface side, respectively. . The liquid discharge head described in the present embodiment is a so-called bender type head that utilizes distortion in the out-of-plane direction of a piezoelectric element.

  The liquid discharge head of this example supplies ink by communicating with an orifice plate 1 provided with a plurality of discharge ports 2 for discharging ink, a plurality of individual liquid chambers 3 corresponding to the respective discharge ports, and these in common. And a base body 6 on which walls defining the common liquid chamber 11 are arranged. The individual liquid chamber 3 communicates with the discharge port 2 via the communication path 7.

  A displaceable diaphragm 4 is provided on a part of the side surface of the individual liquid chamber 3, and an actuator 5 including a piezoelectric element (piezo element) that is a volume control unit of the individual liquid chamber and an electrode with respect to the diaphragm 4. Is arranged. The piezoelectric element may be a piezoelectric thin film formed by an evaporation method, a sol-gel method, a CVD method, a sputtering method, or the like. By applying a drive voltage signal to the actuator 5 corresponding to the recording information, the diaphragm 4 is displaced, and the volume of the individual liquid chamber 3 is changed, so that a droplet can be discharged from the discharge port 2. It is. The actuator 5 is deformed in the thickness direction so as to increase the volume of the individual liquid chamber when the drive voltage applied thereto decreases, and to decrease the volume of the individual liquid chamber when the drive voltage increases. It shall be.

In the liquid discharge head used in the study for forming the present invention, the discharge port 2 has a circular shape with a diameter of 30 μm, and the liquid to be discharged has a density of 1.0 × 10 ³ kg / m ³ and a viscosity of 2.0 ×. An ink having 10 ⁻³ Pa · s and a surface tension of 3.5 × 10 ⁻² N / m was used.

  In addition, the actuator 5 (upper electrode, piezoelectric element, lower electrode) and the diaphragm 4 have a structure in which the diaphragm and the actuator are combined to have a thickness of 10 μm in order to facilitate deformation of the actuator 5 itself. If the piezoelectric element is configured as a piezoelectric thin film, the actuator can be formed thin, and this thickness can be realized. With such a thin film shape, the time transition δ (t) of the diaphragm displacement, which serves as an index indicating the increase or decrease of the volume of the individual liquid chamber, is the displacement (out-of-plane displacement) of the surface (upper electrode position) of the actuator 5. ). This displacement refers to a displacement in a direction perpendicular to the surface on which the diaphragm is formed. Therefore, by measuring the displacement by, for example, a laser Doppler method, the time transition of the diaphragm displacement and thus the individual liquid chamber 3 The volume change (expansion and contraction) can be known.

  FIG. 4 shows a configuration example of a drive unit used for driving the actuator 5. The actuator 5 is connected to the drive circuit 51 via an electrode wiring for supplying electric power. The drive circuit 51 has an actuator with a drive waveform set by a drive waveform setting unit 53 that is a control unit according to drive data (data for determining the presence or absence of discharge) corresponding to liquid discharge information (for example, recording information). 5 can be activated.

  The drive waveform setting unit 53 sets a drive waveform such that a time transition of the volume increase / decrease of the individual liquid chamber (a time transition of the out-of-plane displacement of the diaphragm) that causes a preferable liquid ejection form occurs.

3. Comparative Example Here, an example (comparative example) studied in the present invention will be described first.

  The drive signal shown in FIG. 5A was applied to the bender type liquid discharge head described with reference to FIGS. 2 and 3 using the drive unit shown in FIG. The time transition (diaphragm displacement time history diagram) of the diaphragm 4 at that time is shown in FIG. 6A to 6G show the droplet discharge state observed at this time. When FIG. 6 is seen in detail, it can be seen that the base of the liquid column on the ejection port 2 side is bent, and this influence causes deflection in the ejection direction of the liquid droplet (hereinafter also referred to as “flection”).

  The inventor diligently investigated the cause of this twist. First, as is clear from a comparison between FIGS. 5A and 5B, in the case of a bender type liquid discharge head, the voltage change and the displacement of the diaphragm 4 do not always coincide with each other. Therefore, the factor analysis is performed based on not only the drive signal but also the diaphragm displacement time history diagram.

In FIG. 5B, the horizontal axis represents time and the vertical axis represents the displacement of the diaphragm, and the transition in the direction in which the amount of displacement increases indicates that the individual liquid chamber 3 is expanded. Further, in FIG. 5B, t _B indicates a point in time when the liquid column is observed to be divided on the discharge port side, and a section T indicates the minimum displacement point of the diaphragm that appears after the completion of the drive signal input in FIG. It shows the time from the [delta] _L emergence to time t _B that dividing of the liquid column is observed.

  The discharge process is analyzed based on the above policy as follows.

  The diaphragm 4 is displaced in the direction in which the individual liquid chamber 3 is expanded by the first signal waveform portion P1 (the diaphragm displacement time history line C1 in FIG. 5A), as shown in FIG. 6A. Pull the meniscus into the outlet. Next, the diaphragm 4 is displaced in the direction in which the individual liquid chamber 3 is contracted by the second signal waveform portion P2 (diaphragm displacement time history line C2 in FIG. 5A), and FIG. In this way, the meniscus is raised to form a liquid column.

  Next, the diaphragm 4 is displaced in the direction in which the individual liquid chamber 3 is re-expanded by the third signal waveform portion P3 (the diaphragm displacement time history line C3 in FIG. 5A), and the meniscus is placed in the discharge port. Pulling in and resizing (adjusting) the thickness of the protruding liquid column as shown in FIG. Next, the diaphragm 4 is displaced in the direction in which the individual liquid chamber 3 is contracted by the fourth signal waveform portion P4 (the diaphragm displacement time history line C4 in FIG. 5A), and the volume of the individual liquid chamber is initially set. To return to the initial state, the initial standby voltage V1 is restored. The discharge state after completion of the fourth signal P4 input is shown in FIG. 6D, and the liquid column does not break even after the main drive signal input is completed as shown in FIG.

In the diaphragm displacement time history diagram of FIG. 5B, the displacement of the diaphragm is accompanied by the change in the internal volume of the individual liquid chamber 3 caused by the coupled behavior with ink after the completion of the input of the fourth signal waveform portion P4. There appeared the minimum displacement point [delta] _L of the minimum, the diaphragm displacement point next becomes maximum appears. After the maximum displacement point occurrence and is displaced in a direction to contract the individual liquid chamber 3, the diaphragm displacement at time t _C falls below the minimum displacement point [delta] _L. Correspondingly, as shown in FIG. 6 (e), a meniscus overshoot occurs at the base of the liquid column, and the base of the liquid column is bent, as shown in FIGS. 6 (f) and 6 (g). It is probable that the droplet was twisted.

4). Embodiments Accordingly, the present inventors have observed the discharge port portion from the outside to control the occurrence of liquid droplets by controlling so that meniscus overshoot does not occur before the liquid column protruding from the discharge port is broken. I thought that it could be prevented.

  Here, the configuration to which the present invention is effectively applied is summarized as follows.

The liquid ejection head includes an ejection port that ejects liquid (ink, etc.), an individual liquid chamber that communicates with the ejection port, a diaphragm that forms part of the inner surface of the individual liquid chamber, and the diaphragm Is deformed by an actuator, and the volume of the individual liquid chamber is changed to discharge the liquid. Here, the waveform of the main drive signal applied to the actuator to perform the discharge includes a waveform portion for expanding the individual liquid chamber, a waveform portion for contracting the individual liquid chamber, and an individual liquid chamber. A corrugated portion for reinflation and a corrugated portion for contracting the individual liquid chamber are included. Further, after completing the input of the main drive signal minimum displacement point [delta] _L of the displacement of the vibration plate is minimum appears.

In the characteristic configuration of the present invention, the following auxiliary drive signal is input after the main drive signal is input. That is, after the minimal displacement point δ _L appears on the diaphragm displacement time history line, the diaphragm displacement until time t _B when the liquid column division is observed on the discharge port side does not fall below the minimal displacement point δ _L. Thus, the auxiliary drive signal includes a waveform portion for expanding the individual liquid chamber and a waveform portion for returning to the initial standby voltage.

  The present inventors considered that the desired effect can be surely obtained by using such an auxiliary drive signal, and verified the result based on the following examples.

Example 1
A drive signal shown in FIG. 7A is applied to the liquid ejection head described with reference to FIGS. 2 and 3 using the drive unit shown in FIG. FIG. 7B shows a displacement time history diagram of the diaphragm 4 at that time. As in FIG. 5B, in FIG. 7B, the horizontal axis indicates time, the vertical axis indicates the displacement of the diaphragm, and the transition in the direction in which the amount of displacement increases indicates that the individual liquid chamber 3 is expanded. Yes. The time t _B of FIG. 5 (a) shows the time when the cutting portion of the liquid column was observed. FIGS. 8A to 8F show the observed droplet discharge state.

  In FIG. 7A, the first waveform portion P1 to the fourth waveform portion P4 form the waveform of the main drive signal. In this embodiment, the first waveform portion P1 to the fourth waveform portion P4 are the same as those in the comparative example. Accordingly, the discharge process up to the completion of the main drive signal input is the same as in the comparative example, and the individual liquid chamber 3 is expanded, contracted, re-expanded and re-contracted, as shown in FIGS. A liquid column is formed. The discharge state after the completion of the main drive signal input is shown in FIG. 8D. As shown in this figure, the liquid column is not broken even after the completion of the main drive signal input.

  Note that the voltages of the second waveform portion P2 and the third waveform portion P3 of the main drive signal may be the same as the initial standby voltage V1. In addition, it is possible to appropriately adjust the diaphragm displacement by changing the voltage of each waveform portion and the application time so that desired discharge performance (discharge amount Vd, discharge speed v) can be obtained.

Now, after the main drive signal input is completed, the diaphragm 4 has a minimum displacement point δ _L of the diaphragm due to the coupled behavior with the ink, and then the diaphragm 4 is displaced in the direction in which the individual liquid chamber 3 is expanded. To do.

Here, in this embodiment, the auxiliary drive signal is input after the main drive signal input is completed. The auxiliary drive signal includes the fifth waveform portion P5 and the sixth waveform portion P6 in FIG. After minimum displacement point [delta] _L is encountered, the diaphragm displacement time of the fifth waveform portion P5 contained in the auxiliary drive signal to displace the vibrating plate 4 in the direction of expanding the individual liquid chamber 3 (FIG. 7 (b) History line C5), diaphragm displacement in the direction of contracting the individual liquid chamber 3 was suppressed (FIG. 8E). Finally, the sixth waveform portion P6 returns the individual liquid chamber to the initial standby voltage V1 for returning to the initial volume.

  As a result of inputting the auxiliary drive signal as described above, a cut portion of the liquid column is observed before the meniscus overshoot occurs as shown in FIG. 8F, and the liquid column is not bent. As shown in FIG. 8 (g), discharge without deviation was realized.

Example 2
In the second embodiment, the main drive signal is the same as that of the first embodiment, and the sixth waveform portion P6 of the auxiliary drive signal that is input thereafter is input after the liquid column cutting portion is positively observed. changed. Even if such a change is made, as in Example 1, as shown in FIG. 8 (f), the cut portion of the liquid column is observed before the meniscus overshoot occurs, and the liquid column is bent. As shown in FIG. 8 (g), discharge without deviation was realized.

5). Others Of course, the various numerical values described above are merely examples.

  In the above example, the case where the present invention is applied to the liquid ejecting apparatus and the head in the form of an ink jet recording apparatus has been described. However, the present invention is preferably applied not only to the recording apparatus but also to various liquid ejecting apparatuses such as a patterning apparatus and a coating apparatus. Is possible. Suitable and universal liquid ejection head drive that can achieve finer ejection droplets without reducing the diameter of the ejection port, as liquids with various physical properties and various head structures are used depending on the device This is because a control guideline can be given.

  Further, in the above-described embodiment, the form in which the individual liquid chamber 3 contracts by applying a positive drive voltage to the actuator 5 has been described. However, the present invention also applies to a form in which the individual liquid chamber 3 contracts by applying a negative drive voltage. It goes without saying that the invention is applicable.

1 is a schematic perspective view showing an ink jet recording apparatus as an example of a liquid ejection apparatus to which the present invention can be applied. FIG. 2 is a configuration example of a liquid discharge head applicable to the present invention, and shows a schematic front view seen from the discharge port forming surface side. 2 is a configuration example of a liquid discharge head applicable to the present invention, and shows a cross-sectional view taken along the line CC of FIG. It is a block diagram which shows the structural example of the drive part of an actuator (piezoelectric element). (A) And (b) is a wave form diagram which shows the drive voltage waveform in the comparative example applied to the liquid discharge head of FIG. 3, respectively, and a diaphragm displacement time history line figure accompanying this. (A)-(g) is explanatory drawing of the liquid discharge state in a comparative example. (A) And (b) is a wave form diagram which shows the drive voltage waveform in the Example applied to the liquid discharge head of FIG. 3, respectively, and a diaphragm displacement time history line figure accompanying this. (A)-(g) is explanatory drawing of the liquid discharge state in an Example.

Explanation of symbols

2 Discharge port 3 Individual liquid chamber 4 Vibration plate 5 Actuator

Claims (5)

A discharge port for discharging liquid, an individual liquid chamber communicating with the discharge port, a diaphragm that forms part of the inner surface of the individual liquid chamber, and a volume of the individual liquid chamber by deforming the diaphragm And a liquid ejecting method for ejecting a liquid by changing the volume of the individual liquid chamber.
A corrugated portion for expanding the individual liquid chamber, a corrugated portion for contracting the individual liquid chamber, and a corrugated portion for reexpanding the individual liquid chamber in order to cause the liquid to be discharged; A main drive signal including a waveform portion for contracting the individual liquid chamber is input to the actuator;
With respect to the minimum displacement point δ _L of the diaphragm that appears after completion of the input of the main drive signal, the diaphragm displacement until the time t _B at which the liquid column division is observed on the discharge port side after the appearance is minimal displacement. inputting a waveform portion for inflating the individual liquid chamber so as not to fall below the point [delta] _L, an auxiliary drive signal including a waveform portion for the return to contract the volume of the individual liquid chamber initial state to the actuator ,
A liquid discharge method characterized by the above.   The waveform portion of the auxiliary drive signal for returning the volume of the individual liquid chamber to the initial state is input after the time point at which the separation of the liquid column formed in the discharge process is observed. Item 2. A liquid ejection method according to Item 1.   The actuator includes a piezoelectric element and an electrode, and the piezoelectric element is deformed in response to application of a voltage to the electrode, whereby the diaphragm is displaced, and the volume of the individual liquid chamber is changed. The liquid ejection method according to claim 1 or 2.   The liquid ejection method according to claim 3, wherein the piezoelectric element has a form of a piezoelectric thin film. A discharge port for discharging liquid, an individual liquid chamber communicating with the discharge port, a diaphragm that forms part of the inner surface of the individual liquid chamber, and a volume of the individual liquid chamber by deforming the diaphragm In a liquid ejection apparatus that ejects liquid by a volume change of the individual liquid chamber, using a liquid ejection head that includes an actuator to be changed,
A main drive signal is input to the actuator, and a controller that inputs an auxiliary drive signal after the input is provided.
The main drive signal includes a waveform portion for expanding the individual liquid chamber, a waveform portion for contracting the individual liquid chamber, and a re-expansion of the individual liquid chamber in order to cause the liquid to be discharged. And a corrugated portion for contracting the individual liquid chamber,
Said auxiliary drive signal to the minimum displacement point [delta] _L of the diaphragm appearing after completion of input of the main drive signal, after the occurrence of at the discharge port side to the time t _B that the liquid column interrupted is observed including a corrugated portion for inflating the individual liquid chamber so that the vibration plate displacement does not fall below the minimum displacement point [delta] _L, and a waveform portion for the contract the volume of the individual liquid chamber back into an initial state,
A liquid discharge apparatus characterized by the above.

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