JP3794587B2 - Image forming apparatus and ink discharge driving method - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an image on a recording medium by expanding and contracting an ink chamber with a piezoelectric element and ejecting ink from a nozzle of the ink chamber.

An image forming apparatus such as an ink jet printer forms an image on a recording sheet by ejecting ink from the recording head onto the recording sheet while relatively moving the recording head and the recording sheet. As the ink discharge means, the ink chamber is deformed by the piezoelectric element, and the ink is discharged from the nozzle formed in the ink chamber. However, such an ink discharge means has a problem such as an accidental drop due to crosstalk between adjacent ink chambers. In order to solve this problem, a technique of performing a share mode drive in which the ink discharge timings of adjacent ink chambers are shifted is known (see Patent Document 1). In this image forming apparatus, a potential difference is generated between the columns on both sides of the ink chamber to simultaneously deform both columns, thereby expanding and contracting the ink chamber to eject ink from the nozzles. In an ink chamber that should not eject ink, the potential difference between both electrodes of the column of the ink chamber is set to 0 to prevent deformation of the ink chamber and to prevent accidental drop from the ink chamber that should not eject ink.
JP-A-7-76084

  However, such an image forming apparatus has a drawback that it is not possible to simultaneously eject ink from adjacent nozzles by the share mode driving described above, and thus improvement in image quality cannot be expected. Further, although the deformation of the column of the ink chamber adjacent to the expanding and contracting ink chamber is prevented, there is no effect in preventing the warping of the long line type head.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an image forming apparatus capable of preventing warpage of a long line-type head and recording a high-quality image.

In order to achieve the above object, the present invention provides a plurality of ink chambers filled with ink arranged in a line, and a voltage is applied to a piezoelectric element provided on the outer peripheral portion or outside of the ink chamber. In the image forming apparatus in which the ink chamber is expanded and contracted and ink is ejected from the nozzle of the ink chamber onto the recording medium, the piezoelectric element is disposed on the vibration plate along a plane substantially parallel to the nozzle surface, and the deformation of d31 A plate-like piezoelectric element that expands and contracts an ink chamber. A common electrode is provided on the lower surface of the piezoelectric element, and individual electrodes corresponding to the ink chambers are provided on the upper surface, and a plurality of adjacent ink chambers. A fixed electrode is provided above the partition wall that divides
Wherein each individual electrode corresponding to each ink chamber, together with the control on and off for short-circuiting and the common electrode and the electrode comprises a short-circuiting means possible short circuit for short-circuiting said common electrode and the fixed electrode It is characterized in that it comprises.

According to the present invention, the piezoelectric element is disposed along a plane substantially parallel to the nozzle surface, and includes a short-circuit means for each ink chamber. In the present invention, if the electrodes of the piezoelectric elements in the ink chambers of the nozzles that should not eject ink are short-circuited to the same potential, deformation of the piezoelectric elements in the ink chambers can be prevented, so that crosstalk can be prevented. In addition, since the inherent rigidity of the piezoelectric element can be ensured by short-circuiting the electrodes of the piezoelectric element, it is possible to prevent bending of the long line type head in the longitudinal direction. Furthermore, ink can be ejected from the nozzles of the ink chamber adjacent to the ink chamber of the nozzle to be ejected, and the image quality can be improved.
In addition, according to the present invention, the piezoelectric element includes an electrode (fixed electrode) disposed above a partition wall that partitions the plurality of adjacent ink chambers, and includes a short circuit that short-circuits the electrode. Accordingly, the rigidity of the ink chamber partition wall can be ensured by the piezoelectric element, so that the longitudinal rigidity of the line type recording head can be improved.

According to the second aspect of the present invention, when forming an image, the individual electrodes of the piezoelectric elements corresponding to the ink chambers that do not eject ink are short-circuited with the common electrode by the short-circuit means, so that the ink is Crosstalk to an ink chamber that is not ejected can be prevented.

  According to the third aspect of the present invention, the short-circuit means is provided with a switching element for short-circuit on / off.

  According to the fourth aspect of the present invention, when the power is turned off or during printing standby, the short-circuit means short-circuits the electrodes of the piezoelectric element, so that the rigidity of the piezoelectric element can be ensured when an image is not formed. Furthermore, the longitudinal deformation of the image forming apparatus due to the deformation of the piezoelectric element due to the electromotive force can be prevented, the occurrence of a potential difference between both electrodes of the piezoelectric element can be prevented, the circuit load can be reduced, and the circuit can be protected.

According to the fifth aspect of the present invention, a plurality of ink chambers filled with ink are arranged in a line shape, and a voltage is applied to a piezoelectric element provided on the outer peripheral portion or the outer side of the ink chamber. In an ink ejection method in which an ink chamber is expanded and contracted to eject ink from a nozzle of an ink chamber onto a recording medium, a single plate-like piezoelectric element is disposed on a diaphragm along a plane substantially parallel to the nozzle surface, The ink chamber is expanded and contracted by deformation of d31 of the piezoelectric element, and a common electrode is provided on the lower surface of the piezoelectric element, and an individual electrode corresponding to each ink chamber is partitioned on the upper surface from a plurality of adjacent ink chambers. A fixed electrode is provided above the partition wall, and for each individual electrode corresponding to each ink chamber, a short-circuit unit capable of on / off control for short-circuiting the electrode and the common electrode is provided. Using a configuration in which a short circuit for short-circuiting said common electrode and the constant electrode, when forming an image, the individual electrodes of the piezoelectric element corresponding to the ink chamber not to eject ink, the common by the shorting means It is characterized by short-circuiting with the electrode .

According to the fifth aspect of the present invention, in the ink ejection driving method, when an image is formed, the electrodes (individual electrodes and common electrodes) of the piezoelectric elements in the ink chamber that does not eject ink are short-circuited. Since the short circuit is used, the crosstalk to the ink chamber where ink is not discharged can be prevented.

According to the sixth aspect of the present invention, a plurality of ink chambers filled with ink are arranged in a line shape, and a voltage is applied to a piezoelectric element provided on the outer peripheral portion or the outer side of the ink chamber. In an ink ejection method in which an ink chamber is expanded and contracted to eject ink from a nozzle of an ink chamber onto a recording medium, a single plate-like piezoelectric element is disposed on a diaphragm along a plane substantially parallel to the nozzle surface, The ink chamber is expanded and contracted by deformation of d31 of the piezoelectric element, and a common electrode is provided on the lower surface of the piezoelectric element, and an individual electrode corresponding to each ink chamber is partitioned on the upper surface from a plurality of adjacent ink chambers. A fixed electrode is provided above the partition wall, and for each individual electrode corresponding to each ink chamber, a short-circuit unit capable of on / off control for short-circuiting the electrode and the common electrode is provided. Using the configuration with a short circuit for short-circuiting said common electrode and the constant electrode, when the power is turned off, or during the printing standby, by the shorting means the individual electrodes of the piezoelectric element, shorting the common electrode and the constantly It is characterized by that.

According to the sixth aspect of the present invention, in the ink ejection driving method, the electrode of the piezoelectric element is always short-circuited by the short-circuit means when the power is turned off or during printing standby. The rigidity of the element can be secured. Furthermore, the longitudinal deformation of the image forming apparatus due to the deformation of the piezoelectric element due to the electromotive force can be prevented, the occurrence of a potential difference between both electrodes of the piezoelectric element can be prevented, the circuit load can be reduced, and the circuit can be protected.

  This piezoelectric element applies a pressure wave by deformation in the piezoelectric lateral direction (d31). Therefore, it is possible to secure the original rigidity of the piezoelectric element and prevent the recording head from bending in the longitudinal direction. Also, if the nozzles are arranged in a full line type that is arranged in multiple lengths corresponding to the full width of the recording medium, it is possible to prevent crosstalk and prevent accidental drops, etc. A long recording head can be configured.

  In this specification, “recording” represents the concept of forming an image in a broad sense including characters. A “recording medium” is a medium on which an image is formed by a recording head (called an image forming medium, a recording medium, an image receiving medium, a recording paper, etc.), and is a continuous sheet, a cut sheet, a seal sheet, an OHP sheet. Regardless of resin sheet, film, cloth, and other materials and shapes, various media are included.

  According to the present invention, it is possible to prevent warping of a long line type recording head, and it is possible to operate adjacent ink chambers and form a high-quality image.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  In FIG. 1, an image forming apparatus 10 includes a recording head 12, a belt conveyance unit 18 that is disposed to face the recording head 12, conveys the recording paper 16 while maintaining the planarity of the recording paper 16, and the recording paper. 16 is provided, and a paper discharge unit 22 that discharges recording paper on which an image has been formed to the outside.

  The recording head 12 is a so-called full-line head in which a line-type head having a length corresponding to the paper width of the recording paper 16 is fixedly arranged in a direction orthogonal to the paper feeding direction. Recording heads 12K, 12C, 12M corresponding to the respective color inks in the order of black (K), cyan (C), magenta (M), yellow (Y) from the upstream side along the conveyance direction (arrow A) of the recording paper 16. 12Y is arranged. Each of these recording heads has ink units 13 arranged in a staggered manner as shown in FIG. 2, and recording is performed by ejecting each color ink from the ink unit 13 onto the recording paper 16 while conveying the recording paper 16. A color image or the like is formed on the paper 16.

  A roll paper 26 is detachably set in the paper supply unit 20. In the vicinity of the paper feeding unit 20, drawer rollers 21 and 21 for pulling out the recording paper 16 from the roll paper 26 are provided. The power of a motor (not shown) is transmitted to at least one of the drawing rollers 21 and 21, and the drawn recording paper 16 is conveyed from right to left in FIG. Reference numeral 24 is a cutter for cutting disposed between the rollers 21 and 21, and the recording paper 16 drawn from the roll paper 26 by this cutter 24 is cut into a desired size.

  The belt transport unit 18 has a structure in which an endless belt 38 is wound between rollers 30, 32, 34, and 36, and at least a portion facing the recording head 12 forms a flat surface. The belt 38 has a width that is greater than the width of the recording paper 16, and can adsorb the recording paper 16 on the belt surface. The power of a motor (not shown) is transmitted to at least one of the rollers 30, 32, 34, and 36 around which the belt 38 is wound, and the belt 38 is driven counterclockwise in FIG. The recording sheet 16 sucked up is conveyed from the right to the left in FIG.

  Reference numeral 82 is a recording paper detection section for reading the position and size of the recording paper, reference numeral 84 is a recording position detection section for determining ink ejection timing to the recording paper 16, and reference numeral 88 is a paper jam of the recording paper 16 or the next paper. It is a recording paper end detection unit for determining supply timing. Furthermore, the image forming apparatus 10 is provided with a system controller (not shown) that controls the image forming apparatus 10 in an integrated manner based on the detection results of these detection units. This system controller is composed of a central processing unit (CPU) and its peripheral circuits, and generates, for example, drive signals and control signals for each motor for conveying the recording paper 16 and image forming signals for the recording head 12.

  Next, the structure of the recording head 12 will be described. Since the recording heads 12K, 12C, 12M, and 12Y provided for each ink color have the same structure, the recording head is represented by reference numeral 12 as a representative of these.

  2 is a perspective view showing a structural example of the recording head 12, FIG. 3A is a plan perspective view, FIG. 3B is a partially enlarged view, FIG. 4 is a partially enlarged view, and FIG. 5 is a sectional view taken along line xx in FIG.

  In order to increase the dot pitch formed on the recording paper surface, it is necessary to increase the nozzle pitch in the recording head 12. As shown in FIGS. 3 and 4, the recording head 12 of this example includes a plurality of ink units 13 including nozzles 56 that eject ink droplets and ink chambers 54 corresponding to the nozzles 56. It has a structure arranged in a (two-dimensional shape), thereby achieving an increase in apparent nozzle pitch density. The ink chamber 54 provided corresponding to each nozzle 56 and formed by cutting or the like has a substantially square planar shape, and nozzles 56 and supply ports 55 are provided at both corners on a diagonal line. Yes. Each ink chamber 54 communicates with a common channel (not shown) via a supply port 55.

  In FIG. 5, the ink chamber 54 is provided in the flow path forming member 42. A grounded common electrode 46 is attached to the upper surface of the flow path forming member 42, that is, the upper portion of the vibration plate 44 constituting the top surface of the ink chamber 54, and a single plate-like shape is attached to the upper surface of the common electrode 46. A piezoelectric element 48 is provided. An individual electrode 50 corresponding to the ink chamber 54 is attached to the upper surface of the piezoelectric element 48.

  By applying a driving voltage to the electrode 50, the piezoelectric element 48 is deformed and ink is ejected from the nozzle 56. When ink is ejected, new ink is supplied to the ink chamber 54 from the common flow path through the supply port 55.

  As shown in FIG. 4, a large number of ink units 13 having such a structure are arranged along a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. The structure is arranged in a grid pattern. With a structure in which a plurality of ink units 13 are arranged at a constant pitch d along the direction of an angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ.

  That is, in the main scanning direction, the nozzles 56 (56-11, 56-12, 56-13, 56-14, 56-15, 56-16...) Are arranged in a single straight line at a constant pitch P. Can be handled equivalently to things. With such a configuration, it is possible to realize a high-density single line nozzle arrangement in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction. Hereinafter, for convenience of explanation, it is assumed that the nozzles 56 are linearly arranged at a constant interval (pitch P) along the longitudinal direction (main scanning direction) of the head.

  When the nozzles are driven by a full line head having a nozzle row corresponding to the full width of the paper, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially driven from one side to the other (3) ) The nozzle is divided into blocks, and each block is sequentially driven from one side to the other. One line is formed in the width direction of the paper (direction perpendicular to the paper conveyance direction). Alternatively, the driving of the nozzle that prints a line composed of a plurality of rows of dots) is defined as main scanning.

  In particular, when the nozzles 56 arranged in a matrix as shown in FIG. 4 are driven, the main scanning as described in the above (3) is preferable. That is, nozzles 56-11, 56-12, 56-13, 56-14, 56-15, 56-16 are made into one block (other nozzles 56-21 ..., 56-26 are made into one block, nozzle 56-31... 56-36 as one block,...) And nozzles 56-11, 56-12, 56-13, 56-14, 56-15 and 56-16 are set according to the conveyance speed of the recording paper 16. By sequentially driving, one line is printed in the width direction of the recording paper 16.

  On the other hand, by relatively moving the above-mentioned full line head and the paper, printing of one line (a line formed by one line of dots or a line composed of a plurality of lines) formed by the above-described main scanning is repeatedly performed. This is defined as sub-scanning.

  In FIG. 2, a connection substrate 52 for electrical connection with the system controller of the image forming apparatus 10 is attached to the end of the recording head 12. A conductive layer pattern 58 connected to all the electrodes 50 of the recording head 12 is formed on the connection substrate 52.

FIG. 6A is a drive circuit diagram of the piezoelectric element 48. The electrode 50 and the power source are connected via a drive switch SW ₁ , while the common electrode 46 is grounded by a ground circuit 62. Further, the electrode 50 and the common electrode 46 is grounded circuit 60 and the ground via the short-circuit switch SW ₂ for short on-off. The drive switch SW ₁ and the short-circuit switch SW ₂ are controlled by the system controller provided in the image forming apparatus 10 described above.

When a voltage is applied to the piezoelectric element 48 in the recording head 12 having such a configuration, the piezoelectric element 48 is deformed, and the piezoelectric element 48 and the vibration plate 44 are bent downward in FIG. 7, thereby expanding and contracting the ink chamber 54. Ink is ejected from the nozzle 56. That is, in FIG. 6A, when the drive switch SW ₁ is turned on and the short-circuit switch SW ₂ is turned off and a voltage is applied to the electrode 50, a potential difference is generated between the electrodes 46 and 50, and the piezoelectric element 48 is deformed. As the piezoelectric element 48 is deformed, the diaphragm 44 is deformed, the volume of the ink chamber 54 is changed to expand and contract the ink chamber 54, and ink is ejected from the nozzle 56 (see FIG. 7).

  Although not shown, the piezoelectric element 48 and the diaphragm 44 are bent upward by applying a voltage between the electrodes 46 and 50, the voltage is released, the ink chamber 54 is returned, and ink is ejected from the nozzle 56. Also good.

As shown in FIG. 6B, when the drive switch SW ₁ is turned off and the short-circuit switch SW ₂ is turned on, both electrodes of the piezoelectric element 48 have the same potential. For example, a physical external force from the outside of the piezoelectric element 48 is obtained. It is possible to prevent the deformation of the piezoelectric element 48 due to the above.

  Next, the operation of the image forming apparatus configured as described above will be described.

When the drive switch SW ₁ is turned on, a voltage is applied to the electrode 50 from the power source. Hereinafter, an operation of ejecting ink by the ink unit 13 when the drive voltage is applied will be described. The applied drive voltage is applied as a drive voltage pulse having a drive waveform based on the image formation pattern.

When the power of the image forming apparatus 10 is turned off or during image formation standby (that is, during printing standby), the drive switch SW ₁ is turned off and the short-circuit switch SW ₂ is turned on as shown in FIG. The Therefore, no driving voltage is applied to the electrode 50 of the piezoelectric element 48, the piezoelectric element 48 is not driven as shown in FIG. 5, and ink is not ejected from the nozzle 56. At this time, the short-circuit switch SW ₂ is always turned on by the system controller, and both electrodes of the piezoelectric element 48 are always grounded. Thereby, the rigidity of the piezoelectric element 48 can be ensured when an image is not formed.

For performing image formation based on an image forming pattern, when ink is ejected from the ink chamber 54, the system controller turns on the drive switch SW _1, the short-circuit switch SW ₂ is turned off. As a result, a driving voltage is applied to the electrode 50, and the piezoelectric element 48 is deformed as shown by a two-dot chain line in FIG. 7, and the vibration plate 44 corresponding to the top surface of the ink chamber 54 protrudes toward the ink chamber 54. Ink is discharged from the ink chamber 54 through the nozzle 56. The ejected ink is ejected onto the recording surface of the recording paper 16 (FIG. 1), and an image is formed on the recording paper 16. When the application of the driving voltage is completed, the deformed piezoelectric element 48 and the diaphragm 44 are restored to the state before the deformation. With this return, new ink is supplied from the ink supply path to the ink chamber 54 in an amount substantially equal to the amount of ink discharged.

  Next, a case where an ink chamber 54a that ejects ink and an ink chamber 54b that should not eject ink are adjacent to each other as shown in FIG. 8 based on the image forming pattern will be described.

In this case, with the drive timing of the driving voltage for ejecting ink, to ground the common electrode and the electrode 50 by turning on the short-circuit switch SW ₂ for each ink chamber that should not discharging the adjacent ink. That is, the system controller turns on the drive switch SW ₁ and turns off the short-circuit switch SW ₂ in the ink unit of the ink chamber 54 a that discharges ink. At the same time the system controller turns off the driving switch SW ₁ in the ink unit of the ink chamber 54b, the short-circuit switch SW ₂ is turned on.

  Thereby, while ink is ejected through the nozzle 56 in the ink chamber 54a, the potential difference between the electrode 50 of the piezoelectric element 48 and the common electrode 46 corresponding to the ink chamber 54b is maintained at 0 in the adjacent ink chamber 54b. The deformation of the piezoelectric element 48 is prevented. Therefore, since the original rigidity of the piezoelectric element 48 corresponding to the ink chamber 54b can be maintained, crosstalk from the ink chamber 54a to the ink chamber 54b can be removed, and accidental drop ejection can be prevented.

  Such an ink ejection operation is repeatedly performed, and an image based on the image formation pattern is formed on the recording paper 16 being conveyed.

  As described above, according to the image forming apparatus of the present embodiment, it is possible to eject ink from the nozzles in the ink chamber adjacent to the ink chamber 54 of the nozzle 56 to be ejected, and improvement in image quality can be expected. Further, both electrodes of the piezoelectric element 48 in the ink chamber 54b of the nozzle 56 that should not eject ink are short-circuited to have the same potential, and deformation of the piezoelectric element 48 in the ink chamber 54b can be suppressed. Therefore, when the nozzles 56 of the recording head 12 are arranged in a full line type in which a plurality of nozzles are arranged over a length corresponding to the entire width of the recording medium, crosstalk can be prevented and warping can be prevented by increasing rigidity.

  Next, an image forming apparatus according to a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same and similar member as 1st Embodiment shown in FIG. 5, and the detailed description is abbreviate | omitted.

  As shown in FIG. 9, the recording head 130 according to the present embodiment includes a fixed electrode 132 above a partition wall 54 c that partitions a plurality of adjacent ink chambers 54 in addition to the configuration of the recording head 12. These fixed electrodes 132 are attached to the piezoelectric element 48, and each fixed electrode 132 is connected to a ground circuit 134. On the other hand, the common electrode 46 is connected to the ground circuit 134. Thus, both the fixed electrode 132 of the piezoelectric element 48 and the common electrode 46 above the partition wall 54c are provided with a short circuit that is always short-circuited.

  The operation of the recording head 130 configured as described above will be described. When a drive voltage is applied to the electrode 50 and ink is ejected from the nozzle 56, the potential difference between the fixed electrode 132 and the common electrode 46 of the piezoelectric element 48 is different. Since it is always kept at 0, deformation of the piezoelectric element 48 portion above the partition wall 54c that partitions the plurality of adjacent ink chambers 54 is prevented. Therefore, crosstalk to the ink chamber where ink is not discharged can be prevented, and the rigidity of the piezoelectric element 48 above the partition wall portion 54c can be secured, so that the longitudinal rigidity of the long recording head 12 can be further improved.

1 is a side view showing an image forming apparatus to which an image forming apparatus according to an embodiment of the present invention is applied. 1 is a perspective view showing a recording head as an image forming apparatus according to an embodiment of the present invention. FIG. 1 is a plan perspective view and an enlarged view showing a recording head as an image forming apparatus according to an embodiment of the present invention. 1 is a partially enlarged view showing a recording head as an image forming apparatus according to an embodiment of the present invention. Xx sectional drawing which shows the detailed structure of the recording head as an image forming apparatus which concerns on embodiment of this invention Drive circuit diagram of piezoelectric element in recording head as image forming apparatus according to embodiment of the present invention Circuit diagram showing the state when the power is turned off or waiting for printing FIG. 3 is an enlarged partial sectional view showing the operation of the recording head as the image forming apparatus according to the embodiment of the invention. FIG. 6 is an enlarged partial cross-sectional view showing another operation of the recording head as the image forming apparatus according to the embodiment of the present invention. FIG. 6 is an enlarged partial cross-sectional view showing another aspect of the recording head as the image forming apparatus according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 12 ... Recording head, 16 ... Recording paper, 46 ... Common electrode, 48 ... Piezoelectric element, 50 ... Electrode, 54 ... Ink chamber, 56 ... Nozzle, 60, 62, 134 ... Grounding circuit, 132 ... Fixed electrode, SW ₁ ... drive switch, SW ₂ ... short-circuit switch

Claims (6)

A plurality of ink chambers filled with ink are arranged in a line shape, and a voltage is applied to a piezoelectric element provided on the outer peripheral portion or outside of the ink chamber, whereby the ink chamber is expanded and contracted from the nozzle of the ink chamber. In an image forming apparatus that ejects ink onto a recording medium,
The piezoelectric element is a plate-shaped piezoelectric element that is disposed on the diaphragm along a plane substantially parallel to the nozzle surface and expands and contracts the ink chamber by deformation of d31. While a common electrode is provided, an individual electrode corresponding to each ink chamber is provided on the upper surface, and a fixed electrode is provided above a partition wall that partitions a plurality of adjacent ink chambers.
For each individual electrode corresponding to each ink chamber, provided with a short-circuit means capable of on / off control to short-circuit the electrode and the common electrode ,
An image forming apparatus comprising: a short circuit that short-circuits the fixed electrode and the common electrode . The image forming apparatus according to claim 1, wherein when forming an image, the individual electrodes of the piezoelectric elements corresponding to the ink chambers that do not eject ink are short-circuited with the common electrode by the short-circuit unit. The image forming apparatus according to claim 1, wherein the short-circuit unit includes a switching element for short-circuit on / off. The image according to any one of claims 1 to 3 , wherein the short-circuit means always short-circuits the individual electrode of the piezoelectric element with the common electrode when the power is turned off or during printing standby. Forming equipment. A plurality of ink chambers filled with ink are arranged in a line shape, and a voltage is applied to a piezoelectric element provided on the outer peripheral portion or outside of the ink chamber, whereby the ink chamber is expanded and contracted from the nozzle of the ink chamber. In an ink ejection method for ejecting ink onto a recording medium,
A plate-like piezoelectric element is disposed on the diaphragm along a plane substantially parallel to the nozzle surface, and the ink chamber is expanded and contracted by deformation of d31 of the piezoelectric element,
A common electrode is provided on the lower surface of the piezoelectric element, and an individual electrode corresponding to each ink chamber is provided on the upper surface, and a fixed electrode is provided above a partition that partitions a plurality of adjacent ink chambers,
For each individual electrode corresponding to each ink chamber, provided with a short-circuit means capable of on / off control to short-circuit the electrode and the common electrode,
Using a configuration comprising a short circuit that short-circuits the fixed electrode and the common electrode,
In forming an image, the individual electrodes of the piezoelectric element corresponding to the ink chamber not to eject ink, the ink discharge drive wherein the shorting with the common electrode by the short-circuiting means. A plurality of ink chambers filled with ink are arranged in a line shape, and a voltage is applied to a piezoelectric element provided on the outer peripheral portion or outside of the ink chamber, whereby the ink chamber is expanded and contracted from the nozzle of the ink chamber. In an ink ejection method for ejecting ink onto a recording medium,
A plate-like piezoelectric element is disposed on the diaphragm along a plane substantially parallel to the nozzle surface, and the ink chamber is expanded and contracted by deformation of d31 of the piezoelectric element,
A common electrode is provided on the lower surface of the piezoelectric element, and an individual electrode corresponding to each ink chamber is provided on the upper surface, and a fixed electrode is provided above a partition that partitions a plurality of adjacent ink chambers,
For each individual electrode corresponding to each ink chamber, provided with a short-circuit means capable of on / off control to short-circuit the electrode and the common electrode,
Using a configuration comprising a short circuit that short-circuits the fixed electrode and the common electrode,
Power off, or during the printing standby, by the shorting means the individual electrodes of the piezoelectric element, the common electrode and the ink discharge drive wherein the shorting constantly.

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