JP2010214851A - Liquid discharging device and ink-jet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid discharging device which can easily achieve the complement of non-discharging in a recording head, and can obtain a high resolution. <P>SOLUTION: The liquid discharging device is provided with a liquid discharging member 10 equipped with a pressure chamber 11 and a liquid discharging slot 13 which communicates with the pressure chamber 11 and discharges liquid 12 in the pressure chamber to the outside, and a pressure giving means 20 which increases pressure in the pressure chamber 11 and discharges the liquid 12 from the liquid discharging slot 13. The part of the liquid discharging member 10 where the liquid discharging slot 13 is formed is formed of a sheet material 16 and a piezoelectric means 30 which changes the discharging direction of the liquid droplet discharged from the liquid discharging slot 13 by transforming the shape of the liquid discharging slot 13 by transforming the sheet material 16 is provided at the outer periphery of the liquid discharging slot 13 in the sheet material 16. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus used as a recording head that realizes higher resolution of an ink jet recording apparatus and complements ejection defects, and an ink jet recording apparatus including the liquid ejecting apparatus.

  As one of the ink jet recording methods in which ink is ejected from the ejection port of the recording head and adhered to a recording material such as paper, a thermal method in which bubbles are generated in the ink in the tube by heating and the ink is ejected, and a voltage is used. Ink is ejected by a method of applying pressure to ink droplets, such as a piezo type that uses a piezoelectric element (piezo element) that deforms when applied and applies voltage to the piezo element to eject the ink out of the tube by deformation. The method is adopted.

  In an ink jet recording apparatus using a recording head of such an ejection method, ejection failure may occur due to clogging of ejection ports due to foreign matters or bubbles mixed in ink.

  Conventionally, a discharge failure detection method, a non-discharge complementing method, a control method, and various discharge amount control methods and apparatuses have been proposed for this discharge failure problem.

  Patent Document 1 discloses a configuration in which image data to be added to an abnormal print element is moved, superimposed on image data of another print element, and an image without an image defect is obtained by complementing the print. ing.

JP-A-6-79956

  The image complementing method of Patent Document 1 achieves complementary printing for non-ejection nozzles in order to reduce image defects caused by abnormal nozzles such as non-ejection. However, according to the multi-scan method disclosed in Patent Document 1, the nozzle that performs complementary recording prints the superimposed data, and the printing speed has to be reduced.

  Inkjet printers are increasing in resolution year by year, and the resolution of the ejection port array for ejecting the liquid of the recording head is increased to 600 dpi and 1200 dpi. Accordingly, the size of the ejected ink droplets for forming an image tends to be reduced year by year from about 15 pl (picoliter) to 5 pl and 2 pl.

  In the case of a piezo type recording head, the structure is provided with a piezo element for each ejection port, so the head structure is complicated, and the ink is reduced when the piezo element is miniaturized as the resolution of the ejection port array increases. There is a problem in that it is difficult to obtain a volume change necessary for extruding.

  The present invention has been made in view of the above circumstances, and provides a liquid ejection apparatus that can easily compensate for non-ejection and can achieve high resolution, and an ink jet recording apparatus including the liquid ejection apparatus. It is intended to do.

The liquid discharge device of the present invention includes a liquid discharge member having a pressure chamber and a liquid discharge port that communicates with the pressure chamber and discharges the liquid in the pressure chamber to the outside, and increases the pressure in the pressure chamber from the liquid discharge port. A liquid ejecting apparatus comprising pressure applying means for ejecting liquid,
The portion of the liquid discharge member provided with the liquid discharge port is formed of a thin plate material,
Piezoelectric means for changing the discharge direction of liquid droplets discharged from the liquid discharge port by deforming the thin plate material on the outer periphery of the liquid discharge port of the thin plate material to change the shape of the liquid discharge port. It is characterized by having.

  The piezoelectric means may be composed of a single piezoelectric element, but is composed of a plurality of individually controllable piezoelectric elements arranged at different positions in the circumferential direction on the outer periphery of the liquid discharge port. Preferably there is.

  The plurality of piezoelectric elements are common to the plurality of piezoelectric elements, and are formed in order from the thin plate material side, the first electrode layer and the piezoelectric film, and the plurality of piezoelectric elements on the piezoelectric film. The second electrode layer is preferably formed in a pattern according to each piezoelectric element.

  An ink jet recording apparatus according to the present invention includes a recording head in which a plurality of liquid ejection apparatuses according to the present invention are arranged in a line.

  The liquid discharge device according to the present invention changes the shape of the liquid discharge port by deforming the thin plate material on the outer periphery of the liquid discharge port of the thin plate material provided with the liquid discharge port of the liquid discharge member. Since the piezoelectric means for changing the discharge direction of the liquid droplets discharged from the recording medium is desired, not only directly under the discharge port but also within the allowable range of the deformation amount of the discharge port when droplets are ejected onto the recording medium. It can be dropped at a position. According to such a recording head in which a plurality of liquid ejection devices are arranged, when an adjacent liquid ejection port fails to eject, the ejection port that has failed to eject ink to a location where droplets should be ejected. The droplets can be supplemented with droplets ejected from normal ejection openings. In addition, since it is possible to eject droplets to a position different from the position immediately below the ejection port, it is possible to measure high resolution by performing droplet ejection from a single ejection port to a plurality of locations.

  Since the ink jet recording apparatus of the present invention includes a recording head in which a plurality of the liquid ejecting apparatuses of the present invention are arranged in a row, if a certain liquid ejecting apparatus fails to eject, the adjacent normal liquid ejecting apparatus It is possible to supplement the droplet ejection by the liquid ejection device that has failed to eject by the device, and it is possible to easily complement the ejection failure. Further, from one liquid ejecting apparatus, an image having a resolution higher than that normally obtained by the number of liquid ejecting apparatuses arranged in a line such as by performing two droplets by deflection on the same line can be obtained.

Sectional drawing of the principal part showing the structure of the liquid ejection apparatus according to the present invention FIG. 1 is a partially enlarged view of the liquid ejection device in FIG. FIG. 2 is a bottom view of the liquid ejection device of FIG. FIG. 1 is a partially enlarged view showing a drive mode of the liquid ejection apparatus of FIG. The partially expanded view which shows another drive form of the liquid discharge apparatus of FIG. FIG. 1 is a cross-sectional view of a main part of a recording head in which a large number of liquid ejection devices in FIG. 1 are arranged. The figure which shows the structural example of the inkjet recording device provided with the recording head of FIG. Partial top view of the ink jet recording apparatus of FIG. The block diagram which shows the structure of the liquid discharge apparatus of another form FIG. 9 is a bottom view of the vicinity of the discharge port of the liquid discharge apparatus shown in FIG. The block diagram which shows the structure of the liquid discharge apparatus of another form The block diagram which shows the structure of the liquid discharge apparatus of another form The figure which shows the drive form of the liquid discharge apparatus of FIG. The figure which shows the piezoelectric element drive waveform in the liquid discharge apparatus of FIG.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

<Liquid Discharge Device of First Embodiment>
FIG. 1 is a schematic cross-sectional view showing a main part of a liquid ejection apparatus 1 according to a first embodiment of the present invention, and FIG. 2 is an enlarged view showing a part of the liquid ejection apparatus 1 in FIG. . FIG. 3 is a partial bottom view of the liquid ejection apparatus 1 enlarged in FIG. In order to facilitate visual recognition in each figure, the scale of the constituent elements is appropriately changed from the actual one.

  The liquid ejection apparatus 1 according to the present embodiment includes a liquid ejection member 10 having a pressure chamber 11 and a liquid ejection port 13 that communicates with the pressure chamber 11 and ejects the liquid (ink) 12 in the pressure chamber 11 to the outside. 11 is provided with pressure applying means 20 for increasing the pressure in the liquid 11 and discharging the liquid 12 from the liquid discharge port 13. The pressure chamber is connected to an ink storage unit (not shown), and ink is appropriately supplied from the ink storage unit.

  In the present embodiment, the pressure applying unit 20 includes a pressure chamber driving piezoelectric element (hereinafter referred to as a pressure chamber driving piezoelectric element 20) provided corresponding to the pressure chamber 11 of the liquid ejection member 10. However, a means such as a heater for foaming the liquid may be provided.

  The liquid discharge member 10 forms a pressure chamber 11 and a flow path 14 communicating with the pressure chamber 11 by dry etching or wet etching on a substrate 15, and a thin plate material (nozzle plate) 16 having a liquid discharge port 13 in the substrate 15. Is pasted. The nozzle plate 16 is preferably formed of a flexible material that easily vibrates. In addition, a vibration plate (diaphragm) 18 that forms the upper wall surface of the pressure chamber 11 by processing the substrate 15 and transmits the expansion and contraction of the piezoelectric element 20 to the pressure chamber 11 is formed, and the piezoelectric element 20 for pressure driving vibrates. An arrangement is formed on the plate 18.

  The liquid discharge apparatus 1 of the present embodiment further discharges from the discharge port 13 by changing the shape of the discharge port 13 by deforming the nozzle plate 16 around the discharge port 13 of the nozzle plate 16 having the discharge port 13. There is provided a piezoelectric means 30 for driving a discharge port for changing the discharge direction of the droplets to be discharged.

  In the present embodiment, the piezoelectric means 30 for driving the discharge port includes a plurality of piezoelectric elements 30 </ b> A to 30 </ b> D that can be individually controlled at different positions in the circumferential direction on the outer periphery of the discharge port 13 on the outer surface of the nozzle plate 16. (See FIG. 3). The piezoelectric elements 30A to 30D include the first electrode layer 31 and the piezoelectric film 32 formed from the nozzle plate 16 side in common to the four elements 30A to 30D, and the four elements 30A to 30D on the piezoelectric film 32. It consists of 2nd electrode layers 33A-33D patterned corresponding to each of 30D. Here, the second electrode layers 33A to 33D are arranged in an intermittent ring shape. In other words, in the present embodiment, the piezoelectric elements 30A to 30D are specified and separated from each other by the shape of the patterned second electrode layers 33A to 33D.

  The piezoelectric element 20 for driving pressure is an element in which a lower electrode layer 21, a piezoelectric film 22, and an upper electrode layer 23 are sequentially laminated on a vibration plate 18. An electric field is applied in the film thickness direction by the upper electrode layer 23.

  In the liquid ejection device 1, the electric field strength applied to the piezoelectric element 20 is increased or decreased to expand and contract the piezoelectric element 20, thereby controlling the ejection of the liquid 12 from the pressure chamber 11 and the ejection amount. The pressure applying means may be provided with a heater, such as a thermal ink jet that ejects ink by generating bubbles in the ink in the tube by heating.

As the substrate 15, a silicon substrate is preferable because of its good thermal conductivity and workability, and in particular, a stacked substrate such as an SOI substrate in which a SiO ₂ film and a Si active layer are sequentially stacked on a silicon substrate is preferably used. It is done. Further, between the diaphragm 18 and the lower electrode layer 21 of the pressure chamber driving piezoelectric element 20, a buffer layer for improving the lattice matching and an adhesion for improving the adhesion between the electrode and the substrate. A layer or the like may be provided.

  The substrate 15 on which the pressure chamber 11 is formed and the vibration plate 18 may be integral or separate. When the substrate is configured separately from the substrate, the substrate is not limited to silicon. Glass, stainless steel (SUS), yttrium stabilized zirconia (YSZ), alumina, sapphire, silicon carbide, and the like can be used.

The first electrode layer 31 of the discharge opening driving piezoelectric elements 30A to 30D, as the main component of the lower electrode layer 21 of the pressure chamber driving piezoelectric element 20 is not particularly _{limited, Ir, Au, Pt, IrO} 2, RuO 2 , LaNiO _3, and a metal or metal oxide such as SrRuO _3, and combinations thereof.

  The main components of the second electrode layer 33 of the discharge port driving piezoelectric elements 30A to 30D and the upper electrode layer 23 of the pressure chamber driving piezoelectric element 20 are not particularly limited, and the first electrode layer 31 and the lower electrode layer 21 are not particularly limited. Examples thereof include electrode materials generally used in semiconductor processes, such as Al, Ta, Cr, and Cu, and combinations thereof.

  The thickness of each electrode layer 31, 33, 21, 23 is not particularly limited and is preferably 50 to 500 nm.

  The film thicknesses of the piezoelectric film 32 of the discharge port driving piezoelectric elements 30A to 30D and the piezoelectric film 22 of the pressure chamber driving piezoelectric element 20 are not particularly limited, and a thin film of 10 nm to 100 μm is preferable, and a thin film of 100 nm to 20 μm is particularly preferable. preferable.

  The film formation method of the piezoelectric films 32 and 22 is not particularly limited, but gas phase methods such as sputtering, plasma CVD, MOCVD, and PLD; liquid phase methods such as sol-gel and organometallic decomposition; and aerosols Examples include the deposition method.

  In addition, it is preferable that the piezoelectric elements 30A to 30D for driving the discharge ports are formed directly on the nozzle plate 16 and the piezoelectric element 20 for driving the pressure chambers is directly formed on the diaphragm 18 by vapor deposition or the like. A piezoelectric element configured by polishing a thin piezoelectric body and including an electrode may be attached to a thin plate material. However, since it is necessary to form a very fine structure, it is easy and preferable to form a film directly by vapor deposition or the like.

  The composition of the piezoelectric films 32 and 22 is not particularly limited, and is preferably composed of one or more perovskite oxides (which may contain inevitable impurities) represented by the following general formula (P). .

General formula ABO ₃ (P)
(A: Element of A site, including at least one element selected from the group consisting of Pb, Ba, Sr, Bi, Li, Na, Ca, Cd, Mg, K, and lanthanide elements.
B: Element of B site, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Mg, Sc, Co, Cu, In, Sn, Ga, Zn, Cd, Fe, Ni, Hf , And at least one element selected from the group consisting of Al.
O: oxygen.
The molar ratio of the A site element, the B site element, and the oxygen element is 1: 1: 3 as a standard, but these molar ratios may deviate from the reference molar ratio within a range where a perovskite structure can be taken. )
As the perovskite oxide represented by the general formula (P),
Lead titanate, lead zirconate titanate (PZT), lead zirconate, lead lanthanum titanate, lead lanthanum zirconate titanate, lead zirconium niobate titanate titanate, lead zirconium niobate titanate titanate, titanium titanate zinc niobate Lead-containing compounds such as lead acid, and mixed crystal systems thereof;
Examples thereof include lead-free compounds such as barium titanate, barium strontium titanate, bismuth sodium titanate, bismuth potassium titanate, sodium niobate, potassium niobate, lithium niobate, and mixed crystal systems thereof.

  Since the electrical characteristics become better, the perovskite oxide represented by the general formula (P) is composed of Mg, Ca, Sr, Ba, Bi, Nb, Ta, W, and Ln (= lanthanide element (La , Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu)).

  4 and 5 are cross-sectional views in the vicinity of the ejection port showing the driving mode of the ejection port driving piezoelectric means 30 of the liquid ejection device 1. FIG. 4 shows a drive mode when a voltage is applied only to one piezoelectric element 30D among the four piezoelectric elements 30A to 30D shown in FIG. 3, and FIG. 5 shows all of the four piezoelectric elements 30A to 30D. It shows a driving mode when the same voltage is applied.

As shown in FIG. 4, when a voltage is applied only to one piezoelectric element 30D, the nozzle plate 16 in the vicinity of the piezoelectric element 30D is deformed, the ejection port is deformed, and the ejection direction of the liquid 12 is changed to the direct downward direction A _1. To the diagonal direction A ₂ . The amount of change can be controlled by the voltage applied to the piezoelectric element 30D.

  The piezoelectric film 32 of the piezoelectric elements 30 </ b> A to 30 </ b> D is formed so that the expansion / contraction direction thereof is the in-film direction, and when a voltage is applied, the periphery of the discharge port 13 of the nozzle plate is directed upward. Or the internal stress which warps downward works. A voltage is applied to the piezoelectric elements 30 </ b> A to 30 </ b> D, that is, the shape of the discharge port is changed as the piezoelectric film expands and contracts by applying a voltage to the upper and lower electrode layers and applying an electric field to the piezoelectric film 32. it can. It is possible to control whether the piezoelectric film 32 is warped upward or downward, depending on whether the applied voltage is positive or negative.

Further, when the same voltage is simultaneously applied to the piezoelectric elements 30 </ b> A to 30 </ b> D, as shown in FIG. 5, it is possible to control so that the periphery of the ejection port is entirely warped downward. In this way, the diameter d ₀ (see FIG. 2) of the discharge port 13 can be increased to d ₁ , and the discharge amount (droplet size (volume)) can be easily adjusted. .

The droplet volume Vd is expressed as follows.
Vd = πr ² · v / 2f
Here, r is a discharge port radius, v is a droplet velocity, and f is a pressure resonance frequency.

  That is, since the droplet volume Vd is proportional to the square of the ejection port radius, the droplet volume can be easily increased by increasing the aperture.

  In order to make the deformation around the discharge port sufficient, as shown in FIG. 2, the diameter D of the flow path 14 is located between the inner peripheral diameter Din and the outer peripheral diameter of the piezoelectric element. It is preferable to form such that

  As shown in FIG. 3, in this embodiment, four piezoelectric elements 30 </ b> A to 30 </ b> D are intermittently arranged in a ring shape as piezoelectric means for driving the discharge port. The present invention is not limited to this, and any configuration that can change the discharge direction of the liquid droplets discharged from the liquid discharge port 13 may be used. For example, it may include only one of the piezoelectric elements 30A to 30D illustrated in FIG. 3, or may include two adjacent elements or two elements facing each other. Furthermore, it is good also as providing one element of the length which two adjacent elements connected. The shape of each piezoelectric element is not necessarily an arc shape along the circumferential direction, but is preferably an arc shape as shown in FIG. Further, the length of the arc is preferably 90 ° or less even when only one piezoelectric element is provided, and when two or more piezoelectric elements are provided, the center angle of each element is It is preferably less than 90 ° and substantially the same angle. The number and arrangement of the piezoelectric elements can be determined according to the purpose of deflecting the droplet (higher resolution or complementation of non-ejection nozzles) and the method (in which direction the nozzles adjacent to each other are complemented). For example, when it is only necessary to change the ejection direction in a predetermined direction, only one piezoelectric element may be provided. When it is desired to freely change the ejection direction, it is preferable to provide at least three, or four or more piezoelectric elements.

  Japanese Patent Application Laid-Open No. 7-156408 proposes a method of changing the size of ejected droplets by providing a piezoelectric element in the vicinity of the ejection port. Specifically, in thermal ink jet, there is a method of changing the droplet size by changing the volume between the heater and the discharge port by making the vicinity of the discharge port convex toward the pressure chamber or outward. Proposed. However, Japanese Patent Laid-Open No. 7-156408 has no description or suggestion of the idea of changing the liquid discharge direction from the liquid discharge port as in the present invention. Effects such as resolution cannot be obtained.

"Recording head"
With reference to FIG. 6, a description will be given of a recording head 3 in which a plurality of liquid ejection devices are provided. FIG. 6 is a cross-sectional view showing a part of the recording head and the recording medium (recording paper 116). 6 includes a large number of liquid ejection devices (nozzles) 1 a, 1 b, 1 c,... Arranged in the X direction, and FIG. 6 is perpendicular to the Y direction of the recording head 3. A part of the cross section is shown. Each of the nozzles 1a, 1b, 1c,... Corresponds to the liquid ejecting apparatus 1 described above. In FIG. 6, each element is equivalent to an element having the same reference numeral (excluding the alphabet) of the liquid ejecting apparatus 1.

  As shown in FIG. 6, the recording head 3 communicates with a number of pressure chambers 11a, 11b, 11c,... And the pressure chambers 11a, 11b, 11c,. There are a large number of liquid discharge ports 13a, 13b, 13c,... For discharging liquid to the outside, and pressure chamber driving piezoelectric elements 20a, 20b, 20c,. ing. The pressure chambers 11a, 11b, 11c,... Are provided on a common substrate 15 ′. Similarly, the liquid discharge ports 13a, 13b, 13c,... Are provided on a common thin plate material (nozzle plate) 16 ′. The substrate 15 ′ and the nozzle plate 16 ′ constitute a connected liquid discharge member 10 ′ in which a large number of liquid discharge members 10 of the above embodiment are arranged.

  .. Are provided on the outer periphery of each of the liquid discharge ports 13a, 13b, 13c,... For changing the discharge direction of liquid droplets discharged from the respective liquid discharge ports 13a, 13b, 13c,. In this embodiment, each of the piezoelectric means 30a, 30b, 30c,... Is formed of four piezoelectric elements as shown in FIG.

A method for complementing non-ejection nozzles in the recording head 3 and a method for increasing the resolution will be described. In FIG. 6, as schematically shown for the nozzle 1a, the droplet 12a is ejected directly below the ejection port 13a when the piezoelectric element for driving the ejection port is not driven. The positions immediately below the ejection ports 13a, 13b,... At the X-direction position of the recording paper 116 are denoted as _Xa1 , _Xb1,. Here, for example, when the discharge port 13b of the nozzle 1b does not discharge, information to be ejected by the nozzle 1b is supplemented by the adjacent nozzle 1a. A predetermined voltage is applied to the piezoelectric element 30D (see FIG. 4) of the discharge port driving piezoelectric means 30a of the nozzle 1a to change the droplet discharge direction (flying direction), and X _b1 to be ejected by the nozzle 1b. Drip to the position of. In this way, by complementing the droplet ejection of the non-ejection nozzle by the adjacent nozzle, it is possible to suppress the generation of streaks that occur in the print image due to the non-ejection of the nozzle and print a high-quality image.

  Further, even when there is some problem in the nozzle shape and the liquid droplet is not discharged directly below, the liquid droplet is discharged by applying a predetermined voltage to the piezoelectric elements 30A to 30D (see FIG. 4) of the piezoelectric means 30 for driving the discharge port. By changing the direction (flying direction) and correcting the ejection direction, it is possible to correct the droplet landing place where it should be. In this case, it is only necessary to print all nozzle discharge patterns dedicated to the monitor from the heads of the respective colors in advance, read this pattern with a reading device, and give correction information to the ink jet recording device.

Further, for all nozzles, in addition to droplet ejection for each nozzle arrangement cycle, droplets can be ejected to a position that is a half cycle of the nozzle arrangement cycle in the X direction, whereby high resolution can be measured. Specifically, in FIG. 6, as schematically shown for the nozzle 1 a, the nozzle ₁ a applies droplets to a position X _a2 that is a half cycle of the nozzle arrangement cycle in addition to droplets to the position X _a1 immediately below the nozzle. Control to do. This makes it possible to obtain twice the resolution without increasing the number of nozzles. That is, according to the recording head of this embodiment, it is possible to solve the problem that the volume change necessary for ink extrusion cannot be obtained due to the miniaturization of the piezoelectric element for driving the pressure chamber. That is, the resolution can be increased while maintaining the size of the piezoelectric element that can obtain the volume change necessary for ink extrusion.

  In the recording head, the pressure chambers may include not only multiple rows in the X direction but also multiple rows in the Y direction.

"Inkjet recording device"
With reference to FIG. 7 and FIG. 8, a configuration example of an ink jet recording apparatus including the recording head 3 of the above embodiment will be described. FIG. 7 is an overall view of the apparatus, and FIG. 8 is a partial top view.

  The illustrated ink jet recording apparatus 100 includes a printing unit 102 having a plurality of ink jet recording heads (hereinafter simply referred to as “heads”) 3K, 3C, 3M, and 3Y provided for each ink color, and each head 3K, An ink storage / loading unit 114 that stores ink to be supplied to 3C, 3M, and 3Y, a paper feeding unit 118 that supplies recording paper 116, a decurling unit 120 that removes curling of the recording paper 116, and a printing unit An adsorption belt conveyance unit 122 that conveys the recording paper 116 while maintaining the flatness of the recording paper 116, and a print detection unit that reads a printing result by the printing unit 102. 124 and a paper discharge unit 126 that discharges printed recording paper (printed matter) to the outside.

  Each of the heads 3K, 3C, 3M, and 3Y forming the printing unit 102 is the recording head 3 of the above embodiment.

  In the decurling unit 120, heat is applied to the recording paper 116 by the heating drum 130 in the direction opposite to the curl direction, and the decurling process is performed.

  In the apparatus using roll paper, as shown in FIG. 7, a cutter 128 is provided at the subsequent stage of the decurling unit 120, and the roll paper is cut into a desired size by this cutter. The cutter 128 includes a fixed blade 128A having a length equal to or larger than the conveyance path width of the recording paper 116, and a round blade 128B that moves along the fixed blade 128A. The fixed blade 128A is provided on the back side of the print. The round blade 128B is arranged on the print surface side with the conveyance path interposed therebetween. In an apparatus using cut paper, the cutter 128 is unnecessary.

  The decurled and cut recording paper 116 is sent to the suction belt conveyance unit 122. The suction belt conveyance unit 122 has a structure in which an endless belt 133 is wound between rollers 131 and 132, and at least portions facing the nozzle surface of the printing unit 102 and the sensor surface of the printing detection unit 124 are horizontal ( Flat surface).

  The belt 133 has a width that is wider than the width of the recording paper 116, and a plurality of suction holes (not shown) are formed on the belt surface. An adsorption chamber 134 is provided at a position facing the nozzle surface of the printing unit 102 and the sensor surface of the print detection unit 124 inside the belt 133 that is stretched between the rollers 131 and 132. The recording paper 116 on the belt 133 is sucked and held by suctioning at 135 to make a negative pressure.

  The power of a motor (not shown) is transmitted to at least one of the rollers 131 and 132 around which the belt 133 is wound, so that the belt 133 is driven in the clockwise direction in FIG. The recording paper 116 is conveyed from left to right in FIG.

  Since ink adheres to the belt 133 when a borderless print or the like is printed, the belt cleaning unit 136 is provided at a predetermined position outside the belt 133 (an appropriate position other than the print region).

  A heating fan 140 is provided on the upstream side of the printing unit 102 on the paper conveyance path formed by the suction belt conveyance unit 122. The heating fan 140 heats the recording paper 116 by blowing heated air onto the recording paper 116 before printing. Heating the recording paper 116 immediately before printing makes it easier for the ink to dry after landing.

  The printing unit 102 is a so-called full-line head in which line-type heads having a length corresponding to the maximum paper width are arranged in a direction orthogonal to the paper feed direction (main scanning direction) (see FIG. 8). Each of the print heads 3K, 3C, 3M, and 3Y is a line-type head in which a plurality of ink discharge ports (nozzles) are arranged over a length exceeding at least one side of the maximum-size recording paper 116 targeted by the ink jet recording apparatus 100. It is configured.

  Heads 3K, 3C, 3M, and 3Y corresponding to the respective color inks are arranged in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side along the feeding direction of the recording paper 116. ing. A color image is recorded on the recording paper 116 by ejecting the color ink from each of the heads 3K, 3C, 3M, 3Y while conveying the recording paper 116.

  The print detection unit 124 includes a line sensor that images the droplet ejection result of the print unit 102 and detects ejection defects such as nozzle clogging from the droplet ejection image read by the line sensor.

  Each of the heads 3K, 3C, 3M, and 3Y includes the nozzle 1 (1a, 1b, 1c...) Of the above-described embodiment, and can deflect the flight direction of the droplet (ink droplet) from each ejection port. Therefore, when an adjacent nozzle becomes defective due to clogging or the like, droplets are ejected by complementing with a normal nozzle. For example, control is performed so that the ejection failure nozzles detected in the immediately preceding line for each line are complemented by the adjacent normal nozzles.

  A post-drying unit 142 including a heating fan or the like for drying the printed image surface is provided at the subsequent stage of the print detection unit 124. Since it is preferable to avoid contact with the print surface until the ink after printing is dried, a method of blowing hot air is preferred.

  A heating / pressurizing unit 144 is provided downstream of the post-drying unit 142 in order to control the glossiness of the image surface. The heating / pressurizing unit 144 presses the image surface with a pressure roller 145 having a predetermined surface irregularity shape while heating the image surface, and transfers the irregular shape to the image surface.

The printed matter obtained in this manner is outputted from the paper output unit 126. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. In the ink jet recording apparatus 100, there is provided sorting means (not shown) for switching the paper discharge path in order to select the print product of the main image and the print product of the test print and send them to the discharge units 126A and 126B. It has been.
When the main image and the test print are simultaneously printed on a large sheet of paper, the cutter 148 may be provided to separate the test print portion.
The ink jet recording apparatus 100 is configured as described above.

  The present invention is not limited to the above-described embodiment, and the design can be changed as appropriate without departing from the spirit of the present invention.

  In the above embodiment, it has been described that droplet ejection from a non-ejection nozzle is complemented by an adjacent normal nozzle instead of a non-ejection nozzle, but for all nozzles, in addition to droplet ejection for each nozzle arrangement cycle The high resolution can be measured by ejecting droplets in the same direction (for example, the X direction) at a position that is a half cycle of the nozzle arrangement cycle.

`` Design change example ''
Hereinafter, other forms of liquid ejection devices will be described. In the following, the same elements as those of the liquid ejecting apparatus shown in FIG.

  FIG. 9 is a diagram showing a schematic configuration of the second liquid ejection device 5, and FIG. 10 is a bottom view showing the vicinity of the ejection port of the liquid ejection device 5. The liquid ejection device 5 is different from the liquid ejection device shown in FIG. 1 in that the piezoelectric element 50 provided around the ejection port is formed in a continuous ring shape.

  Further, in this example, the piezoelectric element 50 is not used to drive the discharge port but is used as a sensor, and a current detection means 55 is connected to the piezoelectric element 50. Whether or not the liquid has been normally discharged can be detected by detecting, by the piezoelectric element 50, minute vibrations in the vicinity of the discharge port that are generated when the liquid is discharged from the liquid discharge device 5. For example, when an ink is ejected, an alternating current having a higher amplitude than that at the time of non-ejection is detected, so that a certain threshold value is provided and compared with the amplitude of the detection signal, so that ejection or non-ejection can be determined. It should be noted that, in place of the piezoelectric element 50, the sensor is similarly provided with a configuration including a plurality of intermittent ring-shaped piezoelectric elements 30 </ b> A to 30 </ b> D provided on the outer periphery of the discharge port 13 of the liquid discharge apparatus 1 described above. Can be used.

FIG. 11 is a diagram showing a schematic configuration of the third liquid ejection device 6.
Similar to the second liquid ejection device 5, the liquid ejection device 6 includes a ring-shaped piezoelectric element 50 around the ejection port. Here, the piezoelectric element 50 is connected to an AC power source 60.

  In this example, the piezoelectric element 50 is used for shaking the meniscus (liquid level position M) at the discharge port 13. That is, it is used to apply an AC voltage to the piezoelectric element 50 and vibrate ink near the nozzle opening. It is possible to diffuse ink that has been thickened by exposure to the outside air near the nozzle opening by shaking the meniscus, and to suppress ink ejection failure due to clogging. Although the meniscus can be shaken by the piezoelectric element 20 for driving the pressure chamber, if the meniscus is shaken by the piezoelectric element 50 around the discharge port, it is possible to design a waveform with a higher degree of freedom. A waveform suitable for shaking the meniscus has such a magnitude that gives a slight vibration that does not cause ink to be ejected from the nozzle, and includes a frequency of pressure resonance.

  In the liquid ejection apparatus 1 according to the embodiment of the present invention shown in FIG. 1, the piezoelectric elements 30A to 30D for driving the ejection ports can be used for fine adjustment of the meniscus M, shaking of the meniscus, and the like.

  FIG. 12 is a diagram showing a schematic configuration of the fourth liquid ejection apparatus 7, and FIG. 13 is a diagram showing one of its drive modes.

  Similarly to the second and third liquid ejecting apparatuses 5, the liquid ejecting apparatus 7 includes a ring-shaped piezoelectric element 50 around the ejection opening. Here, the piezoelectric element 50 is a piezoelectric means for driving the discharge port. Further, the liquid ejection device 7 includes a power source 70 for applying a voltage to the piezoelectric element 20 for driving the pressure chamber, a power source 71 for applying a voltage to the piezoelectric element 50, and a control means 72 for controlling the both power sources 70, 71. I have.

  The control means 72 controls the drive timing of the piezoelectric element 50 for driving the discharge port and the piezoelectric element 20 for driving the pressure chamber, and the operation of the two is linked to thereby adjust the shape of the pressure chamber 11 and the meniscus. Control can be performed with higher accuracy. Specifically, by combining the control of both piezoelectric elements, it is possible to control the ink droplet size, prevent bubbles from being mixed into the pressure chamber, and the like.

  For example, as shown in FIG. 13, after the droplet is discharged, the discharge port is used to improve the breakage of the droplet by increasing the volume of the pressure chamber 11 on the driving side (the vibration plate 18 is convex upward). When nothing is done with the driving piezoelectric element 50, there is a concern that the liquid level of the liquid is greatly drawn and bubbles are mixed in. However, the piezoelectric element 50 causes the discharge port 13 to protrude upward (warp to the pressure chamber side). ) To prevent air bubbles from entering.

  FIG. 14 shows examples of drive waveforms of the piezoelectric element 20 for driving the pressure chamber and the piezoelectric element 50 for driving the discharge port in the liquid discharge apparatus 7. The vertical axis represents voltage, and the horizontal axis represents time.

  Step I is a state in which a voltage is applied to the piezoelectric element 20 for driving the pressure chamber so that the diaphragm 18 protrudes downward. In the next step II, the diaphragm 18 is returned to the flat side, thereby removing the ink reservoir. Ink the ink into the pressure chamber. After 5 μs (microseconds), in step III, the vibration plate 18 is pushed down, and ink is ejected. Next, in step IV, the diaphragm 18 is raised upward to cut a droplet. At the same time, a voltage is applied to the piezoelectric element 50 for driving the discharge port so that the discharge port is convex upward. In step V, the diaphragm 18 is returned to a convex state. At this time, the ink is returned at a speed at which re-ejection is not performed. Subsequent Step VI is in the next discharge waiting state.

  By controlling as described above, it is possible to improve the breakage of the droplets and at the same time prevent the bubbles from entering the pressure chamber.

  The meniscus control and the control of the piezoelectric elements 20 and 50 differ depending on the ink viscosity, the ejection frequency, and the like, and therefore need to be set as appropriate. However, by controlling both in combination, a wide and robust design is possible.

1, 1a, 1b, 1c, ... Liquid discharge device (nozzle)
3, 3K, 3C, 3M, 3Y Recording head 5, 6, 7, Liquid ejection device 10 Liquid ejection member 10 'Connection liquid ejection member 11, 11a, 11b, 11c, ... Pressure chamber 12 Liquid (ink)
12a Liquid droplets 13, 13a, 13b, 13c,... Liquid discharge port 14 Flow path 15, 15 ′ Substrate 16, 16 ′ Thin plate material (nozzle plate)
20, 20a, 20b, 20c, ... Pressure applying means (piezoelectric element)
21 Lower electrode layer 22 Piezoelectric film 23 Upper electrode layers 30, 30a, 30b, 30c, ... Discharge port driving piezoelectric means 30A to 30D Discharge port driving piezoelectric element 31 First electrode layer 32 Piezoelectric film 33 Second Electrode layer 33D Piezoelectric element 50 Piezoelectric element 55 Current detection means 60 AC power supply 70 Power supply for piezoelectric element for driving pressure chamber 71 Power supply for piezoelectric element for driving discharge port 72 Control means 100 Inkjet recording apparatus 116 Recording paper

Claims (4)

A liquid ejection member having a pressure chamber and a liquid ejection port that communicates with the pressure chamber and ejects the liquid in the pressure chamber to the outside; and a pressure applying unit that increases the pressure in the pressure chamber and ejects the liquid from the liquid ejection port. A liquid ejection device comprising:
The portion of the liquid discharge member provided with the liquid discharge port is formed of a thin plate material,
Piezoelectric means for changing the discharge direction of liquid droplets discharged from the liquid discharge port by deforming the thin plate material on the outer periphery of the liquid discharge port of the thin plate material to change the shape of the liquid discharge port. A liquid ejecting apparatus comprising the liquid ejecting apparatus.   2. The liquid ejecting apparatus according to claim 1, wherein the piezoelectric means comprises a plurality of individually controllable piezoelectric elements arranged at different positions in the circumferential direction on the outer periphery of the liquid ejection port. .   The plurality of piezoelectric elements are formed in order from the thin plate material side in common to the plurality of piezoelectric elements, and the plurality of piezoelectric elements on the piezoelectric film. The liquid ejection apparatus according to claim 2, comprising: a second electrode layer patterned according to each of the piezoelectric elements.   An ink jet recording apparatus comprising a recording head in which a plurality of liquid ejecting apparatuses according to claim 1 are arranged in a row.

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