JP2012045889A - Liquid ejection head and recording device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid ejection head which can improve the utilization efficiency of space in a substrate and a flow path member and form a space for forming an orifice, and a recording device using the same.SOLUTION: A liquid ejection head includes a first flow path member 4 including a plurality of liquid ejection holes 8 which open to one principal plane, a plurality of liquid pressurizing chambers 10 which are continuous with the plurality of liquid ejection holes 8 and which open to the other principal plane, a plurality of liquid introduction chambers 15 which open to the other principal plane, and an orifice 12 continuous with the plurality of the pressurizing chambers 10 from the liquid introduction chamber 15, a substrate 21 which has a plurality of through-holes 30 opening at the positions of the plurality of liquid introduction chambers 15 and a pressurizing part 50 for pressurizing liquid of the plurality of liquid pressurizing chambers 10 and which is laminated on the first flow path member 4 in such a manner that the plurality of liquid pressurizing chambers 10 are covered, and a second flow path member 40 having a manifold 5 continuous with the plurality of liquid introduction holes 15 passing through the plurality of through-holes 30.

Description

  The present invention relates to a liquid discharge head that discharges droplets and a recording apparatus using the same.

  In recent years, printing apparatuses using inkjet recording methods such as inkjet printers and inkjet plotters are not only printers for general consumers, but also, for example, formation of electronic circuits, manufacture of color filters for liquid crystal displays, manufacture of organic EL displays It is also widely used for industrial applications.

  In such an ink jet printing apparatus, a liquid discharge head for discharging liquid is mounted as a print head. This type of print head includes a heater as a pressurizing unit in an ink flow path filled with ink, heats and boiles the ink with the heater, pressurizes the ink with bubbles generated in the ink flow path, A thermal head system that ejects ink as droplets from the ink ejection holes, and a part of the wall of the ink channel filled with ink is bent and displaced by a displacement element, and the ink in the ink channel is mechanically pressurized, and the ink A piezoelectric method is known in which droplets are discharged from discharge holes.

  In addition, in such a liquid discharge head, a serial type that performs recording while moving the liquid discharge head in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording medium, and main scanning from the recording medium There is a line type in which recording is performed on a recording medium conveyed in the sub-scanning direction with a liquid discharge head that is long in the direction fixed. The line type has the advantage that high-speed recording is possible because there is no need to move the liquid discharge head as in the serial type.

  In order to print droplets at a high density in any of the serial type and line type liquid discharge heads, the density of the liquid discharge holes for discharging the droplets formed in the liquid discharge head must be increased. There is a need to.

  Therefore, by having a liquid discharge hole directly connected to the liquid pressurizing chamber, and providing a diaphragm and a piezoelectric element in a portion of the liquid pressurizing chamber facing the liquid discharge hole, the piezoelectric element is expanded and contracted. A liquid discharge head comprising a plurality of liquid discharge elements for bending and deforming a piezoelectric element and a diaphragm and discharging liquid droplets from the liquid discharge hole, wherein a liquid flow from a common flow path to the liquid pressurizing chamber There is known a liquid discharge head in which supply is performed through a through hole formed in the diaphragm and the piezoelectric element (see, for example, Patent Document 1).

JP-A-9-226114

  However, in the liquid discharge head described in Patent Document 1, the through holes provided in the piezoelectric element and the vibration plate restrict the supply of the liquid between the liquid pressurizing chamber and the common flow path and the propagation of the vibration of the liquid. It is necessary to play the role of restricting the restriction, and for that purpose, the size of the through hole must be very small, and the size of the through hole is only slightly varied, and the liquid discharge characteristics vary greatly. There was a problem.

  Accordingly, an object of the present invention is to provide a liquid discharge head capable of improving the utilization efficiency of the flow path member and the space in the substrate and providing a space for forming a squeeze, and a recording apparatus using the liquid discharge head.

  The liquid discharge head of the present invention includes a plurality of liquid discharge holes that are open on one main surface, and a plurality of liquid pressurizations that are connected to the plurality of liquid discharge holes and that are open on the other main surface. A first flow path member having a chamber, a plurality of liquid introduction chambers open to the other main surface, and a squeezing connected from the liquid introduction chamber to the plurality of pressurization chambers, and the plurality of liquids A pressurizing section that pressurizes the liquid in the pressurizing chamber; and a plurality of through holes that open at positions of the plurality of liquid introducing chambers, respectively, and the first pressurizing chamber covers the plurality of liquid pressurizing chambers. A substrate laminated on the flow path member and a second flow path member having a manifold connected to the plurality of liquid introduction holes through the plurality of through holes.

  It is preferable that the plurality of liquid pressurization chambers connected to one liquid introduction chamber are arranged at substantially rotationally symmetric positions around the liquid introduction chamber.

  It is preferable that a unit composed of one liquid introduction chamber and a plurality of the liquid pressurization chambers connected to the liquid introduction chamber is arranged in a matrix.

  The plurality of liquid ejection holes are arranged at equal intervals on the virtual straight line when projecting the plurality of liquid ejection holes so as to be orthogonal to the virtual straight line with respect to the virtual straight line. It is preferable that the liquid pressurizing chambers connected to the liquid ejection holes projected to adjacent positions on the virtual straight line are not adjacent to each other.

  The plurality of liquid ejection holes are arranged at equal intervals on the virtual straight line when projecting the plurality of liquid ejection holes so as to be orthogonal to the virtual straight line with respect to the virtual straight line. It is preferable that the liquid pressurizing chambers connected to the liquid ejection holes projected to adjacent positions on the virtual straight line are not connected to the same liquid introduction chamber.

  It is preferable that the plurality of aperture openings connected to the liquid introduction chamber do not face each other.

  It is preferable that the plurality of aperture openings connected to the liquid introduction chamber are open in the same plane.

  It is preferable that the liquid introduction chamber of the first flow path member and the opening connected to the manifold of the second flow path member are directly connected.

  In addition, the recording apparatus of the present invention includes the liquid discharge head, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the plurality of pressure units and the transport unit. It is characterized by being.

  According to the liquid discharge head of the present invention, since the liquid is supplied to the plurality of liquid pressurizing chambers through one penetration and the liquid introduction chamber, the use efficiency of the space in the flow path member and the substrate can be increased and It is possible to secure a space in which is provided.

1 is a schematic configuration diagram of a printer that is a recording apparatus according to an embodiment of the present invention. FIG. 2 is a schematic partial plan view of a liquid ejection head according to an embodiment of the present invention. FIG. 3 is a partial longitudinal sectional view of the liquid ejection head of FIG. 2. It is a fragmentary longitudinal cross-sectional view of the other liquid discharge head of this invention. It is a fragmentary longitudinal cross-sectional view of the other liquid discharge head of this invention. It is a schematic partial top view of the liquid discharge head of the other liquid discharge head of this invention. It is a schematic partial top view of the liquid discharge head of the other liquid discharge head of this invention.

  FIG. 1 is a schematic configuration diagram of a color ink jet printer which is a recording apparatus including a liquid discharge head according to an embodiment of the present invention. This color inkjet printer 1 (hereinafter referred to as printer 1) has four liquid ejection heads 2. These liquid discharge heads 2 are arranged along the conveyance direction of the printing paper P and are fixed to the printer 1. The liquid discharge head 2 has an elongated shape in a direction from the front to the back in FIG. This long direction is sometimes called the longitudinal direction.

  In the printer 1, a paper feed unit 114, a transport unit 120, and a paper receiver 116 are sequentially provided along the transport path of the printing paper P. In addition, the printer 1 is provided with a control unit 100 for controlling the operation of each unit of the printer 1 such as the liquid discharge head 2 and the paper feeding unit 114.

  The paper supply unit 114 includes a paper storage case 115 that can store a plurality of printing papers P, and a paper supply roller 145. The paper feed roller 145 can send out the uppermost print paper P among the print papers P stacked and stored in the paper storage case 115 one by one.

  Between the paper feed unit 114 and the transport unit 120, two pairs of feed rollers 118a and 118b and 119a and 119b are arranged along the transport path of the printing paper P. The printing paper P sent out from the paper supply unit 114 is guided by these feed rollers and further sent out to the transport unit 120.

  The transport unit 120 includes an endless transport belt 111 and two belt rollers 106 and 107. The conveyor belt 111 is wound around belt rollers 106 and 107. The conveyor belt 111 is adjusted to such a length that it is stretched with a predetermined tension when it is wound around two belt rollers. Thus, the conveyor belt 111 is stretched without slack along two parallel planes each including a common tangent line of the two belt rollers. Of these two planes, the plane closer to the liquid ejection head 2 is a transport surface 127 that transports the printing paper P.

  As shown in FIG. 1, a conveyance motor 174 is connected to the belt roller 106. The transport motor 174 can rotate the belt roller 106 in the direction of arrow A. The belt roller 107 can rotate in conjunction with the transport belt 111. Therefore, the conveyance belt 111 moves along the direction of arrow A by driving the conveyance motor 174 and rotating the belt roller 106.

  In the vicinity of the belt roller 107, a nip roller 138 and a nip receiving roller 139 are arranged so as to sandwich the conveyance belt 111. The nip roller 138 is urged downward by a spring (not shown). A nip receiving roller 139 below the nip roller 138 receives the nip roller 138 biased downward via the conveying belt 111. The two nip rollers are rotatably installed and rotate in conjunction with the conveyance belt 111.

  The printing paper P sent out from the paper supply unit 114 to the transport unit 120 is sandwiched between the nip roller 138 and the transport belt 111. As a result, the printing paper P is pressed against the transport surface 127 of the transport belt 111 and is fixed on the transport surface 127. The printing paper P is transported in the direction in which the liquid ejection head 2 is installed according to the rotation of the transport belt 111. The outer peripheral surface 113 of the conveyor belt 111 may be treated with adhesive silicon rubber. Thereby, the printing paper P can be securely fixed to the transport surface 127.

  The four liquid discharge heads 2 are arranged close to each other along the conveyance direction by the conveyance belt 111. Each liquid discharge head 2 has a liquid discharge head main body 13 at the lower end. A large number of liquid ejection holes 8 for ejecting liquid are provided on the lower surface of the liquid ejection head body 13.

  Liquid droplets (ink) of the same color are ejected from the liquid ejection holes 8 provided in one liquid ejection head 2. Since the liquid ejection holes 8 of each liquid ejection head 2 are arranged at equal intervals in one direction (a direction parallel to the printing paper P and perpendicular to the conveyance direction of the printing paper P and the longitudinal direction of the liquid ejection head 2), Printing can be performed without gaps in one direction. In other words, when the liquid discharge holes 8 are projected so as to be orthogonal to a virtual straight line parallel to the longitudinal direction, the liquid discharge holes 8 are arranged at equal intervals on the virtual straight line. It is.

  The colors of the liquid ejected from each liquid ejection head 2 are magenta (M), yellow (Y), cyan (C), and black (K), respectively. Each liquid discharge head 2 is arranged with a slight gap between the lower surface of the liquid discharge head main body 13 and the transport surface 127 of the transport belt 111.

  The printing paper P transported by the transport belt 111 passes through the gap between the liquid ejection head 2 and the transport belt 111. At that time, droplets are ejected from the liquid ejection head body 13 constituting the liquid ejection head 2 toward the upper surface of the printing paper P. As a result, a color image based on the image data recorded in the control unit 100 is formed on the upper surface of the printing paper P.

  A separation plate 140 and two pairs of feed rollers 121a and 121b and 122a and 122b are arranged between the transport unit 120 and the paper receiver 116. The printing paper P on which the color image is printed is conveyed to the peeling plate 140 by the conveying belt 111. At this time, the printing paper P is peeled from the transport surface 127 by the right end of the peeling plate 140. Then, the printing paper P is sent out to the paper receiving unit 116 by the feed rollers 121a to 122b. In this way, the printed printing paper P is sequentially sent to the paper receiving unit 116 and stacked on the paper receiving unit 116.

  Note that a paper surface sensor 133 is installed between the liquid ejection head 2 and the nip roller 138 that are the most upstream in the transport direction of the printing paper P. The paper surface sensor 133 includes a light emitting element and a light receiving element, and can detect the leading end position of the printing paper P on the transport path. The detection result by the paper surface sensor 133 is sent to the control unit 100. The control unit 100 can control the liquid ejection head 2, the conveyance motor 174, and the like so that the conveyance of the printing paper P and the printing of the image are synchronized based on the detection result sent from the paper surface sensor 133.

Next, the liquid discharge head 2 and the first flow path member 4 used for the same will be described. The liquid discharge head 2 includes a liquid discharge head main body 13 and a housing (not shown). The case is made of, for example, metal, and a hole through which a signal cable for transmitting a drive signal passes is partially opened. A signal cable for transmitting a drive signal connected to the control unit 100 passes through the hole, and is closed with a resin lid or the like. The liquid discharge head main body 13 has a manifold opening 5b, and the liquid to be discharged is supplied from an external liquid tank through the manifold opening 5b.

  The liquid discharge head body 13 is formed by laminating a substrate which is a piezoelectric actuator unit 21 including a pressurizing portion on the first flow path member 4 and further connecting a second flow path member 40. FIG. 2 is a partial plan view of the liquid discharge head main body 13, and FIG. 3 is a longitudinal sectional view of a part of FIG. FIG. 2 shows a part of the liquid discharge head body 13 in the longitudinal direction, and the actual liquid discharge head 13 is long in the left-right direction of FIG. Further, in FIG. 3, although the internal flow path is shown, the portion indicated by a chain line is usually indicated by a continuous line for ease of viewing, and the structure other than the flow path through which the liquid passes is omitted.

  The first flow path member 4 has a plurality of liquid pressurizing chambers 10 opened on one main surface. The planar shape of the liquid pressurizing chamber 10 is a quadrangle or a circle with rounded corners. These liquid pressurizing chambers 10 are arranged over almost the entire surface of the upper surface of the first flow path member 4 facing the piezoelectric actuator unit 21. Further, the opening of each liquid pressurizing chamber 10 is closed by bonding the piezoelectric actuator unit 21 to one main surface of the first flow path member 4.

  A liquid discharge hole 8 is provided at the bottom of the liquid pressurizing chamber 10. When the liquid discharge hole 8 is projected so as to be orthogonal to the virtual straight line L1 parallel to the longitudinal direction of the first flow path member 4, the liquid discharge hole 8 is spaced by 1200 dpi on the virtual straight line L1 shown in FIG. Projected.

  Individual electrodes 35 to be described later are formed at positions facing the respective liquid pressurizing chambers 10 on the upper surface of the piezoelectric actuator unit 20. The individual electrode 35 is slightly smaller than the liquid pressurizing chamber 10, has a shape substantially similar to the liquid pressurizing chamber 10, and fits in a region facing the liquid pressurizing chamber 10 on the upper surface of the piezoelectric actuator unit 20. Is arranged.

  Further, these liquid discharge holes 8 are disposed in a region facing the piezoelectric actuator unit 20 on the lower surface side of the first flow path member 4. These liquid discharge holes 8 occupy an area having almost the same size and shape as the piezoelectric actuator unit 21 as one group, and the liquid discharge holes 8 are displaced by displacing the displacement elements 50 of the corresponding piezoelectric actuator units 21. A droplet can be ejected from 8.

  A plurality of liquid introduction chambers 15 are open on one first main surface of the first flow path member. One liquid introduction chamber 15 is connected to a plurality of liquid pressurizing chambers 10 via a plurality of apertures 12. The squeezing 12 restricts the movement of the liquid between the liquid introduction chamber 15 and the liquid pressurizing chamber 10 and the propagation of the pressure wave. In the ejection method described below, the pressure wave is reflected by the aperture 12. Further, by adopting the above-described structure, the distance from the liquid discharge hole 8 to the squeeze 12 can be shortened, whereby the AL described later is shortened, so that the drive frequency for discharging the liquid can be increased.

The liquid introduction chamber 15 and the liquid pressurization chamber 10 are efficiently arranged by arranging the liquid pressurization chamber 10 connected to the liquid introduction chamber 15 at a substantially rotationally symmetric position with respect to the liquid introduction chamber 15. In addition, since the structure around each liquid pressurizing chamber 10 is approximate, variations in the liquid ejection characteristics hardly occur. In FIG. 2, the entire flow path connecting the liquid introduction chamber 15 and the liquid pressurization chamber 10 is a squeeze 12, but a part of the flow path connecting the liquid introduction chamber 15 and the liquid pressurization chamber 10 is further constricted. It is also possible to make the creaking part work as a squeeze. The shape of the squeezed portion 12 is basically the same in design, but the liquid introducing chamber 15 and the liquid pressurizing chamber 10 are efficiently arranged under such conditions. For this purpose, the liquid pressurizing chamber 10 may be provided on a concentric circle with the liquid introducing chamber 15 as the center. In addition, since the units composed of one liquid introduction chamber 15 and a plurality of liquid pressurization chambers 10 connected to the liquid introduction chamber 13 are arranged in a matrix shape, an efficient arrangement can be achieved. Since the structure around the unit is approximate, the liquid ejection characteristics are less likely to vary.

  The liquid ejection holes 8 are arranged at equal intervals on the virtual straight line L1 when the liquid ejection holes 8 are projected so as to be orthogonal to the virtual straight line L1 with respect to the virtual straight line L1. Since the liquid pressurizing chambers 8 connected to the liquid discharge holes 8 projected to the adjacent positions on L1 are not adjacent, the pixels recorded adjacently in the main scanning direction on the recording medium are the first. Since it is not ejected from the adjacent liquid pressurizing chamber 10 through which vibration is transmitted through one flow path member 4, it is difficult to be affected by the structural crosstalk, so that the recording accuracy is improved.

  Further, the liquid ejection holes 8 are arranged at equal intervals on the virtual straight line L1 when the liquid ejection holes 8 are projected so as to be orthogonal to the virtual straight line L1 with respect to the virtual straight line L1. Since the liquid pressurizing chamber 10 connected to the liquid discharge hole 8 projected to an adjacent position on L1 is not connected to the same liquid introducing chamber 15, recording is performed adjacent to the main scanning direction on the recording medium. The recorded pixels are not easily affected by fluid crosstalk through the liquid introduction chamber 15, so that the recording accuracy can be improved.

  Furthermore, since the openings of the orifice 12 connected to the liquid introduction chamber 15 are not opposed to each other, the pressure wave transmitted from the orifice 12 is less likely to enter the other orifice 12 directly. This can be suppressed, and the recording accuracy can be improved. Note that that the apertures of the aperture 12 do not face each other means that there are no apertures of other apertures in the portion where the aperture of the aperture 12 is extended as shown in FIG. 6B.

  A manifold 5 is formed inside the second flow path member 40. The manifold 5 is connected to the liquid introduction chamber 15 and supplies liquid supplied from the outside to the liquid pressurization chamber. The manifold 5 and the liquid introduction chamber 15 are connected via a through hole 30 of the piezoelectric actuator 21. Since the flow paths connected to the plurality of liquid pressurizing chambers 10 gather in the liquid introduction chamber 15 and are connected to the manifold 5, the number of through holes 30 opened in the piezoelectric actuator 21 can be reduced, and the piezoelectric actuator 21 has an area. It can be used efficiently.

  The first flow path member 4 included in the liquid discharge head body 13 has a stacked structure in which a plurality of plates are stacked. These plates are plates 22, 23, 24, 25, and 26 in order from the upper surface of the first flow path member 4. A number of holes are formed in these plates. Each plate is laminated in alignment such that these holes communicate with each other to form the liquid introduction chamber 15, the squeezing 12, the liquid pressurizing chamber 10, and the liquid discharge hole 8. The thickness of the plates 22 to 26 and the second plate is about 10 to 1000 μm.

  The second flow path member is made of, for example, plastic. A lid 41 is joined to the second flow path member main body 42, and an electrode 45 for supplying a voltage to the piezoelectric actuator is passed through the inside, and this electrode 45 is a connection substrate such as an external FPC (Flexible Printed Circuit). 60 electrodes 60a. The second flow path member is provided with a displacement element 50 or a space 47 having substantially the same planar shape as the liquid pressurizing chamber 10 so that the displacement element 50 can be displaced.

As shown in FIG. 3, the piezoelectric actuator unit 21 has a laminated structure including two piezoelectric ceramic layers 21a and 21b. Each of these piezoelectric ceramic layers 21a and 21b has a thickness of about 20 μm. The total thickness of the piezoelectric actuator unit 21 is about 40 μm. Each of the piezoelectric ceramic layers 21 a and 21 b extends so as to straddle the plurality of liquid pressurizing chambers 10. The piezoelectric ceramic layers 21a and 21b are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The piezoelectric actuator unit 21 includes a common electrode 34 made of a metal material such as Ag—Pd and an individual electrode 35 made of a metal material such as Au. The individual electrode 35 is disposed at a position facing the liquid pressurizing chamber 10 on the upper surface of the piezoelectric actuator unit 201. One end of the individual electrode 35 is drawn out of a region facing the liquid pressurizing chamber 10 to form a connection electrode. This connection electrode is finally electrically connected to the control unit 100 via the electrode 45 and the connection substrate 60. Although details will be described later, a drive signal is supplied from the control unit 100 to the individual electrode 35.

  The common electrode 34 is formed over almost the entire surface in the area between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. However, when the structure in which the liquid flows directly inside the through hole 30 is to prevent the common electrode 34 from being exposed on the inner wall of the through hole 30, the liquid may enter the common electrode 34 and enter. It can suppress that the insulation of the piezoelectric ceramic layer 21b between the common electrode 34 and the separate electrode 35 deteriorates by the infiltrated liquid.

  As shown in FIG. 3, the common electrode 34 and the individual electrode 35 are arranged so as to sandwich only the uppermost piezoelectric ceramic layer 21b. A region sandwiched between the individual electrode 35 and the common electrode 34 in the piezoelectric ceramic layer 21b is referred to as an active portion, and the piezoelectric ceramic in that portion is polarized. In the piezoelectric actuator unit 21 of the present embodiment, only the uppermost piezoelectric ceramic layer 20b includes an active portion, and the piezoelectric ceramic 21a does not include an active portion and functions as a diaphragm. The piezoelectric actuator unit 21 has a so-called unimorph type configuration.

  As will be described later, when a predetermined drive signal is selectively supplied to the individual electrode 35, pressure is applied to the liquid in the liquid pressurizing chamber 10 corresponding to the individual electrode 35. As a result, droplets are discharged from the corresponding liquid discharge ports 8. That is, the portion of the piezoelectric actuator unit 20 that faces each liquid pressurizing chamber 10 corresponds to the individual displacement element 50 corresponding to each liquid pressurizing chamber 10 and the liquid discharge port 8. That is, in the laminated body composed of two piezoelectric ceramic layers, the displacement element 50 which is a piezoelectric actuator having a unit structure as shown in FIG. The piezoelectric actuator unit 20 includes a plurality of displacement elements 50 as pressurizing portions. The diaphragm 21a is located directly above the chamber 10 and is formed by a common electrode 34, a piezoelectric ceramic layer 21b, and individual electrodes 35. . In the present embodiment, the amount of liquid ejected from the liquid ejection port 8 by one ejection operation is about 1 to 10 pl (picoliter).

The actual driving procedure in the present embodiment is such that the first electrode V1V (volt, which may be omitted hereinafter) is set in advance so that the individual electrode 35 has a higher potential than the common electrode 34, and every time there is a discharge request. The individual electrode 35 and the common electrode 34 are once set to a low potential, for example, the same potential by applying a second voltage lower than the first voltage V1, and then set to a high potential again at a predetermined timing. As a result, the piezoelectric ceramic layers 20a and 20b return to their original shapes at the timing when the individual electrode 35 becomes low potential, and the volume of the liquid pressurizing chamber 10 is compared with the initial state (state where the potentials of both electrodes are different). To increase. At this time, a negative pressure is applied to the liquid pressurizing chamber 10 and the liquid is sucked into the liquid pressurizing chamber 10 from the manifold 5 side. After that, at the timing when the individual electrode 35 is set to a high potential again, the piezoelectric ceramic layers 20a and 20b are deformed so as to protrude toward the liquid pressurizing chamber 10, and the volume of the liquid pressurizing chamber 10 is reduced so that the inside of the liquid pressurizing chamber 10 Becomes a positive pressure, the pressure on the liquid rises, and droplets are ejected. That is, a drive signal including a pulse based on a high potential is supplied to the individual electrode 35 in order to eject a droplet. This pulse width is AL (Acoustic Lengt) which is the length of time during which the pressure wave propagates from the squeezing 12 to the liquid discharge hole 8 in the liquid pressurizing chamber 10.
h) is ideal. According to this, when the inside of the liquid pressurizing chamber 10 is reversed from the negative pressure state to the positive pressure state, both pressures are combined, and the liquid droplet can be ejected with a stronger pressure.

  In the printer 1, in order to increase the printing speed, it is necessary to shorten the cycle for supplying the drive signal. On the other hand, when ejection is performed by the above-described stroke, the pulse width of the drive signal is set to a value close to AL. In addition, after the discharge operation is finished, residual vibration remains in the flow path. However, when the period for supplying the drive signal is shortened, the influence of the residual vibration is increased, and the discharge characteristics are changed. Since the period of residual vibration is also AL, it is necessary to shorten AL in order to perform high-speed printing. According to the structure as described above, it is possible to design the distance from the aperture 12 to the liquid ejection hole 8 to be short, and it is possible to design a liquid ejection head suitable for high-speed printing.

  In gradation printing, gradation expression is performed by the number of droplets ejected continuously from the liquid ejection holes 8, that is, the droplet amount (volume) adjusted by the number of droplet ejections. For this reason, the number of droplet discharges corresponding to the specified gradation expression is continuously performed from the liquid discharge hole 8 corresponding to the specified dot region. In general, when liquid ejection is performed continuously, it is preferable that the interval between pulses supplied to eject liquid droplets is AL. As a result, the period of the residual pressure wave of the pressure generated when discharging the previously discharged liquid droplet coincides with the pressure wave of the pressure generated when discharging the liquid droplet discharged later, and these are superimposed. Thus, the pressure for discharging the droplet can be amplified. In this case, it is considered that the speed of the liquid droplets ejected later increases, but this is preferable because the landing points of a plurality of liquid droplets are close.

  In this embodiment, the displacement element 50 using piezoelectric deformation is shown as the pressurizing unit. However, the present invention is not limited to this, and any other device that can pressurize the liquid in the liquid pressurizing chamber 10 may be used. For example, the liquid in the liquid pressurizing chamber 10 may be heated and boiled to generate pressure, or may be one using MEMS (Micro Electro Mechanical Systems).

  FIG. 4 is a partial longitudinal sectional view of another liquid discharge head of the present invention. Although the basic configuration is the same as that shown in FIG. 3, the second flow path member 240 is joined to the second flow path member main body 242 with a connection substrate 260, which is an FPC, as a lid. By doing so, the assembly of the liquid discharge head body 213 is facilitated.

  FIG. 5 is a partial longitudinal sectional view of another liquid discharge head of the present invention. Compared with the liquid discharge head main body 13 shown in FIG. Note that these different points can be individually applied to the liquid discharge head body 13 shown in the second embodiment.

  First, the second flow path member 340 is directly connected to the first flow path member 304, and the opening of the manifold 305 is directly connected to the liquid introduction chamber 315. Since the second flow path member enters the through hole 330 of the piezoelectric actuator unit 321 so that the liquid does not contact the through hole 330, the piezoelectric actuator unit 321 is affected by the liquid from the cross section. Can be suppressed. Note that the first flow path member 304 may enter the through-hole 330.

  Second, a connection substrate 360 that is an FPC is disposed between the first flow path member 304 and the second flow path member 340. Thereby, the connection between the piezoelectric actuator unit 321 and the connection substrate 360 is facilitated. The individual electrode 35 of the piezoelectric actuator unit 321 and the electrode 360 a of the connection substrate 360 are connected by a connection electrode 345. Although they are not connected in the figure, they are connected at portions other than this cross section.

Thirdly, the openings of the plurality of apertures 312 connected to the liquid introduction chamber 315 are opened in the same direction. This makes it difficult for the pressure wave transmitted from the orifice 12 to directly enter another orifice 312, thereby suppressing fluid crosstalk and improving the recording accuracy. In other words, since the openings of the plurality of orifices 312 connected to the liquid introduction chamber 315 are open in the same plane, it is difficult to be affected by fluid crosstalk.

  FIG. 6 is a partial longitudinal sectional view of another liquid discharge head of the present invention. Similar to the liquid discharge head shown in FIG. 2, it is actually a part of the liquid discharge head that is long in the left-right direction in the drawing.

  With respect to the liquid introduction hole 415, the liquid pressurizing chamber 410 connected to the liquid introduction hole 415 is disposed at a position rotated 90 degrees on a concentric circle. A unit composed of one liquid introduction hole 415 and a liquid pressurizing chamber 410 connected to the liquid introduction hole 415 is inclined in the long side with respect to the direction, and the units are arranged in a matrix. . By doing so, the area efficiency is improved. In other words, the liquid introduction chamber region 418 including the liquid introduction hole 415 and the liquid pressurizing chamber 410 are combined to form a matrix. In addition, each structure can be arranged efficiently by providing the connection electrode 435b drawn out of the liquid pressurization chamber 410 from the individual electrode 435 in the liquid introduction chamber region 418. Furthermore, when a common electrode is provided directly below the individual electrode 435, the structures can be arranged apart so that the influence of piezoelectric deformation generated in this portion is reduced, so that subsequent loss talk can be further suppressed.

  The liquid discharge holes 408 are equally spaced when projected so as to be orthogonal to the virtual straight line L4.

  FIG. 7 is a partial longitudinal sectional view of another liquid discharge head of the present invention. Similar to the liquid discharge head shown in FIG. 2, it is actually a part of the liquid discharge head that is long in the left-right direction in the drawing. With respect to the liquid introduction hole 515, the liquid pressurizing chamber 510 connected to the liquid introduction hole 515 is disposed at a position rotated by 60 degrees on a concentric circle. A unit composed of one liquid introduction hole 515 and a liquid pressurizing chamber 510 connected to the liquid introduction hole 515 is inclined with respect to the direction on the long side, and the units are arranged in a matrix. .

  The liquid discharge holes 508 are equally spaced when projected so as to be orthogonal to the virtual straight line L5.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 4, 204, 304 ... 1st flow path member 5, 205, 305 ... Manifold 8, 208, 308, 408, 508 ... Liquid discharge hole 10, 210, 310, 410, 510 ... Liquid pressurizing chambers 12, 212, 312, 412, 512 ... Squeeze 13, 213, 313, 413, 513 ... Liquid discharge head body 15, 215, 315 415, 515 ... Liquid introduction chamber 21, 212, 312 ... Piezoelectric actuator unit 21a, 212a, 312a ... Piezoelectric ceramic layer (vibrating plate)
21b, 212b, 312b ... Piezoelectric ceramic layers 22-26, 222-226, 322-326 ... Plates 30, 230, 330 ... Through holes 34, 234, 334 ... Common electrodes of piezoelectric actuator units 35, 235, 335 ... individual electrode 435b ... connection electrode 36 ... connection electrode 40, 240, 340 ... second flow path member 45, 245, 345 ... electrode 47, 247 ...・ Space 50, 250, 350 ... Displacement element (pressure unit)
60, 260, 350: Connection board 60a, 260a, 360a: Connection board electrodes L1, L4, L5: Virtual straight line

Claims (9)

  A plurality of liquid discharge holes opened on one main surface, a plurality of liquid pressurizing chambers connected to the plurality of liquid discharge holes and opened on the other main surface, and the other main surface A first flow path member having a plurality of liquid introduction chambers that are open to each other and a squeezing connected from the liquid introduction chamber to the plurality of pressurization chambers; A plurality of through-holes that are open at positions of the pressurizing unit and the plurality of liquid introduction chambers, respectively, and are stacked on the first flow path member so as to cover the plurality of liquid pressurization chambers; A liquid ejection head comprising: a substrate; and a second flow path member having a manifold connected to the plurality of liquid introduction holes through the plurality of through holes.   The liquid ejection according to claim 1, wherein the plurality of liquid pressurizing chambers connected to one liquid introduction chamber are arranged at substantially rotationally symmetric positions around the liquid introduction chamber. head.   3. The liquid discharge head according to claim 1, wherein units including one liquid introduction chamber and a plurality of the liquid pressurization chambers connected to the liquid introduction chamber are arranged in a matrix. 4. .   The plurality of liquid ejection holes are arranged at equal intervals on the virtual straight line when projecting the plurality of liquid ejection holes so as to be orthogonal to the virtual straight line with respect to the virtual straight line. 4. The liquid discharge head according to claim 1, wherein the liquid pressurizing chambers connected to the liquid discharge holes projected at adjacent positions on a virtual straight line are not adjacent to each other. 5.   The plurality of liquid ejection holes are arranged at equal intervals on the virtual straight line when projecting the plurality of liquid ejection holes so as to be orthogonal to the virtual straight line with respect to the virtual straight line. 5. The liquid pressurizing chamber connected to the liquid discharge hole projected at an adjacent position on a virtual straight line is not connected to the same liquid introducing chamber. 6. Liquid discharge head.   6. The liquid ejection head according to claim 1, wherein openings of the plurality of apertures connected to the liquid introduction chamber are not opposed to each other.   The liquid ejection head according to claim 1, wherein the openings of the plurality of apertures connected to the liquid introduction chamber are open in the same plane.   8. The liquid introduction chamber of the first flow path member and an opening connected to the manifold of the second flow path member are directly connected to each other. Liquid discharge head.   A liquid discharge head according to claim 1, a transport unit that transports a recording medium to the liquid discharge head, and a controller that controls the plurality of pressure units and the transport unit. A recording apparatus.

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