JP2017094691A - Liquid discharge head, and recording device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge head in which a flow channel can be arranged with high area efficiency, and provide a recording device using the same.SOLUTION: A plurality of first common flow channels extend in a first direction, and are arrayed in a second direction intersecting the first direction. First discharge holes 8A and second discharge holes 8B as discharge holes 8 are arranged alternately along the second direction on a discharge hole line 9B. A first compression chamber 10A, which is a compression chamber extending from the first discharge hole 8A in the first direction, is connected to the first discharge hole 8A. A first throttle 12A extending in a third direction is connected to the first compression chamber 10A. The first throttle 12A is connected to the first common flow channel. A second compression chamber 10B and a second throttle 12B connected to the second discharge hole 8B extend in a direction opposite to the first compression chamber 10A and the first throttle 12A.SELECTED DRAWING: Figure 4

Description

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

  Conventionally, as a print head, for example, a liquid discharge head that performs various types of printing by discharging a liquid onto a recording medium is known. The liquid discharge head includes, for example, a discharge hole for discharging a liquid, a pressure chamber for pressurizing the liquid so that the liquid is discharged from the discharge hole, a first common flow path for supplying the liquid to the pressure chamber, What is provided with the 2nd common flow path which collect | recovers liquids from a pressure chamber is known. The liquid flows from the first common flow path to the second common flow path through the pressurizing chamber even when the discharge is not performed so that the clogging of the flow path is difficult to occur due to the liquid retention. It is known to circulate liquids including the outside. In such a liquid discharge head, the plurality of first common flow paths and the plurality of second common flow paths are shaped to extend in the short direction of the liquid discharge head, and alternately in the longitudinal direction of the liquid discharge head. It is known to place. Further, the discharge holes are arranged side by side in the longitudinal direction of the liquid discharge head, and the flow path connecting the pressurizing chamber and the common flow path (the first common flow path and the second common flow path) is defined as the liquid discharge head. It is known to have a shape extending in the longitudinal direction (see, for example, Patent Document 1).

JP 2009-143168 A

  The liquid discharge head as described in Patent Document 1 has a problem that it is difficult to arrange various flow paths with high area efficiency. That is, when a liquid discharge head having a predetermined resolution is designed, the liquid discharge head becomes large, and it is difficult to design a liquid discharge head having a predetermined size to have a high resolution.

  Accordingly, an object of the present invention is to provide a liquid discharge head capable of arranging flow paths with high area efficiency, and a recording apparatus using the same.

The liquid discharge head of the present invention includes a plurality of discharge holes, a plurality of pressurizing chambers connected to the plurality of discharge holes, a plurality of squeezes, and a flow path member having a plurality of first common flow paths. A plurality of pressurizing units that pressurize each of the pressurizing chambers, and when viewed in plan, the plurality of first common flow paths extend in a first direction, and The plurality of pressurizing chambers are arranged in a second direction that intersects the first direction, and the plurality of pressurizing chambers include a plurality of pressurizing chamber rows in which the pressurizing chambers are arranged at predetermined intervals along the first direction. The plurality of pressurizing chamber rows are arranged in the second direction, and one row of the pressurizing chamber rows is disposed on both sides of the first common flow path. The first common flow path and the pressurizing chamber belonging to the pressurizing chamber row respectively The plurality of discharge holes constitute a plurality of discharge hole rows in which the discharge holes are arranged at predetermined intervals along the second direction, and the plurality of discharge hole rows are: The first discharge holes and the second discharge holes, which are the discharge holes, are alternately arranged in the first direction, and in the discharge hole row, the pressurization is performed in the first discharge hole. A first pressurizing chamber that is a chamber is connected, and the first pressurizing chamber is connected to the first pressurizing chamber, and the center of gravity of the area of the first pressurizing chamber is the first pressurizing chamber. It is arranged on the first direction side with respect to the first discharge hole connected to the chamber, and the end of the first restriction on the first common flow path side is the first pressurization of the first restriction. It is arranged on the third direction side, which is the direction opposite to the first direction, from the end on the chamber side. A second pressurizing chamber that is the pressurizing chamber is connected, and the second pressurizing chamber is connected to the second pressurizing chamber, and the center of gravity of the area of the second pressurizing chamber is 2 is arranged on the third direction side with respect to the second discharge hole connected to the pressurizing chamber, and the end of the second restriction on the first common flow path side is the second restriction of the second restriction. 2 It is arrange | positioned rather than the edge part by the side of a pressurization chamber at the said 1st direction side.

  The recording apparatus of the 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 liquid discharge head. .

  According to the liquid ejection head of the present invention, the flow path can be arranged with high area efficiency.

(A) is a side view of a recording apparatus including a liquid ejection head according to an embodiment of the present invention, and (b) is a plan view. (A) is a top view of the head main body which is the principal part of the liquid discharge head of FIG. 1, (b) is a top view which remove | excluded the 2nd flow-path member from (a). FIG. 3 is an enlarged plan view of a part of FIG. FIG. 3 is an enlarged plan view of a part of FIG. FIG. 3 is an enlarged plan view of a part of FIG. (A) is the fragmentary longitudinal cross-sectional view along the VV line of FIG. 4, (b) is a fragmentary longitudinal cross-sectional view of the head main body of Fig.2 (a).

  FIG. 1A is a schematic side view of a color inkjet printer 1 (hereinafter sometimes simply referred to as a printer) which is a recording apparatus including a liquid discharge head 2 according to an embodiment of the present invention. (B) is a schematic plan view. The printer 1 moves the print paper P relative to the liquid ejection head 2 by transporting the print paper P as a recording medium from the guide roller 82 </ b> A to the transport roller 82 </ b> B. The control unit 88 controls the liquid ejection head 2 based on image and character data, ejects liquid toward the recording medium P, causes droplets to land on the printing paper P, and prints on the printing paper P. Record such as.

  In the present embodiment, the liquid discharge head 2 is fixed to the printer 1, and the printer 1 is a so-called line printer. As another embodiment of the recording apparatus of the present invention, the operation of moving the liquid ejection head 2 by reciprocating in the direction intersecting the transport direction of the printing paper P, for example, the direction substantially orthogonal, and the printing paper P There is a so-called serial printer that alternately conveys.

  A flat head mounting frame 70 (hereinafter sometimes simply referred to as a frame) is fixed to the printer 1 so as to be substantially parallel to the printing paper P. The frame 70 is provided with 20 holes (not shown), and the 20 liquid discharge heads 2 are mounted in the respective hole portions, and the portion of the liquid discharge head 2 that discharges the liquid is the printing paper P. It has come to face. The distance between the liquid ejection head 2 and the printing paper P is, for example, about 0.5 to 20 mm. The five liquid ejection heads 2 constitute one head group 72, and the printer 1 has four head groups 72.

The liquid discharge head 2 has a long and narrow shape in the direction from the front to the back in FIG. 1A and in the vertical direction in FIG. This long direction is sometimes called the longitudinal direction. Within one head group 72, the three liquid ejection heads 2 are arranged along a direction that intersects the conveyance direction of the printing paper P, for example, a substantially orthogonal direction, and the other two liquid ejection heads 2 are conveyed. One of the three liquid ejection heads 2 is arranged at a position shifted along the direction. The liquid discharge heads 2 are arranged so that the printable range of each liquid discharge head 2 is connected in the width direction of the print paper P (in the direction intersecting the conveyance direction of the print paper P) or the ends overlap. Thus, printing without gaps in the width direction of the printing paper P is possible.

  The four head groups 72 are arranged along the conveyance direction of the recording paper P. A liquid, for example, ink is supplied to each liquid ejection head 2 from a liquid tank (not shown). The liquid discharge heads 2 belonging to one head group 72 are supplied with the same color ink, and the four head groups 72 can print four color inks. The colors of ink ejected from each head group 72 are, for example, magenta (M), yellow (Y), cyan (C), and black (K). A color image can be printed by printing such ink under the control of the control unit 88.

  The number of the liquid discharge heads 2 mounted on the printer 1 may be one if it is a single color and the range that can be printed by one liquid discharge head 2 is printed. The number of liquid ejection heads 2 included in the head group 72 and the number of head groups 72 can be changed as appropriate according to the printing target and printing conditions. For example, the number of head groups 72 may be increased in order to perform multicolor printing. Also, if a plurality of head groups 72 that print in the same color are arranged and printed alternately in the transport direction, the transport speed can be increased even if the liquid ejection heads 2 having the same performance are used. Thereby, the printing area per time can be increased. Alternatively, a plurality of head groups 72 for printing in the same color may be prepared and arranged so as to be shifted in a direction crossing the transport direction, so that the resolution in the width direction of the print paper P may be increased.

  Further, in addition to printing colored inks, a liquid such as a coating agent may be printed for surface treatment of the printing paper P.

  The printer 1 performs printing on a printing paper P that is a recording medium. The printing paper P is wound around the paper feed roller 80A, passes between the two guide rollers 82A, passes through the lower side of the liquid ejection head 2 mounted on the frame 70, and thereafter It passes between the two conveying rollers 82B and is finally collected by the collecting roller 80B. When printing, the printing paper P is transported at a constant speed by rotating the transport roller 82 </ b> B and printed by the liquid ejection head 2. The collection roller 80B winds up the printing paper P sent out from the conveyance roller 82B. The conveyance speed is, for example, 50 m / min. Each roller may be controlled by the controller 88 or may be manually operated by a person.

  In addition to the printing paper P, the recording medium may be a roll-like cloth. Further, instead of directly transporting the printing paper P, the printer 1 may transport the transport belt directly and transport the recording medium placed on the transport belt. By doing so, sheets, cut cloth, wood, tiles and the like can be used as the recording medium. Furthermore, a wiring pattern of an electronic device may be printed by discharging a liquid containing conductive particles from the liquid discharge head 2. Still further, the chemical may be produced by discharging a predetermined amount of liquid chemical agent or liquid containing the chemical agent from the liquid discharge head 2 toward the reaction container or the like and reacting.

In addition, a position sensor, a speed sensor, a temperature sensor, and the like may be attached to the printer 1, and the control unit 88 may control each part of the printer 1 according to the state of each part of the printer 1 that can be understood from information from each sensor. . For example, the temperature of the liquid discharge head 2, the temperature of the liquid in the liquid tank, the pressure applied by the liquid in the liquid tank to the liquid discharge head 2, etc. affect the discharge characteristics such as the discharge amount and discharge speed of the discharged liquid. In the case of giving, the drive signal for ejecting the liquid may be changed according to the information.

  Next, the liquid ejection head 2 according to an embodiment of the present invention will be described. FIG. 2A is a plan view showing a head main body 2a which is a main part of the liquid ejection head 2 shown in FIG. FIG. 2B is a plan view showing a state in which the second flow path member 6 is removed from the head main body 2a. 3 to 5 are enlarged plan views of FIG. FIG. 5A is a longitudinal sectional view taken along line VV in FIG. FIG. 5B is a partial longitudinal sectional view along the first common flow path 20 in the vicinity of the opening 20a of the first common flow path 20 of the head body 2a.

  Each figure is drawn as follows for easy understanding of the drawing. 2-5, the flow path etc. which should be drawn with a broken line under other things are drawn with the continuous line. In FIG. 2A, only the pressurizing chamber 10 is shown for the flow path in the first flow path member 4. FIG. 2B shows only the first common flow path 20 and the second common flow path 24 for the flow paths in the first flow path member 4. 2A and 2B, only the outer shape of the piezoelectric actuator substrate 40 is shown.

  3 and 5, the end portion in the third direction is drawn on the lower side of the drawing, and the end portion in the first direction is drawn on the upper side of the drawing. The arrows between the top and bottom of the figure represent the connection of the flow paths. In FIGS. 3 to 5, different parts are omitted.

  In addition to the head main body 2a, the liquid discharge head 2 may include a metal casing, a driver IC, a wiring board, and the like. In addition, the head body 2a includes a first flow path member 4, a second flow path member 6 that supplies liquid to the first flow path member 4, and a piezoelectric actuator in which a displacement element 50 that is a pressurizing unit is built. And a substrate 40. The head body 2a has a flat plate shape that is long in one direction, and this direction is sometimes referred to as a longitudinal direction. Further, the second flow path member 6 serves as a support member, and the head body 2 a is fixed to the frame 70 at both ends in the longitudinal direction of the second flow path member 6.

  The first flow path member 4 constituting the head body 2a has a flat plate shape, and the thickness thereof is about 0.5 to 2 mm. A number of pressurizing chambers 10 are arranged in the plane direction on the pressurizing chamber surface 4-1, which is the first main surface of the first flow path member 4. On the discharge hole surface 4-2, which is the second main surface of the first flow path member 4 and on the opposite side of the pressurizing chamber surface 4-1, the discharge holes 8 through which liquid is discharged are arranged in the plane direction. Many are arranged side by side. Each discharge hole 8 is connected to the pressurizing chamber 10. In the following description, it is assumed that the pressurizing chamber surface 4-1 is located above the discharge hole surface 4-2.

  A plurality of first common channels 20 and a plurality of second common channels 24 are arranged in the first channel member 4 so as to extend along the same direction. The direction along the first common channel 20 and the second common channel 24 is the first direction. The first common flow path 20 and the second common flow path 24 may be collectively referred to as a common flow path. Moreover, the 1st common flow path 20 and the 2nd common flow path 24 are located in a line in the 2nd direction which is a direction which cross | intersects a 1st direction alternately. The second direction is the same direction as the longitudinal direction of the head body 2a.

  The pressurizing chambers 10 are arranged at predetermined intervals along both sides of the first common flow path 20 to constitute a total of two pressurizing chamber rows 11A, one on each side. The first common flow path 20 and the pressurizing chambers 10 arranged on both sides of the first common flow path 20 are connected via a first individual flow path 12.

The pressurizing chambers 10 are arranged at predetermined intervals along both sides of the second common flow path 24, and constitute one pressurization chamber row 11 </ b> A in total on one side. The second common flow path 24 and the pressurizing chambers 10 arranged on both sides thereof are connected via the second individual flow path 14.

  In other words, the pressurizing chambers 10 are arranged side by side on a virtual line, the first common flow path 20 extends along one side of the virtual line, and along the other side of the virtual line. The second common flow path 24 extends. In the present embodiment, the virtual line in which the pressurizing chambers 10 are arranged is a straight line, but may be a curved line or a broken line.

  With the configuration as described above, in the first flow path member 4, the liquid supplied to the first common flow path 20 flows into the pressurizing chambers 10 arranged along the first common flow path 20, and partly The other liquid is discharged from the discharge hole 8, and the other part of the liquid flows into the second common channel 24 located on the opposite side of the first common channel 20 with respect to the pressurizing chamber 10. It is discharged out of the flow path member 4.

  Note that the second common flow path 24 and the second individual flow path 14 used for discharge are not disposed, but only the first common flow path 20 and the first individual flow path 12 that supply the liquid are disposed, and the liquid supply is performed. It may be configured to perform only.

  The second common flow path 24 is disposed on both sides of the first common flow path 20, and the first common flow path 20 is disposed on both sides of the second common flow path 24. One first common channel 20 and one second common channel 24 are connected to 11A, and another first common channel 20 and another first common channel 20 are connected to another pressurizing chamber row 11A. Compared with the case where the two common flow paths 24 are connected, the number of the first common flow paths 20 and the second common flow paths 24 can be reduced to about half, which is preferable. Since the number of first common channels 20 and second common channels 24 is small, the number of pressurizing chambers 10 is increased to increase the resolution, or the first common channel 20 and the second common channel 24 are thickened. Thus, the difference in ejection characteristics from the ejection holes 8 can be reduced, and the size of the head body 2a in the planar direction can be reduced.

  The pressure applied to the portion of the first individual flow path 12 on the first common flow path 20 side connected to the first common flow path 20 is affected by the pressure loss, so that the first individual flow path 12 is added to the first common flow path 20. Varies depending on the position where the two are connected (mainly the position in the first direction). The pressure applied to the portion on the second individual flow path 14 side connected to the second common flow path 24 is the position where the second individual flow path 14 is connected to the second common flow path 24 due to the effect of pressure loss (main Depending on the position in the first direction. If the opening 20a to the outside of the first common channel 20 is arranged at one end in the first direction, and the opening 24a to the outside of the second common channel 24 is arranged at the other end in the first direction. The pressure difference due to the arrangement of the first individual flow paths 12 and the second individual flow paths 14 is canceled out, and the pressure difference applied to the discharge holes 8 can be reduced. Note that both the opening 20a of the first common channel 20 and the opening 24a of the second common channel 24 open to the pressurizing chamber surface 4-1.

  In the state of not discharging, a liquid meniscus is held in the discharge hole 8. Since the pressure of the liquid is a negative pressure (a state in which the liquid is about to be drawn into the first flow path member 4) in the discharge hole 8, the meniscus can be held in balance with the surface tension of the liquid. Since the surface tension of the liquid tries to reduce the surface area of the liquid, the meniscus can be held if the pressure is small even if it is a positive pressure. If the positive pressure increases, the liquid overflows, and if the negative pressure increases, the liquid is drawn into the first flow path member 4, and the liquid cannot be discharged. For this reason, it is necessary to prevent the difference in the pressure of the liquid in the discharge hole 8 from becoming too large when the liquid flows from the first common flow path 20 to the second common flow path 24.

The pressurizing chamber 10 is disposed facing the pressurizing chamber surface 4-1 and receives the pressure from the displacement element 50. The pressurizing chamber 10 and the discharge hole 8 are connected by a descender 7 which is a partial flow path. The planar shape of the pressurizing chamber 10 is a rhombus shape, and is a shape with rounded corners of the rhombus. The planar shape of the pressurizing chamber 10 may be an ellipse, a circle, a rectangle, or the like. The descender 7 is connected to one end of the pressurizing chamber 10 in the longitudinal direction. The first individual flow path 12 is connected to the other end of the pressurizing chamber 10 in the longitudinal direction. The first individual flow path 12 is connected to the first common flow path 20. The first individual flow path 12 may be referred to as a squeeze 12 below.

  The descender 7 has a right cylindrical shape. The descender 7 is connected to the second individual flow path 14 on the discharge hole 8 side. The second individual flow path 14 is connected to the second common flow path 24.

  Then, arrangement | positioning of the pressurization chamber 10 and the discharge hole 8 is demonstrated using FIG. A black circle representing the center of gravity of the area of the pressurizing chamber 10 is drawn in the pressurizing chamber 10 of FIG. 4, but this black circle does not exist in the actual liquid discharge head 2. In the present embodiment, the number of the first common flow paths 20 is 75, the number of the second common flow paths 24 is 76, and the pressure chamber rows 11A are 150 rows. Each pressurizing chamber row 11A includes 16 pressurizing chambers 10. The pressurizing chamber row 11A extends in the first direction and is arranged in the second direction.

  The discharge holes 8 connected to the pressurization chambers 10 belonging to one pressurization chamber row 11A constitute a discharge hole row 9A. The discharge hole array 9A extends in the first direction and is aligned in the second direction. In the present embodiment, the discharge hole array 9A and the pressurizing chamber array 11A are in substantially the same position, but this is not always necessary. However, the area efficiency of arrangement | positioning of a flow path can be made high by making these into the same position.

  The angle formed by the first direction and the second direction is deviated from a right angle. For this reason, the ejection holes 8 belonging to the ejection hole array 9A arranged along the first direction are displaced in the second direction by an angle shifted from the right angle. And since the discharge hole row | line 9A is arrange | positioned along with the 2nd direction, the discharge hole 8 which belongs to the different discharge hole row | line | column 9A is shifted | deviated and arranged in the 2nd direction by that amount. Together, the discharge holes 8 of the first flow path member 4 are arranged at regular intervals in the second direction, so that a predetermined range is filled with pixels formed by the discharged liquid. Can print.

  In addition, the discharge holes 8 form discharge hole rows 9B side by side along the second direction. In one discharge hole row 9B, the discharge holes 8 are arranged at an interval of 37.5 dpi. Since there are 16 discharge hole rows 9B and they are displaced as described above, printing can be performed with a resolution of 600 dpi (= 37.5 dpi × 16) as a whole.

  In each discharge hole row 11, the first discharge holes 8A and the second discharge holes 8B, which are the discharge holes 8, are alternately arranged. A first pressurizing chamber 10A that is a pressurizing chamber 10 is connected to the first discharge hole 8A, and a first constricting 12A that is a squeezing (first individual flow path) 12 is connected to the first pressurizing chamber 10A. It is connected. A second pressurizing chamber 10B that is a pressurizing chamber 10 is connected to the second discharge hole 8B, and a second constricting 12B that is a squeezing (first individual flow path) 12 is connected to the second pressurizing chamber 10B. It is connected.

  The area center of gravity of the first pressurizing chamber 10A is disposed on the first direction side with respect to the discharge hole row 9B, and the area center of gravity of the second pressurizing chamber 10B is first with respect to the discharge hole row 9B. It arrange | positions at the 3rd direction side which is a direction opposite to a direction. That is, the pressurizing chambers 10 corresponding to one discharge hole row 9B are alternately arranged in the first direction. Further, the first pressurizing chambers 10A corresponding to one discharge hole row 9B are arranged along the second direction to form the first pressurization chamber row 11B1, and one discharge hole row 9B. The second pressurizing chambers 10B corresponding to are arranged along the second direction and constitute a second pressurizing chamber row 11B2.

The end of the first squeezing 12A on the first common flow path 20 side is disposed on the third direction side of the end of the first squeezing 12A on the first pressurizing chamber 10A side. In addition, because of the arrangement as described above, the flow of the liquid from the first common flow path 20 through the first squeezing 12A and further through the first pressurizing chamber 10A to the descender 7 is the same as that of the first squeezing 12A. It flows so as to be folded at the connecting portion with the first pressurizing chamber 10A. The angle at which the flowing direction changes in this part is greater than 270 degrees.

  The end of the second restriction 12B on the first common flow path 20 side is disposed closer to the first direction than the end of the second restriction 12B on the second pressurizing chamber 10B side. In addition, because of the arrangement as described above, the flow of the liquid from the first common flow path 20 through the second squeezing 12B and further through the second pressurizing chamber 10B to the descender 7 is the same as that of the second squeezing 12B. It flows so as to be folded back at the connection portion with the second pressurizing chamber 10B. The angle at which the flowing direction changes in this part is greater than 270 degrees.

  In the present embodiment, two rows of pressurizing chambers 11 </ b> A are connected to the first common flow path 20. Further, when the first individual flow path (squeezing) 12, the descender 7, the pressurizing chamber 10, and the second individual flow path 14 are considered as individual discharge flow paths, the discharge characteristics of the liquid discharged from each discharge hole 8 are considered. It is preferable that the individual discharge channels have substantially the same shape so as to reduce the difference.

  When such an arrangement is considered, the individual discharge flow paths of the two rows of pressurizing chambers 11 </ b> A connected to one first common flow path 20 have a line-symmetric structure with respect to the first common flow path 20. It is possible. However, in the case of such a structure, the squeezing 12 of the two pressurizing chamber rows 11 </ b> A is connected to substantially the same position of the first common flow path 20. Therefore, it is impossible to design with such an arrangement in the first place, or there is a possibility that the crosstalk will increase due to the transmission of pressure between the apertures 12 arranged nearby. Therefore, such a structure is not preferable.

  Therefore, first, the individual discharge flow paths of the two rows of pressurizing chambers 11 </ b> A connected to the first common flow path 20 have a rotationally symmetric structure of 180 degrees with respect to the first common flow path 20. Think. In this case, the range in which the aperture 12 is connected to the first common flow path 20 in the first direction is wider than the distribution range of the discharge holes 8 in the first direction. When a liquid flows through the first common flow path 20, pressure loss occurs. Therefore, when the distribution range in the first direction is widened, the difference in pressure applied to each of the apertures 12 is increased, which affects the discharge characteristics. When the difference increases, it becomes difficult to hold the meniscus in the discharge hole 8.

  In view of this, the connecting portion between the squeezing 12 and the pressurizing chamber 10 is configured to be folded back at an angle larger than 270 degrees. By doing so, the range of the squeezing 12 connected to the first common flow path 20 can be narrowed. An example of such arrangement is the structure of FIG. 4 described above. The folding angle at the connecting portion between the squeezing 12 and the pressurizing chamber 10 is preferably 300 degrees or more, and particularly preferably 315 degrees or more.

  In addition, the opening on the first common flow path 20 side of the first throttle 12A connected to the first discharge hole 8A belonging to one discharge hole row 9B is on the first direction side with respect to the discharge hole row 9B. It arrange | positions in the 3rd direction side with respect to the opening by the side of the 1st common flow path 20 of the 2nd aperture 12B connected from the 2nd discharge hole 8B which belongs to the other discharge hole row 9B arrange | positioned adjacently. Is preferred. By doing so, even if the interval between the pressurizing chamber rows 11A is narrowed, the openings do not overlap, so that the arrangement density of the flow paths can be increased. Moreover, since the distribution range regarding the 1st direction of the opening of the squeezing 12 connected to the 1st common flow path 20 becomes narrower, the difference of the pressure added to the squeezing 12 can be made smaller.

The second flow path member 6 is joined to the pressure chamber surface 4-1 of the first flow path member 4. The second flow path member 6 has a first integrated flow path 22 that supplies liquid to the first common flow path 20 and a second integrated flow path 26 that recovers the liquid in the second common flow path 24. . The thickness of the second flow path member 6 is equal to the first flow path member 4.
The thickness is about 5 to 30 mm.

  The second flow path member 6 has a rectangular parallelepiped shape, and has a flat plate shape that is largest in the second direction, then large in the first direction, and smaller in thickness than the first direction and the second direction. A through hole 6 a is disposed at the center of the second flow path member 6. A signal transmission unit such as an FPC (Flexible Printed Circuit) that transmits a drive signal for driving the piezoelectric actuator substrate 40 is passed through the through hole 6a.

  The second flow path member 6 is joined in a region where the piezoelectric actuator substrate 40 of the pressure chamber surface 4-1 of the first flow path member 4 is not connected. More specifically, the piezoelectric actuator substrate 40 is joined so as to surround it. By doing in this way, it can suppress that a part of discharged liquid adheres to the piezoelectric actuator board | substrate 40 as mist. Further, since the first flow path member 4 is fixed on the outer periphery, it is possible to suppress the first flow path member 4 from vibrating due to the driving of the displacement element 50 and causing resonance or the like.

  By disposing the first integrated flow path 22 in the second flow path member 6 which is different from the first flow path member 4 and is thicker than the first flow path member 4, the cross-sectional area of the first integrated flow path 22 is increased. Accordingly, a difference in pressure loss due to a difference in position where the first integrated flow path 22 and the first common flow path 20 are connected can be reduced. The channel resistance of the first integrated channel 22 is preferably 1/100 or less of the first common channel 20. Here, the channel resistance of the first integrated channel 22 is more precisely the channel resistance in the range connected to the first common channel 20 in the first integrated channel 22.

  By disposing the second integrated flow path 26 in the second flow path member 6 that is different from the first flow path member 4 and is thicker than the first flow path member 4, the cross-sectional area of the second integrated flow path 26 is increased. Accordingly, the difference in pressure loss due to the difference in the position where the second integrated channel 26 and the second common channel 24 are connected can be reduced. The channel resistance of the second integrated channel 26 is preferably set to 1/100 or less of the second common channel 24. Here, the channel resistance of the second integrated channel 26 is more precisely the channel resistance in the range connected to the first integrated channel 22 in the second integrated channel 26.

  The first integrated flow path 22 is disposed at one end of the second flow path member 6 in the short direction, the second integrated flow path 26 is disposed at the other end of the second flow path member 6 in the short direction, Each of the flow paths is directed to the first flow path member 4 side so as to be connected to the first common flow path 20 and the second common flow path 24, respectively. With such a structure, the cross-sectional areas of the first integrated flow path 22 and the second integrated flow path 26 can be increased, and the flow path resistance can be decreased. Moreover, since the outer periphery is fixed by the 2nd flow path member 6 by setting it as such a structure, the 1st flow path member 4 can make rigidity high. Furthermore, with such a structure, the through hole 6a through which the signal transmission unit passes can be provided.

  The second flow path member 6 includes a first groove serving as a first integrated flow path body 22a extending in the second direction of the first integrated flow path 22 and a second direction of the second integrated flow path 26. The 2nd groove | channel used as the 2nd integrated flow path main body 26a extended is arrange | positioned. The first integrated channel body 22a and the second integrated channel body 26a have a channel resistance per unit length smaller than that of the first common channel 20 and the second common channel 24. At the end of the first integrated flow path 22 in the second direction, an opening 22c that opens to the outside at the top of the head body 2a is disposed. At the end of the second integrated flow path 26 in the fourth direction, an opening 26c that is open to the outside at the top of the head body 2a is disposed. That is, the hole provided in the second flow path member 6 penetrates the second flow path member 6 up and down, and the groove provided in the second flow path member 6 is the second flow path member 6. It is in the state opened to the lower surface of. By having such a structure, the second flow path member 6 can be manufactured by injection molding a resin in a die or the like combined vertically.

The liquid is supplied from the opening 22c of the first integrated flow path 22, and the opening 26c of the second integrated flow path 26.
However, the present invention is not limited to this, and supply and recovery may be reversed.

  A damper may be provided in the first integrated flow path 22 and the second integrated flow path 26 so that the supply or discharge of the liquid is stabilized against fluctuations in the discharge amount of the liquid. Further, by providing a filter in the first integrated flow path 22 and the second integrated flow path 26, foreign substances and bubbles may be difficult to enter the first flow path member 4.

  A piezoelectric actuator substrate 40 including a displacement element 50 is bonded to the pressurizing chamber surface 4-1 that is the upper surface of the first flow path member 4 so that each displacement element 50 is positioned on the pressurizing chamber 10. Has been placed. The piezoelectric actuator substrate 40 occupies a region having substantially the same shape as the pressurizing chamber group formed by the pressurizing chamber 10. Further, the opening of each pressurizing chamber 10 is closed by joining the piezoelectric actuator substrate 40 to the pressurizing chamber surface 4-1 of the flow path member 4. The piezoelectric actuator substrate 40 has a rectangular shape that is long in the same direction as the head body 2a. The piezoelectric actuator substrate 40 is connected to a signal transmission unit such as an FPC for supplying a signal to each displacement element 50. The second flow path member 6 is provided with a through hole 6a penetrating vertically at the center, and the signal transmission unit is electrically connected to the control unit 88 through the through hole 6a. The signal transmission unit has a shape extending in the short direction from one long side end of the piezoelectric actuator substrate 40 toward the other long side end, and the wiring disposed in the signal transmission unit extends along the short direction. Extending and arranging in the longitudinal direction is preferable because the distance between the wirings can be easily increased.

  Individual electrodes 44 are arranged at positions facing the pressurizing chambers 10 on the upper surface of the piezoelectric actuator substrate 40.

  The flow path member 4 has a laminated structure in which a plurality of plates are laminated. Ten plates from the plate 4a to the plate 4j are laminated in order from the pressurizing chamber surface 4-1 side of the flow path member 4. Many holes and grooves are formed in these plates. For example, the holes and grooves can be formed by etching each plate made of metal. Since the thickness of each plate is about 10 to 300 μm, the formation accuracy of the holes to be formed can be increased. The plates 4d to f are plates having the same shape, and they may be constituted by one plate, but are constituted by three plates in order to form the holes with high accuracy. Each plate is aligned and stacked such that these holes communicate with each other to form a flow path such as the first common flow path 20.

  The pressurizing chamber 10 is opened on the pressurizing chamber surface 4-1 of the flat channel member 4, and the piezoelectric actuator substrate 40 is bonded thereto. The pressurizing chamber surface 4-1 has an opening 20 a for supplying a liquid to the first common flow path 20 and an opening 24 a for recovering the liquid from the second common flow path 24. A discharge hole 8 is opened in the discharge hole surface 4-2 on the opposite side of the pressure chamber surface 4-1 of the flow path member 4. In addition, a plate may be further laminated on the pressurizing chamber surface 4-1, to close the opening of the pressurizing chamber 10, and the piezoelectric actuator substrate 40 may be bonded thereon. By doing so, it is possible to reduce the possibility that the liquid to be discharged comes into contact with the piezoelectric actuator substrate 40, and the reliability can be further increased.

  Regarding the liquid flow, the liquid supplied to the first integrated flow path 22 enters the pressurization chamber 10 through the first common flow path 20 and the first individual flow path 12 in order, and further flows to the descender 7. A part of the liquid is discharged from the discharge hole 8. The liquid that has not been discharged passes through the second individual flow path 14, enters the second common flow path 24, enters the second integrated flow path 26, and is discharged outside the head body 2.

The piezoelectric actuator substrate 40 has a laminated structure composed of two piezoelectric ceramic layers 40a and 40b that are piezoelectric bodies. Each of these piezoelectric ceramic layers 40a and 40b has a thickness of about 20 μm. That is, the thickness from the upper surface of the piezoelectric ceramic layer 40a of the piezoelectric actuator substrate 40 to the lower surface of the piezoelectric ceramic layer 40b is about 40 μm. The thickness ratio between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b is set to 3: 7 to 7: 3, preferably 4: 6 to 6: 4. Both of the piezoelectric ceramic layers 40 a and 40 b extend so as to straddle the plurality of pressure chambers 10. The piezoelectric ceramic layers 40a, 40b may, for example, strength with a dielectric, lead zirconate titanate (PZT), NaNbO ₃ system, BaTiO ₃ system, (BiNa) NbO ₃ system, such as BiNaNb ₅ O ₁₅ system Made of ceramic material.

  The piezoelectric actuator substrate 40 has a common electrode 42 made of a metal material such as Ag—Pd and an individual electrode 44 made of a metal material such as Au. The common electrode 42 has a thickness of about 2 μm, and the individual electrode 44 has a thickness of about 1 μm.

  The individual electrodes 44 are respectively arranged at positions facing the pressurizing chambers 10 on the upper surface of the piezoelectric actuator substrate 40. The individual electrode 44 has a plane shape slightly smaller than that of the pressurizing chamber 10 and has an approximately similar shape to the pressurizing chamber 10, and an extraction electrode 44b drawn from the individual electrode main body 44a. Is included. A connection electrode 46 is formed at a portion of one end of the extraction electrode 44 b that is extracted outside the region facing the pressurizing chamber 10. The connection electrode 46 is a conductive resin containing conductive particles such as silver particles, and is formed with a thickness of about 5 to 200 μm. The connection electrode 46 is electrically joined to an electrode provided in the signal transmission unit.

  As will be described in detail later, a drive signal is supplied from the control unit 88 to the individual electrode 44 through the signal transmission unit. The drive signal is supplied in a constant cycle in synchronization with the conveyance speed of the print medium P.

  The common electrode 42 is formed over almost the entire surface in the region between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b. That is, the common electrode 42 extends so as to cover all the pressurizing chambers 10 in the region facing the piezoelectric actuator substrate 40. The common electrode 42 is a through conductor formed by penetrating the piezoelectric ceramic layer 40a on a common electrode surface electrode (not shown) formed on the piezoelectric ceramic layer 40a so as to avoid the electrode group composed of the individual electrodes 44. Are connected through. Further, the common electrode 42 is grounded via the common electrode surface electricity and held at the ground potential. Similar to the individual electrode 44, the common electrode surface electrode is directly or indirectly connected to the controller 88.

  A portion sandwiched between the individual electrode 44 and the common electrode 42 of the piezoelectric ceramic layer 40 a is polarized in the thickness direction, and becomes a unimorph-structured displacement element 50 that is displaced when a voltage is applied to the individual electrode 44. Yes. More specifically, when an electric field is applied in the polarization direction to the piezoelectric ceramic layer 40a by setting the individual electrode 44 to a potential different from that of the common electrode 42, an active portion where the electric field is applied is distorted by the piezoelectric effect. Work as. In this configuration, when the individual electrode 44 is set to a predetermined positive or negative potential with respect to the common electrode 42 by the control unit 88 so that the electric field and the polarization are in the same direction, a portion sandwiched between the electrodes of the piezoelectric ceramic layer 40a. (Active part) contracts in the surface direction. On the other hand, the piezoelectric ceramic layer 40b, which is an inactive layer, is not affected by an electric field, so that it does not spontaneously shrink and attempts to restrict deformation of the active portion. As a result, there is a difference in strain in the polarization direction between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b, and the piezoelectric ceramic layer 40b is deformed so as to be convex toward the pressurizing chamber 10 (unimorph deformation).

  Next, the liquid discharge operation will be described. The displacement element 50 is driven (displaced) by a drive signal supplied to the individual electrode 44 through a driver IC or the like under the control of the control unit 88. In the present embodiment, liquid can be ejected by various driving signals. Here, a so-called strike driving method will be described.

  The individual electrode 44 is set to a potential higher than the common electrode 42 (hereinafter referred to as a high potential) in advance, and the individual electrode 44 is once set to the same potential as the common electrode 42 (hereinafter referred to as a low potential) every time there is a discharge request. Thereafter, the potential is set again at a predetermined timing. Thereby, at the timing when the individual electrode 44 becomes low potential, the piezoelectric ceramic layers 40a and 40b return to the original (flat) shape (begin), and the volume of the pressurizing chamber 10 is in the initial state (the potentials of both electrodes are different). Increase compared to the state). As a result, a negative pressure is applied to the liquid in the pressurizing chamber 10. Then, the liquid in the pressurizing chamber 10 starts to vibrate with the natural vibration period. Specifically, first, the volume of the pressurizing chamber 10 begins to increase, and the negative pressure gradually decreases. Next, the volume of the pressurizing chamber 10 becomes maximum and the pressure becomes almost zero. Next, the volume of the pressurizing chamber 10 begins to decrease, and the pressure increases. Thereafter, the individual electrode 44 is set to a high potential at a timing at which the pressure becomes substantially maximum. Then, the first applied vibration overlaps with the next applied vibration, and a larger pressure is applied to the liquid. This pressure propagates through the descender and discharges the liquid from the discharge hole 8.

In other words, a droplet can be ejected by supplying a pulse drive signal that is a low potential for a certain period with the high potential as a reference to the individual electrode 44. If this pulse width is AL (Acoustic Length), which is half the time of the natural vibration period of the liquid in the pressurizing chamber 10, in principle, the discharge speed and discharge amount of the liquid can be maximized. The natural vibration period of the liquid in the pressurizing chamber 10 is greatly influenced by the physical properties of the liquid and the shape of the pressurizing chamber 10, but besides that, the physical properties of the piezoelectric actuator substrate 40 and the flow path connected to the pressurizing chamber 10 Also affected by the characteristics of.

DESCRIPTION OF SYMBOLS 1 ... Color inkjet printer 2 ... Liquid discharge head 2a ... Head main body 4 ... 1st flow-path member 4a-4j ... (of 1st flow-path member) 4-1 ... Pressurizing chamber surface 4-2 ... discharge hole surface 6 ... second flow path member 6 ... (through hole of second flow path member) 7 ... partial flow path (decender)
DESCRIPTION OF SYMBOLS 8 ... Discharge hole 8A ... 1st discharge hole 8B ... 2nd discharge hole 9A ... Discharge hole row 9B ... Discharge hole row 10 ... Pressurizing chamber 10A ... 1st addition Pressure chamber 10B ... Second pressurizing chamber 11A ... Pressurizing chamber row 11B1 ... First pressurizing chamber row 11B2 ... Second pressurizing chamber row 12 ... First individual channel (squeezing) )
12A ... 1st squeezing 12B ... 2nd squeezing 14 ... 2nd individual flow path 20 ... 1st common flow path (common flow path)
20a ... opening of (first common flow path) 22 ... first integrated flow path (first groove)
22a ... 1st integrated flow path main body 22c ... (1st integrated flow path) opening 24 ... 2nd common flow path (common flow path)
24a ... (second common channel) opening 26 ... second integrated channel (second groove)
26a: second integrated flow path body 26c: opening (of the second integrated flow path) 40: piezoelectric actuator substrate 40a: piezoelectric ceramic layer 40b: piezoelectric ceramic layer (vibrating plate)
42 ... Common electrode 44 ... Individual electrode 44a ... Individual electrode body 44b ... Extraction electrode 46 ... Connection electrode 50 ... Displacement element (pressure part)
DESCRIPTION OF SYMBOLS 70 ... Head mounting frame 72 ... Head group 80A ... Paper feed roller 80B ... Collection roller 82A ... Guide roller 82B ... Conveyance roller 88 ... Control part P ... Printing paper

Claims (4)

A plurality of discharge holes, a plurality of pressurizing chambers connected to the plurality of discharge holes, a plurality of squeezing parts, a flow path member having a plurality of first common flow paths, and the plurality of pressurizing chambers are pressurized respectively. A liquid discharge head including a plurality of pressure units,
When viewed in plan
The plurality of first common flow paths extend in a first direction and are arranged in a second direction that is a direction intersecting the first direction,
The plurality of pressurizing chambers constitute a plurality of pressurizing chamber rows in which the pressurizing chambers are arranged at predetermined intervals along the first direction, and the plurality of pressurizing chamber rows are the first pressurizing chamber rows. Lined up in two directions,
One row of the pressurizing chamber rows is arranged on both sides of one first common flow path, and the first common flow path and the pressurizing chamber belonging to the pressurizing chamber row are respectively Connected through a squeeze,
The plurality of discharge holes constitute a plurality of discharge hole rows in which the discharge holes are arranged at predetermined intervals along the second direction, and the plurality of discharge hole rows are arranged in the first direction. And
In the discharge hole row, the first discharge holes and the second discharge holes, which are the discharge holes, are alternately arranged,
The first discharge hole is connected to the first pressurizing chamber that is the pressurizing chamber, and the first pressurizing chamber is connected to the first constriction that is the squeezing,
The center of gravity of the area of the first pressurizing chamber is disposed on the first direction side with respect to the first discharge hole connected to the first pressurizing chamber, and the first common flow of the first squeezing chamber is arranged. The end on the road side is disposed on the third direction side, which is the direction opposite to the first direction, than the end on the first pressurizing chamber side of the first throttle,
The second discharge hole is connected to a second pressurizing chamber that is the pressurizing chamber, and the second pressurizing chamber is connected to the second constricting that is the squeezing,
The center of gravity of the area of the second pressurizing chamber is disposed on the third direction side with respect to the second discharge hole connected to the second pressurizing chamber, and the first common flow of the second throttle is arranged. The liquid discharge head, wherein an end portion on the road side is disposed closer to the first direction side than an end portion on the second pressurizing chamber side of the second throttle. When viewed in plan
The opening on the first common flow path side of the first throttle connected from the first discharge hole belonging to one discharge hole row is:
On the first common flow path side of the second throttle connected to the second discharge hole belonging to the other discharge hole row arranged next to the first direction side with respect to the discharge hole row. The liquid ejection head according to claim 1, wherein the liquid ejection head is disposed in the third direction with respect to the opening. The flow path member has a plurality of second common flow paths,
When viewed in plan
The plurality of second common flow paths extend in the first direction and are respectively disposed between the common flow paths,
One row of the pressurizing chamber rows is arranged on both sides of one second common channel, and the second common channel and the pressurizing chambers belonging to the pressurizing chamber row are respectively The liquid discharge head according to claim 1, wherein the liquid discharge head is connected via two individual flow paths.   A liquid discharge head according to claim 1, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the liquid discharge head. Recording device.

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