JP6905050B2 - Liquid discharge head and recording device using it - Google Patents

Description

The present disclosure relates to a liquid discharge head and a recording device using the same.

Conventionally, as a printing head, for example, a liquid ejection head that performs various types of printing by ejecting a liquid onto a recording medium is known. In the liquid discharge head, for example, a large number of discharge holes for discharging liquid are arranged so as to expand two-dimensionally. Printing is performed by landing the liquids discharged from the discharge holes side by side on the recording medium (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2009-143168

The liquid discharge head of the present disclosure is a liquid discharge head having a plurality of discharge holes for discharging liquid, and when the liquid discharge head is viewed in a plan view, the plurality of discharge holes have n rows substantially parallel to each other. The n rows are arranged above, and the n rows are arranged in the order of the first row, which is the direction intersecting the n rows, with the first row, the second row, ..., n rows. The second row is represented by y (x), which is the row in which the discharge hole located at the xth position in the second direction, which is the direction in which the n rows are extended, is arranged. The discharge line pair of the discharge hole located at the xth position in the direction and the discharge line pair located at the x + 1th position is the xth pair, and the affiliation of the discharge hole located at the xth position in the second direction. The difference y (x + 1) -y (x) of the row y (x + 1) to which the discharge hole belongs at the x + 1th position in the second direction with respect to the row y (x) is the difference between the pairs of the xth pair. Expressed as dy (x), the discharge hole pair includes a long-distance pair in which the absolute value of the pair-to-pair row difference is equal to or more than a predetermined value and a short-distance pair in which the absolute value of the pair-to-pair row difference is less than the predetermined value. One or more of the short-distance pairs are arranged between the long-distance pairs arranged adjacent to each other in the second direction, and are arranged adjacent to each other in the second direction. Assuming that the long-distance pair is the x1st pair and the x2nd pair (x2 is larger than x1), dy (x1 + 1) is dy (x1) when the absolute value of dy (x1)> the absolute value of dy (x2). Is positive or negative, and if the absolute value of dy (x1) is less than the absolute value of dy (x2), is dy (x2-1) positive with dy (x2)? It is characterized in that it is negative or matches.

Further, the recording device of the present disclosure includes the liquid discharge head, a transport unit that conveys the recording medium to the liquid discharge head, and a control unit that controls the liquid discharge head.

It is a side view of the recording apparatus including the liquid discharge head which concerns on one Embodiment of this disclosure. It is a top view of the recording apparatus including the liquid discharge head which concerns on one Embodiment of this disclosure. FIG. 5 is an enlarged plan view showing a portion to which one liquid discharge head is attached in a recording device including a liquid discharge head according to an embodiment of the present disclosure. It is a top view of the head body which is the main part of the liquid discharge head of FIG. It is a top view which excluded the 2nd flow path member from FIG. It is an enlarged plan view of a part of FIG. It is an enlarged plan view of a part of FIG. It is a partial vertical sectional view of the head body along the VV line of FIG. There is a vertical cross-sectional view of another part of the head body. It is the arrangement of the discharge holes. It is the arrangement of the other discharge holes of the present disclosure. It is the arrangement of the other discharge holes of the present disclosure.

FIG. 1 is a schematic side view of a color inkjet printer 1 (hereinafter, may be simply referred to as a printer) which is a recording device including a liquid discharge head 2 according to an embodiment of the present disclosure, and FIG. 2 is a schematic side view. It is a plan view of. The printer 1 conveys the printing paper P, which is a recording medium, from the conveying roller 80A to the conveying roller 80B, so that the printing paper P is moved relative to the liquid ejection head 2. The control unit 88 controls the liquid ejection head 2 based on print data or the like which is data such as an image or characters to eject the liquid toward the printing paper P and land the droplets on the printing paper P. , Printing or other recording is performed on the printing paper P.

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. In another embodiment of the recording device, the liquid ejection head 2 is moved in a direction intersecting the conveying direction of the printing paper P, for example, reciprocating in a direction substantially orthogonal to each other, and droplets are ejected in the middle of the movement. Examples thereof include a so-called serial printer in which the operation and the transfer of the printing paper P are alternately performed.

Four flat head mounting frames 70 (hereinafter, may be simply referred to as frames) are fixed to the printer 1 so as to be substantially parallel to the printing paper P. Each frame 70 is provided with five holes (not shown), and five liquid discharge heads 2 are mounted in the respective holes. The five liquid discharge heads 2 mounted on one frame 70 form one head group 72. The printer 1 has four head groups 72, and a total of 20 liquid discharge heads 2 are mounted.

In the liquid ejection head 2 mounted on the frame 70, the portion for ejecting the liquid faces the printing paper P. The distance between the liquid ejection head 2 and the printing paper P is, for example, about 0.5 to 20 mm.

The 20 liquid discharge heads 2 may be directly connected to the control unit 88, or may be connected via a distribution unit that distributes print data between them. For example, the control unit 88 may send the print data to one distribution unit, and one distribution unit may distribute the print data to the 20 liquid discharge heads 2. Further, for example, the control unit 88 distributes the print data to the four distribution units corresponding to the four head groups 72, and each distribution unit distributes the print data to the five liquid discharge heads 2 in the corresponding head group 72. You may. The liquid discharge head 2 has an elongated long shape in the direction from the front to the back in FIG. 1 and in the vertical direction in FIG. In one head group 72, the three liquid ejection heads 2 are arranged along a direction intersecting the conveying direction of the printing paper P, for example, a direction substantially orthogonal to each other, and the other two liquid ejection heads 2 are conveyed. One is lined up between the three liquid discharge heads 2 at positions displaced along the direction. In other words, in one head group 72, the liquid discharge heads 2 are arranged in a staggered pattern. 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 printing paper P, that is, in the direction intersecting the transport direction of the printing paper P, or the edges overlap. Therefore, printing without gaps in the width direction of the printing paper P is possible.

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

The number of the liquid discharge heads 2 mounted on the printer 1 may be one as long as it is a single color and prints a printable range with one liquid discharge head 2. The number of liquid discharge heads 2 included in the head group 72 and the number of head groups 72 can be appropriately changed depending on the printing target and printing conditions. For example, the number of head groups 72 may be increased in order to print more colors. Further, if a plurality of head groups 72 for printing in the same color are arranged and printed alternately in the transport direction, the transport speed can be increased even if the liquid discharge heads 2 having the same performance are used. As a result, the printing area per hour can be increased. Further, a plurality of head groups 72 for printing in the same color may be prepared and arranged so as to be offset in the direction intersecting the transport direction to increase the resolution in the width direction of the printing paper P.

Further, in addition to printing colored ink, in order to perform surface treatment on the printing paper P, a liquid such as a coating agent may be uniformly or patterned with the liquid ejection head 2 for printing. .. As the coating agent, for example, when a recording medium in which the liquid does not easily permeate is used, a coating agent that forms a liquid receiving layer can be used so that the liquid can be easily fixed. In addition, when a recording medium that is easily penetrated by a liquid is used as the coating agent, the liquid penetration is suppressed so that the liquid does not bleed too much or mix with another liquid that has landed next to it. Those that form a layer can be used. The coating agent may be uniformly applied by the coating machine 76 controlled by the control unit 88, in addition to printing by the liquid discharge head 2.

The printer 1 prints on the printing paper P which is a recording medium. The printing paper P is in a state of being wound around the paper feed roller 80A, and the printing paper P sent out from the paper feed roller 80A passes under the liquid discharge head 2 mounted on the frame 70. After that, it passes between the two transfer rollers 82C and is finally collected by the collection roller 80B. When printing, the printing paper P is conveyed at a constant speed by rotating the transfer roller 82C, and is printed by the liquid discharge head 2.

Subsequently, the details of the printer 1 will be described in the order in which the printing paper P is conveyed. The printing paper P sent out from the paper feed roller 80A passes between the two guide rollers 82A and then passes under the coating machine 76. The coating machine 76 applies the above-mentioned coating agent to the printing paper P.

The printing paper P subsequently enters the head chamber 74 in which the frame 70 on which the liquid discharge head 2 is mounted is housed. The head chamber 74 is a space that is roughly isolated from the outside, although it is connected to the outside in a part such as a portion where the printing paper P enters and exits. In the head chamber 74, control factors such as temperature, humidity, and atmospheric pressure are controlled by the control unit 88 and the like, if necessary. In the head chamber 74, the influence of disturbance can be reduced as compared with the outside where the printer 1 is installed, so that the fluctuation range of the above-mentioned control factor can be narrower than that of the outside.

Five guide rollers 82B are arranged in the head chamber 74, and the printing paper P is conveyed on the guide rollers 82B. The five guide rollers 82B are arranged so that the center is convex toward the direction in which the frame 70 is arranged when viewed from the side surface. As a result, the printing paper P conveyed on the five guide rollers 82B has an arc shape when viewed from the side surface, and by applying tension to the printing paper P, the printing paper P between the guide rollers 82B is formed. Is stretched so that it becomes flat. One frame 70 is arranged between the two guide rollers 82B. The angle at which each frame 70 is installed is gradually changed so as to be parallel to the printing paper P conveyed under the frame 70.

The printing paper P that has come out of the head chamber 74 passes between the two transfer rollers 82C, passes through the dryer 78, passes between the two guide rollers 82D, and is collected by the collection roller 80B. The transport speed of the printing paper P is, for example, 100 m / min. Each roller may be controlled by the control unit 88 or may be manually operated by a person.

By drying the liquid adhering to the printing paper P with the dryer 78, it is possible to prevent the printing papers P, which are overlapped and wound up from each other, from adhering to each other or the undried liquid from rubbing against each other in the recovery roller 80B. In order to print at high speed, it is necessary to dry quickly. In order to speed up the drying, the dryer 78 may be dried in order by a plurality of drying methods, or may be dried by using a plurality of drying methods in combination. Examples of the drying method used in such a case include blowing warm air, irradiating infrared rays, and contacting a heated roller. When irradiating infrared rays, infrared rays in a specific frequency range may be applied so that the printing paper P can be dried quickly while reducing damage to the printing paper P. When the printing paper P is brought into contact with the heated roller, the heat transfer time may be lengthened by transporting the printing paper P along the cylindrical surface of the roller. The range of transportation along the cylindrical surface of the roller is preferably 1/4 or more of the cylindrical surface of the roller, and more preferably 1/2 or more of the cylindrical surface of the roller. When printing UV curable ink or the like, a UV irradiation light source may be arranged in place of the dryer 78 or in addition to the dryer 78. The UV irradiation light source may be arranged between each frame 70.

The printer 1 may include a cleaning unit for cleaning the liquid discharge head 2. The cleaning unit performs cleaning by wiping or capping, for example. The wiping is performed by, for example, using a flexible wiper to rub the surface of the portion where the liquid is discharged, for example, the nozzle surface 4-2 described later, to remove the liquid adhering to the surface. Cleaning by capping is performed, for example, as follows. First, by covering the part where the liquid is discharged, for example, the nozzle surface 4-2 described later with a cap (this is called capping), the nozzle surface 4-2 and the cap are almost sealed to create a space. Made. By repeating the discharge of the liquid in such a state, the liquid, the foreign matter, etc., which are clogged in the discharge hole 8 and have a viscosity higher than that in the standard state, are removed. By capping, the liquid being washed is less likely to be scattered on the printer 1, and the liquid is less likely to adhere to the transport mechanism such as the printing paper P or the roller. The nozzle surface 4-2 that has been washed may be further wiped. Wiping and capping cleaning may be performed by a person manually operating the wiper or cap attached to the printer 1, or may be performed automatically by the control unit 88.

The recording medium may be a roll-shaped cloth or the like, in addition to the printing paper P. Further, instead of directly transporting the printing paper P, the printer 1 may directly transport the transport belt and place the recording medium on the transport belt for transport. In that way, sheet paper, cut cloth, wood, tiles, etc. can be used as recording media. Further, the wiring pattern of the electronic device or the like may be printed by discharging the liquid containing the conductive particles from the liquid discharge head 2. Further, a chemical agent may be produced by discharging a predetermined amount of liquid chemical agent or a liquid containing the chemical agent toward the reaction vessel or the like from the liquid discharge head 2 and reacting the mixture.

Further, a position sensor, a speed sensor, a temperature sensor, or 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 which can be obtained from the information from each sensor. .. For example, the temperature of the liquid discharge head 2, the temperature of the liquid in the liquid supply tank that supplies the liquid to the liquid discharge head 2, the pressure that the liquid in the liquid supply tank applies to the liquid discharge head 2, and the like are the liquids to be discharged. When the discharge characteristics, that is, the discharge amount, the discharge speed, and the like are affected, the drive signal for discharging the liquid may be changed according to the information.

FIG. 3 is an enlarged plan view showing a portion of the recording device including the liquid discharge head according to the embodiment of the present disclosure to which one liquid discharge head is attached. The liquid discharge head 2 has a shape in which the dimension in the length direction (direction substantially orthogonal to the transport direction of the printing paper P) is larger than the dimension in the width direction (direction orthogonal to the length direction) and is long. Notches 21 are provided at both ends in the longitudinal direction. Further, the frame 70 has a plurality of positioning portions 71. Then, the cutout portion 21 of the liquid discharge head 2 is in contact with the positioning portion 71 of the frame 70. In this way, the liquid discharge head 2 is positioned with respect to the frame 70. The shape of the cutout portion 21 can be various, for example, a triangular shape or a rectangular shape. The positioning portion 71 can have various shapes such as a columnar shape and a prismatic shape. The shapes of the plurality of positioning portions that come into contact with one liquid discharge head may be different from each other. Further, it is preferable that at least one of the plurality of positioning portions that come into contact with one liquid discharge head is movable.

Next, the liquid discharge head 2 according to the embodiment of the present disclosure will be described. FIG. 4 is a plan view showing a head body 2a, which is a main part of the liquid discharge head 2 shown in FIG. FIG. 5 is a plan view of the head body 2a excluding the second flow path member 6. 6 and 7 are enlarged plan views of FIG. FIG. 8 is a partial vertical cross-sectional view of the head body 2a along the VV line of FIG. FIG. 9 is a vertical cross-sectional view of the head body 2a along the first common flow path 20. However, FIG. 9 also shows a signal transmission unit 60, which is not shown in FIG.

Each figure is drawn as follows for the sake of clarity. In FIGS. 4 to 7, a flow path or the like that is below other objects and should be drawn with a broken line is drawn with a solid line. In FIG. 4, the flow path in the first flow path member 4 is almost omitted, and only the arrangement of the pressurizing chamber 10 is shown. Further, in FIG. 4, the notches 21 formed at both ends of the second flow path member 6 in the longitudinal direction are not shown.

In addition to the head body 2a, the liquid discharge head 2 may include a metal housing, a driver IC, a wiring board, and the like. Further, the head body 2a is a piezoelectric actuator in which a first flow path member 4, a second flow path member 6 that supplies a liquid to the first flow path member 4, and a displacement element 50 that is a pressurizing portion are incorporated. Includes substrate 40. The head body 2a has a flat plate shape that is long in one direction, and that direction may be referred to as a longitudinal direction. Further, the second flow path member 6 serves as a support member for supporting the structure of the head main body 2a, and the head main body 2a is fixed to the frame 70 at both ends of the second flow path member 6 in the longitudinal direction. Will be done.

The first flow path member 4 constituting the head main body 2a has a flat plate shape, and the thickness thereof is about 0.5 to 2 mm. A large number of pressure chambers 10 are arranged side by side in the plane direction on the pressure chamber surface 4-1 which is the first main surface of the first flow path member 4. A discharge hole 8 for discharging a liquid is formed in a plane direction on a discharge hole surface 4-2 which is a second main surface of the first flow path member 4 and is a surface opposite to the pressurizing chamber surface 4-1. Many are arranged side by side. Each of the discharge holes 8 is connected to the pressurizing chamber 10. Hereinafter, the pressurizing chamber surface 4-1 will be described as being located above the discharge hole surface 4-2.

In the first flow path member 4, a plurality of first common flow paths 20 and a plurality of second common flow paths 24 are arranged so as to extend along the first direction. Further, the first common flow path 20 and the second common flow path 24 are alternately arranged in the second direction, which is the direction intersecting the first direction. The second direction is the same as the longitudinal direction of the head body 2a. Further, the direction opposite to the first direction is defined as the third direction, and the direction opposite to the second direction is defined as the fourth direction.

Pressurizing chambers 10 are lined up along both sides of the first common flow path 20, forming a total of two rows of pressurizing chambers 11A, one row on each side. The first common flow path 20 and the pressurizing chambers 10 arranged on both sides thereof are connected via the first individual flow path 12.

Pressurizing chambers 10 are lined up along both sides of the second common flow path 24, forming a total of two rows of pressurizing chambers 11A, one row on each 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 the following, the first common flow path 20 and the second common flow path 24 may be collectively referred to as a common flow path.

In other words, the pressurizing chambers 10 are arranged side by side on the 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 lined up is a straight line, but it may be a curved line or a polygonal line.

With the above configuration, in the first flow path member 4, the liquid supplied to the second common flow path 24 flows into the pressurizing chambers 10 arranged along the second common flow path 24, and a part thereof. Liquid is discharged from the discharge hole 8, and some of the other liquids flow into the first common flow path 20 located on the opposite side of the second common flow path 24 with respect to the pressurizing chamber 10, and the first It is discharged to the outside of the flow path member 4.

The second common flow path 24 is arranged on both sides of the first common flow path 20, and the first common flow path 20 is a row of two pressurizing chambers arranged on both sides of the first common flow path 20. It is connected to 11A. The first common flow path 20 is arranged on both sides of the second common flow path 24, and the second common flow path 24 has two rows of pressurization arranged on both sides of the second common flow path 24. It is connected to the room row 11A.
By arranging in this way, as compared with the case where one first common flow path 20 and one second common flow path 24 are connected to one pressurizing chamber row 11A, the first common flow flow It is preferable because the number of roads 20 and the second common flow path 24 can be halved. Since the number of the first common flow path 20 and the second common flow path 24 can be reduced, the number of pressurizing chambers 10 can be increased to increase the print resolution of the head main body 2a, or the first common flow path 20 and the first common flow path 20 and the first common flow path 24 can be increased in print resolution. It is possible to increase the cross section of at least one of the two common flow paths 24 to reduce the difference in discharge characteristics between the plurality of discharge holes 8 and to reduce the size of the head body 2a in the plane direction.

The pressure applied to the portion of the first individual flow path 12 connected to the first common flow path 20 on the first common flow path 20 side is affected by the pressure loss, and the first individual flow path 12 is connected to the first common flow path 20. It changes depending on the position where is connected (mainly the position in the first direction). The pressure applied to the portion on the side of the second individual flow path 14 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 (mainly) due to the influence of the pressure loss. It depends on the position in the first direction). The opening 20a to the outside of the first common flow path 20 is arranged at one end in the first direction, and the opening 24a to the outside of the second common flow path 24 is in the third direction opposite to the first direction. If it is arranged at the end of, the difference in pressure due to the arrangement of each of the first individual flow paths 12 and each of the second individual flow paths 14 acts to cancel out, and the difference in pressure applied to each discharge hole 8 can be reduced. Both the opening 20a of the first common flow path 20 and the opening 24a of the second common flow path 24 are open to the pressurizing chamber surface 4-1.

In the non-discharging state, the liquid meniscus is held in the discharge hole 8. Since the pressure of the liquid in the discharge hole 8 is negative (a state in which the liquid is about to be drawn into the first flow path member 4), 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 retained even if the pressure is positive if the pressure is small. If the positive pressure increases, the liquid overflows from the discharge hole 8, and if the negative pressure increases, the liquid is drawn into the first flow path member 4, and the state in which the liquid can be discharged cannot be maintained. Therefore, it is necessary to prevent the pressure difference between the liquids in the discharge holes 8 from becoming too large when the liquid is flowed from the second common flow path 24 to the first common flow path 20.

The wall surface of the first common flow path 20 on the discharge hole surface 4-2 side is the first damper 28A. One surface of the first damper 28A faces the first common flow path 20, and the other surface faces the damper chamber 29. The presence of the damper chamber 29 makes the first damper 28A deformable, and the volume of the first common flow path 20 can be changed by deforming the first damper 28A. When the liquid in the pressurizing chamber 10 is pressurized to discharge the liquid, a part of the pressure is transmitted to the first common flow path 20 through the liquid. As a result, the liquid in the first common flow path 20 vibrates, and the vibration is transmitted to the original pressurizing chamber 10 and other pressurizing chambers 10, causing fluid crosstalk that fluctuates the discharge characteristics of the liquid. Sometimes. When the first damper 28A is present, the vibration of the liquid transmitted to the first common flow path 20 causes the first damper 28A to vibrate and attenuate, so that the vibration of the liquid in the first common flow path 20 is difficult to sustain. Therefore, the influence of fluid crosstalk can be reduced. The first damper 28A also serves to stabilize the supply and discharge of the liquid.

The wall surface of the second common flow path 24 on the pressurizing chamber surface 4-1 side is the second damper 28B. One surface of the second damper 28B faces the second common flow path 24, and the other surface faces the damper chamber 29. Similar to the first damper 28A, the second damper 28B can also reduce the influence of fluid crosstalk. The second damper 28B also serves to stabilize the supply and discharge of the liquid.

The pressurizing chamber 10 is arranged so as to face the pressurizing chamber surface 4-1 and extends downward from the pressurizing chamber main body 10a that receives the pressure from the displacement element 50 and the pressurizing chamber main body 10a, and discharges. This is a hollow region including the descender 10b, which is a partial flow path connected to the discharge hole 8 opened in the hole surface 4-2. The pressurizing chamber main body 10a has a right cylindrical shape and a planar shape of a circular shape. Since the planar shape is circular, the amount of displacement when the displacement element 50 is deformed by the same force and the volume change of the pressurizing chamber 10 caused by the displacement can be increased. The descender 10b has a rectangular shape with a diameter smaller than that of the main body 10a of the pressurizing chamber, and has a circular cross section. Further, the descender 10b is arranged at a position where it fits in the pressurizing chamber main body 10a when viewed from the pressurizing chamber surface 4-1.

The plurality of pressurizing chambers 10 are arranged in a staggered manner on the pressurizing chamber surface 4-1. The plurality of pressurizing chambers 10 form a plurality of pressurizing chamber rows 11A along the first direction. In each pressurizing chamber row 11A, the pressurizing chambers 10 are arranged at substantially equal intervals. The pressure chambers 10 belonging to the adjacent pressure chamber rows 11A are arranged in the first direction with a deviation of about half of the above interval. In other words, the pressurizing chamber 10 belonging to a certain pressurizing chamber row 11A is in the first direction with respect to two consecutive pressurizing chambers 10 belonging to the pressurizing chamber row 11A located next to it. It is located almost in the center.

As a result, the pressurizing chambers 10 belonging to every other pressurizing chamber row 11A are arranged along the second direction, forming the pressurizing chamber row 11B.

In the present embodiment, the first common flow path 20 has 51 lines, the second common flow path 24 has 50 lines, and the pressurizing chamber row 11A has 100 rows. Here, the dummy pressurizing chamber row 11D composed of only the dummy pressurizing chamber 10D described later is not included in the number of the above-mentioned pressurizing chamber rows 11A. Further, the second common flow path 24, which is directly connected only to the dummy pressurizing chamber 10D, is not included in the number of the second common flow paths 24 described above. Further, each pressurizing chamber row 11A includes 16 pressurizing chambers 10. However, the pressurizing chamber row 11A located at the end in the second direction and the opposite direction includes eight pressurizing chambers 10 and eight dummy pressurizing chambers 10D. Further, as described above, since the pressurizing chambers 10 are arranged in a staggered pattern, the number of rows of the pressurizing chamber rows 11B is 32.

The plurality of discharge holes 8 are arranged in a grid pattern along the first direction and the second direction on the discharge hole surface 4-2. The plurality of discharge holes 8 form a plurality of discharge hole rows 9A along the first direction. The discharge hole row 9A and the pressurizing chamber row 11A are arranged at substantially the same position. Further, the center of gravity of the area of the pressurizing chamber 10 and the discharge hole 8 connected to the pressurizing chamber 10 are arranged so as to be displaced in the third direction. Therefore, in the present embodiment, the discharge hole columns 9A are 100 columns and the discharge hole rows 9B are 32 rows.

The center of gravity of the area of the pressurizing chamber main body 10a and the discharge hole 8 connected to the pressurizing chamber main body 10a are substantially displaced in the first direction or the third direction. The descender 10b is arranged at a position deviated from the pressurizing chamber main body 10a in the same direction as the discharge hole 8 is deviated. The side wall of the pressurizing chamber main body 10a and the side wall of the descender 10b are arranged so as to be in contact with each other, whereby it is possible to prevent the liquid from staying in the pressurizing chamber main body 10a.

The discharge hole 8 is arranged at the center of the descender 10b. Here, the central portion is a region within a circle that is half the diameter of the descender 10b, centered on the center of gravity of the area of the descender 10b. In other words, the central part is an area in which a figure similar to the cross section of the descender 10b and having an area of 1/4 is arranged so that the center of gravity of the area of the figure and the center of gravity of the cross section of the descender 10b match. be.

The connection portion between the first individual flow path 12 and the pressurizing chamber main body 10a is arranged on the side opposite to the descender 10b with respect to the area center of gravity of the pressurizing chamber main body 10a. As a result, the liquid flowing from the descender 10b spreads over the entire pressurizing chamber main body 10a and then flows toward the first individual flow path 12, so that the liquid is unlikely to stay in the pressurizing chamber main body 10a.

The second individual flow path 14 is drawn out in the plane direction from the surface of the descender 10b on the discharge hole surface 4-2 side and is connected to the second common flow path 24. The drawing direction is the same as the direction in which the descender 10b is displaced with respect to the pressurizing chamber main body 10a.

The angle formed by the first direction and the second direction deviates from a right angle. Therefore, the discharge holes 8 belonging to the discharge hole rows 9A arranged along the first direction are arranged so as to be displaced in the second direction by the angle deviated from the right angle. Since the discharge hole rows 9A are arranged side by side in the second direction, the discharge holes 8 belonging to different discharge hole rows 9A are arranged so as to be displaced in the second direction by that amount. Together, the discharge holes 8 of the first flow path member 4 are arranged side by side at regular intervals in the second direction. As a result, printing can be performed so as to fill a predetermined range with pixels formed by the liquid discharged from the discharge hole 8.

The arrangement of the discharge holes 8 belonging to one discharge hole row 9A is as described above if the discharge holes 8 are arranged completely in a straight line along the first direction so that the different discharge hole rows 9A print different areas. It is possible to print so as to fill a predetermined range. However, in such an arrangement, the deviation between the direction orthogonal to the second direction and the transport direction that occurs when the liquid discharge head 2 is installed in the printer 1 has a large influence on the printing accuracy. Therefore, in order to print a certain area, it is preferable that the liquids discharged from the discharge holes 8 belonging to the plurality of discharge hole rows 9A are mixed and landed. Further, in order to do so, the discharge holes 8 belonging to the discharge hole row 9A are not arranged on a perfect straight line, but are arranged slightly deviated from the straight line.

In the present embodiment, the arrangement of the discharge holes 8 is as follows. In FIG. 6, when the discharge holes 8 are projected in a direction orthogonal to the second direction, 32 discharge holes 8 are projected in the range of the virtual straight line R, and the discharge holes 8 are arranged at intervals of 360 dpi in the virtual straight line R. .. As a result, if the printing paper P is conveyed and printed in the direction orthogonal to the virtual straight line R, printing can be performed at a resolution of 360 dpi. The discharge holes 8 projected in the virtual straight line R belong to all the discharge holes 8 (16 pieces) belonging to the discharge hole row 9A in one row and the two discharge hole rows 9A located on both sides of the discharge hole row 9A. Half (8 pieces) of each of the discharge holes 8. In order to make such a configuration, in each discharge hole row 9B, the discharge holes 8 are arranged at an interval of 22.5 dpi. This is because 360/16 = 22.5.

The first common flow path 20 and the second common flow path 24 are straight lines as long as the discharge holes 8 are lined up in a straight line, and the straight lines are displaced in parallel between the discharge holes 8. In the first common flow path 20 and the second common flow path 24, since there are few deviations, the flow path resistance is small. Further, since the portion that is displaced in parallel is arranged at a position that does not overlap with the pressurizing chamber 10, the fluctuation of the discharge characteristic can be reduced for each pressurizing chamber 10.

A normal pressurizing chamber 10 and a dummy pressurizing chamber 10D are included in one row of ends in the second direction and the opposite fourth direction, that is, two rows of pressurizing chamber rows 11A at both ends. (Therefore, this pressurizing chamber row 11A may be referred to as a dummy pressurizing chamber row 11D1). Further, on the outer side of the dummy pressurizing chamber row 11D1, one row in which only the dummy pressurizing chamber 10D is lined up, that is, two rows of dummy pressurizing chamber rows 11D2 are arranged at both ends. The flow paths, one at each end in the second direction and the opposite fourth direction, that is, two rows in total at both ends, have the same shape as the normal first common flow path 24, but directly. It is not connected to the pressurizing chamber 10, but is connected only to the dummy pressurizing chamber 10D.

The dummy pressurizing chamber 10D is not used for discharging the liquid. When the pressurizing chamber 10 is connected to the second common flow path 24 located at the most end, the pressurizing chamber 10 connected to the second common flow path 24 becomes only one row, and the pressurizing chamber 10 in that row becomes only one row. , There is a possibility that the discharge characteristics will be different from those of the other pressurizing chamber 10. Therefore, a dummy pressurizing chamber 10D is arranged. The basic structure of the dummy pressurizing chamber 10D and the flow path connecting the dummy pressurizing chamber 10D and the common flow path is the flow path connecting the pressurizing chamber 10 and the pressurizing chamber 10 and the common flow path. It is the same, and by arranging such a dummy pressurizing chamber 10D, the state of the liquid flowing in the first common flow path 20 arranged adjacent to the inside of the second common flow path 24 located at the most end. Can be made substantially the same as the other first common flow path 20. As a result, the second common flow path 24 located at the end is arranged adjacent to the inside of the head main body 2a with respect to the first common flow path 20 arranged adjacent to the inside of the head main body 2a. The discharge characteristics of the pressurizing chamber 10 can be made substantially the same as the discharge characteristics of the other pressurizing chambers 10.

In the present embodiment, the dummy pressurizing chamber 10D is not provided with the corresponding discharge hole 8. Further, the piezoelectric actuator substrate 40 is not arranged on the upper part of a part of the dummy pressurizing chamber 10D. Such a dummy pressurizing chamber 10D is configured by closing the holes of the plate 4b arranged under the plate 4a with the plate 4a instead of the plate 4a in which the holes serving as the pressurizing chamber 10 are arranged. There is. The dummy pressurizing chamber 10D may have exactly the same structure as the pressurizing chamber 10, and may not be used for discharging liquid by simply not supplying a drive signal.

The first flow path member 4 is located outside the common flow path group including the first common flow path 20 and the second common flow path 24 in the second direction, and extends in the first direction. It has a road 30. The end flow path 30 is lined up with the opening 30c arranged outside the opening 20a of the first common flow path 20 lined up with the pressurizing chamber surface 4-1 and the pressurizing chamber surface 4-1. It is a flow path connecting the opening 30d arranged outside the opening 24a of the second common flow path 24.

The head body 2a is controlled to keep the temperature constant in order to stabilize the liquid discharge characteristics. Further, the lower the viscosity of the liquid, the more stable the discharge and the circulation of the liquid, so that the temperature is basically set to room temperature or higher. Therefore, it is basically heated, but if the environmental temperature is high, it may be cooled.

In order to keep the temperature constant, the liquid discharge head 2 is provided with a heater, or the liquid to be supplied is temperature-controlled. In any case, if there is a difference between the ambient temperature and the target temperature, heat is dissipated from the ends of the head body 2a in the longitudinal direction (second direction and fourth direction), so that the center of the second direction is used. The temperature of the pressurizing chamber 10 located at the end in the second direction and the fourth direction tends to be lower than the temperature of the liquid in the pressurizing chamber 10 located in the portion. By providing the end flow path 30, the temperature of the pressurizing chambers 10 located at the ends in the second and fourth directions is less likely to drop, and the variation in the discharge characteristics of the liquid discharged from each pressurizing chamber 10 is reduced. It is possible to improve the printing accuracy.

The end flow path 30 is a flow path connecting the first integrated flow path 22 and the second integrated flow path 26. When the flow path resistance of the end flow path 30 is smaller than the flow path resistance of the first common flow path 20 and the second common flow path 24, the amount of liquid flowing in the end flow path 30 increases, and the end flow. The temperature drop inside the road 30 can be further suppressed.

The end flow path 30 is provided with a wide portion 30a in which the width of the flow path is wider than the width of the common flow path, and a damper is provided on the pressurizing chamber side 4-1 of the wide portion 30a. .. One surface of this damper faces the wide portion 30a, and the other surface faces the damper chamber, so that the damper can be deformed. The damping ability of the damper is greatly affected by the part where the crossing of the deformable area is the narrowest. Therefore, by providing a damper facing the wide portion 30a, it is possible to obtain a damper having a high damping ability. The width of the wide portion 30a is preferably twice or more, particularly three times or more the width of the common flow path. If the flow path resistance becomes too low by providing the wide portion 30a, the flow path resistance may be adjusted by providing the narrowing portion 30d.

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 second integrated flow path 26 that supplies the liquid to the second common flow path 24, and a first integrated flow path 22 that collects the liquid in the first common flow path 20. .. The thickness of the second flow path member 6 is thicker than that of the first flow path member 4, and is about 5 to 30 mm.

The second flow path member 6 is joined to a region of the pressure chamber surface 4-1 of the first flow path member 4 to which the piezoelectric actuator substrate 40 is not connected. More specifically, they are joined so as to surround the piezoelectric actuator substrate 40. By doing so, it is possible to prevent a part of the discharged liquid from adhering to the piezoelectric actuator substrate 40 as mist. Further, since the first flow path member 4 is fixed on the outer periphery, it is possible to prevent the first flow path member 4 from vibrating with the driving of the displacement element 50 and causing resonance or the like.

Further, a through hole 6a that vertically penetrates the second flow path member 6 is arranged in the central portion of the second flow path member 6. A signal transmission unit 60 such as an FPC (Flexible Printed Circuit) that transmits a drive signal for driving the piezoelectric actuator board 40 is passed through the through hole 6a.

By arranging the first integrated flow path 22 in the second flow path member 6 which is thicker than the first flow path member 4 and separate from the first flow path member 4, the cross-sectional area of the first integrated flow path 22 is increased. As a result, the difference in pressure loss due to the difference in the position where the first integrated flow path 22 and the first common flow path 20 are connected can be reduced. The flow path resistance of the first integrated flow path 22 (more accurately, the flow path resistance in the range connected to the first common flow path 20 in the first integrated flow path 22) is the flow path resistance of the first common flow path 20. It is preferably 1/100 or less.

By arranging the second integrated flow path 26 in the second flow path member 6 which is thicker than the first flow path member 4 and separate from the first flow path member 4, the cross-sectional area of the second integrated flow path 26 is increased. As a result, the difference in pressure loss due to the difference in the position where the second integrated flow path 26 and the second common flow path 24 are connected can be reduced. The flow path resistance of the second integrated flow path 26 (more accurately, the flow path resistance in the range connected to the first integrated flow path 22 in the second integrated flow path 26) is the flow path resistance of the second common flow path 24. It is preferably 1/100 or less.

The first integrated flow path 22 is arranged at one end of the second flow path member 6 in the lateral direction, and the second integrated flow path 26 is arranged at the other end of the second flow path member 6 in the lateral direction. Each flow path is directed toward the first flow path member 4, and is connected to the first common flow path 20 and the second common flow path 24, respectively. By doing so, the cross-sectional area of the first integrated flow path 22 and the second integrated flow path 26 can be increased, that is, the flow path resistance can be reduced, and the second flow path member 6 can be used with respect to the first flow path member 4. The outer circumference can be fixed to increase the rigidity, and a through hole 6a through which the signal transmission unit 60 passes can be provided.

On the lower surface of the second integrated flow path member 6, a groove serving as a first integrated flow path main body 22a, which is a portion of the first integrated flow path 22 extending in the second direction and having a low flow path resistance, and a second integrated flow path are provided. A groove serving as a second integrated flow path main body 26a, which is a portion of the road 26 having a low flow path resistance extending in the second direction, is arranged. A part of the lower surface of the groove serving as the first integrated flow path main body 22a of the second flow path member 6 is closed by the upper surface of the flow path member 4, and the other part of the lower surface is arranged on the upper surface of the flow path member 4. By connecting to the opening 20a of the first common flow path 20 and the opening 30c of the end flow path 30, the first integrated flow path main body 22a is formed. A part of the lower surface of the groove serving as the second integrated flow path main body 26a of the second flow path member 6 is closed by the upper surface of the flow path member 4, and the other part of the lower surface is arranged on the upper surface of the flow path member 4. By connecting to the opening 24a of the second common flow path 24 and the opening 30d of the end flow path 30, the first integrated flow path main body 22a is formed.

At the end of the first integrated flow path 22 in the second direction, an opening 22b that is open on the upper surface of the second flow path member 6 is arranged. At the end of the second integrated flow path 26 in the fourth direction, an opening 26b that is open on the upper surface of the second flow path member 6 is arranged. In the case of printing, a liquid is supplied from the outside to the opening 26b of the second integrated flow path 26, and the liquid that has not been discharged is collected from the opening 26b of the first integrated flow path 22.

Dampers may be provided in the first integrated flow path 22 and the second integrated flow path 26 to stabilize the supply or discharge of the liquid against fluctuations in the discharge amount of the liquid. Further, by providing a filter inside the first integrated flow path 22 and the second integrated flow path 26, or between the first common flow path 20 or the first common flow path 24, foreign matter and air bubbles can be first removed. It may be difficult to enter the flow path member 4.

A piezoelectric actuator substrate 40 including a displacement element 50 is joined to a pressurizing chamber surface 4-1 which is an upper surface of the first flow path member 4, so that each displacement element 50 is located on the pressurizing chamber 10. Have 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 openings of the respective pressurizing chambers 10 are 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. Further, a signal transmission unit 60 such as an FPC for supplying a signal to each displacement element 50 is connected to the piezoelectric actuator substrate 40. The second flow path member 6 has a through hole 6c penetrating up and down in the center, and the signal transmission unit 60 is electrically connected to the control unit 88 through the through hole 6c. The signal transmission unit 60 has a shape extending from one long side end of the piezoelectric actuator substrate 40 toward the other long side end in the short side direction, and the wiring arranged in the signal transmission unit is along the short side direction. The distance between the wirings can be increased by extending the wires and arranging them in the longitudinal direction.

Individual electrodes 44 are arranged at positions facing each pressurizing chamber 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. Twelve plates from the plate 4a to the plate 4l are laminated in order from the pressure chamber surface 4-1 side of the flow path member 4. Many holes and grooves are formed in these plates. Holes and grooves can be formed, for example, by making each plate out of metal and etching. Since the thickness of each plate is about 10 to 300 μm, the accuracy of forming holes and grooves can be improved. The plates are aligned and laminated so that these holes and grooves communicate with each other to form a flow path such as the first common flow path 20.

The pressurizing chamber main body 10a is open to the pressurizing chamber surface 4-1 of the flat plate-shaped flow path member 4, and the piezoelectric actuator substrate 40 is joined. Further, the pressurizing chamber surface 4-1 has an opening 24a for supplying the liquid to the second common flow path 24 and an opening 20a for collecting the liquid from the first common flow path 20. A discharge hole 8 is opened in the discharge hole surface 4-2, which is a surface of the flow path member 4 opposite to the pressure chamber surface 4-1. A plate may be further laminated on the pressure chamber surface 4-1 to close the opening of the pressure chamber main body 10a, and the piezoelectric actuator substrate 40 may be bonded thereto. By doing so, the possibility that the discharged liquid comes into contact with the piezoelectric actuator substrate 40 can be reduced, and the reliability can be further improved.

The structure for discharging the liquid includes a pressurizing chamber 10 and a discharge hole 8. The pressurizing chamber 10 includes a pressurizing chamber main body 10a facing the displacement element 50 and a descender 10b having a cross-sectional area smaller than that of the pressurizing chamber main body 10a. The pressurizing chamber main body 10a is formed on the plate 4a, and the descender 10b is formed by stacking the holes formed on the plates 4b to k and further closing the portion other than the discharge hole 8 with the nozzle plate 4l. ing.

The first individual flow path 12 is connected to the pressurizing chamber main body 10a, and the first individual flow path 12 is connected to the first common flow path 20. The first individual flow path 12 includes a circular hole penetrating the plate 4b, a through groove extending in a plane direction in the plate 4c, and a circular hole penetrating the plate 4d. The first common flow path 20 is formed by overlapping holes formed in plates 4f to i, and further closing the upper side with a plate 4e and the lower side with a plate 4j.

The second individual flow path 14 is connected to the descender 10b, and the second individual flow path 14 is connected to the second common flow path 24. The second individual flow path 14 is a through groove extending in the plane direction in the plate 4k. The second common flow path 24 is formed by overlapping holes formed in the plates 4f to j, and further closing the upper side with the plate 4e and the lower side with the plate 4k.

Summarizing the flow of the liquid, the liquid supplied to the second integrated flow path 26 passes through the second common flow path 24 and the second individual flow path 14 in order and enters the pressurizing chamber 10, and a part of the liquid is discharged. It is discharged from the hole 8. The liquid that has not been discharged enters the first common flow path 20 through the first individual flow path 12, then enters the first integrated flow path 22, and is discharged to the outside of the head main body 2.

The piezoelectric actuator substrate 40 has a laminated structure composed of two piezoelectric ceramic layers 40a and 40b, which are piezoelectric materials. 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 of the piezoelectric ceramic layer 40a to the piezoelectric ceramic layer 40b is 3: 7 to 7: 3, preferably 4: 6 to 6: 4. Each of the piezoelectric ceramic layers 40a and 40b extends 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 thickness of the common electrode 42 is about 2 μm, and the thickness of the individual electrode 44 is about 1 μm.

The individual electrodes 44 are arranged at positions facing each pressure chamber 10 on the upper surface of the piezoelectric actuator substrate 40. The individual electrode 44 has an individual electrode body 44a whose planar shape is one size smaller than that of the pressurizing chamber body 10a and which has a shape substantially similar to that of the pressurizing chamber body 10a, and an extraction electrode drawn from the individual electrode body 44a. 44b and is included. A connection electrode 46 is formed at one end of the extraction electrode 44b, which is drawn out of 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 to have a thickness of about 5 to 200 μm. Further, the connection electrode 46 is electrically joined to the electrode provided in the signal transmission unit 60.

Further, a surface electrode for a common electrode (not shown) is formed on the upper surface of the piezoelectric actuator substrate 40. The surface electrode for the common electrode and the common electrode 42 are electrically connected to each other through a through conductor (not shown) arranged on the piezoelectric ceramic layer 40a.

Although details will be described later, a drive signal is supplied from the control unit 88 to the individual electrodes 44 through the signal transmission unit 60. The drive signal is supplied at a constant cycle in synchronization with the transport speed of the printing paper P.

The common electrode 42 is formed in a region between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b over substantially the entire surface direction. 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 connected to a surface electrode for a common electrode formed on the piezoelectric ceramic layer 40a at a position avoiding an electrode group composed of individual electrodes 44 via a via hole formed through the piezoelectric ceramic layer 40a. It is grounded and held at the ground potential. The surface electrode for the common electrode is directly or indirectly connected to the control unit 88, like the plurality of individual electrodes 44.

The portion of the piezoelectric ceramic layer 40a sandwiched between the individual electrodes 44 and the common electrode 42 is polarized in the thickness direction, and becomes a displacement element 50 having a unimorph structure that is displaced when a voltage is applied to the individual electrodes 44. There is. More specifically, when an electric field is applied to the piezoelectric ceramic layer 40a at a potential different from that of the common electrode 42 in the polarization direction, the portion to which the electric field is applied is distorted by the piezoelectric effect. Work as. In this configuration, when the individual electrodes 44 are set to positive or negative predetermined potentials 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, the activity sandwiched between the electrodes of the piezoelectric ceramic layer 40a The portion contracts in the plane direction. On the other hand, since the piezoelectric ceramic layer 40b, which is an inactive layer, is not affected by the electric field, it does not spontaneously shrink and tries to regulate the deformation of the active portion. As a result, a difference in strain in the polarization direction occurs between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b, and the piezoelectric ceramic layer 40b is deformed (unimorph deformation) so as to be convex toward the pressurizing chamber 10.

Subsequently, the liquid discharge operation will be described. The displacement element 50 is driven (displaced) by a drive signal supplied to the individual electrodes 44 via a driver IC or the like under the control of the control unit 88. In the present embodiment, the liquid can be discharged by various drive signals, but here, a so-called pulling drive method will be described.

The individual electrode 44 is set to a higher potential (hereinafter referred to as high potential) than the common electrode 42 in advance, and each time there is a discharge request, the individual electrode 44 is once set to the same potential as the common electrode 42 (hereinafter referred to as low potential). After that, the potential is set to high again at a predetermined timing. As a result, the piezoelectric ceramic layers 40a and 40b return to their original (flat) shapes (beginning) at the timing when the individual electrodes 44 become low potentials, and the volume of the pressurizing chamber 10 is in the initial state (the potentials of both electrodes are different). State) increases compared to. 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 in the natural vibration cycle. Specifically, at first, the volume of the pressurizing chamber 10 begins to increase, and the negative pressure gradually decreases. The volume of the pressurizing chamber 10 is then maximized and the pressure is almost zero. Then the volume of the pressurizing chamber 10 begins to decrease and the pressure increases. After that, the individual electrode 44 is set to a high potential at the timing when the pressure becomes almost maximum. Then, the pressure due to the vibration applied first and the pressure applied next overlap, and a larger pressure is applied to the liquid. This pressure propagates in the descender and discharges the liquid from the discharge hole 8.

That is, the droplets can be ejected by supplying the drive signal of the pulse whose potential is low for a certain period of time with reference to the high potential to the individual electrodes 44. Assuming that this pulse width is AL (Acoustic Length), which is half the time of the natural vibration cycle of the liquid in the pressurizing chamber 10, in principle, the discharge rate and the discharge amount of the liquid can be maximized. The natural vibration cycle of the liquid in the pressurizing chamber 10 is greatly affected by the physical properties of the liquid and the shape of the pressurizing chamber 10, but in addition to that, the physical characteristics of the piezoelectric actuator substrate 40 and the flow path connected to the pressurizing chamber 10 It is also influenced by the characteristics of.

The pulse width is actually set to a value of about 0.5AL to 1.5AL because there are other factors to be considered, such as consolidating the ejected droplets into one. Further, since the discharge amount can be reduced by setting the pulse width to a value deviating from AL, the pulse width is set to a value deviating from AL in order to reduce the discharge amount.

The arrangement of the discharge holes 8 of the present disclosure will be described. FIG. 10 shows the arrangement of the discharge holes 8 according to the embodiment of the present disclosure. FIG. 10 shows a first direction and a second direction. The angle formed by the first direction and the second direction is different between FIGS. 10 and 6 and the like because the vertical and horizontal scales of FIG. 10 are different. In FIG. 10, the discharge holes 8 are represented by black dots, and lines connecting the discharge holes 8 are drawn so that the relationship between the adjacent discharge holes 8 can be easily understood.

The discharge hole 8 is arranged on the discharge hole line 9B. There are 16 discharge hole rows 9B, which are the first row, the second row, ..., The 16th row in the direction opposite to the first direction. It should be noted that the reason why the line is reversed from the first direction is to make it easier to compare with the figure, and the following description is the same even if it is not reversed. Hereinafter, the distance between the two discharge holes 8 in the direction orthogonal to the second direction will be described. However, in the present embodiment, the distance between the rows is the same, so that the distance is determined by the two discharge holes 8. It is represented by how many lines are separated. It is preferable that there are 8 or more discharge hole lines.

The discharge holes 8 are arranged at equal intervals in the second direction. When the discharge hole 8 located at the xth position in the second direction is arranged in the y-th row, the position of the discharge hole 8 is represented by [x, y]. Further, it is said that the line to which the discharge hole 8 belongs is y.

In FIG. 10, the positions x and the belonging rows y of the 1st to 35th discharge holes 8 in the second direction are shown in a table. From the 33rd position onward, the same arrangement as the 1st to 2nd positions is repeated.

Recording by the head body 2a is performed while moving the recording medium in a direction orthogonal to the second direction of the liquid discharge head 2. The liquids that land adjacent to each other in the second direction on the recording medium are discharged from the discharge holes 8 adjacent to each other in the second direction. Conversely, the droplets ejected from the ejection holes 8 adjacent to each other in the second direction become pixels adjacent to each other on the recording medium. Further, a pair of discharge holes 8 adjacent to each other in the second direction will be referred to as a discharge hole pair 7.

In order to improve the recording accuracy, the liquid discharge head 2 is installed so that the transport direction of the recording medium and the second direction are orthogonal to each other, but in reality, a certain degree of angular deviation occurs. When there is a deviation in the installation angle, the deviation in the distance between adjacent pixels is the direction orthogonal to the deviation in the installation angle of the liquid discharge head 2 and the second direction of the discharge hole pair 7 for discharging those pixels. Is proportional to the distance of. Therefore, if the discharge hole pairs 7 are arranged apart in the direction orthogonal to the second direction, the deviation of the distance between the pixels becomes large when the installation angle deviates.

When recording an image having a uniform density, when the distance between adjacent pixels on the recording medium becomes shorter, the person perceives the image as having a higher density. On the contrary, when the distance between adjacent pixels on the recording medium becomes long, the person perceives that the density is low. That is, the variation in pixel distance is perceived by humans as the variation in density.

Here, the distance in the direction orthogonal to the second direction of the discharge hole pair 7 is referred to as a pair-to-pair aberration. Further, a discharge hole pair 7 having a pair-to-pair aberration of a predetermined value or more is called a long-distance pair, and a discharge hole pair 7 having a pair-to-pair aberration smaller than a predetermined value is called a short-distance pair. The predetermined value is, for example, 2.

By properly arranging the long-distance pair and the short-distance pair, it is possible to record the density difference so that it is difficult for a person to recognize it. Specifically, the long-distance pairs are arranged continuously, and the short-distance pairs are arranged between the long-distance pairs. Then, the short-distance pair between the long-distance pair is arranged so as to make the density difference of the long-distance pair inconspicuous.

The discharge hole pair 7 including the x-th discharge hole 8 in the second direction and the x + 1-th discharge hole 8 in the second direction is referred to as the x-th pair. The discharge hole pair 7 adjacent to the xth pair is the x + 1th pair, not the X + 2nd pair.

The row to which the x-th discharge hole 8 belongs in the second direction is represented by y (x), and the pair-to-pair row difference of the x-th pair is represented by dy (x). Since the x-th pair is the discharge hole pair 7 of the discharge hole 8 at the position of [x, y (x)] and the discharge hole 8 at the position of [x + 1, y (x + 1)], the pair of the x-th pair The line difference dy (x) is y (x + 1) −y (x).

When the absolute value of the pair-to-row difference is large, the fluctuation of the concentration becomes large when the installation angle of the liquid discharge head 2 deviates. Further, the change of the density when the installation angle deviates is opposite between the discharge hole pair 7 having a positive inter-pair line difference and the discharge hole pair 7 having a negative inter-pair line difference. In the discharge hole pair 7 having a positive line difference and the discharge hole pair 7 having a negative line difference, the inclinations of the discharge holes 8 between the discharge hole pairs 7 are opposite to each other. Therefore, when the installation angle is deviated so that the density of the discharge hole pair 7 having a positive inter-pair row difference becomes high, that is, the distance between the pixels becomes short, the discharge hole pair 7 having a negative inter-pair row difference , The distance between the pixels becomes long and it lands, and the density becomes thin.

When the long-distance pairs are arranged next to each other, when the positive and negative of the pair-to-row difference match, the discharge hole pairs 7 having the same tendency of the concentration fluctuation are adjacent to each other, so that the concentration fluctuation becomes conspicuous. When the long-distance pairs are arranged next to each other, when the positive and negative of the pair-to-row difference are opposite, the difference in the concentration fluctuation becomes large, so that the concentration fluctuation becomes conspicuous. Therefore, the long-distance pairs are not arranged next to each other, and the short-distance pairs are arranged between the long-distance pairs. There may be a plurality of short-distance pairs to be arranged.

When two long-distance pairs are placed with a short-distance pair in between, the concentration difference is more noticeable in the long-distance pair with a larger absolute value of the pair-to-row difference between the long-distance pairs. A short-distance pair arranged adjacent to a long-distance pair having a large absolute value of is matched with a long-distance pair having a large absolute value of the pair-to-row difference. By doing so, the tendency of the concentration fluctuation of the adjacent short-distance pair becomes the same, so that the concentration difference can be made less noticeable.

A more specific explanation of the same content is as follows. Two long-distance pairs arranged with a short-distance pair in between will be described as the x1st pair and the x2nd pair (x2 is larger than x1). When the absolute value of dy (x1)> the absolute value of dy (x2), it is considered that the fluctuation of the concentration is larger in the x1st pair. The discharge hole pairs 7 arranged adjacent to each other on the x2nd side of the x1st pair are x1 + 1th pairs, and the pair-to-pair line difference of the x1 + 1th pairs is dy (x1 + 1). Therefore, by matching whether dy (x1 + 1) is positive or negative with whether dy (x1) is positive or negative, the concentration difference caused by the pair-to-row difference of dy (x1) is conspicuous. It can be difficult.

This corresponds to the relationship between the second pair, which is a long-distance pair, and the fourth pair, which is a long-distance pair, in the discharge hole arrangement of FIG. Since dy (2) = y (3) -y (2) = 14-31 = -17 and dy (4) = y (5) -Y (4) = 28-13 = 15, it is the second. It is considered that the pair has a larger absolute value of the line difference between pairs and is more conspicuous. The pair-to-pair line difference dy (3) = -1 of the third pair, which is a short-distance pair, which is the discharge hole pair 7 arranged adjacent to the fourth pair of the second pair, is set to the second pair. By setting the same negative value as the pair-to-pair row difference dy (2) = -17, the concentration difference caused by the pair-to-pair row difference dy (2) = -17 can be made inconspicuous.

When the absolute value of dy (x1) is less than the absolute value of dy (x2), it is considered that the fluctuation of the concentration is larger in the x2nd pair. The discharge hole pairs 7 arranged adjacent to each other on the x1st side of the x2nd pair are the x2-1th pair, and the pair-to-pair line difference of the x2-1th pair is dy (x2-1). Therefore, by matching whether dy (x2-1) is positive or negative with whether dy (x2) is positive or negative, the concentration difference caused by the pair-to-row difference of dy (x2) is calculated. It can be made inconspicuous.

This corresponds to the relationship between the fourth pair, which is a long-distance pair, and the sixth pair, which is a long-distance pair, in the discharge hole arrangement of FIG.

If the predetermined value of the pair-to-pair line difference that divides the discharge hole pair 7 into a long-distance pair and a short-distance pair is set to 2, the pair-to-pair line difference is 1, except for the discharge hole pair having the smallest pair-to-pair line difference. It becomes a distance pair, and by arranging the surrounding discharge holes 8 for such a long distance pair as described above, it is possible to make the concentration difference difficult to recognize.

When the distances between the discharge hole rows 9B are different, the discharge hole rows 9B having the longest distance among the adjacent discharge hole rows 9B with one discharge hole row 9B in between. The distance between them may be a predetermined value.

When two or more short-distance pairs are arranged between two long-distance pairs, the pair-to-pair difference between the short-distance pairs is positive or negative, or if they all match. The concentration difference of a long-distance pair with a large absolute value of the pair-to-row difference can be made less noticeable.

In other words, this is as follows. The two long-distance pairs will be described as the x1st pair and the x2nd pair (x2 is larger than x1). When the absolute value of dy (x1)> the absolute value of dy (x2), it is considered that the fluctuation of the concentration is larger in the x1st pair. The discharge hole pairs 7 arranged on the x2nd side of the x1st pair are the x1 + 1st pair to the x2-1th pair, and whether the pair-to-pair line difference between these short-distance pairs is positive or negative. If all of the above are matched with whether the pair-to-row difference dy (x1) is positive or negative, the concentration difference caused by the pair-to-row difference of dy (x1) can be made less noticeable.

When the absolute value of dy (x1) is less than the absolute value of dy (x2), it is considered that the fluctuation of the concentration is larger in the x2nd pair. The discharge hole pairs 7 arranged on the x1st side of the x2nd pair are the x1 + 1th pair to the x2-1th pair, and whether the pair-to-pair line difference between these short-distance pairs is positive or negative. If all of the above are matched with whether the pair-to-row difference dy (x2) is positive or negative, the concentration difference caused by the pair-to-row difference of dy (x2) can be made less noticeable.

In order to average the overall density variation, it is preferable to arrange the long-distance pair and the short-distance pair alternately.

Further, the discharge holes 8 are arranged in a straight line in the first direction to form a discharge hole row 9A. The discharge hole row 9A intersects the second direction, is not orthogonal to the second direction, and is arranged obliquely with respect to the second direction. A pressurizing chamber row 11A in which the pressurizing chambers 10 are lined up is formed along the discharge hole row 9A. Then, between the pressurizing chamber rows 11A, the first common flow path 20 and the second common flow path 24 are arranged along the pressurizing chamber row 11A.

The first common flow path 20 and the second common flow path 24 need to supply the liquid required for ejection and allow the liquid to flow so that the solid content of the ink is less likely to settle. Cross-sectional area is required. Even in the head body 2a in which circulation is not performed and the second common flow path 24 does not exist, it is necessary to supply the liquid to be discharged, and the cross-sectional area of the first common flow path 20 needs to be a certain amount or more. be.

Since the discharge hole rows 9A are arranged diagonally with respect to the second direction, the first common flow path 20 and the second common flow path 24 are provided between the adjacent discharge hole rows 9A. It will be possible to arrange it diagonally almost in parallel with.

11 and 12 are discharge hole arrangements in other embodiments of the present disclosure. Parts having little difference from the embodiment shown in FIG. 10 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 11, there are 16 discharge hole rows 9B, and the first to 18th discharge holes are shown in the second direction. From the 17th onward in the second direction, the same arrangement as that of the 1st to 16th discharge holes 8 is repeated. With such an arrangement, the density difference between long-distance pairs can be made inconspicuous. Further, since the discharge hole row 9A can be arranged along the first direction, it is easy to arrange the common flow path.

In FIG. 12, there are eight discharge hole rows 9B, and the first to tenth discharge holes are shown in the second direction. From the 9th onward in the second direction, the same arrangement as that of the 1st to 8th discharge holes 8 is repeated. With such an arrangement, the density difference between long-distance pairs can be made inconspicuous.

1 ... Color inkjet printer 2 ... Liquid discharge head 2a ... Head body 4 ... First flow path member (flow path member)
4a to 4l ... Plates (of the first flow path member) 4-1 ... Pressurized chamber surface 4-2 ... Discharge hole surface 6 ... Second flow path member 6a ... (Second Through hole 7 ... Discharge hole vs. 8 ... Discharge hole 9A ... Discharge hole row 9B ... Discharge hole line 10 ... Pressurization chamber 10a ... Pressurization chamber body 10b・ ・ ・ Partial flow path (descender)
10D ... Dummy pressurizing chamber 11A ... Pressurizing chamber row 11B ... Pressurizing chamber line 12 ... 1st individual flow path 14 ... 2nd individual flow path 20 ... 1st common flow Road (common flow path)
20a ... (first common flow path) opening 21 ... notch 22 ... first integrated flow path 22a ... first integrated flow path body 22b ... (first integrated flow path) ) Opening 24 ... 2nd common flow path (common flow path)
24a ... (second common flow path) opening 26 ... second integrated flow path 26a ... second integrated flow path main body 26b ... (second integrated flow path) opening 28A ... 1 damper 28B ・ ・ ・ 2nd damper 29 ・ ・ ・ damper chamber 30 ・ ・ ・ end flow path 30a ・ ・ ・ wide part 30b ・ ・ ・ narrowed part 30c, 30d ・ ・ ・ (end flow path) opening 40 ... Piezoelectric actuator substrate 40a ... Piezoelectric ceramic layer 40b ... Piezoelectric ceramic layer (diaphragm)
42 ... Common electrode 44 ... Individual electrode 44a ... Individual electrode body 44b ... Drawer electrode 46 ... Connection electrode 50 ... Displacement element (pressurized part)
60 ・ ・ ・ Signal transmission unit 70 ・ ・ ・ Head mounting frame 71 ・ ・ ・ Positioning unit 72 ・ ・ ・ Head group 76 ・ ・ ・ Coating machine 78 ・ ・ ・ Dryer 80A ・ ・ ・ Paper feed roller 80B ・ ・ ・ Recovery Roller 82A ・ ・ ・ Guide roller 82B ・ ・ ・ Conveying roller 88 ・ ・ ・ Control unit P ・ ・ ・ Printing paper

Claims (10)

A liquid discharge head having a plurality of discharge holes for discharging a liquid.
When the liquid discharge head is viewed in a plan view,
All the plurality of discharge holes included in the liquid discharge head are arranged on n rows substantially parallel to each other.
The n rows are designated as the first row, the second row, ... The nth row in order along the first direction, which is the direction intersecting the n rows. The row to which the discharge hole is arranged, which is located at the xth position in the second direction in which the row is extended, is represented by y (x), and is located at the xth position in the second direction. The discharge row pair of the discharge hole located at the x + 1th position with the discharge hole is the x-th pair, and the discharge row pair y (x) of the discharge hole located at the x-th position in the second direction. When the difference y (x + 1) −y (x) of the row y (x + 1) to which the discharge hole belongs, which is located at the x + 1th position in the second direction, is expressed as the pair-to-pair row difference dy (x) of the xth pair. ,
The discharge hole pair includes a long-distance pair in which the absolute value of the pair-to-pair aberration is greater than or equal to a predetermined value and a short-distance pair in which the absolute value of the pair-to-pair aberration is less than the predetermined value.
One or more of the short-distance pairs are arranged between the long-distance pairs arranged adjacent to each other in the second direction.
Assuming that the long-distance pairs arranged adjacent to each other in the second direction are the x1st pair and the x2nd pair (x2 is larger than x1),
When the absolute value of dy (x1)> the absolute value of dy (x2), dy (x1 + 1) matches dy (x1) whether it is positive or negative.
When the absolute value of dy (x1) is less than the absolute value of dy (x2), the liquid is characterized in that dy (x2-1) matches dy (x2) whether it is positive or negative. Discharge head. The liquid discharge head according to claim 1, wherein the predetermined value is 2. The pair-to-pair aberrations of the short-distance pairs between the long-distance pairs arranged adjacent to each other in the second direction are either positive or all negative. The liquid discharge head according to claim 1 or 2. The liquid discharge head according to any one of claims 1 to 3, wherein the short-distance pair is arranged along a plurality of virtual straight lines inclined with respect to a direction orthogonal to the second direction. Each has a plurality of first common flow paths connected to a plurality of pressurizing chambers, and a plurality of pressurizing portions for pressurizing the plurality of pressurizing chambers.
The plurality of discharge holes are connected to the plurality of pressurizing chambers, respectively.
When the liquid discharge head is viewed in a plan view,
Each of the plurality of first common flow paths extends along the virtual straight line.
The liquid discharge head according to claim 4, wherein the plurality of pressurizing chambers are arranged on a plurality of rows of pressurizing chambers arranged along the virtual straight line. Each has a plurality of second common flow paths connected to the plurality of discharge holes.
The liquid discharge head according to claim 5, wherein each of the plurality of second common flow paths extends along the virtual straight line when the liquid discharge head is viewed in a plan view. The liquid discharge head according to any one of claims 1 to 6, a transport unit for transporting a recording medium to the liquid discharge head, and a control unit for controlling the liquid discharge head are provided. Recording device. It has a frame having a positioning portion, and the liquid discharge head has a shape in which the dimension in the length direction is larger than the dimension in the width direction, and has notches at both ends in the length direction. The recording device according to claim 7, wherein the cutout portion is in contact with the positioning portion. The recording apparatus according to claim 7 or 8, further comprising a coating machine for applying a coating agent to the recording medium. The recording apparatus according to any one of claims 7 to 9, further comprising a dryer for drying the liquid adhering to the recording medium.

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