JP5590809B2 - Printing device - Google Patents

Description

  The present invention relates to a printing apparatus that prints an image by ejecting droplets, and more particularly to a printing apparatus that prints an image using a plurality of liquid ejection heads.

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

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

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

  In order to print droplets at a high density regardless of whether the liquid ejection head is of a serial type or a line type, the density of the liquid ejection holes for ejecting the droplets formed in the liquid ejection head is increased. There is a need.

  Accordingly, the liquid discharge head includes a flow path member having a liquid discharge hole connecting the liquid discharge head from the manifold to each of the plurality of liquid pressurization chambers, and a plurality of displacement elements provided so as to cover the liquid pressurization chambers. There is known a technique of stacking and configuring actuator units (see, for example, Patent Document 1). In the liquid ejection head, the liquid pressurizing chamber connected to each liquid ejection hole is displaced by a displacement element provided so as to cover it, thereby ejecting ink from each liquid ejection hole, and 600 dpi in the main scanning direction. Printing is possible at the resolution.

JP 2003-305852 A

  However, since the liquid discharge head described in Patent Document 1 is a silar type, high-resolution and high-speed printing is possible. However, in order to arrange the liquid discharge holes at high density, the liquid discharge head is flown into the flow path member. Since the paths are provided close to each other with high density, there is a possibility that the discharge characteristics for each liquid discharge hole may vary due to crosstalk and flow path arrangement.

  For example, when a certain liquid discharge hole has a larger difference in droplet discharge speed or a larger volume difference than the other liquid discharge holes around it, the liquid is discharged from the liquid discharge hole. Pixels formed by droplet landing have a certain tendency, such as the landing position being shifted in a specific direction or the size of the pixel becoming larger or smaller than the pixels formed around it. As a result, a linear (streaky) printing unevenness occurs in the sub-scanning direction due to the difference in printing density.

  When the variation in the ejection characteristics of the liquid ejection holes is large, the density difference in printing in the main scanning direction becomes large, and stripe-like printing unevenness in the sub-scanning direction becomes more noticeable. In particular, when the variation in the ejection characteristics is caused by the structure of the flow path, periodic density unevenness occurs in the main scanning direction, which may appear to be streaks in the sub-scanning direction.

  Accordingly, an object of the present invention is to provide a printing apparatus in which streak-like printing unevenness hardly occurs on a recording medium.

The recording apparatus according to the present invention includes a liquid discharge hole group including n (n is an integer of 2 or more) liquid discharge holes, and n pressures that pressurize the liquid and discharge liquid droplets from the liquid discharge holes. Part and the liquid
A manifold for supplying the liquid to the body discharge hole , and the manifold branches into a plurality of sub-manifolds along one direction , and the liquid is supplied to the liquid discharge hole via the sub-manifold. The number of the liquid discharge holes is two-dimensionally arranged at equal intervals d in one direction and not overlapping in the direction orthogonal to the one direction (p is an integer of 2 or more). A liquid discharge head, a transport unit that relatively transports the print medium in a direction orthogonal to the one direction with respect to the liquid discharge head, and droplets discharged from the one liquid discharge head. On the other hand, a group of pixels arranged in parallel with the one direction at equal intervals d is formed, and the group of pixels formed by the p liquid ejection heads is formed by shifting in the one direction by d / p. Further comprising a control unit for controlling the pressing so as to form a line consisting of parallel pixels in said one direction relative to the body, the p number of the liquid discharge head, perpendicular to the one direction direction The positions of the liquid ejection holes are arranged such that the integer part i is any one of 1 to n-1 when the amount of the liquid ejection hole group provided in each direction is divided by d. In addition, the pixels formed by the liquid droplets ejected from the liquid ejection holes having the same distance from the sub-manifold are arranged so as not to be continuous in a direction orthogonal to the one direction. .

According to the printing apparatus of the present invention, the liquid ejection hole group including n (n is an integer of 2 or more) liquid ejection holes, and n pieces of liquid that pressurize the liquid and eject liquid droplets from the liquid ejection holes, respectively. A pressure unit, and the two liquid discharge holes are two-dimensionally arranged at equal intervals d in one direction and so as not to overlap in a direction orthogonal to the one direction (p is 2 or more) (Integer) liquid discharge head, transport means for transporting the print medium relative to the liquid discharge head in a direction orthogonal to the one direction, and the liquid droplets discharged from one liquid discharge head By forming a pixel group arranged in parallel to the one direction at equal intervals d with respect to the medium, and forming the pixel group formed by the p liquid ejection heads by shifting d / p in the one direction by d / p. Parallel to the one direction with respect to the print medium A control unit that controls the pressurizing unit so as to form one line of pixels, and the p liquid ejection heads are arranged in a direction orthogonal to the one direction, and each position is respectively In the main scanning direction of the print medium, the liquid ejection hole group is arranged so that the integer part i when the amount by which the liquid ejection hole group is displaced in the one direction is divided by d is any one of 1 to n-1. The pixel density difference caused by the distribution tendency of the discharge characteristics of the liquid discharge holes, which are formed by the p liquid discharge heads and are formed by the p liquid discharge heads, is shifted for each liquid discharge head. However, since the image can be formed on the print medium, the discharge characteristics in the main scanning direction are averaged, and the density unevenness of the continuous pixels in the sub scanning direction of the print medium can be made inconspicuous. The p liquid ejection heads have pixels formed by droplets ejected from the liquid ejection holes having the same distance from the sub-manifold in the one direction.
Since the pixels are arranged so as not to be continuous in the orthogonal direction, it is possible to make the density unevenness of the pixels continuous in the transport direction orthogonal to one direction more inconspicuous.

1 is a schematic configuration diagram of a printer which is a printing apparatus according to an embodiment of the present invention. FIG. 2 is a plan view showing a head body that constitutes the liquid ejection head of FIG. 1. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. 2. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. It is a longitudinal cross-sectional view along the VV line of FIG. FIG. 5 is a schematic diagram illustrating a relationship between a liquid ejection head of a printing apparatus according to an embodiment of the present invention and printed pixels. It is the schematic diagram which showed the relationship between the liquid discharge head of the printing apparatus which concerns on other one Embodiment of this invention, and the pixel printed.

  FIG. 1 is a schematic configuration diagram of a color inkjet printer 1 (hereinafter referred to as a printer 1) which is a printing apparatus according to an embodiment of the present invention. The printer 1 has eight liquid ejection heads 2. Four sets of these liquid discharge heads 2 are arranged in pairs along the transport direction of the printing paper P that is a printing medium, and are fixed to the printer 1. The liquid discharge head 2 has an elongated shape in a direction from the front to the back in FIG. The two liquid discharge heads 2 in a set are fixed while being displaced in the direction from the front side to the back side in FIG.

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

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

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

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

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

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

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

  The eight liquid ejection heads 2 are arranged close to each other along the conveyance direction by the conveyance belt 111. Each liquid discharge head 2 has a head body 13 at the lower end. A large number of liquid ejection holes 8 for ejecting liquid are provided on the lower surface of the head body 13 (see FIG. 3).

  Liquid droplets (ink) of the same color are ejected from the liquid ejection holes 8 provided in the set of liquid ejection heads 2. Since the liquid ejection holes 8 of each liquid ejection head 2 are arranged at equal intervals in one direction (a direction parallel to the printing paper P and perpendicular to the conveyance direction of the printing paper P and the longitudinal direction of the liquid ejection head 2), Printing can be performed without gaps in one direction. Note that the liquid discharge holes 8 are arranged at equal intervals in one direction. More specifically, when the liquid discharge holes 8 are projected perpendicularly to the one direction with respect to a straight line parallel to the one direction, each liquid That is, the discharge holes 8 are arranged at equal intervals. The colors of the liquid ejected from each liquid ejection head 2 in the set are magenta (M), yellow (Y), cyan (C), and black (K), respectively. Each liquid ejection head 2 is disposed with a slight gap between the lower surface of the head body 13 and the transport surface 127 of the transport belt 111.

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

At this time, the images of the respective colors are printed by the pixels on which the liquid droplets ejected from the liquid ejecting head 2 in the set land on the printing paper P. Each color image is formed by arranging pixel lines parallel to one direction in a direction perpendicular to the one direction. Each pixel line is formed by droplets ejected from one liquid ejection head 2. That is, whether one line droplets discharged from one of the liquid discharge head 2 are arranged pixels formed by lands on the print paper P, or formed by landing droplets as described above A pixel and a pixel that is blank because a droplet has not landed are formed side by side. The lines arranged at right angles to the one direction are each formed by droplets ejected from one of the two liquid ejection heads 2. In other words, each color image has two liquid ejection heads for each line. It is formed by sharing in 2.

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

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

  Next, the head main body 13 constituting the liquid discharge head of the present invention will be described. FIG. 2 is a top view showing the head main body 13 shown in FIG. FIG. 3 is an enlarged top view of a region surrounded by the alternate long and short dash line in FIG. 2 and is a part of the head main body 13. FIG. 4 is an enlarged perspective view of the same position as in FIG. 3, in which some of the flow paths are omitted so that the position of the liquid discharge holes 8 can be easily understood. 3 and 4, in order to make the drawings easy to understand, the liquid pressurizing chamber 10 (liquid pressurizing chamber group 9), the squeezing 12, and the liquid discharge holes which are to be drawn by broken lines below the piezoelectric actuator unit 21. 8 is drawn with a solid line. FIG. 5 is a longitudinal sectional view taken along line VV in FIG.

The head body 13 includes a flat plate-like flow path member 4 and a piezoelectric actuator unit 21 that is an actuator unit on the flow path member 4. The piezoelectric actuator unit 21 has a trapezoidal shape, and is disposed on the upper surface of the flow path member 4 so that a pair of parallel opposing sides of the trapezoid is parallel to the longitudinal direction of the flow path member 4. Further, two piezoelectric actuator units 21 are arranged on the flow path member 4 as a whole in a zigzag manner, two along each of two virtual straight lines parallel to the longitudinal direction of the flow path member 4. Yes. The oblique sides of the piezoelectric actuator units 21 adjacent to each other on the flow path member 4 partially overlap in the short direction of the flow path member 4. Although details will be described later, in the area printed by driving the overlapping piezoelectric actuator unit 21, droplets discharged by the two piezoelectric actuator units 21 are mixed and landed. . A manifold 5 that is a part of the liquid flow path is formed inside the flow path member 4. The manifold 5 has an elongated shape extending along the longitudinal direction of the flow path member 4, and an opening 5 b of the manifold 5 is formed on the upper surface of the flow path member 4. A total of ten openings 5 b are formed along each of two straight lines (imaginary lines) parallel to the longitudinal direction of the flow path member 4.
The opening 5b is formed at a position that avoids a region where the four piezoelectric actuator units 21 are disposed. The manifold 5 is supplied with liquid from a liquid tank (not shown) through the opening 5b.

  The manifold 5 formed in the flow path member 4 is branched into a plurality of branches (the manifold 5 at the branched portion may be referred to as a sub-manifold 5a). The manifold 5 connected to the opening 5 b extends along the oblique side of the piezoelectric actuator unit 21 and is disposed so as to intersect with the longitudinal direction of the flow path member 4. In a region sandwiched between two piezoelectric actuator units 21, one manifold 5 is shared by adjacent piezoelectric actuator units 21, and the sub-manifold 5 a branches off from both sides of the manifold 5. These sub-manifolds 5 a extend in the longitudinal direction of the head body 13 adjacent to the regions facing the piezoelectric actuator units 21 inside the flow path member 4.

  The flow path member 4 has four liquid pressurizing chamber groups 9 in which a plurality of liquid pressurizing chambers 10 are formed in a matrix (that is, two-dimensionally and regularly). The liquid pressurizing chamber 10 is a hollow region having a substantially rhombic planar shape with rounded corners. The liquid pressurizing chamber 10 is formed so as to open on the upper surface of the flow path member 4. These liquid pressurizing chambers 10 are arranged over almost the entire surface of the upper surface of the flow path member 4 facing the piezoelectric actuator unit 21. Accordingly, each liquid pressurizing chamber group 9 formed by these liquid pressurizing chambers 10 occupies a region having almost the same size and shape as the piezoelectric actuator unit 21. Further, the opening of each liquid pressurizing chamber 10 is closed by adhering the piezoelectric actuator unit 21 to the upper surface of the flow path member 4.

  In the present embodiment, as shown in FIG. 3, the manifold 5 branches into four rows of E1-E4 sub-manifolds 5a arranged in parallel with each other in the short direction of the flow path member 4, and each sub-manifold The liquid pressurizing chambers 10 connected to 5a constitute a row of liquid pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the four rows are arranged in parallel to each other in the short direction. Yes. Two rows of liquid pressurizing chambers 10 connected to the sub-manifold 5a are arranged on both sides of the sub-manifold 5a.

  As a whole, the liquid pressurizing chambers 10 connected from the manifold 5 constitute rows of the liquid pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the rows are 16 rows parallel to each other in the short direction. It is arranged. The number of liquid pressurizing chambers 10 included in each liquid pressurizing chamber row is a pressurizing unit, and gradually decreases from the long side toward the short side corresponding to the outer shape of the displacement element 50 that is an actuator. It is arranged to be. The liquid discharge holes 8 are also arranged in the same manner. As a result, it is possible to form an image with a resolution of 600 dpi in the longitudinal direction as a whole. That is, the individual flow paths 32 are connected to each sub-manifold 5a at intervals corresponding to 150 dpi on average. This is because the individual flow paths 32 connected to each sub-manifold 5a are not necessarily connected at equal intervals when the 600 dpi liquid discharge holes 8 are divided and connected to the four sub-manifolds 5a. That is, the individual flow paths 32 are formed at intervals of an average of 170 μm (25.4 mm / 150 = 169 μm if 150 dpi) in the extending direction of 5a, that is, the main scanning direction.

  Individual electrodes 35 to be described later are formed at positions facing the liquid pressurizing chambers 10 on the upper surface of the piezoelectric actuator unit 21. The individual electrode 35 is slightly smaller than the liquid pressurizing chamber 10, has a shape substantially similar to the liquid pressurizing chamber 10, and fits in a region facing the liquid pressurizing chamber 10 on the upper surface of the piezoelectric actuator unit 21. Is arranged.

  A large number of liquid discharge holes 8 are formed in the liquid discharge surface on the lower surface of the flow path member 4. These liquid discharge holes 8 are arranged at a position avoiding a region facing the sub-manifold 5 a arranged on the lower surface side of the flow path member 4. Further, these liquid discharge holes 8 are arranged in a region facing the piezoelectric actuator unit 21 on the lower surface side of the flow path member 4 and constitute four liquid discharge hole groups 7a to 7d. These liquid discharge hole groups 7 occupy an area having almost the same size and shape as the piezoelectric actuator unit 21, and the liquid discharge holes 8 are made to drop liquid by displacing the displacement element 50 of the corresponding piezoelectric actuator unit 21. Can be discharged. The liquid discharge holes 8 in each region are arranged at equal intervals along a plurality of straight lines parallel to the longitudinal direction of the flow path member 4.

  Each liquid discharge head 2 has the same structure. Here, “having the same structure” means that the basic structure of the flow path formed in the flow path member 4, that is, the manifold 5, the sub-manifold 5 a and the individual 32 having a common branching method, This means that the relative arrangement of the paths is common, and further, the dimensions of each part of the flow path coincide within the range of variations that occur during manufacturing.

  In the liquid discharge head 2 having the same basic structure of the flow path, the discharge characteristics of the liquid droplets discharged from the respective liquid discharge holes 8, that is, the liquid droplets are discharged separately from the speed, amount, or main liquid droplets. The tendency of the generation of minute droplets called “satellite” that can be generated is similar. For example, the amount of liquid droplets discharged from the liquid discharge holes 8 connected to a specific sub-manifold 5a may tend to be larger than the amount of liquid droplets discharged from other liquid discharge holes 8. . In such a case, when printing is performed with one liquid ejection head, pixels formed by droplets ejected from the liquid ejection holes 8 are continuously formed in the transport direction of the printing paper P, so that an image is displayed. Streaky density unevenness may be noticeable. Even when printing is performed by arranging a plurality of liquid ejection heads 2 at the positions translated in the transport direction, the plurality of liquid ejection heads 2 have a tendency similar to the ejection characteristics of the respective liquid ejection holes 8, and this phenomenon occurs. Occur.

Here, printing by the printing apparatus of the present invention will be described in detail with reference to FIG. In FIG. 6, two liquid discharge heads 201 and 202 and lines L ₁ to L ₂ in which pixels 210 formed on the printing paper P by liquid droplets discharged from the liquid discharge holes 8 provided in them are arranged in a straight line. the relationship between L ₄ is schematically shown. FIG. 6 illustrates the state of the printer shown in FIG. 1 as viewed from above. The printing paper P is below the two liquid ejection heads 201 and 202 that are long in one direction, and the longitudinal direction of the liquid ejection heads 201 and 202 is illustrated in FIG. Lines L _{1 to} L ₄ of pixels are formed while being transported in a transport direction that is a direction perpendicular to the line. In FIG. 6, for the sake of explanation, the interval between the pixels 210 is different in the transport direction and the direction orthogonal to the transport direction. However, in actuality, the pixels 210 are formed at the same interval in the transport direction and the direction orthogonal to the transport direction. May be. Further, although omitted in FIG. 6, pixel lines are also formed in front of and behind the lines L _{1 to} L ₄ , and an image is printed with the entire printed pixels. This image is a single color image or an image for one color of multicolor printing. In the case of multicolor printing, as described above, another color image is formed by another set of liquid ejection heads, and a multicolor image is printed as a whole.

The liquid discharge head 201 has liquid discharge holes 8 formed at equal intervals d in one direction.
The liquid discharge holes 8 of the liquid discharge head 201 are arranged so as not to overlap in a direction orthogonal to one direction. The liquid discharge holes 8 on the other hand has 16 rows in a direction orthogonal to the liquid discharge hole row 1-A to 1-P aligned in a row in one direction in the direction (m = 16). The liquid discharge holes 8 belonging to each of the liquid discharge hole rows 1-A to 1-P are arranged at equal intervals of 16 × d. The liquid discharge head 201 is formed with a flow path similar to that shown in FIG. In FIG. 6, the liquid discharge holes 8 connected to one sub-manifold 5a are surrounded by a broken line so that the distribution of the liquid discharge holes 8 is easily understood, and the liquid discharge holes 8 are divided into four groups. From the left in FIG. 6, the liquid discharge holes 8 are arranged at the left end of the liquid discharge hole array 1-A, followed by the liquid discharge hole 8 at the left end of the liquid discharge hole array 1-I, and similarly the liquid discharge hole array. 1-E, 1-M, 1-B, 1-J, 1-F, 1-N, 1-C, 1-K, 1-G, 1-O, 1-D, 1-L, 1- The leftmost liquid discharge holes 8 of H and 1-P are arranged, and next, the second one from the left among the liquid discharge holes 8 belonging to the liquid discharge hole array 1-A is arranged. Has been placed.

  The liquid discharge head 202 has the same structure as the liquid discharge head 201, and is a position shifted by 6.5 × d in one direction from the position where the liquid discharge head 201 is moved in the direction orthogonal to one direction, that is, The liquid discharge hole group included in the liquid discharge devices 201 and 202 is fixed at a position shifted by 6.5 × d in one direction.

  The amount of shift is characterized by the numerical value when divided by d. In the above case, the numerical value divided by d is 6.5, and a value less than 1 (hereinafter referred to as a fractional part) is an amount to be shifted in order to achieve high resolution in one landing direction. In the case described above, the fractional portion is ½ because two liquid ejection heads are used. If p liquid exposure heads are used, the fractional portion may be 1 / p at a time. By doing so, each liquid discharge head forms a pixel group arranged at equal intervals d in one direction, and p pixel groups are formed by being shifted by d / p. A pixel is formed, and this is one line to be printed. In other words, if printing with a resolution of one liquid ejection head 600 dpi is possible, printing with a resolution of p × 600 dpi is possible with p liquid ejection heads.

  When the integer part i obtained by dividing the shift amount by d is 1 to n-1 when the number n of the liquid discharge holes of one liquid discharge head is 1 to n-1, the liquid discharge holes having the same structure such as the flow path are used. Since the discharged droplets do not land adjacently, the discharge characteristics in the main scanning direction are averaged, so that the density unevenness of pixels continuous in the transport direction orthogonal to one direction can be made inconspicuous. . This is because when the solid is printed without taking the above-mentioned measures, the structure of the flow path etc. is exactly the same, so the discharge characteristics are similar and the droplets discharged from the liquid discharge holes are continuous in one direction. And land. For example, when the discharge amount of the liquid discharge hole is small compared to other liquid discharge holes, pixels that have a small diameter and appear thin to the human eye are continuously formed in one direction. Are continuously formed in a direction perpendicular to one direction, and thin streaky density unevenness is conspicuous in the human eye.

  It is preferable that the integer part i obtained by dividing the shift amount by d is an integer other than a multiple of 16 (= m) and a multiple of 16 (= m) -1 among 1 to n-1. By not making i a multiple of m and a multiple of m −1, the pixels 201 formed by droplets ejected from the liquid ejection holes 8 having similar flow path structures are not continuous in one direction, and in one direction. It is possible to make the density unevenness of pixels continuous in the orthogonal conveyance direction more inconspicuous.

An image is printed on the printing paper P by the pixels 210 formed by droplets ejected from the liquid ejection heads 201 and 202. Each of the lines L _{1 to} L ₄ is formed by a pixel 210 formed by droplets ejected from the two liquid ejection heads 201 and 202 under the control of the control unit 100. A pixel group is formed in which pixels 210 formed by droplets ejected from one liquid ejection head 201 are arranged at equal intervals d. The pixels 210 formed by the droplets discharged from the other liquid discharge head 202 also form a pixel group arranged at equal intervals d. Then, when these pixel groups land with a shift of 0.5d, the two liquid discharge heads 201 and 202 as a whole form one line in which the pixels 210 are formed at equal intervals d / 2.

Although the range of _{L D} from _{L A} is a liquid discharge head 201 itself is printable, because of the arrangement of the liquid ejection head 201 and liquid ejection head 202 is shifted 6.5d minute from _{L A} to _{L B} printable range printing method of this embodiment is in the range from d / 2 left _{L E} from _{L B} than to d / 2 of _{L F L D.} However, it is possible to widen the printable range by arranging other liquid discharge heads so that the print range is continuous beside each of the liquid discharge heads 201 and 202.

The following may be considered as the structure of the flow path that affects the discharge characteristics of the liquid discharge hole 8.
When the manifold 5 has a structure that branches into a plurality of sub-manifolds 5a, the characteristics of the liquid discharge holes 8 may be affected by the difference in distance from the end of the sub-manifold 5a.
In other words, the discharge characteristics of the liquid discharge holes 8 that are close to the end of each sub-manifold 5a are similar, and the discharge characteristics of the liquid discharge holes 8 that are different from the discharge characteristics may differ greatly.
In such a case, it is preferable to reduce the rate at which the pixels 210 formed by the droplets ejected from the liquid ejection holes 8 that are close to the end of each sub-manifold 5a are continuous in the transport direction, and are not continuous. More preferably, it is in a state. For arrangement of the liquid discharge hole 8 of the above, the shift amount of the integer part i is 1 to 1 4, further 2-1 3, further 3-1 2, in particular 4-1 1 are preferred. The shift amount may be a value obtained by adding a value that is an integral multiple of 16d (m × d) to the above-described amount, but in this case, the width of the printable range is narrowed.

Further, as a flow path structure that affects the discharge characteristics of the liquid discharge hole 8, the distance between the sub-manifold 5a and the liquid discharge hole 8 can be considered. The liquid discharge holes 8 belonging to the liquid discharge hole arrays 1-A to 1-D are branched and connected from the sub-manifold 5a located at the center thereof. The dimensions of the squeeze 12 and the liquid pressurizing chamber 10 are designed to be the same so that the acoustic characteristics are close so that the ejection characteristics of the liquid ejection holes 8 are the same. However, since the sub-manifold 5a supplies a large number of liquid ejection holes 8 with a large cross-sectional area, the sub-manifold 5a vibrates due to the influence of vibration when the liquid in the sub-manifold 5a ejects droplets. Is considered to affect the liquid discharge characteristics of each liquid discharge hole 8 through the flow path member 4, the influence of the discharge characteristics is related to the distance from the sub-manifold 5a. Further, in order to increase the cross-sectional area of the sub-manifold 5a as in the above-described structure, the liquid pressurizing chamber 1 located near the sub-manifold 5a in the liquid pressurizing chamber 10 when viewed from the main surface of the flow path member. When 0 overlaps with the sub-manifold 5a, the liquid discharge hole 8 connected to the liquid pressurizing chamber 10 that overlaps the sub-manifold 5a and the liquid connected to the liquid pressurizing chamber 10 that does not overlap with the sub-manifold 5a. It is conceivable that there is a difference in discharge characteristics from the discharge hole 8. In that case, it is preferable to reduce the ratio of pixels 210 formed by droplets ejected from the liquid ejection holes 8 having the same distance between the sub-manifold 5a and the liquid ejection holes 8 in one step direction, and not continuous. More preferably, it is in a state. In the case of the arrangement of the liquid discharge holes 8 described above, the liquid discharge holes 8 belonging to the liquid discharge hole arrays 1-A, 1-E, 1-I, 1-L, the liquid discharge hole arrays 1-B, 1-F, The liquid ejection holes 8 belonging to 1-J and 1-N, the liquid ejection hole arrays 1-C, 1-G, 1-K, and the liquid ejection holes 8 belonging to 1-O, the liquid ejection hole array 1-D, It is preferable that the ratio of pixels 210 formed by droplets discharged from the liquid discharge holes 8 belonging to 1-H, 1-L, and 1-P to be continuous in the transport direction is reduced, and is not continuous. More preferably. For this purpose, 1 shifting amount of the integer part fraction i, 2,5,6,9, 1 0, it is preferable that the 1 3 Contact and 1 4.

Furthermore, the liquid discharge holes having a short distance between the sub-manifold 5a and the liquid discharge holes 8, specifically, the liquid discharge hole arrays 1-A, 1-D, 1-E, 1-H, 1-I, 1 -L, 1-M, 1-P belonging to the liquid ejection holes 8, liquid ejection hole rows 1-B, 1-C, 1-F, 1-G, 1-J, 1-K, 1-N, It is preferable to reduce the rate at which the pixels 210 formed by droplets discharged from the liquid discharge holes 8 belonging to 1-O are continuous in the transport direction, and it is more preferable that the pixels 210 are not continuous. To this end, the integer part component i of the shift amount, Ri yo 1 and 1 4 2d
Contact and 1 3d are preferred, less preferred by 1 1, 5 and 1 0,6 forward in our and 9,7 Contact and 8 and 1 2, 4 Contact and 3 us.

Further, the following may be considered as the flow path structure that affects the discharge characteristics of the liquid discharge hole 8. When the manifold 5 has a structure that branches into a plurality of sub-manifolds 5a, the characteristics of the liquid discharge holes 8 that branch off from the sub-manifolds 5a may be affected by the difference in dimensions of the sub-manifolds 5a. For example, if the sub-manifolds 5a have different cross-sectional shapes or different lengths, the discharge characteristics may be affected by the difference in acoustic characteristics of the sub-manifolds 5a. Further, when the number of liquid discharge holes 8 branched and connected from each sub-manifold 5a is different, the discharge characteristics may be affected by the influence of crosstalk generated through the liquid in each sub-manifold 5a. In such a case, since it is considered that there is a difference in discharge characteristics for each sub-manifold 5a, the shift amount of the liquid discharge head is determined by the liquid droplets discharged from the liquid discharge holes 8 connected to the sub-manifold 5a having the same structure. It is preferable to reduce the rate at which the formed pixels 210 are continuous in the transport direction, and it is more preferable that they are not continuous. For arrangement of the liquid discharge hole 8 of the above, the shift amount of the integer part fraction i pixels formed by droplets discharged from the liquid discharge holes 8 which led to the sub-manifold Then the same structure 4-1 1 210 Is not formed continuously in the conveying direction.

Taken together, the integer part minute i of the shift amount is preferably set to 7 you and 8.

  When printing with a combination of three or more liquid ejection heads, at least one of the liquid ejection heads is arranged so that the relative positions in one direction are shifted, so that the density unevenness of the pixels continues in the conveyance direction of the printing paper. Generation | occurrence | production is suppressed and the stripe-like density | concentration nonuniformity parallel to a conveyance inspection direction can be made not conspicuous. More preferably, none of the liquid discharge heads is arranged at a position translated in a direction perpendicular to one direction, that is, all the liquid discharge heads are relatively shifted in one direction. is there.

FIG. 7 shows another embodiment of the printing apparatus of the present invention. In FIG. 7, lines L _{11 to} L that are formed on the printing paper P by the liquid droplets ejected from the two liquid ejection heads 301 and 302 and the liquid ejection holes 8 provided in them, and in which the pixels 310 are arranged in a straight line. ₁₄ schematically shows the relationship. FIG. 7 is a schematic view of the printer shown in FIG. 1 as viewed from above, in which the printing paper P is below one of the two liquid ejection heads 301 and 302 that are long in one direction, and the one direction of the liquid ejection heads 301 and 302 is. Lines L _{11 to} L ₁₄ of pixels are formed while being transported in a transport direction that is a direction perpendicular to the line.

The liquid discharge head 301 has liquid discharge holes 8 formed at equal intervals d in one direction.
The liquid discharge hole 8 of the liquid discharge head 3 01 is disposed so as whereas not to overlap in a direction perpendicular to the direction. The liquid discharge holes 8 are arranged in 16 lines of 3-A to 3-P parallel to the one direction. The liquid discharge head 301 is formed with the same manifold 5 and sub-manifold 5a as in FIG. 4, but the way of drawing out to the individual flow path 32 from the sub-manifold 5a to the liquid discharge hole 8 is different. Is the arrangement shown in FIG. In FIG. 7, the liquid discharge holes 8 connected to one sub-manifold 5a are surrounded by a broken line so that the distribution of the liquid discharge holes 8 can be easily understood, and the liquid discharge holes 8 are divided into four groups. The liquid discharge holes 8 are 3-A, 3-I, 3-E, 3-M, 3-B, 3-J, 3-F, 3-N, 3-C, 3-K from the left in FIG. , 3-G, 3-O, 3-D, 3-L, 3-H, and 3-P liquid ejection holes 8 are arranged, and the next is 3-D, 3-L, 3-H, 3-P, 3-C, 3-K,
Liquid ejection holes 8 belonging to the 3-G, 3-O, 3-B, 3-J, 3-F, 3-N, 3-A, 3-I, 3-E, 3-M liquid ejection hole arrays Next, the liquid ejection holes 8 belonging to the 3- A liquid ejection hole array are arranged, and thereafter are repeatedly arranged in the same order.

The liquid discharge head 302 has the same structure as the liquid discharge head 301, and is shifted by 9.5d in one direction from the position where the liquid discharge head 301 is moved in the direction orthogonal to one direction, that is, the respective liquids. A group of liquid discharge holes provided in the discharge heads 301 and 302 is fixed at a position shifted by 9.5d in one direction. In the liquid discharge head 301,30 2 basic structures of the flow path is common, but sometimes the ejection characteristics of the droplet A similar trend is observed to be discharged from the liquid discharge holes 8, is such a tendency even, since the liquid discharge head 301 and 302 are arranged offset relative one direction, the density unevenness of the pixels 310 is generated continuously is suppressed in the conveyance direction of the print medium, feeding transportable it can be made inconspicuous parallel streak-shaped density unevenness in a square direction.

  The flow path member 4 included in the head body 13 has a stacked structure in which a plurality of plates are stacked. These plates are a cavity plate 22, a base plate 23, an aperture (squeezing) plate 24, supply plates 25 and 26, manifold plates 27, 28 and 29, a cover plate 30 and a nozzle plate 31 in order from the upper surface of the flow path member 4. is there. A number of holes are formed in these plates. Each plate is aligned and laminated so that these holes communicate with each other to form the individual flow path 32 and the sub-manifold 5a. As shown in FIG. 5, the head main body 13 has a liquid pressurizing chamber 10 on the upper surface of the flow path member 4, the sub-manifold 5a on the inner lower surface side, and the liquid discharge holes 8 on the lower surface. Each portion constituting the path 32 is disposed close to each other at different positions, and the sub manifold 5 a and the liquid discharge hole 8 are connected via the liquid pressurizing chamber 10.

  The holes formed in each plate will be described. These holes include the following. First, the liquid pressurizing chamber 10 formed in the cavity plate 22. Second, there is a communication hole that forms a flow path that connects from one end of the liquid pressurizing chamber 10 to the sub-manifold 5a. This communication hole is formed in each plate from the base plate 23 (specifically, the inlet of the liquid pressurizing chamber 10) to the supply plate 25 (specifically, the outlet of the sub manifold 5a). The communication hole includes the aperture 12 formed in the aperture plate 24 and the individual supply flow path 6 formed in the supply plates 25 and 26.

  Third, there is a communication hole that constitutes a flow channel that communicates from the other end of the liquid pressurizing chamber 10 to the liquid discharge hole 8, and this communication hole is referred to as a descender (partial flow channel) in the following description. . The descender is formed on each plate from the base plate 23 (specifically, the outlet of the liquid pressurizing chamber 10) to the nozzle plate 31 (specifically, the liquid discharge hole 8). Fourthly, there is a communication hole constituting the sub-manifold 5a. The communication holes are formed in the manifold plates 27-30.

  Such communication holes are connected to each other to form an individual flow path 32 from the liquid inflow port (the outlet of the submanifold 5a) from the submanifold 5a to the liquid discharge hole 8. The liquid supplied to the sub manifold 5a is discharged from the liquid discharge hole 8 through the following path. First, from the sub-manifold 5a, it passes through the individual supply flow path 6 and reaches one end of the aperture 12. Next, it proceeds horizontally along the extending direction of the aperture 12 and reaches the other end of the aperture 12. From there, it reaches one end of the liquid pressurizing chamber 10 upward. Further, the liquid pressurizing chamber 10 proceeds horizontally along the extending direction of the liquid pressurizing chamber 10 and reaches the other end of the liquid pressurizing chamber 10. While moving little by little in the horizontal direction from there, it proceeds mainly downward and proceeds to the liquid discharge hole 8 opened on the lower surface.

  As shown in FIG. 5, the piezoelectric actuator unit 21 has a laminated structure including two piezoelectric ceramic layers 21a and 21b. Each of these piezoelectric ceramic layers 21a and 21b has a thickness of about 20 μm. The total thickness of the piezoelectric actuator unit 21 is about 40 μm. Each of the piezoelectric ceramic layers 21a and 21b extends so as to straddle the plurality of liquid pressurizing chambers 10 (see FIG. 3). The piezoelectric ceramic layers 21a and 21b are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The piezoelectric actuator unit 21 includes a common electrode 34 made of a metal material such as Ag—Pd and an individual electrode 35 made of a metal material such as Au. As described above, the individual electrode 35 is disposed at a position facing the liquid pressurizing chamber 10 on the upper surface of the piezoelectric actuator unit 21. One end of the individual electrode 35 is drawn out of a region facing the liquid pressurizing chamber 10 to form a connection electrode 36. The connection electrode 36 is made of, for example, gold containing glass frit, and has a convex shape with a thickness of about 15 μm. The connection electrode 36 is electrically joined to an electrode provided in an FPC (Flexible Printed Circuit) (not shown). Although details will be described later, an ejection signal is supplied to the individual electrode 35 from the control unit 100 through the FPC.

  The common electrode 34 is formed over almost the entire surface in the area between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. That is, the common electrode 34 extends so as to cover all the liquid pressurizing chambers 10 in the region facing the piezoelectric actuator unit 21. The thickness of the common electrode 34 is about 2 μm. The common electrode 34 is grounded in a region not shown, and is held at the ground potential. In the present embodiment, a surface electrode (not shown) different from the individual electrode 35 is formed on the piezoelectric ceramic layer 21b at a position avoiding the electrode group composed of the individual electrodes 35. The surface electrode is electrically connected to the common electrode 34 through a through-hole formed in the piezoelectric ceramic layer 21b, and is connected to another electrode on the FPC in the same manner as many individual electrodes 35. ing.

  As shown in FIG. 5, the common electrode 34 and the individual electrode 35 are disposed so as to sandwich only the uppermost piezoelectric ceramic layer 21b. A region sandwiched between the individual electrode 35 and the common electrode 34 in the piezoelectric ceramic layer 21b is referred to as an active portion, and the piezoelectric ceramic in that portion is polarized. In the piezoelectric actuator unit 21 of the present embodiment, only the uppermost piezoelectric ceramic layer 21b includes an active portion, and the piezoelectric ceramic 21a does not include an active portion and functions as a diaphragm. The piezoelectric actuator unit 21 has a so-called unimorph type configuration.

  As will be described later, when a predetermined ejection signal is selectively supplied to the individual electrode 35, pressure is applied to the liquid in the liquid pressurizing chamber 10 corresponding to the individual electrode 35. As a result, droplets are discharged from the corresponding liquid discharge ports 8 through the individual flow paths 32. That is, the portion of the piezoelectric actuator unit 21 that faces each liquid pressurizing chamber 10 corresponds to an individual displacement element 50 (actuator) corresponding to each liquid pressurizing chamber 10 and the liquid discharge port 8. That is, in the laminate composed of two piezoelectric ceramic layers, the displacement element 50 having a unit structure as shown in FIG. 5 is provided immediately above the liquid pressurizing chamber 10 for each liquid pressurizing chamber 10. Are formed by a diaphragm 21a, a common electrode 34, a piezoelectric ceramic layer 21b, and individual electrodes 35, and the piezoelectric actuator unit 21 includes a plurality of displacement elements 50. In the present embodiment, the amount of liquid ejected from the liquid ejection port 8 by one ejection operation is about 5 to 7 pL (picoliter).

  A large number of individual electrodes 35 are individually electrically connected to the actuator control means via contacts and wirings on the FPC so that potentials can be individually controlled.

In the piezoelectric actuator unit 21 in the present embodiment, when an electric field is applied in the polarization direction to the piezoelectric ceramic layer 21b by setting the individual electrode 35 to a potential different from that of the common electrode 34, the portion where the electric field is applied becomes the piezoelectric effect. Acts as an active part that is distorted by At this time, the piezoelectric ceramic layer 21b expands or contracts in the thickness direction, that is, the stacking direction, and tends to contract or extend in the direction orthogonal to the stacking direction, that is, the plane direction, due to the piezoelectric lateral effect. On the other hand, since the remaining piezoelectric ceramic layer 21a is an inactive layer that does not have a region sandwiched between the individual electrode 35 and the common electrode 34, it does not spontaneously deform. In other words, the piezoelectric actuator unit 21 uses the upper piezoelectric ceramic layer 21b (that is, the side away from the liquid pressurizing chamber 10) as a layer including the active portion and the lower side (that is, close to the liquid pressurizing chamber 10). In this configuration, the individual electrode 35 is connected to the common electrode 34 by the actuator control means so that the electric field and the polarization are in the same direction. When the potential is positive or negative, the portion (active portion) sandwiched between the electrodes of the piezoelectric ceramic layer 21b contracts in the plane direction. On the other hand, the piezoelectric ceramic layer 21a, which is an inactive layer, is not affected by an electric field, so that it does not spontaneously shrink and tries 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 21b and the piezoelectric ceramic layer 21a, and the piezoelectric ceramic layer 21b is deformed so as to protrude toward the liquid pressurizing chamber 10 (unimorph deformation). .

  In the actual driving procedure in this embodiment, the individual electrode 35 is set to a potential higher than the common electrode 34 (hereinafter referred to as a high potential) in advance, and the individual electrode 35 is temporarily set to the same potential as the common electrode 34 every time there is a discharge request. (Hereinafter referred to as a low potential), and then set to a high potential again at a predetermined timing. As a result, the piezoelectric ceramic layers 21a and 21b return to the original shape at the timing when the individual electrode 35 becomes low potential, and the volume of the liquid pressurizing chamber 10 is compared with the initial state (the state where the potentials of both electrodes are different). To increase. At this time, a negative pressure is applied to the liquid pressurizing chamber 10 and the liquid is sucked into the liquid pressurizing chamber 10 from the manifold 5 side. Thereafter, at the timing when the individual electrode 35 is set to a high potential again, the piezoelectric ceramic layers 21a and 21b are deformed so as to protrude toward the liquid pressurizing chamber 10, and the volume of the liquid pressurizing chamber 10 is reduced so that the inside of the liquid pressurizing chamber 10 Becomes a positive pressure, the pressure on the liquid rises, and droplets are ejected. That is, an ejection signal including a pulse based on a high potential is supplied to the individual electrode 35 in order to eject a droplet. The ideal pulse width is AL (Acoustic Length), which is the length of time during which the pressure wave propagates from the manifold 5 to the liquid discharge hole 8 in the liquid pressurizing chamber 10. According to this, when the inside of the liquid pressurizing chamber 10 is reversed from the negative pressure state to the positive pressure state, both pressures are combined, and the liquid droplet can be ejected with a stronger pressure.

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

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

  The liquid discharge head 2 as described above is manufactured as follows, for example.

  A tape composed of a piezoelectric ceramic powder and an organic composition is formed by a general tape forming method such as a roll coater method or a slit coater method, and a plurality of green sheets that become piezoelectric ceramic layers 21a and 21b after firing are produced. . An electrode paste to be the common electrode 34 is formed on a part of the green sheet by a printing method or the like. Further, if necessary, a via hole is formed in a part of the green sheet, and a via conductor is inserted into the via hole.

  Next, each green sheet is laminated to produce a laminate, and pressure adhesion is performed. The laminated body after pressure contact is fired in a high-concentration oxygen atmosphere, and then the individual electrodes 25 are printed on the fired body surface using an organic gold paste, fired, and then the connection electrode 36 is printed using an Ag paste. And the piezoelectric actuator unit 21 is produced by baking.

  Next, the flow path member 4 is produced by laminating plates 22 to 31 obtained by a rolling method or the like. Holes to be the manifold 5, the individual supply flow path 6, the liquid pressurizing chamber 10, the descender, and the like are processed in the plates 22 to 31 into a predetermined shape by etching.

  These plates 22 to 31 are preferably formed of at least one metal selected from the group consisting of Fe—Cr, Fe—Ni, and WC—TiC, particularly when ink is used as a liquid. Since it is desired to be made of a material having excellent corrosion resistance against ink, Fe-Cr is more preferable.

  The piezoelectric actuator 21 and the flow path member 4 can be laminated and bonded via an adhesive layer, for example. A well-known adhesive layer can be used as the adhesive layer. However, in order not to affect the piezoelectric actuator 21 and the flow path member 4, an epoxy resin, a phenol resin, or a polyphenylene ether having a thermosetting temperature of 100 to 150 ° C. It is preferable to use at least one thermosetting resin adhesive selected from the group of resins. By heating to the thermosetting temperature using such an adhesive layer, the piezoelectric actuator 21 and the flow path member 4 can be heat-bonded.

  Thereafter, in order to electrically connect the piezoelectric actuator 21 and an external circuit as necessary, an electrode such as FPC is joined to the connection electrode 36 to obtain the liquid discharge head 2.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 4 ... Flow path member 5 ... Manifold 5a ... Sub manifold 5b ... Opening 6 ... Individual supply flow path 7a, b, c, d ... Liquid ejection hole group 8 ... Liquid ejection hole 9 ... Liquid pressurization chamber group 10 ... Liquid pressurization chamber 11a, b, c, d ... Liquid pressurization chamber row 12 ... Squeezing 15a, b, c, d ... Liquid ejection hole array 21 ... Piezoelectric actuator unit 21a ... Piezoelectric ceramic layer (vibrating plate)
21b ... Piezoelectric ceramic layer 22-31 ... Plate 32 ... Individual flow path 34 ... Common electrode 35 ... Individual electrode 36 ... Connection electrode 50 ... Displacement element

Claims (1)

a liquid ejection hole group consisting of n (n is an integer of 2 or more) liquid ejection holes;
N pressure units that pressurize the liquid and discharge liquid droplets from the liquid discharge holes,
A manifold for supplying the liquid to the liquid discharge hole,
The manifold is branched into a plurality of sub-manifolds along one direction, and the liquid is supplied to the liquid discharge holes via the sub-manifolds.
P liquid discharge heads (p is an integer of 2 or more) are arranged so that the liquid discharge holes are two-dimensionally arranged at equal intervals d in the one direction and not in a direction perpendicular to the one direction. When,
Conveying means for relatively conveying the print medium in a direction orthogonal to the one direction with respect to the liquid ejection head;
The pixel group formed by p liquid ejection heads is formed by droplets ejected from one liquid ejection head to form a pixel group arranged in parallel to the one direction at equal intervals d with respect to the print medium. And a controller that controls the pressurizing unit so as to form one line of pixels parallel to the one direction with respect to the print medium by forming the first and second components by shifting d / p in the one direction. ,
The p liquid ejection heads are arranged in a direction orthogonal to the one direction, and the positions of the liquid ejection heads are integer parts i obtained by dividing the amount of displacement of the liquid ejection hole group provided in the one direction by d. Are arranged to be any one of 1 to n-1, and pixels formed by droplets ejected from the liquid ejection holes having the same distance from the sub-manifold are in a direction perpendicular to the one direction. A printing apparatus characterized by being arranged not to be continuous.

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