JP4639887B2 - Droplet discharge head and droplet discharge apparatus - Google Patents

Description

  The present invention relates to a droplet discharge head and a droplet discharge device.

  In a droplet discharge device typified by an ink jet recording device, it is required to record a high-quality image at high speed. For this reason, an inkjet recording head has been proposed in which a plurality of head units in which nozzles are two-dimensionally arranged in a plane (matrix arrangement) are arranged in two rows in a staggered manner (see Patent Documents 1 to 3, etc.).

In the ink jet recording head in which a plurality of head units are arranged in a staggered manner as described above, for example, when a so-called θ shift (or skewing of paper, etc.) occurs, white streaks, black streaks, etc. occur in the obtained recorded image, and the image quality is low. May decrease. This is because when the nozzles at the joint portion are separated in the width direction of the ink jet recording head between the head units adjacent to each other in the longitudinal direction of the ink jet recording head, the ink droplet dots formed by these nozzles due to the θ shift This is because there is a large separation in the width direction of the paper.
JP 2003-127363 A

  In consideration of the above facts, the present invention is a droplet discharge head capable of suppressing deterioration in image quality due to white stripes / black stripes and the like even when θ deviation occurs in the head unit, and a droplet discharge equipped with this droplet discharge head It is an object to obtain a device.

According to the first aspect of the present invention, there is provided a long droplet discharge head in which a plurality of nozzles for discharging droplets are arranged in a two-dimensional plane in a staggered arrangement in a plurality of rows . The positions in the width direction orthogonal to the longitudinal direction of the droplet discharge heads are arranged so as to be periodically different in the longitudinal direction of the head unit, and the joints of the head units adjacent in the longitudinal direction of the droplet discharge heads In the portion, the nozzles at both ends in the longitudinal direction of the head unit are on the adjacent head unit side in the width direction .

In this way, in the joint between adjacent head units, when the nozzles at both ends in the longitudinal direction of the head unit are on the side of the adjacent head unit in the width direction, this is compared with a configuration in which the nozzles are spaced apart in the width direction. Even when a θ deviation, skew of the discharged member, etc. (hereinafter collectively referred to as “θ deviation”) occurs, a change in the dot position of the droplet in the width direction of the discharged member (deviation) Less. For this reason, even if the θ deviation occurs, it is possible to prevent the image quality from being deteriorated.

  According to a second aspect of the present invention, there is provided the liquid droplet ejection head according to the first aspect, wherein the nozzles overlap each other when viewed in the width direction between adjacent head units in the longitudinal direction of the liquid droplet ejection head. The head unit is arranged so that a wrap region is formed.

  When the nozzles are overlapped in the width direction between adjacent head units, it is possible to reduce the influence on the image quality even if a failure occurs in one of the two head units corresponding to the overlap region.

  According to a third aspect of the present invention, in the second aspect of the present invention, the nozzle at the end of the overlap region is in the width direction with the nozzle adjacent to the overlap region in the head unit including the overlap region. It is arrange | positioned so that it may adjoin.

  In this way, by arranging the nozzles at the end of the overlap region in the width direction close to the nozzles adjacent to the overlap region in the head unit including the overlap region, at the end of the overlap region , Θ and white streaks and black streaks due to deviation can be reduced.

  According to a fourth aspect of the invention, in the invention of the second or third aspect, the nozzle at the end of the overlap region is adjacent to the overlap region in the head unit adjacent to the overlap region. It arrange | positions so that it may adjoin with a nozzle in the width direction.

  In this way, by arranging the nozzles at the end of the overlap area close to the nozzle adjacent to the overlap area in the head unit adjacent to the overlap area in the width direction, at the end of the overlap area , Θ and white streaks and black streaks due to deviation can be reduced.

  According to the arrangement of the nozzles in the head unit, the head unit can be arranged by overlapping the nozzles so that either one of the conditions of claim 3 or claim 4 is satisfied. The head unit can also be arranged with overlapping nozzles so that both the conditions of Item 2 and Claim 3 are satisfied. In the latter case, the head unit may be arranged by overlapping the nozzles so that both the distance between adjacent nozzles in claim 3 and the distance between adjacent nozzles in claim 4 are minimized. preferable.

In the invention described in claim 5, in the invention described in claim 2, the position in the width direction of the nozzle adjacent the leading SL overlapping area, adjacent the overlap region of the head unit including the overlap region The head unit is arranged so as to be between the nozzle and the adjacent nozzle of the head unit adjacent to the overlap region.

  As described above, the position in the width direction of the nozzle adjacent to the overlap region is determined so that the adjacent nozzle in the overlap region of the head unit including the overlap region and the adjacent nozzle of the head unit adjacent to the overlap region are By setting the interval between, the white stripes and black stripes can be suppressed to a small level and the image quality can be prevented from deteriorating even when the θ deviation occurs.

  In the invention according to claim 6, in the invention according to any one of claims 2 to 5, in the overlap region, a distance between nozzles overlapping at an end portion side of the overlap region is set. The head unit is disposed so as to be smaller than the distance between the overlapping nozzles on the center side of the overlap region.

  As a result, the two nozzles are less likely to be displaced in the longitudinal direction due to the θ shift at the end of the overlap region, so that white stripes and black stripes can be reduced.

  In the present invention, the distance between the nozzles arranged so as to be close in the width direction at the joint of the head units can be, for example, equal to or less than the width of the head unit.

  According to an eighth aspect of the invention, in the invention according to any one of the first to seventh aspects, when the divided portion is configured by dividing the head unit in the width direction, It is characterized in that the dots of the liquid droplets ejected from the nozzles are arranged so as to be evenly arranged on the ejected member.

  That is, since one droplet discharge head is divided in the width direction, that is, in the moving direction of the recording member, one droplet discharge head corresponds to discharge of different liquids, for example, image recording of a plurality of colors. It becomes possible.

  According to a ninth aspect of the present invention, in the invention according to any one of the first to eighth aspects, droplets ejected from a nozzle far from a nozzle far from a longitudinal center line and a nozzle close to the head unit in the head unit. The nozzles are arranged so that the dots are mixedly arranged on the discharged member.

  As a result, even if the θ deviation occurs in the ink jet recording head, the dot position deviation occurs in the head unit in the width direction of the recording member in a dispersed manner, making it difficult to be recognized as an image defect, and preventing deterioration in image quality. .

  According to a tenth aspect of the present invention, the liquid droplet ejection head according to any one of the first to ninth aspects is provided.

  Since the droplet discharge head according to any one of claims 1 to 7 is provided, it is possible to prevent the image quality from being deteriorated even if the θ shift occurs in the droplet discharge head.

  In the liquid droplet ejection head of the present invention, a common flow path for supplying liquid in common to a plurality of ejectors that eject liquid droplets from the nozzles is disposed between two adjacent ejector rows, and the common It is good also as a structure by which the at least one of the top | upper surface or bottom face of a flow path is made into the damper which has flexibility.

  In this configuration, since the common flow path is arranged between two adjacent ejector rows so as to extend over these ejector rows, the width of the common flow path can be set large. For this reason, a sufficient acoustic capacity can be ensured for the damper constituting at least one of the top surface or the bottom surface of the common flow path.

  In addition, since the common flow path can be arranged so as to overlap the ejectors constituting two adjacent ejector rows, even if the arrangement density of the ejectors, that is, the nozzle density is increased, the common flow path is as described above. Can be set large to ensure a sufficient acoustic capacity. That is, it is possible to achieve both a high nozzle density and a sufficient acoustic capacity in the common flow path.

  Furthermore, in this droplet discharge head, the nozzles of the two ejector rows to which the liquid is supplied from the common flow path may be arranged so as to be outside as viewed from the center line of the common flow path.

  In this configuration, since the interval between the nozzles of the two ejector rows is increased, a wide common channel width can be secured between these nozzles.

  Further, in this droplet discharge head, a liquid supply path for supplying a liquid from the common flow path to the ejector may be arranged between the two adjacent ejector rows.

  In this configuration, since the common flow path is disposed so as to overlap with the liquid supply path, it is possible to secure a wider width of the common flow path without reducing the arrangement density of the ejectors.

  Further, in the liquid droplet ejection head, the ejector includes a pressure chamber for storing the liquid, an actuator for ejecting liquid droplets by applying energy to the liquid by applying a voltage, and an electrode pad for applying a voltage to the actuator. , And the electrode pad may be arranged between the two adjacent ejector rows.

  In this droplet discharge head, an actuator to which voltage is applied causes energy to act on the liquid stored in the pressure chamber to discharge droplets from the nozzle.

  Since the common flow path is disposed so as to overlap with the electrode pads, a wider width of the common flow path can be secured without reducing the arrangement density of the ejectors.

  Further, in this droplet discharge head, the common flow path is shaped to bulge outward from the nozzle when viewed from the center line of the common flow path at a position avoiding the nozzle.

  That is, the common flow path can ensure a wider width at a position where the nozzle is avoided. For this reason, the acoustic capacity of the common channel can be further increased.

  Furthermore, in this droplet discharge head, the damper may be made of a resin film.

  Thereby, it becomes possible to ensure a larger acoustic capacity in the common flow path.

  The liquid droplet ejection head further includes a nozzle plate on which the nozzles are formed, and the damper also serves as the nozzle plate.

  As a result, the number of plates constituting the ejector is reduced as compared with a configuration in which the nozzle plate and the damper are separate members, so that the manufacturing cost of the droplet discharge head can be reduced.

  Furthermore, in this droplet discharge head, with respect to an ejector group composed of a plurality of ejectors, an upstream side flow path is arranged outside both ends of the droplet discharge head in the longitudinal direction of the ejector group, and the common flow path is A plurality may be provided so as to be connected to the upstream flow path and to be divided along the longitudinal direction of the head unit (that is, the longitudinal direction of the droplet discharge head) and at the central portion of the ejector group.

  In this configuration, the head units including the ejector group are arranged in a staggered manner in a plurality of rows, and the upstream flow path is disposed outside the both end portions of the ejector group. A plurality of common channels are connected to the upstream channels at both ends, and the plurality of common channels are arranged along the longitudinal direction of the head unit and divided at the central portion of the ejector group. Accordingly, it is possible to efficiently arrange the upstream flow path and the plurality of common flow paths that have a large space with respect to the plane area of the long droplet discharge head without increasing the size of the recording head. . For this reason, the width of the long droplet discharge head (the width in the direction orthogonal to the longitudinal direction) can be reduced, and downsizing can be realized. Moreover, since the common flow path is divided at the central portion of the ejector group, it is possible to prevent the common flow path from becoming long. For this reason, the channel resistance of the common channel can be reduced, and high ejection stability and frequency characteristics can be secured for each ejector.

  Further, in this droplet discharge head, suction holes for positioning and sucking component plates constituting the head unit, or alignment marks for positioning, are arranged outside both ends of the ejector group. Also good.

  In this configuration, a long-type liquid is provided by arranging suction holes for positioning and sucking the component plates constituting the head unit or the alignment marks for positioning outside the both ends of the ejector group. The suction holes or the alignment marks can be arranged most efficiently with respect to the plane area of the droplet discharge head. For this reason, the width of the long droplet discharge head can be further reduced.

  Furthermore, in this droplet discharge head, the upstream flow path may be divided into a plurality of parts and arranged outside both ends of the ejector group.

  In this configuration, the upstream flow path is divided into a plurality of outer sides of both ends of the ejector group, and each of the divided upstream flow paths is filled with a different type of liquid (for example, ink). By doing so, it is possible to realize multicolor recording with a single droplet discharge head.

  Furthermore, in this droplet discharge head, the common flow path disposed in the head unit may have a different length.

  In this configuration, since the length of the common flow path is different, the end of the common flow path is less likely to be at the same position on the recording medium, and the concentration unevenness along the longitudinal direction of the long droplet discharge head is reduced. Generation can be further reduced.

  Further, in this liquid droplet ejection head, the electric wiring is drawn out in the width direction orthogonal to the longitudinal direction of the head unit, and the electric wiring is bent at a portion overlapping with a row of other head units adjacent in the width direction. Also good.

  In this configuration, the electrical wiring is drawn out along the width direction perpendicular to the longitudinal direction of each head unit, and the electrical wiring of each head unit is folded by bending the electrical wiring at a portion overlapping with the row of other head units adjacent in the width direction. Wiring can be arranged efficiently. For this reason, the width of the head unit can be further reduced.

  Furthermore, in this droplet discharge head, the shape of the head unit may be a substantially rectangular shape or a substantially parallelogram shape.

  In this configuration, by making the shape of the head unit substantially rectangular or a substantially parallelogram, upstream flow paths, suction holes, or alignment marks are provided at both ends (outside both ends of the ejector group) of the staggered head units. The head unit can be arranged efficiently, and the width of the head unit can be further reduced.

  Furthermore, in this droplet discharge head, the number of nozzle rows arranged in the head unit may be set to a power of two.

  In this configuration, by setting the number of nozzle rows arranged in the head unit to a power of 2, the controller data processing can be simplified and the cost of the controller can be reduced.

  Furthermore, in this droplet discharge head, the number of ejectors driven in the head unit is set to a power of two.

  In this configuration, by setting the number of ejectors driven in the head unit to a power of 2, the data processing of the controller can be simplified and the cost of the controller can be reduced.

  Further, in the liquid droplet ejection head, the head units may be completely separated from each other.

  In this configuration, the head units are completely separated from each other, so that each head unit can be replaced, and maintenance is facilitated.

  Furthermore, in this liquid droplet ejection head, a part of the constituent plates constituting the head unit may have an integral bar structure.

  In this configuration, since some of the constituent plates constituting the head unit have an integral bar structure, the head unit can be easily positioned and assembled.

  Since the present invention has the above-described configuration, it is possible to suppress deterioration in image quality due to white stripes / black stripes or the like even when a θ deviation or the like occurs in the head unit.

  FIG. 25 shows the inkjet recording apparatus 112 according to the first embodiment of the present invention. A paper feed tray 116 is provided in the lower part of the casing 114 of the ink jet recording apparatus 112, and the sheets P stacked in the paper feed tray 116 can be taken out one by one by a pickup roll 118. The taken paper P is transported by a plurality of transport roller pairs 120 constituting a predetermined transport path 122. Hereinafter, the “conveying direction” simply refers to the conveying direction of the paper P that is a recording medium, and the “upstream” and “downstream” refer to upstream and downstream in the conveying direction, respectively.

  Above the paper feed tray 116, an endless transport belt 128 stretched between a drive roll 124 and a driven roll 126 is disposed. A recording head array 130 is disposed above the conveyor belt 128 and faces the flat portion 128F of the conveyor belt 128. This opposed area is an ejection area SE where ink droplets are ejected from the recording head array 130. The sheet P transported along the transport path 122 is held by the transport belt 128 and reaches the discharge area SE, and ink droplets corresponding to image information are attached from the recording head array 130 while facing the recording head array 130. The

  Then, by rotating the paper P while being held by the transport belt 128, it is possible to perform image recording by so-called multi-pass by allowing the paper P to pass through the ejection region SE a plurality of times. Of course, the sheet P may be passed through the ejection region SE only once, and image recording may be performed in a so-called one pass.

For example, the transport belt 128 is made of a semiconductive polyimide material (surface resistance value 10 ¹⁰ to 10 ¹³ Ω / □, volume resistance value 10 ⁹ to 10 ¹² Ω · cm), thickness 75 μm, width 380 mm, circumference What was shape | molded in length 1000mm can be used. Moreover, as the drive roll 124 and the driven roll 126, as an example, a φ50 mm SUS roll can be used.

  Instead of the conveyor belt 128, for example, a recording medium (paper P) may be sucked and held on the outer periphery of a conveyance roller formed in a cylindrical shape or a columnar shape and rotated. However, since the flat portion 128F is formed when the conveyor belt 128 is used as in the present embodiment, the recording head array 130 can be disposed corresponding to the flat portion 128F, which is preferable.

  In this embodiment, the recording head array 130 has a long shape in which the effective recording area is equal to or larger than the width of the paper P (the length in the direction orthogonal to the transport direction), and is a so-called FWA (Full Width Array). Yes. In the recording head array 130, four inkjet recording heads 34 corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K) are arranged along the transport direction. Therefore, a full color image can be recorded. Each inkjet recording head 34 is configured by staggering a plurality of head units 12 as will be described later. A method for ejecting ink droplets in the head unit 12 is not particularly limited, and a known method such as a so-called thermal method or a piezoelectric method can be applied. In this embodiment, a piezoelectric method is used.

  Each head unit 12 is controlled by a recording head control means (not shown). For example, the recording head control means determines the ink droplet ejection timing and the ink ejection port (nozzle) to be used according to the image information, and sends a drive signal to the head unit 12.

  The recording head array 130 may be stationary in a direction orthogonal to the transport direction. However, if the recording head array 130 is configured to move as necessary, an image with higher resolution can be obtained by multipass image recording. Can be recorded, or the malfunction of the head unit 12 can be prevented from being reflected in the recording result.

  Four maintenance units 134 corresponding to the respective ink jet recording heads 34 are arranged in the vicinity of the recording head array 130 (in this embodiment, both sides in the transport direction). When performing maintenance on the ink jet recording head 34, the recording head array 130 moves upward as shown in FIG. 2, and the maintenance unit 134 moves into a gap formed between the conveyance belt 128 and the maintenance unit 134. Get in. Then, a predetermined maintenance operation (vacuum, dummy jet, wiping, capping, etc.) is performed while facing the nozzle surface (see FIG. 3).

  In the present embodiment, the four maintenance units 134 are divided into two sets of two, and are arranged on the recording head array 130 and on the upstream side and the downstream side of the recording head array 130 at the time of image recording, respectively. .

  On the upstream side of the recording head array 130, a charging roll 136 connected to a power source (not shown) is disposed. The charging roll 136 is driven between the driven roll 126 while sandwiching the conveyance belt 128 and the paper P, and moves between a pressing position for pressing the paper P against the conveyance belt 128 and a separation position separated from the conveyance belt 128. It is possible. At the pressing position, a predetermined potential difference is generated between the driven roll 126 and the ground, so that the sheet P can be charged and electrostatically attracted to the transport belt 128.

As the charging roll 136, for example, a roll having a diameter of 14 mm in which conductive carbon is coated on the surface of silicone rubber and the volume resistance value is adjusted to about 10 ⁶ to 10 ⁷ Ω · cm can be used.

  The power source may be a DC power source or an AC power source as long as the paper P can be charged to a predetermined potential.

  Note that a registration roll (not shown) is provided further upstream than the charging roll 136, and the paper P is aligned before reaching between the conveyance belt 128 and the charging roll 136.

  A peeling plate 140 is disposed on the downstream side of the recording head array 130, and the paper P can be peeled from the transport belt 128. As the peeling plate 140, for example, an aluminum plate having a thickness of 0.5 mm, a width of 3130 mm, and a length of 100 mm can be used.

  The peeled paper P is conveyed by a plurality of discharge roller pairs 142 constituting a discharge path 144 on the downstream side of the peeling plate 140, and is discharged to a paper discharge tray 146 provided on the top of the housing 114.

  Below the peeling plate 140, a cleaning roll 148 capable of sandwiching the conveying belt 128 with the driving roll 124 is disposed, and the surface of the conveying belt 128 is cleaned.

  A reversing path 152 composed of a plurality of reversing roller pairs 150 is provided between the paper feed tray 116 and the conveying belt 128, and the sheet P on which an image is recorded on one side is reversed and held on the conveying belt 128. By doing so, it is possible to easily record images on both sides of the paper P.

Between the transport belt 128 and the paper discharge tray 146, an ink tank 154 is provided for storing each of the four color inks. Ink in the ink tank 154, by the ink supply piping (not shown), and is supplied to the recording head array 130. As the ink, various known inks such as water-based ink, oil-based ink, and solvent-based ink can be used.

  FIG. 1 shows a schematic configuration of the ink jet recording head 34 according to the first embodiment of the present invention, and FIG. 2 shows the ink jet recording head 34 in a perspective view. Further, FIG. 3 shows the head unit 12 constituting the ink jet recording head 34 partially enlarged.

  As shown in FIG. 2, the ink jet recording head 34 is longer than the maximum width of the paper P as a recording medium. This ink jet recording head 34 is composed of a plurality of rectangular head units 12, and each head unit 12 is shifted by a half pitch between the upstream side and the downstream side of the conveyed paper P (see FIG. 1), and is staggered. Two rows are arranged in a shape. Hereinafter, the terms “longitudinal direction” and “width direction” simply mean the longitudinal direction and the width direction of the long head 34.

  As shown in FIGS. 1 and 2, the head unit 12 is formed with a rectangular ejector region (an ejector group array portion) 14 in which a plurality of ejectors are arrayed. In the ejector region 14, a nozzle 16 (see FIGS. 3 and 4 to 6) is formed for each ejector.

In the ink jet recording apparatus 112 equipped with the recording head array 130, as shown in FIG. Ink droplets corresponding to the information are ejected. Accordingly, on the paper P on which image recording has been completed, an area recorded by the ejector area 14A located upstream of the recording head array 130 in the paper conveyance direction and an ejector area located downstream of the recording head array 130 in the paper conveyance direction. The areas recorded by 14B are alternately arranged along the width direction of the paper P. Here, in the head units 12 adjacent in the width direction of the paper P to be conveyed, the end portions of the ejector regions 14A and 14B are arranged so as to contact (or overlap) each other when viewed in the paper feed direction. An area that cannot be printed is prevented from occurring in the print area. The first embodiment is an example in which the end portions of the ejector regions 14A and 14B are in contact with each other when viewed in the paper feeding direction, and the second to fifth embodiments described later are examples in which they overlap.

  In this way, by arranging a plurality of head units 12 along the width direction of the paper P to form a print area, the recording head array 130 does not need to move along the width direction of the paper P, and Since the image is formed on the entire surface of the paper P by the movement, high productivity can be obtained. When forming a multicolor image, a plurality of inkjet recording heads 34 containing different color inks may be arranged side by side in the conveyance direction of the paper P as shown in FIG.

  Further, as shown in FIG. 2, a base plate 18 for fixing the head unit 12 is disposed on the opposite side of the ejector regions 14A and 14B of the head unit 12. Two ink flow paths 20 for supplying ink to the two rows of head units 12 are formed in the base plate 18. Two heat radiating plates 22 are attached to both ends on the back side of the base plate 18, and a circuit board 24, which is a controller for controlling the drive of the recording head array 130, is disposed on the heat radiating plate 22. Further, an electrical wiring 26 that connects each head unit 12 (the front side in FIG. 2) and the circuit board 24 is supported on a side portion of the base plate 18, and a switch IC 28 is provided in the electrical wiring 26. In addition, although illustration is abbreviate | omitted, the electrical wiring 26 connected to each head unit 12 (back side of FIG. 2), switch IC28, and the circuit board 24 are similarly provided in the back | inner side of FIG.

  As shown in FIG. 1, upstream flow paths 30 </ b> A and 30 </ b> B are disposed on both ends of the head unit 12 in the longitudinal direction outside the both ends of the ejector region 14 (both ends in the longitudinal direction of the head unit 12). Yes. The upstream flow paths 30A and 30B are connected to the ink flow path 20 (see FIG. 2), and ink is supplied from the ink flow path 20 to the head unit 12 through the upstream flow paths 30A and 30B. . A plurality of common flow paths 32 that supply ink to the ejectors arranged in the ejector region 14 are connected to the upstream flow paths 30A and 30B, respectively. The plurality of common flow paths 32 extend along the longitudinal direction from both ends of the head unit 12, and the common flow paths 32 are divided at the central portion of the ejector region 14. That is, the end portion of the common flow path 32 is located near the center portion of the head unit 12. In FIG. 1, for the sake of clarity, four common flow paths 32 are connected to the upstream flow paths 30A and 30B and schematically shown. However, in actuality, as described later, the number of nozzles is, for example, 600 npi, which is configured to connect a large number of common flow paths 32.

  As shown in FIGS. 3 and 4, the head unit 12 includes a nozzle 16 that ejects a plurality of ink droplets formed in a matrix, and a pressure chamber 36 that ejects ink droplets from the nozzles 16 that communicate with each other by pressurizing the ink. And the above-mentioned common flow path 32 (see FIG. 1). A nozzle communication chamber 38 that communicates the nozzle 16 and the pressure chamber 36 and an ink supply path 42 that communicates the opening 40 of the common flow channel 32 and the pressure chamber 36 are provided. 36, the nozzle communication chamber 38, and the ink supply path 42 constitute an ejector 60.

  The head unit 12 includes a nozzle plate 44 in which the nozzles 16 are formed, ink pool plates 46 and 48 in which the nozzle communication chamber 38 and the common flow path 32 are formed, a nozzle communication chamber 38 and an opening 40. The through plate 50, the ink supply path plate 52 in which the ink supply path 42 is formed, and the pressure chamber plate 54 in which the pressure chamber 36 is formed are aligned and laminated, and are bonded by a bonding means such as an adhesive. ing.

  Further, a vibration plate 57 is bonded to the pressure chamber plate 54 so as to cover the upper surfaces of the plurality of pressure chambers 36, and a piezoelectric element 58 is bonded to the upper surface of the vibration plate 57 corresponding to each pressure chamber 36. . Electrical wiring 26 (see FIG. 2) is connected to the piezoelectric element 58 through an electrode pad 59.

  In FIG. 4, the orientation of the piezoelectric element 58 and the electrode pad 59 is changed from the actual one in accordance with the cross section of the ink jet recording head 12, but in actuality, as shown in FIG. Inclined.

  The nozzle plate 44 is formed in a film shape (thin film shape) from a flexible resin material, and constitutes one surface (the bottom surface in FIG. 4) of the common flow path 32 as can be seen from FIG. ing. Therefore, the part which comprises the common flow path 32 among the nozzle plates 44 functions as the damper 44D of the common flow path 32, and the nozzle plate 44 serves as the damper 44D.

  A protective plate for protecting the periphery of the nozzle 16 may be joined to the ink droplet ejection side of the nozzle plate 44 as necessary.

  As shown in FIG. 5, the nozzles 16 are two-dimensionally arranged in a plane (matrix arrangement) in each of the head units 12. And the dots of the ink droplets ejected from the nozzles 16A and 16B located far from the longitudinal center line CL-1 of each head unit 12, and the dots of the ink droplets ejected from the nozzles 16C and 16D located near to each other. However, the nozzles 16 are arranged so as to be mixed and arranged on the paper P when viewed in the longitudinal direction of the inkjet recording head 34.

  Further, between the head units 12 adjacent to each other in the longitudinal direction of the ink jet recording head 34, the nozzles 16 in each head unit 12 are arranged so that the nozzles 16 located at the joints 13 are close to each other in the width direction. Has been placed. For example, between the head unit 12A and the head unit 12B, the nozzle 16B of the head unit 12A and the nozzle 16A of the head unit 12B located at the joint 13 are close to each other in the width direction.

  As shown in FIG. 3, the ejectors 60 are grouped in two adjacent rows, and the common flow path 32 is arranged in the center of the group, that is, between each row. Therefore, the common flow path 32 is provided in common for the two ejector rows.

  In this way, by arranging the common flow path 32 between the two rows of ejector rows, as compared with the configuration in which the common flow channel 32 ′ is arranged corresponding to each of the one row of ejector rows as shown in FIG. Thus, the width can be increased.

  In addition, each nozzle 16 of the ejector 60 is disposed so as to be on the outside, that is, at a position away from the center line CL when viewed from the center line CL of the common flow path 32. Therefore, for example, as compared with an example in which the nozzles 16 are arranged in the vicinity of the center line CL, the intervals of the nozzles 16 between the target rows are wide. In general, it is necessary to form the common flow path 32 while avoiding the nozzles 16. However, in this embodiment, since the intervals between the nozzles 16 are wide, the common flow path 32 between these nozzles 16 is made wider. Can do.

Here, the direction in which ink droplets of the head unit 12 is discharged to the vertical direction (when viewed in plan as shown in i.e. Figure 3) when viewed in the vertical direction, the common flow channel 32 and the ink supply path 42 It is arranged overlapping. Accordingly, it is possible to ensure a wide width of the common flow path 32 without reducing the arrangement density of the ejectors 60 as compared with the configuration in which the common flow path 32 is disposed so as not to overlap the ink supply path 42. ing.

  Further, the common flow path 32 is disposed so as to overlap the electrode pad 59. Therefore, it is possible to ensure a wide width of the common flow path 32 without reducing the arrangement density of the ejectors 60 as compared with the configuration in which the common flow path 32 is disposed so as not to overlap the electrode pad 59. Yes.

  In the head unit 12, the number of columns of the nozzles 16 arranged in the ejector region 14 is set to a power of two. Further, the number of ejectors may be set to a power of two. Thereby, the data processing of the circuit board (controller) 24 that drives the head unit 12 can be simplified, and the cost of the circuit board 24 can be reduced.

  Each head unit 12 is completely separated, and is configured to be replaceable for each head unit 12. For this reason, maintenance is easy.

  Next, operations of the ink jet recording apparatus 112 and the recording head array 130 according to the present embodiment will be described.

  In the ink jet recording apparatus 112 of this embodiment, as described above, the paper P taken out from the paper feed tray 116 is transported and reaches the transport belt 128. Then, it is pressed against the conveyance belt 128 by the charging roll 136 and is held by adhering (adhering) to the conveyance belt 128 by the voltage applied from the charging roll 136.

  On the other hand, as shown in FIG. 1, in each head unit 12 constituting the ink jet recording head 34 of the recording head array 130, a plurality of common flow paths are formed from the upstream flow paths 30A and 30B provided at both ends thereof. 32 is supplied with ink. The ink stored in the common flow path 32 is supplied to each ejector 60 in the ejector region 14 and is filled into the pressure chamber 36 through the opening 40 and the ink supply path 42 as shown in FIG. When a driving voltage is applied from the circuit board 24 (see FIG. 2) to each piezoelectric element 58, the diaphragm 57 is bent and deformed together with the piezoelectric element 58, and the pressure chamber 36 is expanded or compressed. Accordingly, when a volume change occurs in the pressure chamber 36, a pressure wave is generated in the pressure chamber 36. The ink moves by the action of the pressure wave, and ink droplets are ejected from the nozzle 16 to the outside.

  Then, while the paper P passes through the ejection area SE by the circulation of the transport belt 128, ink droplets are ejected from the recording head array 130 as described above, and an image is recorded on the paper P. When recording an image in only one pass, the paper P is peeled from the transport belt 128 by the peeling plate 140, transported by the discharge roller pair 142, and discharged to the paper discharge tray 146. On the other hand, when performing image recording by multi-pass, after the paper P is circulated and passed through the ejection region SE until the required number of times is reached, the paper P is peeled from the transport belt 128 by the peeling plate 140, The paper is conveyed by the discharge roller pair 142 and discharged to the paper discharge tray 146.

  Here, as shown in FIG. 5, in the ink jet recording head 34 of the present embodiment, each head unit 12 is arranged so that the nozzles 16 located at the joints 13 of the adjacent head units 12 are close to each other in the width direction. A nozzle 16 is arranged inside. For this reason, even when the θ deviation occurs in the ink jet recording head 34, the deterioration of the image quality due to this is prevented.

FIG. 7 shows an inkjet recording head 172 that does not fall under the present invention for comparison. In the head unit 174 of the ink jet recording head 172 of the comparative example 1, the nozzle 176 moves from the lower side to the upper side in order in the longitudinal direction (from left to right in FIG. 7) (176D → 176C → 176B → 176A). However, when reaching the uppermost nozzle 176A, a regular nozzle arrangement is made to shift to the lowermost nozzle 176D . In the joint 173 of the adjacent head units 174, the interval between the nozzles 176 is wide in the width direction.

When the θ shift occurs in the ink jet recording head 172 of Comparative Example 1, the dot position shift between the head units 174 increases at the joint 173. In general, since the inclination angle θ of the θ deviation is sufficiently small, the deviation amount δ of the dot position deviation is expressed as follows:
δ = y · sinθ
Can be approximated by For example, considering the case where the inclination angle θ is 0.05 degree, since the inter-nozzle distance y at the joint 173 is about 70 mm in the comparative example 1, the displacement amount δ is also about 60 μm, so-called white stripe / black stripe, etc. May be visually recognized.

  On the other hand, in the present embodiment, the inter-nozzle distance y at the joint 13 is about 15 mm, which is smaller than Comparative Example 1. Therefore, even if the same inclination angle θ deviation occurs, the deviation amount δ falls within about 13 μm. Therefore, it is possible to prevent the image quality from being deteriorated due to the white stripe / black stripe. In particular, in the ink jet recording apparatus 112 of the present invention, even when image recording is performed in one pass instead of multi-pass, deterioration in image quality can be prevented. Moreover, since it is one pass, it can record images at high speed.

  In the present invention, the fact that the nozzle 16 is “close” at the joint 13 of the head unit 12 means that at least the two nozzles 176 as in Comparative Example 1 shown in FIG. The purpose of this is to exclude the configuration in a different position. That is, any nozzle arrangement that satisfies this requirement is widely included in the concept of “proximity” in the present invention. However, as described above, from the viewpoint of reducing the amount δ of the dot position deviation caused by the θ deviation, it is preferably at least smaller than the width of the head unit 12, and the distance y between the nozzles is set to 30 mm or less. More preferably.

  In Comparative Example 1, since the nozzles 176 are regularly arranged in the head unit 174 as described above, the distance between adjacent nozzles 176 in the head unit 174 is also as shown in FIG. Regular changes exist. Therefore, when the θ deviation occurs in the ink jet recording head 172, the positional deviation amount δ between adjacent dots is 26 μm when the distance y between adjacent nozzles is 30 mm and the inclination angle θ is 0.05 degrees, for example. . This value is small compared to the amount δ (about 60 μm) of the dot position deviation at the joint 17, but this is repeated periodically, so that in some cases, the image result is easily visible to the human eye. In some cases, the image quality is slightly reduced.

  On the other hand, in the present embodiment, in the head unit 12, the dots of the nozzles 16A and 16B that are far from the longitudinal center line CL-1 and the dots of the nozzles 16C and 16D that are close to each other are mixed. The nozzles 16 are arranged so as to be aligned, and the regularity of the distance between the adjacent nozzles 16 in the head unit 12 is relaxed as shown in FIG. For this reason, even when the inkjet recording head 34 has a θ shift, the dot position shift described above occurs in a distributed manner, so that it is difficult to be recognized as an image defect, and a reduction in image quality can be suppressed.

  In the present embodiment, only the portion of the joint 13 of the head unit 14 may be subjected to a shingling process. As a result, robustness against misalignment between the head units can be improved, and the manufacturing yield of the inkjet recording head 34 can be improved.

  As shown in FIG. 3, the common flow path 32 of the present embodiment is arranged between the two ink jet columns in common with the ejectors 60 of the two ejector rows. Compared with a configuration in which a common flow path is arranged corresponding to each of the ejector rows (see the common flow channel 32 ′ in FIG. 6), the width is wider and the acoustic capacity is also larger. Therefore, crosstalk can be more reliably prevented between the ejectors 60, and ink supply (refill) to the pressure chamber 36 can be performed more smoothly and in a short time, and excellent ejection stability can be obtained.

  In particular, in this embodiment, a part of the nozzle plate 44 functions as the damper 44D, but in general, the acoustic capacity of the common flow path 32 is proportional to the sixth power of the width of the damper 44D. For this reason, by making the common flow path 32 wide, as a result, in the present embodiment in which the damper 44D is also wide, a large acoustic capacity can be secured in the common flow path 32.

  And, in this way, by arranging the wide common flow path 32 between the two rows of ejector rows, a configuration in which a common flow path having the same width as in this embodiment is arranged in one ejector row, In comparison, the ejectors 60, that is, the nozzles 16 can be arranged at a higher density. That is, while ensuring a sufficient acoustic capacity in the common flow path 32, the nozzles 16 are two-dimensionally arranged with high density, and a high-quality image can be recorded at high speed.

Further, in the head unit 12 of the present embodiment, as shown in FIG. 1, a plurality of common flow paths 32 are connected to the upstream flow paths 30A and 30B at both ends of the head unit 12, and are arranged along the longitudinal direction. Therefore, the upstream flow paths 30A and 30B and the common flow path 32 having a large space with respect to the plane area of the ink jet recording head 34 can be efficiently arranged without increasing the size of the recording head array 130. In addition, in the present embodiment, as described above, the nozzles 16 can be arranged at a high density while ensuring a sufficient acoustic capacity in the common flow path 32. In this respect as well, the width of the head unit 12 is reduced. be able to. Therefore, the head width (W _H ) of the inkjet recording head 34 and further the recording head array 130 can be reduced, and the recording head array 130 can be reduced in size. Thereby, it is possible to prevent the occurrence of color misregistration between the head units 12 of a plurality of colors (between the ink jet recording heads 34) and to reduce the size of the entire ink jet recording apparatus 112.

  Moreover, the common flow path 32 connected to the upstream flow paths 30A and 30B is divided at the central portion of the ejector region 14, so that the common flow path 32 can be prevented from becoming long. For this reason, the flow path resistance of the common flow path 32 can be reduced, and high ejection stability and frequency characteristics can be ensured for each ejector 60.

  Next, an inkjet recording head 312 according to a second embodiment of the present invention will be described. In each of the following embodiments, the arrangement of the nozzles is different from that in the first embodiment, but the overall configuration of the ink jet recording head and the ink jet recording apparatus is substantially the same, and thus the description thereof is omitted. .

As shown in FIG. 9, in the second embodiment, the nozzle 316 moves from the lower side to the upper side in order in the longitudinal direction (from left to right in FIG. 9) in the head unit 314, and the uppermost nozzle 316. In this case, a regular nozzle arrangement that shifts to the lowest nozzle 316 is adopted .
In the second embodiment, as shown in FIG. 8A, an overlap region 318 in which the nozzles 316 overlap when viewed in the width direction is formed at the joint between adjacent head units 314. (The nozzles constituting the overlap region are indicated with halftone dots on the drawing). For this reason, even if a failure occurs in the nozzle 316 constituting the overlap region 318, the influence of the failure can be obtained by using another nozzle 316 that also forms the overlap region 318 and does not have a failure. Can be eliminated (or reduced).

  Furthermore, in the second embodiment, when paying attention to a specific head unit 314, the nozzle 316A adjacent to the overlap region 318 is positioned close to the nozzle 316B located at the end of the overlap region 318 in the width direction. Thus, each head unit 314 is arranged by adjusting the overlap amount.

  For this reason, when the θ shift occurs, white stripes and black stripes generated at the boundary portion of the overlap region 318 can be suppressed, and a high-quality image can be obtained.

  In general, when the accuracy of mounting the head unit is low, white stripes and black stripes are likely to occur when the ink droplet ejection characteristic difference between adjacent head units 314 affects the boundary portion of the overlap region. However, in this embodiment, even in such a case, the occurrence of white stripes and black stripes at the boundary portion of the overlap region 318 can be reduced.

  For comparison, the head unit 314 similar to that shown in FIG. 8A is used in FIG. 8B, but the nozzle 316 </ b> C adjacent to the overlap region 318 is at the end of the overlap region 318. The example which is spaced apart from the nozzle 316D located in the width direction is shown. In Comparative Example 2, it is difficult to suppress white stripes, black stripes, and the like that occur at the boundary portion of the overlap region 318 when the θ deviation occurs.

  Next, an ink jet recording head 322 according to a third embodiment of the present invention will be described.

  As shown in FIG. 10, also in the third embodiment, the head unit 324 is arranged so that the overlap region 328 is configured by the adjacent head units 324.

  As shown in FIG. 11, in the third embodiment, in addition to the nozzle arrangement of the second embodiment shown in FIG. 9, the nozzle 326B is formed at one end in the longitudinal direction and at one end in the width direction. Has been.

  The head units 324 are alternately arranged 180 degrees in a staggered manner along the longitudinal direction to form an ink jet recording head 322.

  Further, in the overlap region 328, the distance L1 in the width direction between the nozzles (nozzles 326A and 326B in FIG. 10) that overlap at the end of the overlap region 328 is the same in the overlap region 328. The nozzles are overlapped so as to be smaller than the distance L2 in the width direction between the nozzles (nozzles 326C and 326D) that overlap on the inner side.

  Thus, in the third embodiment, the distance between the nozzles 326A and 326B that overlap with the adjacent head unit 324 is reduced at the end (boundary portion) of the overlap region 328, and these nozzles 326A and 326B In this arrangement, the head unit is not easily affected by a positional shift (particularly θ shift) when the head unit is mounted. For this reason, the entire inkjet recording head 322 can easily suppress the occurrence of white stripes / black stripes or the like at the end (boundary portion) of the overlap region 328.

  Next, an inkjet recording head 332 according to a fourth embodiment of the invention will be described. The nozzle arrangement in the head unit 334 in the fourth embodiment is the same as that in the third embodiment. The adjacent head unit 334 forms an overlap region 338, and the nozzle 336 at the end of the overlap region 338 is adjacent to the nozzle 336 adjacent to the overlap region 338 in the adjacent head unit 334. (For example, in the example of FIG. 12A, the nozzle 336D and the nozzle 336E are close to each other).

  Accordingly, in the fourth embodiment, as in the third embodiment, the distance in the width direction of the nozzles 336D and 336E is reduced at the end (boundary portion) of the overlap region 338. It becomes easy to suppress generation | occurrence | production etc.

  Furthermore, in the fourth embodiment, as shown in FIG. 12B, the nozzle 336C adjacent to the overlap region 338 is a nozzle at the end of the overlap region 338 in the same head unit 334B as the nozzle 336C. 336B and the nozzle 336A at the end of the overlap region 338 in the adjacent head unit 334A (when viewed in the width direction). The head unit 334 is arranged so that the distance L2 in the width direction between the nozzle 336C and the nozzle 336A and the distance L3 in the width direction between the nozzle 336C and the nozzle 336B are substantially equal.

  For this reason, in the fourth embodiment, as shown in FIG. 12C, even when the position of the nozzle 16 is entirely displaced due to the θ shift, the nozzle 336C and the nozzle 336B are separated at the boundary of the overlap region 338. The average of the distance L5 in the longitudinal direction and the distance L4 in the longitudinal direction between the nozzles 336C and 336A is close to the original distance (the distance in the state where no θ deviation occurs). Therefore, white lines / black lines and the like generated between the dot lines formed by the nozzles 336A and 336B and the dot lines formed by the nozzle 336C are reduced.

  In the fourth embodiment, if at least the nozzle 336C is located between the nozzle 336A and the nozzle 336B when viewed in the width direction, for example, even if the nozzle 336D and the nozzle 336E are not close to each other, The effect of is demonstrated. However, in order to more surely reduce the white stripe / black stripe generated between the dot lines at the nozzles 336A and 336B and the dot line at the nozzle 336C, the distance L2 and the distance L3 are It is preferable that they are substantially equal, for example, in a range of 0.8 <L2 / L3 <1.2.

  Next, an inkjet recording head 342 according to a fifth embodiment of the invention will be described.

  As shown in FIG. 14, in the head unit 344 according to the fifth embodiment, as in the first embodiment, the ink droplets ejected from the nozzles 326A and 326B located far from the longitudinal center line CL-1 The nozzles 346 are arranged so that the dots of the ink droplets ejected from the nozzles 346C and 346D located at close positions are mixedly arranged on the paper P when viewed in the longitudinal direction of the inkjet recording head 34.

  Further, as shown in FIG. 13A, as in the third and fourth embodiments, the overlap region 348 is configured by the adjacent head units 344, and the nozzles are formed at the end of the overlap region 348. The head unit 344 is arranged so that the nozzles 346C and 346D in FIG. 13A are close to each other.

  Accordingly, in the fifth embodiment as well, as in the first embodiment, when the inkjet recording head 342 generates the θ shift, the dot position shift occurs in a distributed manner and is difficult to be recognized as an image defect. The decrease can be suppressed.

  Similarly to the third and fourth embodiments, since the distance between the nozzles 346C and 346D is small at the end (boundary portion) of the overlap region 348, the occurrence of white stripes / black stripes, etc. It becomes easy to suppress.

  In FIG. 13B, for comparison, the same head unit 344 as that of the fifth embodiment is used, but an example not applicable to the present invention is shown. In Comparative Example 3, the nozzles 346 </ b> A ′ and 346 </ b> B ′ are separated in the width direction at the boundary of the overlap region 348. For this reason, unlike the example shown in FIG. 13A, it is difficult to suppress the occurrence of white stripes / black stripes.

  In each of the above embodiments, the material of the damper is preferably composed of, for example, a resin film from the viewpoint of obtaining a large acoustic capacity in the common flow path 32.

  Further, as the damper according to the present invention, an example in which a part of the nozzle plate 44 also serves as a damper has been described, but a damper separate from the nozzle plate 44 may be provided. In any case, if at least one of the top surface or the bottom surface of the common flow path is a damper, the acoustic capacity of the common flow path can be reliably increased.

  Further, it is preferable that the nozzle plate 44 also serves as a damper as in the above-described embodiment, because the number of plates necessary for configuring the ejector 60 is reduced, so that the manufacturing cost of the head unit can be reduced. In this case, if the nozzle plate 44 itself is made of a resin film, it is particularly preferable since it is possible to achieve both a sufficient acoustic capacity in the common flow path and a reduction in the number of plates described above.

  Next, various modifications of the present invention will be described below. In any of the modifications, in the vicinity of the nozzle joint between the head units or in the vicinity of the overlap region, the image quality deterioration due to the white stripe / black stripe due to the θ deviation is prevented. Although any structure of the first to third embodiments can be adopted, the configurations of the common flow path and the upstream flow path are different from those shown in FIG. 1, FIG. 3, FIG. Below, the same code | symbol is attached | subjected to the member same as said each embodiment, and the overlapping description is abbreviate | omitted.

  FIG. 15 shows the head unit 62 of the first modification partially enlarged.

  The common flow path 64 according to the first modification bulges further outward from the center line CL in a position where the nozzle 16 is avoided when viewed in plan, compared to the common flow path 32 of the first embodiment, It is formed so as to be located outside the nozzle 16, and as a whole has a shape that is locally constricted in the vicinity of the nozzle 16.

  Therefore, in the first modified example, the width of the common flow path 64 is wider at a position where the nozzle 16 is avoided as compared with the above embodiments. For this reason, in the first modification, a larger acoustic capacity can be ensured.

  FIG. 16 shows a partially enlarged head unit 66 of a second modification of the present invention. In the second modified example, compared with the first embodiment, only the structure of the portion for supplying ink from the common flow path 32 to the pressure chamber 36 is different, but the other parts are all the same, The same members as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 16, in the second modification, instead of the ink supply path 42 of the first embodiment, an ink supply hole 68 that connects the common flow path 32 and the pressure chamber 36 in the thickness direction of the head unit is formed. Has been. Since the ink supply hole 68 does not have the spread (length) as the ink supply path 42 when viewed in plan, the head unit can be further downsized.

  In the example shown in FIG. 16, the common flow path 32 having the same shape as that of the first embodiment is used as the common flow path of the second modification. For example, the common flow path having the same shape as that of the first modification is used. 64 may be sufficient.

  FIG. 17 shows an ink jet recording head 70 of a third modification. In the ink jet recording head 70, the upstream flow paths 72 </ b> A and 74 </ b> A and the upstream flow paths 72 </ b> B and 74 </ b> B divided into two are disposed outside the ejector regions 14 at both longitudinal ends of the head unit 12. Has been. Further, the ejector group 14 is also substantially divided within the head unit 12, and divided regions 14-1 and 14-2 are formed. A plurality of common flow paths 32 that supply ink to the respective ejectors 60 are connected to the upstream flow paths 72A and 74A and the upstream flow paths 72B and 74B, respectively.

  In such an ink jet recording head 70, the upstream flow paths 72A and 74A and the upstream flow paths 72B and 74B that are divided into two are disposed at both ends of the head unit 12, and therefore, the upstream flow path 72A, By filling different types of ink in 72B and upstream flow paths 74A and 74B, two-color recording can be realized by one inkjet recording head 70.

  In this configuration, it is particularly preferable to arrange the nozzles 16 as shown in FIG. 5 because the dots of the ink droplets from the nozzles 16 are arranged at equal intervals in each divided region. For example, the nozzles 16B and 16D constituting the divided area 14-1 and the nozzles 16A and 16B constituting the divided area 14-2 are all equally spaced in the longitudinal direction. Therefore, when the ejector group 14 is divided into two in this way, for example, in the case of the head unit 12 having a nozzle density of 600 npi as a whole, the nozzle density is 300 npi for each color.

  In FIG. 17, the upstream flow paths 72A and 74A and the upstream flow paths 72B and 74B divided into two are arranged, but may be divided into three or more. Accordingly, it is possible to realize image recording with more colors with a single recording head.

  FIG. 18 shows an ink jet recording head 80 including the head unit 12 according to the fourth modification. In the inkjet recording head 80, long common flow paths 82 and short common flow paths 84 are alternately connected to the upstream flow paths 30A and 30B at both ends of the head unit 12 along the longitudinal direction. For this reason, the end portions of the common flow paths 82 and 84 are non-uniformly positioned at the center in the longitudinal direction of the head unit 12.

  In such an ink jet recording head 80, since the lengths of the common flow paths 82 and 84 are different, the end portions of the common flow paths 82 and 84 are rarely at the same position in the width direction of the paper. For this reason, it is possible to reduce the occurrence of density unevenness along the longitudinal direction of the head unit 12.

  FIG. 19 shows an inkjet recording head 90 including a head unit 12 according to a fifth modification of the present invention. In the ink jet recording head 90, the upstream flow paths 72A and 74A and the upstream flow paths 72B and 74B divided into two are arranged on the outer side in the longitudinal direction of the ejector region 14 of the head unit 12, and these A plurality of suction holes 92 and alignment marks 94 and 96, which are head components, are disposed further outside the upstream flow paths 72A and 74A and the upstream flow paths 72B and 74B. The suction holes 92 are used for stacking and sucking constituent plates of the head unit 12 such as the nozzle plate 44 and the ink pool plate 46 when the inkjet recording head 90 is manufactured. The alignment marks 94 and 96 are used for positioning the head unit 12 when the inkjet recording head 90 is manufactured.

In such an ink jet recording head 90, the suction hole 92 and the alignment marks 94 and 96 are disposed outside the upstream flow paths 72A and 74A and the upstream flow paths 72B and 74B, so that a long ink jet recording head is provided. The suction holes 92 and the alignment marks 94 and 96 can be arranged most efficiently with respect to 90 plane areas. For this reason, the head width (W _H ) of the inkjet recording head 90 can be further reduced.

  Further, the plurality of head units 12 may have a bar structure in which a part of the configuration plates (for example, the nozzle plate 44) is configured integrally. Thereby, manufacture of the inkjet recording head 90 becomes easy.

  FIG. 20 shows an inkjet recording head 100 including a head unit 102 according to a sixth modification of the present invention. In the ink jet recording head 100, a plurality of head units 102 are arranged in a staggered manner, and each head unit 102 is extended between other head units 102 adjacent in the width direction orthogonal to the longitudinal direction. A support 104 is provided. In addition, an electrical wiring 106 is drawn out in each head unit 102 in the width direction orthogonal to the longitudinal direction (the other row side arranged in a staggered manner), and the electrical wiring 106 is supported by the support portion 104. The electric wiring 106 is bent upward at the upper portion of the support portion 104, that is, at a portion overlapping with another head unit 102 adjacent in the width direction orthogonal to the longitudinal direction, thereby forming a bent portion 106A.

As described above, in each head unit 102, the electric wiring 106 is drawn out to the support portion 104 between the head units 102 in other rows arranged in a staggered manner, and the electric wiring 106 is bent at an upper portion of the support portion 104. The electric wiring 106 can be efficiently arranged. For this reason, the head width (W _H ) of the inkjet recording head 100 can be further reduced.

  As described above, in any of the embodiments and modifications, characteristics required for the recording head, such as downsizing, productivity, ejection stability, reduction in density unevenness, robustness, ejector utilization rate, controller cost, and multicolor compatibility ( Requirements) can be met at a high level.

  Table 1 shows that the inkjet recording heads 34, 70, 80, 90, 100 of the present invention and the recording heads of Comparative Examples 4 to 6 described later are reduced in size, productivity, ejection stability, and density unevenness. The result of evaluating the characteristics (requirements) required for the print head, such as robustness, ejector utilization rate, controller cost, and multi-color correspondence is shown.

  In the evaluation of Table 1, the present invention includes any of the first to fifth embodiments and the first to sixth modifications of the present invention described above.

  Comparative Example 4 is a long head unit in which the entire width direction of the paper P is integrally formed, Comparative Example 5 is an inkjet recording head in which trapezoidal head units shown in FIG. 21 are arranged, and Comparative Example 6 is shown in FIG. The inkjet recording head shown is used. Further, as shown in FIG. 24, Comparative Example 7 uses an inkjet recording head 250 in which a plurality of rectangular head units 252 are arranged in an oblique direction. Each head unit 252 is formed with a rectangular ejector region 254.

  The evaluation shown in Table 1 is carried out in four stages. “◎” is very good, “◯” is good, “Δ” is not very satisfactory, and “×” is not satisfactory at all.

  In the evaluation of Table 1, the ejector utilization rate indicates whether the number of ejectors that cannot be used at the end of the head bar is small, and the controller cost indicates the ease of data processing.

  From Table 1, the head units of Comparative Examples 4 to 6 have “×” or “Δ” in any of the characteristics (requirements), which is an unsatisfactory evaluation, whereas in the head unit of the present invention, all The requirement of “◎” or “◯” indicates that the evaluation is excellent. In particular, the discharge stability, the ejector utilization rate, and the multicolor compatibility are very excellent. Accordingly, various satisfactory characteristics can be obtained with the head unit of the present invention.

  In each of the above embodiments, the ink jet recording apparatus provided with the head unit that ejects ink droplets of each color of black, yellow, magenta, and cyan is exemplified as the liquid droplet ejecting apparatus of the present invention. The ejection head and the droplet ejection apparatus are not limited to those that record an image (including characters) on the recording paper P. That is, the recording medium is not limited to paper, and the liquid to be ejected is not limited to ink. For example, it is used for industrial purposes, such as creating color filters for displays by discharging ink onto polymer films or glass, or forming bumps for component mounting by discharging solder in a welded state onto a substrate. In general, the liquid droplet ejection apparatus is widely included.

  In these droplet discharge devices, the present invention may be applied not only to the FWA but also to a partial width array (PWA) having a main scanning mechanism and a sub-scanning mechanism. Furthermore, instead of the multipath type, a single path type may be used.

It is a block diagram which shows the inkjet recording head provided with the head unit of 1st Embodiment of this invention. It is a perspective view showing an ink jet recording head provided with a head unit of a 1st embodiment of the present invention. It is explanatory drawing which shows arrangement | positioning of the ejector and common flow path of the head unit of 1st Embodiment of this invention. It is sectional drawing which shows the ejector and common flow path of the head unit of 1st Embodiment of this invention, and explanatory drawing which shows a piezoelectric element part combined with this sectional drawing. (A) is explanatory drawing which shows nozzle arrangement | positioning in the inkjet recording head of 1st Embodiment of this invention, (B) is a graph which shows the distance between nozzles in this inkjet recording head. It is explanatory drawing which shows the arrangement | positioning of the ejector of a head unit which does not correspond to this invention, and a common flow path for a comparison. (A) is explanatory drawing which shows the nozzle arrangement | positioning in the inkjet recording head of the comparative example 1, (B) is a graph which shows the distance between nozzles in this inkjet recording head. (A) is explanatory drawing which shows the nozzle arrangement in the inkjet recording head of 2nd Embodiment of this invention, (B) is explanatory drawing which shows the nozzle arrangement in the inkjet recording head of the comparative example 2. FIG. It is explanatory drawing which shows nozzle arrangement | positioning in the head unit of 2nd Embodiment of this invention. It is explanatory drawing which shows the nozzle arrangement | positioning in the inkjet recording head of 3rd Embodiment of this invention. It is explanatory drawing which shows nozzle arrangement | positioning in the head unit of 3rd Embodiment of this invention. (A) is explanatory drawing which shows nozzle arrangement | positioning in the inkjet recording head of 4th Embodiment of this invention, (B) is explanatory drawing which shows the inter-nozzle distance in the state in which (theta) deviation has not arisen, (C ) Is an explanatory view showing the inter-nozzle distance in a state where the θ deviation occurs. (A) is explanatory drawing which shows nozzle arrangement in the inkjet recording head of 5th Embodiment of this invention, (B) is explanatory drawing which shows nozzle arrangement in the inkjet recording head of the comparative example 3. FIG. It is explanatory drawing which shows nozzle arrangement | positioning in the head unit of 5th Embodiment of this invention. It is explanatory drawing which shows arrangement | positioning of the ejector and common flow path of the head unit of 2nd Embodiment of this invention. It is explanatory drawing which shows arrangement | positioning of the ejector and common flow path of the head unit of 3rd Embodiment of this invention. It is a block diagram which shows the inkjet recording head provided with the head unit of the 3rd modification of this invention. It is a block diagram which shows the inkjet recording head provided with the head unit of the 4th modification of this invention. It is a block diagram which shows the inkjet recording head provided with the head unit of the 5th modification of this invention. It is a block diagram which shows the inkjet recording head provided with the head unit of the 6th modification of this invention. FIG. 10 is a configuration diagram illustrating an ink jet recording head including a head unit of Comparative Example 4. FIG. 10 is a configuration diagram illustrating an ink jet recording head including a head unit of Comparative Example 5. 10 is a configuration diagram showing an ink jet recording head including a head unit of Comparative Example 6. FIG. 10 is a configuration diagram showing an ink jet recording head including a head unit of Comparative Example 7. FIG. 1 is a schematic diagram illustrating an overall configuration of an inkjet recording apparatus of the present invention.

Explanation of symbols

12 Head unit 14 Ejector area 14A Ejector area 14B Ejector area 16 Nozzle 18 Base plate 20 Ink flow path 22 Heat sink 24 Circuit board 26 Electrical wiring 28 Switch IC
30A upstream flow path 30B upstream flow path 32 common flow path 34 inkjet recording head 36 pressure chamber 38 nozzle communication chamber 40 opening 42 ink supply path 44 nozzle plate 44D damper 46 ink pool plate 50 through plate 52 ink supply path plate 54 Pressure chamber plate 57 Vibration plate 58 Piezoelectric element 62 Head unit 64 Common channel 66 Head unit 68 Ink supply hole 70 Inkjet recording head 72A Upstream channel 72B Upstream channel 80 Inkjet recording head 82 Common channel 84 Common channel 90 Inkjet recording head 92 Suction hole 94 Alignment mark 100 Inkjet recording head 102 Head unit 104 Support section 106 Electrical wiring 106A Bending section 112 Inkjet recording apparatus 114 Housing 116 Paper feed tray 118 Pickup roll 120 Conveying roller pair 122 Conveying path 124 Drive roll 126 Driven roll 128 Conveying belt 128F Flat portion 130 Recording head array 134 Maintenance unit 136 Charging roll 140 Release plate 142 Discharging roller pair 144 Discharging path 146 Discharging tray 148 Cleaning roll 150 Inversion roller pair 152 Inversion path 154 Ink tank 312 Inkjet recording head 314 Head unit 316 Nozzle 316 Nozzle 318 Overlap area 322 Inkjet recording head 324 Head unit 326 Nozzle 328 Overlap area 332 Inkjet recording head 334 Head unit 336 Nozzle 338 Over Lap region 342 Inkjet recording head 344 Head unit Doo 346 nozzle 348 overlap region P paper SE discharge area

Claims (10)

A long droplet discharge head in which a plurality of nozzles for discharging droplets are arranged in a two-dimensional plane in a staggered arrangement in a plurality of rows,
The position of the nozzle in the width direction orthogonal to the longitudinal direction of the droplet discharge head is arranged so as to be periodically different in the longitudinal direction of the head unit,
In the joint portion of the head units adjacent in the longitudinal direction of the droplet discharge head , the nozzles at both ends in the longitudinal direction of the head unit are on the side of the adjacent head unit in the width direction. Discharge head. The droplet discharge head according to claim 1,
A droplet discharge characterized in that the head unit is arranged so that an overlap region where the nozzles overlap in the width direction is formed between the head units adjacent in the longitudinal direction of the droplet discharge head. head.   The nozzle at the end of the overlap region is disposed so as to be close to the nozzle adjacent to the overlap region in the head unit including the overlap region in the width direction. The droplet discharge head described.   The nozzle at the end of the overlap region is disposed so as to be close to the nozzle adjacent to the overlap region in the head unit adjacent to the overlap region in the width direction. Alternatively, the droplet discharge head according to claim 3. Widthwise position of the nozzle adjacent the leading SL overlap region, and adjacent nozzles in the overlap region of the head unit including the overlap region, and adjacent nozzles of the head unit adjacent to the overlap region, the The droplet discharge head according to claim 2 , wherein the head unit is disposed so as to be in between.   In the overlap region, the head unit is arranged so that the distance between the nozzles overlapping on the end side of the overlap region is smaller than the distance between the nozzles overlapping on the center side of the overlap region. The liquid droplet ejection head according to claim 2, wherein the liquid droplet ejection head is provided.   The distance between the nozzles arranged so as to be close to each other in the width direction at the joint of the head units is equal to or less than the width of the head unit. Droplet discharge head.   When the divided portions are configured by dividing the head unit in the width direction, the dots of the liquid droplets discharged from the nozzles of the divided portions are arranged so as to be evenly arranged on the member to be discharged. The droplet discharge head according to any one of claims 1 to 7.   2. The nozzles are arranged in the head unit so that dots of liquid droplets discharged from a nozzle far from a longitudinal center line and a nozzle close to the longitudinal center line are mixedly arranged on the member to be discharged. The droplet discharge head according to claim 8.   A droplet discharge apparatus comprising the droplet discharge head according to claim 1.

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