JP2014144615A - Head module, liquid discharge head, and liquid discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fall of a liquid making an entry into a gap between head modules, without increasing components.SOLUTION: A head module includes a nozzle surface that comprises a nozzle for discharging a liquid, and a side surface that crosses the nozzle surface. A first water-repellent area, which includes a base brought into contact with the nozzle surface, and a second hydrophilic area, which has a boundary between itself and the first area elongated to the other lateral side from one lateral side crossing the base, are formed on the side surface. A distance between the boundary and the base is gradually decreased toward the lateral side from a maximal distance position. The above problem is solved by the head module.

Description

  The present invention relates to a head module, a liquid discharge head, and a liquid discharge apparatus, and more particularly to a replaceable head module, a liquid discharge head including the same, and a liquid discharge apparatus.

  A technique for forming a long recording head by connecting a plurality of head modules is known. In such a recording head, a gap is generated at the connecting portion of the head modules. If ink enters the gap, the ink that has entered may drop during printing, which may adversely affect the printed matter. Therefore, it is preferable to close this gap. However, when the head module can be replaced, it is difficult to close the gap.

  In order to deal with such problems, Patent Document 1 discloses a technique in which a gap in which a capillary force acts between the head modules from the lower part to the upper part is provided between the head modules, and a collecting unit that collects the liquid in the gaps is provided on the upper part of the head module. Have been described.

  Patent Document 2 describes a technique in which the side surface of the head module is formed in a lyophilic solution, the ink adhering to the nozzle surface is sucked into the gap, and the sucked ink is absorbed by the ink absorbing member. .

  According to Patent Documents 1 and 2, since the ink that has entered the gap is collected or absorbed, the print quality can be maintained without dropping the ink that has entered the gap.

JP 2008-62389 A Japanese Utility Model Publication No. 2006-321172

  However, Patent Document 1 requires a collecting means and Patent Document 2 requires an absorbing member, leading to an increase in the size and cost of the apparatus.

  The present invention has been made in view of such circumstances, and provides a head module, a liquid discharge head, and a liquid discharge apparatus that prevent the liquid that has entered the gap between the head modules from falling without increasing the number of components. With the goal.

  In order to achieve the above object, one aspect of a head module includes a nozzle surface having a nozzle for discharging a liquid and a side surface intersecting the nozzle surface, and the side surface includes a bottom side in contact with the nozzle surface. And a hydrophilic second region extending from one side where the boundary of the first region intersects the bottom to the other side is formed, and the distance between the boundary and the bottom is The distance gradually decreases from the position with the largest distance toward the side.

  According to this aspect, the water-repellent first region that includes the bottom that is in contact with the nozzle surface on the side surface that intersects the nozzle surface, and the one side that intersects the bottom side from the first side to the other side A hydrophilic second region extending to the side is formed, and the distance between the boundary and the base is gradually decreased from the position where the distance is the largest toward the side, so that the liquid attached to the side is appropriately Can be discharged. In addition, since the time until discharging can be shortened, it is possible to discharge before performing the liquid discharging operation.

  It is preferable that the first region and the second region are formed on the two opposite side surfaces, and the respective boundaries on the two side surfaces are formed to have a mirror image inversion relationship. As a result, when connecting a plurality of head modules, the boundaries of the side surfaces of the respective head modules can be matched and connected, so that the liquid that has entered the gap between the contact portions can be appropriately discharged.

  The position where the distance is greatest is an intermediate position between the one side and the other side, and the boundary is preferably formed symmetrically with respect to the intermediate position. As a result, when connecting a plurality of head modules, the boundaries of the side surfaces of the respective head modules can be matched and connected, so that the liquid that has entered the gap between the contact portions can be appropriately discharged.

  The first region is preferably formed by a water repellent material applied to the side surface. Thereby, the liquid that has entered the gap becomes easy to flow and can be appropriately discharged.

  The side surface may have a water-repellent third region in which a boundary with the second region extends from one side to the other side. Thereby, the liquid which accumulates in the 2nd field among the liquid which entered into the crevice between contact parts can be reduced, and it can discharge appropriately.

  The boundary between the first region and the second region and the boundary between the second region and the third region may be formed in parallel. Moreover, it is preferable that the distance between the boundary between the first region and the second region and the boundary between the second region and the third region is gradually increased toward the side. By forming the third region in this manner, the liquid that has entered the gap between the contact portions can be appropriately discharged.

  The nozzle surface preferably has water repellency. Thereby, it becomes difficult for the liquid to enter the gap between the contact portions.

  In order to achieve the above object, one aspect of the liquid discharge head is a head module holding unit that holds and holds a plurality of head modules connected in series, and the boundaries of the side surfaces of adjacent head modules are made to coincide with each other. The head module holding means to contact was provided.

  According to this aspect, the water-repellent first region that includes the bottom that is in contact with the nozzle surface on the side surface that intersects the nozzle surface, and the one side that intersects the bottom side from the first side to the other side Forming a hydrophilic second region extending to the side, and gradually decreasing the distance between the boundary and the base from the position where the distance is the largest toward the side, and each side surface of the adjacent head module Since the boundaries are brought into contact with each other and are continuously connected and held, the liquid that has entered the gap between the contact portions can be appropriately discharged.

  In order to achieve the above object, one aspect of the liquid ejection apparatus includes: a conveyance unit that conveys a recording medium; a liquid ejection head holding unit that holds the liquid ejection head facing the recording medium; and a nozzle of the liquid ejection head. And a control unit that performs recording on the recording medium by discharging the liquid, and the liquid discharge head holding unit holds the boundary between the first region and the second region inclined with respect to the horizontal.

  According to this aspect, the water-repellent first region that includes the bottom that is in contact with the nozzle surface on the side surface that intersects the nozzle surface, and the one side that intersects the bottom side from the first side to the other side Forming a hydrophilic second region extending to the side, and gradually decreasing the distance between the boundary and the base from the position where the distance is the largest toward the side, and each side surface of the adjacent head module Since the liquid discharge head that is held in contact with the boundary being matched and continuously connected is used, the liquid that has entered the gap of the contact portion can be appropriately discharged.

  You may provide the wiping cleaning means which wipes and cleans the nozzle surface of a liquid discharge head. Further, the control means may cause the liquid ejection head to be purged. Thus, even when the liquid remains on the nozzle surface during wiping cleaning or purging and the liquid enters the gap between the contact portions, the liquid can be appropriately discharged.

  According to the present invention, it is possible to prevent the liquid that has entered the gap from falling onto the recording medium without increasing the number of components that receive the liquid that enters the gap and falls.

Side view of inkjet recording device Plan view of inkjet recording apparatus Schematic diagram of wiping unit Block diagram of inkjet recording device Perspective view of inkjet head Diagram showing the configuration of the side of the head module Side view of the head module side Illustration of the action of the side of the head module The figure which shows the modification of a structure of a head module side surface Side view of inkjet recording device The figure which shows the inclination of the nozzle surface of each ink jet head Top view of inkjet head Enlarged view of FIG. Plan view showing nozzle arrangement of head module Cross section of recording element The figure which shows the composition of the side of the head module

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
[Outline of inkjet recording apparatus]
FIG. 1 is a side view showing an ink jet recording apparatus according to the present embodiment. The ink jet recording apparatus 200 (an example of a liquid ejection apparatus) has an ink jet head 220 (an example of a recording medium) on a recording surface of a sheet 1 (an example of a recording medium) that is transported in a horizontal direction (Y direction) by a transport unit 210 (an example of a transport unit). This is a printer that ejects ink from the nozzle surface 230 of an example of a liquid ejection head to form an image. The inkjet head 220 is held with the nozzle surface 230 horizontal. The nozzle surface 230 refers to the entire surface of the inkjet head 220 that faces the paper 1.

  FIG. 2 is a plan view of the ink jet recording apparatus 200. The ink jet recording apparatus 200 includes a moisturizing cap 280 and a wiping unit 290 in a direction (X direction) orthogonal to the transport direction (Y direction) of the paper 1 by the transport unit 210.

  The inkjet head 220 is configured to be movable in the X direction by a head moving mechanism (not shown). When the apparatus is stopped for a long time, the ink jet head 220 is moved from a position where the image can be formed on the paper 1 (image forming position) to a position of the moisturizing cap 280 (moisturizing position), and the nozzle surface 230 is moved to the moisturizing cap 280. Covered with. Thereby, non-ejection due to drying is prevented.

  The moisturizing cap 280 is provided with a pressurizing / suction mechanism (not shown) for pressurizing and sucking the inside of the nozzle, and a cleaning liquid supply mechanism (not shown) for supplying a cleaning liquid into the moisturizing cap 280.

  The wiping unit 290 (an example of wiping and cleaning means) is disposed between the transport unit 210 and the moisturizing cap 280. The wiping unit 290 cleans the nozzle surface 230 by wiping the nozzle surface 230 of the inkjet head 220 with the wiping web to which the cleaning liquid is applied when the inkjet head 220 moves from the image forming position to the moisturizing position.

[Overview of wiping unit]
FIG. 3 is a schematic diagram illustrating a schematic configuration of the wiping unit 290. As shown in the figure, the wiping unit 290 is driven to rotate by a sending-side web core 292 that sends out the wiping web 291 before wiping, and a winding motor (not shown), so that the wiping web 291 that has been wiped off is removed. A winding side web core 293 to be wound up, a first guide roll 294 that rotates in contact with the wiping web 291 sent out from the sending side web core 292, and guides to the cleaning liquid application unit 295, and a predetermined amount on the wiping web 291. A cleaning liquid application unit 295 that applies a cleaning liquid, a second guide roll 296 that rotates in contact with the wiping web 291 delivered from the cleaning liquid application unit 295, and guides the wiping web 291 to the pressure roll 297. And a pressing roll 297 that is brought into contact with the surface 230 with a predetermined pressure.

  The wiping web 291 is formed of a sheet made of knitting or weaving using ultrafine fibers such as polyethylene terephthalate, polyethylene, nylon, and the like, and is formed in a strip shape having a width corresponding to the width of the nozzle surface 230 of the inkjet head 220. Is done. The wiping web 291 is provided in a state where the wiping web 291 is wound around the delivery-side web core 292 in a roll shape and the tip is fixed to the take-up-side web core 293.

  The delivery-side web core 292 is fitted and attached to a delivery shaft (not shown) that is fixed at one end and supported horizontally. The delivery shaft has a double tube structure, and an outer cylinder is rotatably supported around the inner cylinder. A reverse rotation prevention mechanism and a friction mechanism are disposed between the inner cylinder and the outer cylinder, and the outer cylinder is configured to rotate only in one direction (the feeding direction of the wiping web 291) with a certain resistance.

  The winding-side web core 293 is fitted and mounted on a winding shaft (not shown) that is rotatably supported horizontally. A winding motor is connected to the winding shaft, and the winding-side web core 293 is driven by the winding motor and rotates in one direction (winding direction of the wiping web 291).

  The take-up shaft has a double structure, and an outer cylinder is rotatably supported around the inner cylinder. A torque limiter is disposed between the inner cylinder and the outer cylinder, and is configured such that the outer cylinder slides with respect to the inner cylinder when a load (torque) exceeding a certain level is applied. Thereby, it is possible to prevent excessive tension from being applied to the wiping web 291.

  The first guide roll 294 is rotatably supported by a horizontally installed shaft (not shown), and guides the wiping web 291 sent from the sending-side web core 292 toward the cleaning liquid application unit 295.

  The cleaning liquid application unit 295 sprays the cleaning liquid onto the wiping web 291 from the cleaning liquid nozzle, and quantitatively applies the cleaning liquid to the wiping web 291. The method for applying the cleaning liquid to the wiping web 291 is not limited to spraying from the cleaning liquid nozzle. For example, the aspect provided using an anilox roll etc. can be considered.

  The second guide roll 296 is rotatably supported by a horizontally installed shaft (not shown), and guides the wiping web 291 sent from the cleaning liquid application unit 295 toward the pressing roll 297.

  The pressing roll 297 is horizontally installed with one end of its shaft portion being rotatably supported. The pressing roll 297 is composed of a rubber roll corresponding to the width of the wiping web 291, and causes the wiping web 291 to contact the nozzle surface 230 of the inkjet head 220 with a predetermined pressure.

[Operation of wiping unit]
Next, the operation of the wiping unit 290 configured as described above will be described.

  The operation of the wiping unit 290 is controlled by a control device that controls the entire inkjet recording apparatus 200. The control device wipes and cleans the nozzle surface 230 by the wiping unit 290 in the process of moving the ink jet head 220 from the image recording position to the moisturizing position.

  The entire wiping unit 290 is configured to be movable up and down by a wiping device main body lifting mechanism. The wiping unit 290 is positioned at a predetermined standby position except during cleaning, and is positioned at a predetermined operating position that is a position raised by a predetermined amount from the standby position during cleaning.

  In the state where the wiping unit 290 is located at the operating position, it becomes possible to wipe the nozzle surface 230 of each inkjet head 220 by each wiping unit 290. That is, when the inkjet head 220 passes through each wiping unit 290, the wiping web 291 wound around the pressure roll 297 can be pressed against the nozzle surface 230.

  The control device controls the conveyance of the wiping web 291 by controlling the driving of the winding motor in accordance with the timing at which the inkjet head 220 reaches the wiping unit 290. Thereby, the wiping web 291 is unwound from the sending-side web core 292 and travels, and is taken up by the winding-side web core 293.

  At this time, the delivery shaft of the delivery-side web core 292 is given friction by a friction mechanism, while the take-up shaft of the take-up web core 293 slips when a certain load is applied by the torque limiter, so that the wiping web 291 It is possible to run the vehicle with a certain tension applied thereto.

  In addition, the control device controls the cleaning liquid application unit 295 simultaneously with the traveling of the wiping web 291 to wet the wiping web 291 with the cleaning liquid. The amount of cleaning liquid of an appropriate amount of the wiping web 291 (an amount suitable for wiping the nozzle surface 230) is the absorption capacity of the wiping web 291, the liquid repellency (ink contact angle) of the nozzle surface 230, the ink physical properties, the nozzle diameter. It depends on. Therefore, the cleaning liquid may be ejected from the cleaning liquid applying unit 295 according to the amount of cleaning liquid required.

  As a result, the wiping web 291 can be in a state of being wetted by an appropriate amount of cleaning liquid, and the wiping web 291 has an optimal absorption capacity. As a result, it is possible to prevent the cleaning liquid from entering the liquid and dripping when the nozzle surface 230 is wiped off.

  The wiping web 291 to which the cleaning liquid is given in a fixed amount in this way is guided to the pressing roll 297 by the second guide roll 296, and is pressed against the nozzle surface 230 at the pressing roll 297 by driving by the take-up motor. 230 is wiped and cleaned.

  At this time, the wiping web 291 travels in the direction opposite to the moving direction of the nozzle surface 230 and wipes the nozzle surface 230. Thereby, the nozzle surface 230 can be wiped off efficiently. In addition, the nozzle surface 230 can be wiped using the new surface (unused area) of the wiping web 291 at all times.

  The wiping web 291 that has wiped the nozzle surface 230 is wound around the winding-side web core 293. In addition, the inkjet head 220 is moved to the moisturizing position by the head moving mechanism, and the nozzle surface 230 is covered with the moisturizing cap 280.

[System configuration of inkjet recording apparatus]
FIG. 4 is a block diagram illustrating a system configuration of the inkjet recording apparatus 200. As shown in the figure, the ink jet recording apparatus 200 includes a control unit 202, an ink supply unit 204, a moving mechanism 206, and the like in addition to the above-described transport unit 210, ink jet head 220, moisturizing cap 280, and wiping unit 290. Is done.

  The control unit 202 performs overall control of the ink jet recording apparatus 200. For example, in addition to the conveyance of the paper 1 by the conveyance unit 210, the image recording by the inkjet head 220, the movement of the inkjet head 220 to the moisturizing position by the moving mechanism 206, the wiping cleaning of the nozzle surface 230 by the wiping unit 290, all of the inkjet head 220 is performed. A pressure purge for discharging ink from the nozzles is controlled.

  The ink supply unit 204 includes an ink tank and a pump (not shown), and supplies ink ejected from the nozzles of the inkjet head 220 to the inkjet head 220.

  The moving mechanism 206 moves the inkjet head 220 to the image recording position or the moisturizing position.

[Configuration of inkjet head]
FIG. 5A is a perspective view of the inkjet head 220 viewed from the nozzle surface 230 side. As shown in the figure, the inkjet head 220 includes a plurality of (here, five) head modules 240 and support members 250 and 252 that support the respective side surfaces of the plurality of head modules 240 in contact with each other. And a plurality of head modules 240 are arranged in the width direction of the paper 1 (X direction in FIG. 1) and connected to form a long line head.

  The inkjet head 220 is configured such that each head module 240 can be replaced. FIG. 5B is a perspective view showing a state where one head module 240 is removed from the inkjet head 220.

  As shown in FIG. 5B, each head module 240 includes a nozzle plate 244 in which a plurality of nozzles 242 are formed, and a fixing portion 246 for fixing the head module 240 to the support member 250. The surface of the nozzle plate 244 is water repellent and has water repellency. The entire nozzle surface 230 may be water repellent by performing water repellent treatment on the surface of the fixing portion 246 and the surface of the support member 250.

  Here, of the side surfaces intersecting with the nozzle surface 230 of the head module 240, the side surface that contacts the adjacent head module 240 or the support member 252 is denoted by reference numeral 260, and the side surfaces other than the side surface 260 are denoted by reference numeral 270.

[Configuration of the side of the head module]
Next, an example of the configuration of the side surface of the head module will be described. 6A is a perspective view of the head module 240 as viewed from the side surface 260, and FIG. 6B is a diagram showing the dimensions of the configuration of the side surface 260. FIG. Here, among the side surfaces 260, the bottom side in contact with the nozzle surface 230 is denoted by reference numeral 232, the side side in contact with the left side surface 270 in the figure is denoted by reference numeral 272L, and the side side in contact with the right side surface 270 in the figure is denoted by reference numeral 272R.

  As shown in FIG. 6, the side surface 260 of this example includes a relatively water-repellent water-repellent region 260 </ b> A (an example of a first region) and a relatively hydrophilic region 260 </ b> B (second region). Example).

  The water repellent region 260 </ b> A is formed including the entire bottom side 232 of the side surface 260. Further, the water repellent region 260A and the hydrophilic region 260B are formed to contact each other and have a boundary 262, and the boundary 262 extends from the side 272L to the side 272R. Here, the intersection of the boundary 262 and the side 272L is represented as a point L, and the intersection of the boundary 262 and the side 272R is represented as a point R.

  The distance in the Z direction between the boundary 262 and the base 232 is the largest at a certain point on the boundary 262, and gradually decreases toward the side 272L and 272R. Here, the gradual decrease refers to a state of continuously and smoothly decreasing.

In the example shown in FIG. 6B, the distance h in the Z direction between the boundary 262 and the base 232 has a maximum value h _{P at the} point P. Further, in the region of the boundary 262 that is closer to the side 272L than the point P, the distance h decreases continuously and smoothly from the point P toward the point L, and becomes the minimum value h _L at the point L. Similarly, in the region of the boundary 262 that is closer to the side 272R than the point P, the distance h decreases continuously and smoothly from the point P toward the point R, and reaches the minimum value h _R at the point R.

In this example, the distance w _{L in} the Y direction between the point P and the side 272L and the distance w _{R in} the Y direction between the point P and the side 272R have a relationship of w _L = w _R. However, w _L and w _R may be different values. An embodiment in which w _L = 0 or w _R = 0 is also possible. In this case, point P = point L or point P = point R.

Further, in this example, the minimum value h _L of the distance h in the region closer to the side 272L than the point P in the boundary 262, and the minimum value of the distance h in the region closer to the side 272R than the point P in the boundary 262. the value _{h R,} has the relation of _h L = h _R, it may be a different value from the _{h L} and _{h R.} A mode in which h _L = 0 or h _R = 0 is also possible.

  Further, in this example, the boundary 262 is formed from a straight line from the point P to the point L and from the point P to the point R. However, a form formed by a curve is also possible. Further, the point P may not be an intersection of two lines but a vertex on a curve.

  In any case, the inkjet head 220 is brought into contact with the boundaries 262 of the side surfaces 260 of the head modules 240 arranged adjacent to each other, so that each head module 240 is supported by the support member 250, 252 to support. That is, the boundary 262 formed on each side surface 260 in contact with each other needs to have a mirror image inverted relationship. For this reason, the water repellent region 260A and the hydrophilic region 260B are formed on the two side surfaces 260 of each head module 240 in a mirror image reversal relationship.

  FIG. 7 is an enlarged view of the side surface 260 when the head module 240 is viewed from the side surface 270 side. As shown in the figure, the water repellent region 260A is formed by applying a water repellent material to the surface of the side surface 260 having hydrophilicity. Thereby, the water repellent region 260A has a width in the X direction more than the hydrophilic region 260B. Accordingly, when the side surfaces 260 of the plurality of head modules 240 are brought into contact with each other, the gap between the water repellent areas 260A is small and the gap between the hydrophilic areas 260B is large.

  Note that the method of forming the water repellent region 260A and the hydrophilic region 260B is not limited thereto, and the hydrophilic region 260B may be formed by applying a hydrophilic material to the surface of the side surface 260 having water repellency. A mode is also possible in which the water-repellent region 260A is formed by applying a material and the hydrophilic region 260B is formed by applying a hydrophilic material.

[Operation of the side of the head module]
Next, the operation of the side surface of the head module configured as described above will be described.

  When pressure purge for discharging ink from all the nozzles 242 of the ink jet head 220 or wiping cleaning of the nozzle surface 230 in the wiping unit 290 is performed, ink or cleaning liquid adheres to the nozzle surface, and a part of them is brought into contact with each other. Enters the gap between the head modules 240. In FIG. 8, this ink or cleaning liquid is represented by reference numeral 2, and is hereinafter referred to as liquid 2.

  As shown in FIG. 8A, when the amount of the liquid 2 present on the bottom 232 is small, the water repellent property of the water repellent region 260A on each side surface 260 of the two head modules 240 that form a gap facing each other. Due to the action and the water repellent action of the nozzle surface 230, the liquid 2 is bounced without entering the inside of the gap between the head modules 240 (upper part in FIG. 8) and falls as it is.

  On the other hand, when the amount of the liquid 2 existing on the bottom 232 is large, or when the liquid 2 adhering to the nozzle surface 230 is pushed in by the wiping web 291 of the wiping unit 290, the liquid 2 is between the head modules 240. Get inside the gap.

  The liquid 2 that has entered the inside forms a single aggregate as shown in FIG. When the liquid 2 that has become an aggregate increases in size and reaches the hydrophilic region 260B, it is attracted from the water-repellent region 260A to the hydrophilic region 260B due to the difference in surface energy between the water-repellent region 260A and the hydrophilic region 260B. To flow.

  Further, as shown in FIG. 8 (c), the liquid 2 that has reached the hydrophilic region 260B has a downward slope toward the side 272L formed by the boundary 262 or a downward slope toward the side 272R formed by its own weight and gravity. And is discharged from the side surface 270 side of the head module 240. In particular, as shown in FIG. 7, when the water repellent region 260A and the hydrophilic region 260B are formed, the flow of the liquid 2 is further promoted.

  By configuring the side surface 260 in this manner, the liquid 2 can be immediately discharged (dropped) regardless of whether the amount of the liquid 2 entering the gap between the head modules 240 is small or large. Therefore, the liquid 2 falls toward the moisturizing cap 280 and the wiping unit 290. Thereby, it is not necessary to increase the number of components that receive the liquid 2 that falls into the gap between the head modules 240, and the liquid 2 can be prevented from falling on the paper 1 during image formation.

[Modified example of configuration of side surface of head module]
FIG. 9 is a diagram illustrating a modified example of the configuration of the side surface 260. As shown in the figure, the side surface 260 in this modification includes a relatively water-repellent water-repellent region 260A, a relatively hydrophilic hydrophilic region 260B, and a relatively water-repellent water-repellent region. 260C.

  The water repellent area 260A is formed in the same manner as the water repellent area 260A shown in FIG. Further, the water repellent region 260A and the hydrophilic region 260B are formed to have a boundary 262 in contact with each other.

The water repellent region 260C is formed of the same water repellent material as the water repellent region 260A. Moreover, the hydrophilic region 260B and the water-repellent region 260C, which is formed with a boundary 264 in contact with each other, the boundary 264 is formed in parallel separated by a boundary 262 and the distance _{h d.}

  By configuring the side surface 260 in this manner, when the liquid 2 enters the gap between the head modules 240, the liquid 2 that has reached the hydrophilic region 260B is repelled by the water repellent action of the water repellent region 260C. It becomes easy to flow along the down slope formed by the boundary 262.

Therefore, the liquid 2 is less likely to accumulate in the hydrophilic region 260B, and the time from when the liquid 2 enters between the head modules 240 to when it falls can be shortened. Time until this fall can be controlled by the distance h _d. That is, the time can be shortened as the distance _hd is smaller.

The shape of the water repellent region 260C may be determined according to the shape of the water repellent region 260A. The distance _{h d} rather than a constant, sides 272L, widely toward the 272R (increasing), or narrow may be (gradually decreases). Since the sides 272L, the flow rate of the liquid 2 closer to 272R increases, the distance _{h d} may include a mode where widely closer sides 272L, the 272R is preferred.

<Second Embodiment>
[Outline of inkjet recording apparatus]
FIG. 10 is a schematic side view showing the ink jet recording apparatus according to this embodiment. The inkjet recording apparatus 100 is a single-pass line printer that forms an image on the recording surface of paper 1 (an example of a recording medium), and includes a transport drum 110, inkjet heads 120M, 120K, 120C, and 120Y.

  Two grippers 112 for gripping the leading edge of the paper 1 are provided at positions facing each other across the rotation axis of the conveyance surface of the conveyance drum 110. A number of suction holes (not shown) are formed in a predetermined pattern on the conveyance surface of the conveyance drum 110. The paper 1 introduced from the paper supply unit 102 and wrapped around the peripheral surface of the transport drum 110 while being gripped by the gripper 112 is sucked and held on the peripheral surface of the transport drum 110 by being sucked from the suction holes. While being carried, the paper is conveyed in the paper conveyance direction which is the rotation direction of the conveyance drum 110.

  The four inkjet heads 120M, 120K, 120C, and 120Y are sequentially arranged from the upstream side at a predetermined interval in the paper conveyance direction of the conveyance drum 110, respectively. Magenta ink (M ink), black ink (K ink), cyan ink (C ink), yellow ink (on the surface (nozzle surface) of each inkjet head 120M, 120K, 120C, 120Y facing the conveying drum 110, respectively. A plurality of nozzles for discharging (Y ink) are formed over the entire width of the paper 1.

The inkjet heads 120M, 120K, 120C, and 120Y are held so that the nozzle surfaces 122M, 122K, 122C, and 122Y are parallel to the tangential direction at the position where the conveyance surface of the conveyance drum 110 faces. Therefore, the nozzle surfaces 122M, 122K, 122C, and 122Y are inclined by θ _M , θ _K , θ _C , and θ _{Y with} respect to the horizontal (Y direction), respectively, as shown in FIG. . In this embodiment, as an example, θ _M = 24 degrees, θ _K = 8 degrees, θ _C = 8 degrees, and θ _Y = 24 degrees.

  Returning to the description of FIG. 10, a control unit (not shown) controls the ink jet heads 120 </ b> M, 120 </ b> K, 120 </ b> C, and 120 </ b> Y to discharge ink from each nozzle. Thereby, an image is formed on the recording surface of the sheet 1 conveyed by the conveyance drum 110.

  The paper 1 on which the image is formed on the recording surface by the ink jet heads 120M, 120K, 120C, and 120Y is discharged from the paper discharge unit 104.

  As described above, the ink jet recording apparatus 100 can form an image on the entire recording surface of the paper 1 by one transport (single pass) by the transport drum 110.

[Inkjet head structure]
Next, an example of the structure of the inkjet heads 120M, 120K, 120C, and 120Y will be described. Since the inkjet heads 120M, 120K, 120C, and 120Y corresponding to the respective colors have the same structure, the heads 120 will be representatively represented below.

  FIG. 12 is a plan view showing a structural example of the head 120, and is a view of the head 120 as viewed from the nozzle surface 122 side. FIG. 13 is a partially enlarged view of FIG.

  As shown in FIG. 12, the head 120 has a structure in which n head modules 120-i (i = 1, 2, 3,..., N) are connected along the X direction, and the entire width of the sheet 1. A plurality of nozzles (not shown in FIG. 12) are provided over a length corresponding to.

  Each head module 120-i is supported by a head module support member 120B from both sides of the head 120 in the short direction. Further, both end portions of the head 120 in the longitudinal direction are supported by a head support member 120D. Each head module 120-i has the same configuration as the configuration of the side surface shown in FIG. 6 in the side surface facing and abutting against the adjacent head module 120-i or the head support member 120D. That is, a water-repellent region including a bottom side in contact with the nozzle surface 122 and a hydrophilic region extending from one side where the boundary of the water-repellent region intersects the bottom side to the other side are formed. The distance is configured to gradually decrease from the position having the largest distance toward the side. In addition, as shown in FIG. 9, you may provide the water repellent area | region which touches a hydrophilic area | region further.

  As shown in FIG. 13, each head module 120-i has a structure in which a plurality of nozzles are arranged in a matrix (two-dimensional). In FIG. 13, an oblique solid line denoted by reference numeral 132 represents a nozzle row in which a plurality of nozzles are arranged in a row.

  FIG. 14 is a plan view showing the nozzle arrangement of the head module 120-i. As shown in the figure, the head module 120-i has a large number of nozzles 130 in a matrix form along a column direction W that forms an angle α with respect to the Y direction and a row direction V that forms an angle β with respect to the X direction. The substantial nozzle arrangement density in the X direction is increased. In FIG. 14, the nozzle groups (nozzle rows) arranged along the column direction W are shown with reference numeral 134, and the nozzle groups (nozzle rows) arranged along the row direction V are assigned reference numeral 136. Is shown.

  Note that the nozzle arrangement applicable to the present embodiment is not limited to the nozzle arrangement illustrated in FIG. 14, for example, along the row direction along the X direction and the column direction oblique to the X direction and the Y direction. The present invention can also be applied to an embodiment in which a plurality of nozzles are arranged in a matrix.

  FIG. 15 is a cross-sectional view of a recording element corresponding to one nozzle 130. As shown in the figure, the head 120 (head module 120-i) of this example includes a nozzle plate 144 in which a nozzle 130 is formed, and a flow path in which flow paths such as a pressure chamber 146 and a common flow path 148 are formed. It has a structure in which plates 150 and the like are laminated and joined. The nozzle plate 144 constitutes a part of the nozzle surface 122 of the head 120, and a plurality of nozzles 130 communicating with the pressure chambers 146 are two-dimensionally formed.

  The flow path plate 150 constitutes a side wall portion of the pressure chamber 146 and forms a supply port 152 as a throttle portion (most narrowed portion) of an individual supply path that guides ink from the common flow path 148 to the pressure chamber 146. It is a forming member. For convenience of explanation, the flow path plate 150 has a structure in which one or a plurality of substrates are stacked, although it is illustrated in FIG. 15 in a simplified manner.

  The nozzle plate 144 and the flow path plate 150 can be processed into a required shape by a semiconductor manufacturing process using silicon as a material.

  The common flow path 148 communicates with an ink tank (not shown) that is an ink supply source, and the ink supplied from the ink tank is supplied to each pressure chamber 146 via the common flow path 148.

  A diaphragm 154 constituting a part of the pressure chamber 146 (the top surface in FIG. 15) includes an individual electrode 156 and a lower electrode 158, and the piezoelectric body 160 is sandwiched between the individual electrode 156 and the lower electrode 158. A piezoelectric actuator 162 having the above structure is joined. When the diaphragm 154 is formed of a metal thin film or a metal oxide film, it functions as a common electrode corresponding to the lower electrode 158 of the piezoelectric actuator 162. In the aspect in which the diaphragm is formed of a non-conductive material such as resin, a lower electrode layer made of a conductive material such as metal is formed on the surface of the diaphragm member.

  By applying a driving voltage to the individual electrode 156, the piezo actuator 162 is deformed to change the volume of the pressure chamber 146, and ink is ejected from the nozzle 130 due to the pressure change accompanying this. When the piezo actuator 162 returns to its original state after ink ejection, new ink is refilled into the pressure chamber 146 from the common flow path 148 through the supply port 152.

  As shown in FIG. 14, the ink chamber unit having such a structure is arranged in a lattice pattern with a fixed arrangement pattern along a row direction V that forms an angle β with respect to the X direction and a column direction W that forms an angle α with respect to the Y direction. By arranging a large number, the high-density nozzle head of this example is realized. In such a matrix arrangement, when the interval between adjacent nozzles in the Y direction is Ls, the nozzles 130 in the X direction are treated substantially equivalently to those in which the nozzles 130 are arranged linearly at a constant pitch P = Ls / tan θ. Can do.

  In this example, the piezo actuator 162 is applied as a means for generating ink ejection force ejected from the nozzles 130 provided in the head 120. However, a heater is provided in the pressure chamber 146, and the pressure of film boiling caused by heating of the heater is used. It is also possible to apply a thermal method that ejects ink.

  FIG. 16 is a diagram illustrating a configuration of a side surface that abuts on an adjacent head module 120-i among the side surfaces intersecting with the nozzle surface 122 of the head module 120-i. As shown in the figure, this side surface has a water repellent region 260A formed including the bottom side in contact with the nozzle surface 122, and a hydrophilic region 260B formed in contact with the water repellent region 260A at the boundary 262. The boundary 262 extends from one side intersecting the bottom side to the other side.

Further, as shown in FIG. 16 (a), from among point P of the boundary 262 to the point L is formed as a straight line with a slope of theta _L with respect to the nozzle surface 122 (bottom in contact with) the boundary 262 from among point P to the point R is formed as a straight line with a slope of theta _R with respect to the nozzle surface. Here, θ _K <θ _L = θ _R <θ _M is set.

FIG. 16B shows a case where the head module 120-i is used for the inkjet head 120K. The nozzle surface of the inkjet head 120 is inclined by θ _{K with} respect to the horizontal (Y direction). That is, of the boundary 262 of the head module 120-i, the line from the point P to the point L is a straight line having an inclination of θ _L −θ _K (> 0) with respect to the horizontal, and the point P to the point R is horizontal. On the other hand, it is a straight line having an inclination of θ _R + θ _K.

  Accordingly, the liquid 2 that has entered the gap between the head module 120-i and the head module 120- (i + 1) and has reached the hydrophilic region 260B is directed from the point P toward the point L or from the point P toward the point R. And flows along the boundary 262.

FIG. 16C shows a case where the head module 120-i is used for the inkjet head 120M. In this case, in the boundary 262 of the head module 120-i, the point P to the point L is a straight line having an inclination of θ _L −θ _M (<0) with respect to the horizontal, and the point P to the point R is A straight line having an inclination of θ _R + θ _M with respect to the horizontal.

  Accordingly, the liquid 2 that has entered the gap between the head module 120-i and the head module 120- (i + 1) and has reached the hydrophilic region 260B is directed from the point L toward the point P or from the point P toward the point R. And flows along the boundary 262.

In this example, the angles θ _L and θ _R formed by the nozzle surface 122 (bottom side in contact with the nozzle surface) 122 and the boundary 262 are set to satisfy the relationship θ _K <θ _L = θ _R <θ _M. However, the angle is limited to this. Instead, it is only necessary to satisfy an angle (θ _L ≠ θ _M ) at which the boundary 262 does not become horizontal when the nozzle surface is held inclined with respect to the horizontal. Note that the larger the angle between the boundary 262 and the horizontal, the faster the liquid 2 that has entered the gap can be discharged.

  In this way, the side surface 260 is configured and the boundary 262 is tilted and held with respect to the horizontal, so that the ink jet head used in a state where the nozzle surface is tilted with respect to the horizontal enters the gap between the head modules. The liquid can be drained (dropped) immediately. Accordingly, it is possible to prevent the ink from dropping onto the recording medium during image formation without increasing the number of components that receive the ink that falls into the gap between the head modules and falls.

  The technical scope of the present invention is not limited to the scope described in the above embodiment. The configurations and the like in the embodiments can be appropriately combined between the embodiments without departing from the gist of the present invention.

  2 ... Liquid, 120, 220 ... Inkjet head, 120-i, 240 ... Head module, 122, 230 ... Nozzle surface, 130, 242 ... Nozzle, 144, 244 ... Nozzle plate, 232 ... Bottom, 260, 270 ... Side, 260A, 260C ... water repellent area, 260B ... hydrophilic area, 262, 264 ... boundary, 272L, 272R ... side, 280 ... moisturizing cap, 290 ... wiping unit

Claims (12)

A nozzle surface with a nozzle for discharging liquid;
A side surface intersecting the nozzle surface;
With
The side surface includes a water-repellent first region including a bottom side in contact with the nozzle surface, and a hydrophilic property in which a boundary between the first region and the first region extends from one side to the other side. A second region of
The head module in which the distance between the boundary and the base gradually decreases from the position where the distance is the largest toward the side. The first region and the second region are formed on two opposing side surfaces,
The head module according to claim 1, wherein each of the boundaries on the two side surfaces is formed to have a mirror image reversal relationship.   3. The head module according to claim 2, wherein the position where the distance is the largest is an intermediate position between the one side and the other side, and the boundary is formed in line symmetry with respect to the intermediate position. .   4. The head module according to claim 1, wherein the first region is formed of a water repellent material applied to the side surface. 5.   5. The head according to claim 1, wherein the side surface has a water-repellent third region in which a boundary with the second region extends from the one side to the other side. module.   The head module according to claim 5, wherein a boundary between the first region and the second region and a boundary between the second region and the third region are formed in parallel.   The head module according to claim 5, wherein a distance between a boundary between the first region and the second region and a boundary between the second region and the third region gradually increases toward the side. .   The head module according to claim 1, wherein the nozzle surface has water repellency.   9. A head module holding means for holding a plurality of head modules according to any one of claims 1 to 8 connected in series, wherein the boundaries of the side faces of adjacent head modules are brought into contact with each other. A liquid discharge head provided with a head module holding means. Conveying means for conveying the recording medium;
Liquid discharge head holding means for holding the liquid discharge head according to claim 9 so as to face the recording medium;
Control means for recording on the recording medium by discharging liquid from the nozzles of the liquid discharge head;
With
The liquid discharge head holding unit is a liquid discharge apparatus that holds a boundary between the first region and the second region with an inclination with respect to the horizontal.   The liquid discharge apparatus according to claim 10, further comprising a wiping cleaning unit that wipes and cleans a nozzle surface of the liquid discharge head.   The liquid ejection apparatus according to claim 10, wherein the control unit causes the liquid ejection head to be purged.

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