JP5168912B2 - Liquid discharge head, liquid discharge head unit, and image forming apparatus - Google Patents

Description

  The present invention relates to a liquid discharge head, a liquid discharge head unit, and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, and a multifunction machine of these, for example, a liquid ejection apparatus including a recording head composed of a liquid ejection head (droplet ejection head) that ejects liquid droplets of a recording liquid (liquid) As a liquid while transporting a medium (hereinafter also referred to as “paper”, but the material is not limited, and a recording medium, a recording medium, a transfer material, recording paper, etc. are also used synonymously). The recording liquid (hereinafter also referred to as ink) is attached to a sheet to form an image (recording, printing, printing, and printing are also used synonymously).

  The image forming apparatus means an apparatus for forming an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. The term “not only” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium. Further, the liquid is not limited to the recording liquid and ink, and is not particularly limited as long as it is a liquid capable of forming an image. Further, the liquid ejection apparatus means an apparatus that ejects liquid from a liquid ejection head, and is not limited to an apparatus that forms an image.

  As a liquid discharge head (droplet discharge head) used in such an image forming apparatus, a liquid chamber (a flow path, a pressurized liquid chamber, a pressure chamber, and the like have the same meaning) communicated with a nozzle for discharging a droplet. As a pressure generating means (actuator means) for generating pressure to pressurize the liquid inside, a thermal head that generates pressure due to bubbles using an electrothermal conversion element, a diaphragm using a piezoelectric element (electromechanical conversion element) There are piezoelectric heads that generate pressure by being deformed, and electrostatic heads that generate pressure by deforming the diaphragm with an electrostatic force generated between an electrode and the diaphragm.

  The liquid ejection head includes an edge shooter type in which the nozzle axial direction and the liquid supply flow direction are parallel, and a side shooter type in which the nozzle axial direction and the liquid supply flow direction are orthogonal to each other. The edge shooter type, for example, in a thermal type head, has a basic structure obtained by attaching an electrothermal conversion element or wiring to a flow path plate and attaching a top plate, and is widely used in early printers for mass production. However, on the other hand, the refill response speed is slow, the discharge power is lower than that of the side shooter type, and cavitation is likely to occur.

  On the other hand, in the side shooter type, for example, in a thermal type head, the nozzle is positioned directly above the electrothermal conversion element, which has the effect of measuring the liquid with a broom, and the droplet discharge amount is uniformed. Cavitation does not occur because it communicates with the atmosphere, so the head life is long, the bubble generation direction matches the discharge direction, the discharge power increases, and no large shock waves are transmitted to the flow path side, so refilling is fast, meniscus is also Since it is stable, it is suitable for high-speed printing and is the mainstream of current printers.

  By the way, with increasing demands for high image quality, high speed, and high reliability for image forming apparatuses, it is essential to increase the density and the number of nozzles of the liquid ejection head. A negative pressure is generated in the surroundings due to the discharge from the nozzle, and the liquid droplets discharged from the nozzles around the head are bent (hereinafter referred to as “end deviation”) due to the influence, and the problem that the ink does not land at an appropriate position. It has become clear. This edge twist phenomenon is particularly easy to achieve high density and multi-nozzle, and it appears remarkably in thermal type and side shooter type heads that use many droplets.

Therefore, as described in Patent Document 1, a plurality of large nozzle row groups composed of rows of large nozzles that eject ink with a large volume of ink droplets, and ink with a volume smaller than the ink droplets ejected from the large nozzles An ink jet recording head including a plurality of small nozzle row groups each including a row of small nozzles that discharge the nozzle, wherein the interval between the large nozzle row group and the small nozzle row group is wider than the interval between the large nozzle row groups. is there.
JP 2005-169927 A

Further, as described in Patent Document 2, a plurality of discharge ports for discharging liquid arranged in a predetermined direction at a predetermined density on the same plane, and at least an array range of the plurality of discharge ports There is an ink jet recording head that has, at a side end portion, a convex region that extends in a direction different from the arrangement direction of the plurality of ejection ports and protrudes from the same plane.
JP 2004-216774 A

In addition, although not directly related to the end twist, Patent Document 3 discloses a bubble discharge passage having an opening end on one side in a region in contact with the opening end edge on the diaphragm side of the inner wall of the common liquid chamber and the other side opening to the outside. And a head for quickly discharging bubbles generated in a common liquid chamber to the outside through a bubble discharge path is described.
JP 2003-072065 A

In Patent Document 4, an air inlet having an opening in the head moving direction is formed in the recording head, and the air introduced from the air inlet is in the same direction as the ink discharging direction of the recording head and from the outlet to the head. It describes what is discharged from a discharge port provided in front of the moving direction.
JP 2002-272859 A

Patent Document 5 discloses an ink jet recording head that discharges ink from a nozzle while sending air from the air duct to the nozzle. A movable means is provided in the air duct, and the air duct is used as a nozzle forming surface of the nozzle plate during ink jet recording and recording standby. An ink jet recording head is described in which air is ejected while being further protruded, and air is ejected by retracting an air duct toward the nozzle plate during the maintenance operation of the recording head.
Japanese Patent No. 3782844

  However, since the configuration described in Patent Document 1 is not a measure against an increase in head area or the occurrence of pressure reduction, optimization is required each time the design of the nozzle diameter, the number of nozzles, etc. changes, and the cost is reduced. Leading up. Further, in the configuration described in Patent Document 2, it is difficult to completely block the air flow from the surroundings only by the convex portion, and since it is not a measure against the occurrence of decompression as in the former case, it is a fundamental measure. It is not.

  SUMMARY An advantage of some aspects of the invention is that it provides a liquid discharge head, a liquid discharge head unit, and an image forming apparatus including the liquid discharge head, which are free from an end deviation.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
In a liquid discharge head having a nozzle surface in which a plurality of nozzles that discharge droplets are arranged side by side and arranged in a plurality of rows in a direction that intersects the direction in which the nozzles are arranged,
One is open to the atmosphere at the nozzle surface and the other open to the atmosphere at a surface other than the nozzle face, air communicating passage communicating the provided and the surface side other than the nozzle surface and the nozzle surface side through the internal head It is,
The atmosphere communication path is on the nozzle surface side in a region sandwiched between two adjacent nozzle rows and between a nozzle at an end of the nozzle row and a nozzle adjacent to the nozzle at the end. It was set as the structure opened to air | atmosphere .

The liquid discharge head unit according to the present invention is
In a liquid ejection head unit in which a plurality of liquid ejection heads having a nozzle surface provided with a nozzle row in which a plurality of nozzles for ejecting liquid droplets are arranged side by side are arranged in a direction intersecting with the arrangement direction of the nozzles ,
Between the outermost nozzle row in the arrangement direction of the plurality of nozzle rows of the liquid discharge head unit and the nozzle row adjacent to the outermost nozzle row , one opens to the atmosphere on the nozzle surface, and the other opens to the air An atmosphere communication path is provided that opens to the atmosphere on a surface other than the nozzle surface and communicates the nozzle surface side and the surface side other than the nozzle surface through the inside of the head unit ,
The atmosphere communication path is configured to open to the atmosphere between the nozzle at the end of the nozzle row and the nozzle adjacent to the nozzle at the end on the nozzle surface side .

  The image forming apparatus according to the present invention includes the liquid discharge head or the liquid discharge head unit according to the present invention.

According to the liquid discharge head according to the present invention and the liquid discharge head unit according to the present invention, the bending (end deflection) of the droplet discharge does not occur.

  According to the image forming apparatus of the present invention, since the liquid discharge head or the liquid discharge head unit according to the present invention is provided, it is possible to form a high-quality image with no edge deviation.

Embodiments of the present invention will be described below with reference to the accompanying drawings. A first embodiment of a liquid discharge head unit according to the present invention including the liquid discharge head according to the present invention will be described with reference to FIGS. 1 is an explanatory plan view of the main part of the head, FIG. 2 is an explanatory sectional view taken along the line AA in FIG. 1, and FIG. 3 is an explanatory sectional view taken along the line BB in FIG.
This liquid discharge head unit HU is a unit in which a plurality of (here, three) liquid discharge heads H are integrally formed. In other words, this liquid discharge head unit HU is a nozzle (nozzle hole) for stacking the actuator substrate 1 common to the three liquid discharge heads H, the flow path forming member 2 and the nozzle plate 3 to discharge liquid droplets. 4 is formed, a flow path (liquid chamber) 5 is formed, and bubbles due to film boiling are generated in the individual flow path 5A in which a part of the flow path 5 is partitioned on the actuator substrate 1 facing the nozzle 4. Thermoelectric heat conversion elements (heating resistors: heaters) 6 are provided as pressure generating means for generating discharge energy, and ink supply holes 7 for supplying recording liquid (ink) to the flow path 5 are formed.

  Here, on the nozzle surface 3 a of the nozzle plate 3, a plurality of nozzle rows 4 </ b> A configured by arranging a plurality of nozzles 4 in a row are arranged side by side in a direction crossing the direction in which the nozzles 4 are arranged. In addition, two nozzle rows 4A and 4A are arranged in one liquid discharge head H.

  One side opens to the atmosphere at the nozzle surface 3a of the nozzle plate 3, and the other side opens to the atmosphere at a surface other than the nozzle surface, that is, the bottom surface 1a of the actuator substrate 1 on the opposite side of the nozzle surface 3a. And an air communication path 8 that communicates the surface 1a side other than the nozzle surface with the inside of the head. The atmosphere communication path 8 includes an atmosphere communication hole 8 a formed in the nozzle plate 3, an atmosphere communication hole 8 b formed in the flow path forming member 2, and an atmosphere communication hole 8 c formed in the actuator substrate 1.

  Here, in one liquid discharge head H, one opens to the atmosphere in the region sandwiched between the two nozzle rows 4A and 4A of the nozzle surface 3a, and the other is the atmosphere on the bottom surface 1a which is a surface other than the nozzle surface. The atmosphere communication path 8 is provided so as to communicate the nozzle surface 3a side and the bottom surface 1a side other than the nozzle surface through the inside of the head.

  Further, in the liquid discharge head unit HU, one of the liquid discharge head units HU opens to the atmosphere on the inner side of the outermost nozzle row 4A (4M) in the arrangement direction of the plurality of nozzle rows 4A, and one is open to the atmosphere on the nozzle surface 3a. An air communication path 8 is provided that opens to the atmosphere at the bottom 1a that is the surface other than the nozzle surface, and communicates the nozzle surface 3a side and the bottom surface 1a side that is a surface other than the nozzle surface through the inside of the head unit. It becomes the composition which is. Further, the liquid discharge head unit HU is configured such that an atmospheric communication path 8 is provided corresponding to each nozzle row 4A.

Here, an example of the manufacturing process of the nozzle plate 3 will be described with reference to FIGS. 4 is a schematic explanatory view for explaining the manufacturing process, FIG. 5 is an explanatory plan view of a main part of the nozzle plate, and FIG. 6 is a cross-sectional explanatory view taken along line CC in FIG.
Here, the nozzle 4 of the nozzle plate 3 and the atmosphere communication hole 8a constituting the atmosphere communication path 8 are formed using a laser. Laser processing methods are roughly classified into the following two methods, and any method may be used in the present invention. One is a method in which a laser is narrowed down by an optical system and focused on the nozzle plate 3 to make one hole per hole. The other is a method of drilling many nozzle holes at once using a mask. In the former, since it takes time to move the drilling point one by one, the latter is superior in terms of processing efficiency, that is, production cost.

  Further, as shown in FIG. 5, a method of using a mask includes a method (contact type) in which a mask 21 is brought into close contact with a nozzle plate 3 before drilling through a sacrificial layer 20 and irradiated with laser light 22 (not shown). However, there is a system (lens interposition type) in which a lens is interposed between the mask and the nozzle plate. In the former contact type, the light interference degree changes depending on the contact degree between the mask and the nozzle plate. Moreover, when the degree of adhesion varies on one nozzle plate, the shape and size of the nozzles to be perforated vary, which leads to variations in droplet discharge amount. On the other hand, the latter lens intervening type is the most excellent method in that uniform nozzle drilling can be performed without depending on the degree of adhesion of the mask.

As a laser light source, an excimer laser is preferable. A YAG laser has a defect that a hole is opened, but the edge surface is rough, and an infrared CO ₂ laser has a defect that a crater is generated around the hole. Therefore, it is difficult to perform fine processing because the processing shape is easily broken. On the other hand, laser ablation processing using an excimer laser performs sublimation etching by a photochemical reaction that cuts a covalent bond of a carbon atom, so that the processing shape is not easily broken and very high-precision processing can be performed. Here, the laser ablation processing method means a method of performing sublimation processing with a laser without going through a liquid phase state.

  Therefore, here, as shown in FIGS. 5 and 6, the nozzle plate 3 and the air communication hole 8 a are formed in the nozzle plate 3 using an excimer laser with a lens interposed type. In this case, the atmosphere communication hole row 8A in which the air communication holes 8a are arranged is arranged between the nozzle rows 4A and 4A in which the plurality of nozzles 4 are arranged.

Next, the manufacturing process of the entire head will be described with reference to FIGS. 7 is a cross-sectional explanatory view corresponding to a cross section taken along the line BB in FIG. 1 and FIG. 8 is a cross-sectional explanatory view corresponding to a cross section taken along the line AA in FIG. is there.
First, as shown in FIGS. 7A and 8A, a thermal oxide film 32 is formed on the Si substrate 31 as a heat storage layer for efficiently transferring the heat of the heater to the recording liquid (ink). Then, a heating resistance layer 33 serving as a heater is formed to a thickness of about 0.3 to 1 μm by electron beam evaporation or sputtering. As the heating resistance layer material, metal borides such as HfB ₂ and ZrB ₂ are generally used because of their good characteristics, but other materials may be used as long as they generate desired heat when energized. On this heat generating resistance layer, a low resistance wiring material layer 34 such as Al or Cu is formed by electron beam evaporation, sputtering or the like in the same manner as the heat generating resistance layer with a film thickness of about 0.3 to 1 μm.

  Next, as shown in each figure (b), a desired wiring pattern 35 is formed on the low resistance wiring material 34 and the heating resistance layer 33 using a resist 30 by lithography and etching techniques. As shown, the low-resistance wiring material 34 on the wiring pattern 35 is patterned into a desired heater shape again by lithography and etching techniques to form a heater 36 (the low-resistance wiring material 34 is not shown because it does not appear in the cross section). ).

Next, as shown in each figure (d), the film thickness serves as an ink-resistant layer 37 such as SiO ₂ having a film thickness of about 0.5 to 3 μm and a cavitation-resistant layer 38 for withstanding cavitation that occurs when the ink is defoamed. A film of Ta or the like of about 0.5 to 1 μm is formed by sputtering or the like.

  Next, as shown in each figure (e), a resist pattern 30 for forming the air communication holes 8c and the ink supply holes 7 is formed on the Si substrate 31 by lithography, and the resist pattern 30 is used as a mask to prevent cavitation. The layer 38 and the ink-resistant layer 37 are opened by dry etching with a metal dry etching apparatus. Further, the oxide film 32 is opened by dry etching the thermal oxide film 32 using an oxide film dry etching apparatus. As a result, diggings 39 and 30 for the atmosphere communication hole 8c and the ink supply port 7 are formed, and the Si substrate 31 is exposed.

Next, as shown in each figure (f), the atmospheric air communicating hole 8c and the ink supply hole 7 are formed in the Si substrate 31 by penetrating and etching the Si substrate 31 using an ICP dry etching apparatus. In etching an ICP etcher, it is effective to use a Bosch process in which etching is performed while alternately switching between etching and deposition processes to protect the sidewall. Specifically, in the etching step, the pressure is 100 to 200 mT, the coil power is 2000 to 3000 W, the one cycle etching time is 7 to 10 sec, the SF ₆ flow rate is 300 to 500 sccm, the platen power is 60 to 100 W, and the pressure is 20 to 50 mT in the deposition step. A good shape can be obtained under the etching conditions of power 1800 to 2500 W, 1 cycle deposition time 3 to 5 sec, and C ₄ F ₈ flow rate 100 to 200 sccm.

  Next, as shown in each figure (g), after removing the resist, a film having ink resistance, such as polyparaxylylene, is deposited by a deposition apparatus. At this time, an ink-resistant film 11 is also formed in the ICP etching portion, and the actuator substrate 1 is completed.

  Next, as shown in each figure (h), a dry film resist is pasted on the actuator substrate 1 as the flow path forming member 2 to form the flow paths 6 and the air communication holes 8b by lithography.

  Next, as shown in each figure (i), the nozzle plate 3 mentioned above is adhere | attached. Thereby, the atmosphere communication hole 8 is formed by the communication between the atmosphere communication hole 8 a of the nozzle plate 3, the atmosphere communication hole 8 b of the flow path forming member 2, and the atmosphere communication hole 8 c of the actuator substrate 1.

Therefore, an effect of preventing the end deflection in the liquid discharge head configured as described above will be described with reference to FIGS. 9 and 10 as well.
In the liquid discharge head provided with the atmosphere communication path 8, as shown in FIG. 9A, a certain viscosity around the discharge ink droplet is obtained by discharging the droplet from the nozzle in the end region of the image data. The air it has moves in the same direction as the ink droplets. Then, the air in the entire nozzle row moves in the same direction as the ink droplets, and the portion is in a decompressed state. For this reason, the air other than the area around the ejected ink droplets moves in the depressurized direction, and an air flow (atmospheric pressure flow) as indicated by the white arrow is generated, and is generated in the end region of the nozzle row. The ejection direction of ink droplets ejected from a certain nozzle is bent toward the center of the nozzle row by this air flow, and landed at a position 41 that deviates from the target position. As a result, as shown in FIG. 9B, the landing areas 43 and 44 are shifted to the center portion of the nozzle row, and a streak 45 (end deviation) is generated.

  On the other hand, as shown in FIG. 10, in the liquid discharge head provided with the atmosphere communication path 8, the atmosphere in the vicinity of the nozzle 4 at the shortest distance via the actuator substrate 1 and the flow path forming member 2 when droplets are discharged. Since air is supplied from the opening of the communication passage 8 to the nozzle surface side, the pressure is not reduced by droplet discharge. Therefore, the end deviation of the nozzle row does not occur, and the liquid droplets can be landed at the designed position 42, thereby enabling high quality printing.

  Thus, in this liquid ejection head, one opens to the atmosphere in the region sandwiched between the plurality of nozzle rows on the nozzle surface, the other opens to the atmosphere on the surface other than the nozzle surface, and the nozzle surface side Since an atmosphere communication path is formed to communicate with the surface side other than the nozzle surface through the inside of the head, when the nozzle surface side space between the nozzle rows is going to become negative pressure along with droplet discharge, the atmosphere communication path is connected. Thus, since the atmosphere is supplied to the nozzle surface side, the pressure is not reduced, and the droplet discharge bend (end deflection) does not occur.

  Further, in a liquid discharge head unit in which a plurality of liquid discharge heads are integrally formed, the liquid discharge head unit is opened to the atmosphere on the inner side of the outermost nozzle row in the arrangement direction of the plurality of nozzle rows, and one is open to the atmosphere on the nozzle surface. However, the other side is open to the atmosphere on the surface other than the nozzle surface, and the atmosphere communication path is provided to connect the nozzle surface side and the surface side other than the nozzle surface through the inside of the head unit. At the same time, when the nozzle surface side space inside the outermost nozzle row is going to be negative pressure, the atmosphere is supplied to the nozzle surface side through the atmosphere communication path, so the pressure is not reduced and the droplet discharge is bent. (Edge misalignment) does not occur.

  Next, a second embodiment of the liquid discharge head unit according to the present invention including the liquid discharge head according to the present invention will be described with reference to FIGS. 11 is an explanatory plan view of the main part of the head, and FIG. 12 is an explanatory sectional view taken along the line CC of FIG.

  In this embodiment, the atmosphere communication path 8 is also provided between adjacent nozzle rows 4A (4N) and 4A (4N) of a plurality of liquid discharge heads H constituting the liquid discharge head unit HU. Thereby, it is possible to prevent the space corresponding to the nozzle rows of the adjacent liquid discharge heads H from being in a negative pressure state, and it is possible to suppress not only the end deviation but also the bending inside the liquid discharge head unit. That is, if air is introduced between the nozzle rows of the individual liquid discharge heads in the first embodiment, a difference may occur between the spaces between the nozzle rows of the adjacent liquid discharge heads H, which may cause droplet bending. However, such inconvenience can be suppressed by introducing the atmosphere into this space.

Next, a third embodiment of the liquid discharge head unit according to the present invention including the liquid discharge head according to the present invention will be described with reference to FIGS. 13 is a cross-sectional explanatory view similar to the cross section corresponding to the line AA in FIG. 1, and FIG. 14 is a cross-sectional explanatory view similar to the cross section corresponding to the line BB in FIG.
In this embodiment, liquid tanks 51 to 53 which are recording liquid storage means for storing recording liquid (liquid) supplied to each liquid discharge head H constituting the liquid discharge head unit HU are integrally provided. In this case, since the other side of the atmosphere communication path 8 is opened on the back side of the head here, the liquid tanks 51 to 53 are formed in a shape that does not block the other opening of the atmosphere communication path 8. The liquid tanks 51 to 53 store recording liquids of different colors, for example, and supply the recording liquids to the flow paths 5 of the liquid discharge heads H through the supply holes 7 respectively.

Next, an example of the image forming apparatus according to the present invention including the liquid discharge head unit according to the present invention will be described with reference to FIGS. FIG. 15 is a schematic configuration diagram showing a mechanism part of the apparatus, and FIG. 16 is a plan view of an essential part of the apparatus.
The carriage 113 is slidably held in the main scanning direction by the main guide rod 111 and the secondary guide rod 112 horizontally mounted on the left and right main side plates 101A and 101B, and the direction indicated by the arrow through the timing belt by a main scanning motor (not shown). Move and scan in the carriage main scanning direction.

  The carriage 113 includes a liquid ejection head unit according to the present invention having a plurality of nozzle rows that eject droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). The head 114 is mounted with a plurality of nozzles (ejection ports) arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward. The recording head 114 is provided with a nozzle row of each color in which a plurality of nozzles 4 that discharge each droplet of yellow (Y), cyan (C), magenta (M), and black (K) are arranged.

  The carriage 113 is also equipped with a head tank 115 for each color for supplying ink of each color to the recording head 114. Each color head tank 115 is replenished and supplied with each color ink from each color ink cartridge 120 mounted on the cartridge loading section 117 via a flexible supply tube 116 for each color. The cartridge loading section 117 is provided with a supply pump unit 118 that is a liquid feeding means for feeding ink in the ink cartridge 120. The supply tube 116 is held on the front stay 121 by a holding member 122 in the middle.

  On the other hand, as a paper feeding unit for feeding the paper 142 stacked on the paper stacking unit (pressure plate) 141 of the paper feeding tray 140, a half-moon roller (feeding) that separates and feeds the paper 142 one by one from the paper stacking unit 141. A separation pad 144 made of a material having a large friction coefficient is provided facing the paper roller 143 and the paper feed roller 143, and the separation pad 144 is urged toward the paper feed roller 143 side.

  A guide member 145 for guiding the paper 142, a counter roller 146, a transport guide member 147, and a tip pressure roller for feeding the paper 142 fed from the paper feeding unit to the lower side of the recording head 114. And a holding belt 148 that is a conveying means for electrostatically attracting the fed paper 142 and conveying it at a position facing the recording head 114.

  The conveyor belt 151 is an endless belt, and is configured to wrap around the conveyor roller 152 and the tension roller 153 and circulate in the belt conveyance direction (sub-scanning direction). Further, a charging roller 156 that is a charging unit for charging the surface of the transport belt 151 is provided. The charging roller 156 is disposed so as to come into contact with the surface layer of the conveyor belt 151 and to rotate following the rotation of the conveyor belt 151. Further, a guide member 157 serving as a platen portion is disposed on the back side of the conveyance belt 151 corresponding to the printing area by the recording head 114. The transport belt 151 rotates in the belt transport direction when the transport roller 152 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 142 recorded by the recording head 114, a separation claw 161 for separating the paper 142 from the conveying belt 151, a paper discharge roller 162, and a paper discharge roller (spur roller). 163, and a paper discharge tray 163 below the paper discharge roller 162.

  A double-sided unit 171 is detachably attached to the back surface of the apparatus main body. The duplex unit 171 takes in the paper 142 returned by the reverse rotation of the transport belt 151, reverses it, and feeds it again between the counter roller 146 and the transport belt 151. The upper surface of the duplex unit 171 is a manual feed tray 172.

  Further, a maintenance / recovery mechanism 181 including a recovery means for maintaining and recovering the nozzle state of the recording head 114 is disposed in a non-printing area on one side in the scanning direction of the carriage 113. The maintenance / recovery mechanism 181 includes a cap member 182 for collectively capping the nozzles 11 of the recording head 114, a wiper blade 183 that is a blade member for wiping the nozzle surface, and a thickened recording liquid. An empty discharge receptacle 184 for receiving droplets when performing empty discharge for discharging droplets that do not contribute to recording in order to be discharged is provided.

  Then, the waste liquid of the recording liquid generated by the maintenance / recovery operation by the maintenance / recovery mechanism 181, the ink discharged to the cap 182, the ink attached to the wiper blade 183 and removed by the wiper cleaner 185, The discharged ink is discharged and stored in a waste liquid tank (not shown).

  In addition, in the non-printing area on the other side of the carriage 113 in the scanning direction, there is an empty space for receiving liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. A discharge receiver 188 is disposed, and the idle discharge receiver 188 includes an opening 189 along the nozzle row direction of the recording head 114.

  In the ink jet recording apparatus configured as described above, the paper 142 is separated and fed one by one from the paper feed tray 140, and the paper 142 fed substantially vertically upward is guided by the guide 145, and the conveyance belt 151 and the counter roller 146, and the leading end is guided by the conveying guide 147 and pressed against the conveying belt 151 by the leading end pressing roller 149, and the conveying direction is changed by approximately 90 °.

  At this time, a charging voltage pattern in which a positive output and a negative output are alternately repeated from the AC bias supply unit of the control unit (not shown) to the charging roller 156, that is, an alternating voltage is applied and the conveying belt 151 is alternating, That is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction which is the circumferential direction. When the sheet 142 is fed onto the conveying belt 151 that is alternately charged with plus and minus, the sheet 142 is attracted to the conveying belt 151, and the sheet 142 is conveyed in the sub-scanning direction by the circumferential movement of the conveying belt 151.

  Therefore, by driving the recording head 114 according to the image signal while moving the carriage 113, ink droplets are ejected onto the stopped sheet 142 to record one line, and after the sheet 142 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 142 reaches the recording area, the recording operation is finished, and the paper 142 is discharged onto the paper discharge tray 163.

  During printing (recording) standby, the carriage 113 is moved to the maintenance / recovery mechanism 181 side, and the ejection surface (nozzle surface) of the recording head 114 is capped by the cap member 182 to keep the nozzle in a wet state. Prevents ejection failure due to recording liquid drying. Further, the recording liquid is sucked from the nozzle by a suction pump (not shown) with the cap member 182 capping the ejection surface of the recording head 114 (referred to as “nozzle suction” or “head suction”) to increase the viscosity. Perform recovery operation to discharge liquid and bubbles. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the recording head 114 is maintained.

  As described above, since the image forming apparatus includes the recording head 114 including the highly reliable liquid discharge head unit (or liquid discharge head) according to the present invention, it is possible to form a high-quality image without edge deviation. .

  In each of the above embodiments, the printer configuration has been described as the image forming apparatus according to the present invention. However, the present invention is not limited to this, and can be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. Further, the present invention can also be applied to an image forming apparatus using a recording liquid other than ink, a fixing processing liquid, a DNA sample, a resist or the like, and other apparatuses for ejecting liquid droplets.

FIG. 2 is an explanatory plan view of a main part showing a first embodiment of a liquid discharge head unit according to the present invention including the liquid discharge head according to the present invention. FIG. 2 is a cross-sectional explanatory view taken along line AA in FIG. 1. It is a cross-sectional explanatory drawing which follows the BB line of FIG. It is typical explanatory drawing with which it uses for description of an example of the manufacturing process of a nozzle plate. It is principal part plane explanatory drawing of a nozzle plate. FIG. 6 is a cross-sectional explanatory view taken along the line CC in FIG. 5. FIG. 2 is an explanatory cross-sectional view corresponding to a cross section taken along line AA of FIG. 1 for explaining the manufacturing process of the entire head. It is a cross-sectional explanatory drawing equivalent to the cross section which follows the BB line of FIG. FIG. 6 is a schematic explanatory diagram of a comparative example that is used to explain an effect of preventing end deflection in the liquid discharge head. FIG. 6 is a schematic explanatory diagram for explaining an end twist preventing action in the liquid discharge head. It is principal part plane explanatory drawing which shows 2nd Embodiment of the liquid discharge head unit which concerns on this invention including the liquid discharge head which concerns on this invention. FIG. 12 is a cross-sectional explanatory view taken along the line CC in FIG. 11. FIG. 9 is a cross-sectional explanatory view corresponding to a cross section taken along line AA of FIG. 1 showing a third embodiment of the liquid discharge head unit according to the present invention including the liquid discharge head according to the present invention. It is a cross-sectional explanatory drawing equivalent to the cross section which follows the BB line of FIG. FIG. 2 is a schematic configuration diagram illustrating a mechanical unit of an image forming apparatus according to the present invention including a liquid ejection head according to the present invention. It is principal part plane explanatory drawing of the apparatus.

Explanation of symbols

HU ... Liquid discharge head unit H ... Liquid discharge head 1 ... Actuator substrate 2 ... Flow path forming member 3 ... Nozzle plate 4 ... Nozzle 5 ... Flow path (liquid chamber)
6. Heating resistor (heater)
7 ... Ink supply port 8 ... Air communication path 8a, 8b, 8c ... Air communication hole 51-53 ... Recording liquid storage means (liquid tank)
113 ... Carriage 114 ... Recording head (liquid ejection head)

Claims (9)

In a liquid discharge head having a nozzle surface in which a plurality of nozzles that discharge droplets are arranged side by side and arranged in a plurality of rows in a direction that intersects the direction in which the nozzles are arranged,
One is open to the atmosphere at the nozzle surface and the other open to the atmosphere at a surface other than the nozzle face, air communicating passage communicating the provided and the surface side other than the nozzle surface and the nozzle surface side through the internal head It is,
The atmosphere communication path is on the nozzle surface side in a region sandwiched between two adjacent nozzle rows and between a nozzle at an end of the nozzle row and a nozzle adjacent to the nozzle at the end. A liquid discharge head characterized by being open to the atmosphere .   2. The liquid discharge head according to claim 1, wherein the nozzle is provided so as to face a pressure generating means for generating a pressure for discharging a droplet from the nozzle.   The liquid discharge head according to claim 2, wherein the pressure generating means is an electrothermal conversion element.   4. The liquid discharge head according to claim 1, wherein a surface other than the nozzle surface in which the other of the atmospheric communication passages is open is a surface opposite to the nozzle surface. 5. . 5. The liquid ejection head according to claim 1, wherein the atmosphere communication path that opens at a central portion of the nozzle row in the nozzle arrangement direction is provided on the nozzle surface side. Discharge head. In a liquid ejection head unit in which a plurality of liquid ejection heads having a nozzle surface provided with a nozzle row in which a plurality of nozzles for ejecting liquid droplets are arranged side by side are arranged in a direction intersecting with the arrangement direction of the nozzles ,
Between the outermost nozzle row in the arrangement direction of the plurality of nozzle rows of the liquid discharge head unit and the nozzle row adjacent to the outermost nozzle row , one opens to the atmosphere on the nozzle surface, and the other opens to the air An atmosphere communication path is provided that opens to the atmosphere on a surface other than the nozzle surface and communicates the nozzle surface side and the surface side other than the nozzle surface through the inside of the head unit ,
The liquid is characterized in that the atmosphere communication path is open to the atmosphere between the nozzle at the end of the nozzle row and the nozzle adjacent to the nozzle at the end on the nozzle surface side. Discharge head unit. The liquid discharge head unit according to claim 6, wherein the atmosphere communication passage opening between the adjacent liquid discharge heads is provided. The liquid ejection head unit according to claim 6 or 7, the liquid discharge head has two nozzle arrays, before Symbol atmosphere communication path which is open in correspondence with each nozzle array between the two nozzle rows A liquid discharge head unit provided.   An image forming apparatus for forming an image by discharging droplets, comprising the liquid discharge head according to any one of claims 1 to 5 or the liquid discharge head unit according to any one of claims 6 to 8. An image forming apparatus.

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