JP5633265B2 - Liquid ejection head and image forming apparatus - Google Patents

Description

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

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. As an apparatus, an ink jet recording apparatus or the like is known. This liquid discharge recording type image forming apparatus means that ink droplets are transported from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected onto a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). And a serial type image forming apparatus that forms an image by ejecting liquid droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting liquid droplets without moving the recording head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” 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 (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  A liquid discharge head used in such an image forming apparatus of a liquid discharge recording method generally has a plurality of nozzle rows that discharge droplets, and a plurality of individual liquid chambers (pressurization chambers, It is also called a pressure chamber, an individual liquid chamber, a pressurized liquid chamber, a pressurized liquid chamber, etc. Hereinafter, it is referred to as a “pressurized liquid chamber”), and a common liquid chamber (common flow) is included in a plurality of pressurized liquid chambers. The ink is supplied from the supply passage portion through the supply passage portion.

  Incidentally, an image forming apparatus is required to output a higher quality image at a higher printing speed. Therefore, both the number of nozzles and the arrangement density tend to increase. As a result, the interval between the pressurized liquid chambers is narrowed and the driving frequency tends to be high.

  As the number of nozzles increases and the nozzle array becomes denser as the nozzle arrangement increases in density, when pressure is applied to the desired pressurized liquid chamber to perform droplet discharge, other adjacent pressure is applied. Mutual interference (this is called “adjacent crosstalk”) in which pressure fluctuations also occur in the liquid chamber is likely to occur. When adjacent crosstalk occurs, droplet ejection is performed from a nozzle corresponding to a pressurized liquid chamber that does not perform droplet ejection, or the ejection state of the ejected droplets becomes unstable, resulting in a reduction in image quality.

  In order to suppress this adjacent crosstalk, the nozzle communication passage (communication pipe) communicating between the pressurized liquid chamber and the nozzle is narrowed, the rigidity of the communication pipe interval wall is increased, or the height of the pressurized liquid chamber is increased. However, if the communication pipe is made narrow, the impedance of the liquid chamber including the pressurized liquid chamber will increase and the discharge characteristics will be reduced. Will take longer. Further, regarding the crosstalk (hereinafter referred to as “overall crosstalk”) in which the entire flow path plate forming the flow path such as the pressurized liquid chamber is deformed by the internal pressure of the pressurized liquid chamber and the droplet discharge characteristics are deteriorated. By reducing the height of the pressurized liquid chamber, the internal pressure is further increased and the droplet discharge characteristics are deteriorated.

  Therefore, conventionally, it is known to increase the rigidity of the partition walls by giving a curvature to the liquid chamber interval wall (Patent Document 1). Further, there is a configuration in which a space portion formed of a vibration plate is provided between the flow path substrate and the vibration plate, and the space portion of the pressure generation chamber on the flow path substrate is narrower than the width of the space portion. Known (Patent Document 2).

JP 2008-155472 A JP 2002-103618 A

  However, as described in Patent Document 1 described above, in order to produce a liquid chamber structure in which the partition wall has a curvature, it is necessary to use an anodizing method, which increases costs due to new capital investment. In addition, there is a problem that it is difficult to form the liquid chamber with high accuracy.

  Further, as described in Patent Document 2, even if the displacement area of the piezoelectric element is secured by the space portion by the diaphragm, the width of the flow path of the flow path substrate through which the liquid flows is narrow and the fluid resistance value is increased. Therefore, there is a problem that the discharge performance is deteriorated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to suppress crosstalk with a simple configuration and ensure droplet discharge performance.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
A nozzle member formed with a plurality of nozzles for discharging droplets;
A flow path member in which a plurality of groove-like individual liquid chambers communicating with the nozzle are formed;
A wall surface member that forms one surface of the individual liquid chamber,
The individual liquid chamber is a triangle having a surface opposite to the wall member as a top surface and a partition wall between the plurality of individual liquid chambers as a side wall surface, and the top surface and the side wall surfaces as two surfaces. Convex-shaped or triangular frustum-shaped convex portions having two surfaces as the top surface and the side wall surface and parallel to the side wall surface are provided.

  Here, the said convex part can be set as the structure provided with two or more in the direction in alignment with the top | upper surface and wall surface of the said individual liquid chamber.

Moreover, the said convex part can be set as the structure which is provided in the both-sides wall surface of the said separate liquid chamber , and is arrange | positioned alternately in the direction of the flow of a liquid.

  In addition, the plurality of convex portions may be alternately arranged on both sides of the partition wall between adjacent individual liquid chambers in the liquid flow direction.

The plurality of individual liquid chambers have the same shape,
The adjacent individual liquid chambers are arranged in a staggered manner in the nozzle arrangement direction,
The said convex part can be set as the structure arrange | positioned in the same position in the direction of the liquid flow in each individual liquid chamber.

  Moreover, the said convex part can be set as the structure which is not in contact with the said wall surface member.

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

  According to the liquid ejection head of the present invention, the individual liquid chamber has a top surface and a side when the surface opposite to the wall surface member is a top surface and the partition surface between the plurality of individual liquid chambers is a side wall surface. Since it has a triangular pyramid shape with two wall surfaces, or a triangular frustum-shaped convex part with a top surface and a side wall surface as two surfaces and a surface parallel to the side wall surface, it has a simple structure. Crosstalk can be suppressed by increasing the rigidity of the liquid chamber interval wall, and droplet ejection performance can be ensured.

  According to the image forming apparatus of the present invention, since the liquid discharge head according to the present invention is provided, a high-quality image can be formed.

1 is an external perspective view illustrating a first embodiment of a liquid ejection head according to the present invention. It is principal part cross-sectional explanatory drawing along the liquid chamber longitudinal direction of the head. It is principal part cross-sectional explanatory drawing of the liquid chamber short direction along the XX line of FIG. It is a plane explanatory view explaining the liquid chamber composition of the head. It is the principal part expansion perspective view similarly of a convex part. It is plane explanatory drawing explaining the liquid chamber structure in 2nd Embodiment of this invention. It is plane explanatory drawing explaining the liquid chamber structure in 3rd Embodiment of this invention. It is principal part expansion perspective explanatory drawing of the convex part part explaining the liquid chamber structure in 4th Embodiment of this invention. 1 is an overall configuration diagram illustrating an example of an image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. A first embodiment of a liquid discharge head according to the present invention will be described with reference to FIGS. 1 is an explanatory perspective view of the appearance of the head, FIG. 2 is an explanatory sectional view of the main part along the longitudinal direction of the liquid chamber of the head, and FIG. 3 is an essential view of the lateral direction of the liquid chamber along the line XX in FIG. FIG.

  The liquid discharge head includes a flow path plate (flow path substrate, liquid chamber substrate) 1 as a flow path member, a vibration plate member 2 bonded to the lower surface of the flow path plate 1, and an upper surface of the flow path plate 1. A plurality of pressurized liquids as individual flow paths each having a nozzle plate 3 and a plurality of nozzles 4 for discharging droplets (liquid droplets) communicated with each other via a nozzle communication path (communication pipe) 5. The chamber 6 is formed, and the inlet 8 and the supply path 7 as the fluid resistance portion are connected to each pressurized liquid chamber 6 from the common liquid chamber 10 formed in the frame member 17 through the inlet 9 formed in the diaphragm member 2. Ink is supplied through. Here, the nozzle plate 3 and the flow path plate 1 may be formed integrally.

  The flow path plate 1 anisotropically etches the silicon substrate to form openings and grooves such as the nozzle communication path 5, the pressurized liquid chamber 6, and the supply path 7. A portion left by etching that forms the nozzle communication path 5 and the pressurized liquid chamber 6 is a flow path interval wall (liquid chamber interval wall) 30.

  The diaphragm member 2 is a wall surface member that forms the wall surfaces of the liquid chambers 6 and the supply passages 7, and includes a deformable first layer 2A and a second layer 2B laminated on the first layer 2A. The vibration region (diaphragm portion) 2a formed of the deformable first layer 2A that forms the wall surface of the liquid chamber 6 is provided, and the vibration region 2a is formed on the island-shaped convex portion 2b formed of the second layer 2B. The piezoelectric element column 12A of the laminated piezoelectric member 12 which is a columnar electromechanical transducer as a driving element (actuator unit, pressure generating unit) that generates energy for deforming 2a and ejecting droplets is joined.

  The piezoelectric member 12 is formed by forming piezoelectric element columns 12A and 12B in a comb-teeth shape by half-cut dicing. The piezoelectric element column 12A is a driving piezoelectric element column that applies a driving waveform, and the piezoelectric element column 12B applies a driving waveform. Instead, it becomes a non-driving piezoelectric element column which is a column supporting the flow path interval wall 6a. That is, the piezoelectric element columns 12 </ b> A and 12 </ b> B of the piezoelectric element member 12 have a so-called bi-pitch structure that is arranged at a density twice the arrangement density of the pressurized liquid chambers 6. The lower end surface of the piezoelectric element member 12 is joined to the base member 13.

  The piezoelectric member 12 includes, for example, a lead zirconate titanate (PZT) piezoelectric layer 21 having a thickness of 10 to 50 μm / layer and an internal electrode layer 22A made of silver and palladium (AgPd) having a thickness of several μm / layer. , 22B are alternately stacked, and the internal electrodes 22 are alternately electrically connected to the individual electrodes 23 and the common electrode 24 which are end face electrodes (external electrodes) on the end faces. An individual electrode line of the FPC 15 is soldered to the individual electrode 23, and the common electrode 24 is provided with an electrode layer at the end of the piezoelectric member 12 and is turned to the end surface on the individual electrode 23 side so that the GN electrode (common of the FPC 15 is common). Electrode line). A driver IC (not shown) is mounted on the FPC 15 to control application of a driving voltage to the driving piezoelectric element column 12A.

  The nozzle plate 3 is formed from a nickel (Ni) metal plate, and is manufactured by an electroforming method (electroforming). In the nozzle plate 3, nozzles 4 having a diameter of 10 to 35 μm are formed corresponding to the pressurized liquid chambers 6, and are bonded to the flow path plate 1 with an adhesive. A water repellent layer is provided on the droplet discharge side surface (surface in the discharge direction: discharge surface or surface opposite to the liquid chamber 6 side) of the nozzle plate 3.

  Further, a frame member 17 formed by injection molding with epoxy resin or polyphenylene sulfite is joined to the outer peripheral side of the piezoelectric actuator composed of the piezoelectric element column 12 mounted with (connected to) the FPC 15 and the base member 13. doing. A common liquid chamber 10 is formed in the frame member 17, and a supply port is formed through a connecting pipe to supply ink to the common liquid chamber 10 from the outside. It is connected to an ink supply source such as an ink cartridge.

  In this head, the piezoelectric element columns 12 are diced at intervals of 300 dpi. It is arranged in two rows facing each other, and the pressurized liquid chamber 6 and the nozzle 4 are arranged in a staggered arrangement with two rows at an interval of 150 dpi, and a resolution of 300 dpi can be obtained in one scan. It is said.

  In the liquid discharge head configured as described above, for example, by lowering the voltage applied to the piezoelectric element column 12A from the reference potential, the piezoelectric element column 12A contracts, and the diaphragm portion forming the liquid chamber wall surface of the diaphragm member 2 descends. Then, the volume of the liquid chamber 6 expands so that ink flows into the liquid chamber 6 and then the voltage applied to the piezoelectric element columns 12A is increased to extend the piezoelectric element columns 12A in the stacking direction. Is deformed in the direction of the nozzle 4 to shrink the volume of the liquid chamber 6, the ink in the liquid chamber 6 is pressurized, and ink droplets are ejected (jetted) from the nozzle 4.

  Then, by returning the voltage applied to the piezoelectric element column 12A to the reference potential, the diaphragm member 2 is restored to the initial position, and the liquid chamber 6 expands to generate a negative pressure. The liquid chamber 6 is filled with ink. Therefore, after the vibration of the meniscus surface of the nozzle 4 is attenuated and stabilized, the operation proceeds to the next droplet discharge.

  Note that the driving method of the head is not limited to the above example (pulling-pushing), and it is also possible to perform striking or pushing depending on the direction to which the driving waveform is given.

Next, the configuration of the pressurized liquid chamber in this head will be described with reference to FIGS. 4 is an explanatory plan view for explaining the configuration of the pressurized liquid chamber, and FIG. 5 is an enlarged perspective explanatory view of the convex portion.
The pressurizing liquid chamber 6 vibrates with the top surface 31 facing the diaphragm member 2 which is a wall surface member, side wall surfaces 32a and 32b of the liquid chamber interval wall 30 (referred to as “side wall surface 32” when not distinguished). It is defined by the vibration region 2 a of the plate member 2. Further, on the wall surface of the pressurized liquid chamber 6, a triangular pyramid-shaped convex portion 33 having the top surface 31 and the side wall surface 32a or the side wall surface 32b as two surfaces has a liquid flow direction (in this case, the liquid chamber 6 A plurality (pieces) are provided at predetermined intervals along the longitudinal direction.

  Here, the protrusion 33 has vertices 33a and 33b on the top surface 31 and the side wall surface 32 in the liquid flow direction, and vertices 33c and 33d spaced apart in the liquid flow direction on the boundary between the top surface 31 and the side wall surface 32. The surface including the vertices 33a, 33c and 33d is in contact with the top surface 31, the surface including the vertices 33b, 33c and 33d is in contact with the side wall surface 32, and the surface including the vertices 33a, 33b and 33c and the vertices 33a and 33b , 33d face the liquid chamber 6, respectively, and the plane including the vertices 33a, 33b, 33c rises toward the side between the vertices 33a, 33b along the liquid flow direction, and the vertices 33a, 33b, 33d Is formed in a direction falling from the side between the vertices 33a and 33b.

  Further, the convex portion 33 on the side wall surface 32a side and the convex portion 33 on the side wall surface 32b side are formed so that their positions are shifted in the liquid flow direction (the positions of the vertices 33a and 33b are shifted in the liquid flow direction). ing. Thereby, since there is no position where the area of the cross section in the liquid flow direction of the pressurized liquid chamber 6 becomes extremely narrow, the flow of the liquid in the pressurized liquid chamber is not hindered, and a decrease in filling property and the like can be suppressed.

  Further, the convex portion 33 is not in contact with the joint surface 1 a of the flow path plate 1 with the diaphragm member 2. This does not hinder the transition of the vibration region 2a.

  As described above, the triangular pyramid-shaped convex portion having the top surface and the wall surface of the individual liquid chamber (pressurized liquid chamber) formed in a groove shape as two surfaces is formed, so that the rigidity of the liquid chamber interval wall is increased. Increase, and adjacent crosstalk can be suppressed. Further, since the convex portion has a triangular pyramid shape, the flow of the liquid in the individual liquid chamber is not hindered, and the fluid resistance value hardly increases, so that it is possible to suppress a drop in the droplet discharge performance.

  Further, by forming a triangular pyramid-shaped convex portion over the entire partition wall of the individual liquid chamber formed in a groove shape, the rigidity of the entire liquid chamber interval wall can be further increased.

  Here, when a silicon substrate is used as a flow path plate and an individual liquid chamber (pressurized liquid chamber 6) is formed by etching, a triangular pyramid shape can be formed only by mask design due to the etching rate and the crystal orientation plane of silicon. Since the convex portion 33 can be formed, it is not necessary to change the construction method for the liquid chamber that does not form the triangular pyramid-shaped convex portion 33, and the rigidity of the partition wall is improved without increasing the cost. be able to.

  Specifically, in the mask for forming the protective film for wet etching, a plurality of convex shielding portions protruding from the mask shielding portion on the side wall portion into the pressurized liquid chamber are arranged along the side wall corresponding portion. . Since a convex protective film is formed at this portion, etching is not performed at the start of etching, but etching proceeds from both sides along the side wall of the convex protective film as etching progresses, and comes into contact with the diaphragm member 2. The convex part disappears from the surface. If left as it is for a long time, the convex part disappears completely, but by controlling the etching time to an appropriate time, the side in contact with the diaphragm member disappears, and the convex part of the triangular pyramid shape only on the top surface side Can leave. Actually, since the etching time is determined to be a predetermined value to define the height to the top surface of the pressurized liquid chamber 6, the size of the convex shielding portion of the wet etching mask is controlled, It is preferable to adjust so that the triangular pyramid shape remains with the etching time of the predetermined value.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is an explanatory plan view of a pressurized liquid chamber portion in the same embodiment.
Here, the protruding portions 33 on the side wall surface 32a side and the protruding portions 33 on the side wall surface 32b side are shifted so that they are alternately arranged in the liquid flow direction (the positions of the vertices 33a and 33b are the flow of the liquid). Are formed on the side wall surface 32 facing each other in a direction shifted to a position where the convex portion 33 is not formed.

  In this way, the triangular pyramid-shaped convex portions 33 can be evenly arranged over the entire area of the liquid chamber interval wall 30 by alternately shifting the positions of the convex portions 33 between the side wall surfaces 32a and 32b. The rigidity of the entire partition wall 30 can be increased uniformly. In addition, the flow of the liquid in the individual liquid chamber is smoother than that of the first embodiment, the non-uniformity of the flow of the liquid is reduced, the increase of the fluid resistance value is reduced, and the droplet discharge performance is improved. it can.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is an explanatory plan view of a pressurized liquid chamber portion in the same embodiment.
Here, the plurality of pressurized liquid chambers 6 have the same shape, and are alternately arranged in the liquid flow direction and arranged in a staggered manner in the nozzle arrangement direction. In this case, the portions of the communication pipe 5 from the pressurized liquid chamber 6 to the nozzle 4 are also alternately arranged in a staggered manner.

  At this time, the positions of the convex portions 33 are alternately arranged in the direction of liquid flow between the adjacent pressurized liquid chambers 6 and 6.

  Thereby, the rigidity of the communication pipe portion and the rigidity of the entire area of the liquid chamber interval wall can be uniformly increased.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is an enlarged perspective explanatory view of the convex portion of the pressurized liquid chamber portion in the same embodiment.
Here, the convex portion 33 has a triangular frustum shape in which a surface 33e parallel to the side wall surface 32 is provided and the above-described vertex 33a is removed. That is, the convex part 33 of the triangular frustum shape which has the surface 33e which has the top surface 31 and the side wall surface 32 as two surfaces and is parallel to the side wall surface is provided.

  Even if it is such a shape, the same effect as each said embodiment is acquired, and also the rigidity of convex part 33 itself becomes higher than the said embodiment, and the rigidity of a liquid chamber space | interval wall can be improved further.

  Such a configuration is inevitably formed in the course of etching when wet etching is performed using the same mask as in the first embodiment. As in the first embodiment, the etching time or the convex shape is formed. It can be easily formed by controlling the size of the shielding portion. If the etching is further continued in the state of the second embodiment, the surface 33e parallel to the side wall surface 32 becomes gradually smaller by the etching, and eventually becomes the shape of the first embodiment.

  Note that an ink cartridge in which a tank for supplying ink to the liquid discharge head of each of the above embodiments is integrated can be configured.

Next, an example of the image forming apparatus according to the present invention including the liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 9 is a schematic configuration diagram for explaining the overall configuration of the mechanism portion of the apparatus, and FIG. 10 is a plan view for explaining a main portion of the mechanism portion.
This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 221A and 221B. The main scanning motor that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 is supplied with ink supplied to the same head as the liquid discharge head according to the present invention for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). A recording head 234 composed of a liquid ejection head unit with an integrated tank is arranged in a sub-scanning direction perpendicular to the main scanning direction with a nozzle row composed of a plurality of nozzles, and mounted with the ink droplet ejection direction facing downward. Yes.

  The recording head 234 is configured by attaching liquid discharge head units 234a and 234b each having two nozzle rows to one base member, and one nozzle row of one head 234a receives black (K) droplets. The other nozzle row ejects cyan (C) droplets, the other nozzle row of the other head 234b ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. To do. Here, a configuration in which droplets of four colors are ejected in a two-head configuration is used, but it is also possible to arrange four nozzle rows per head and eject each of the four colors with one head.

  Further, the ink of each color is replenished and supplied from the ink cartridge 210 of each color to the tank 235 of the recording head 234 via the supply tube 236 of each color.

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

  In order to feed the sheet 242 fed from the sheet feeding unit to the lower side of the recording head 234, a guide member 245 for guiding the sheet 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller. And a conveying belt 251 which is a conveying means for electrostatically attracting the fed paper 242 and conveying it at a position facing the recording head 234.

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A double-sided unit 271 is detachably attached to the back surface of the apparatus main body. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272.

  Further, a maintenance / recovery mechanism 281 that is a head maintenance / recovery device according to the present invention includes a recovery means for maintaining and recovering the nozzle state of the recording head 234 in the non-printing area on one side of the carriage 233 in the scanning direction. Is arranged. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “caps 282” when not distinguished) for capping each nozzle surface of the recording head 234, and nozzle surfaces. A wiper blade 283 that is a blade member for wiping the ink, and an empty discharge receiver 284 that receives liquid droplets for discharging the liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing.

  Further, in the non-printing area on the other side in the scanning direction of the carriage 233, there is an empty space for receiving a liquid droplet when performing an empty discharge for discharging a liquid droplet that does not contribute to the recording in order to discharge the recording liquid thickened during the recording. A discharge receiver 288 is disposed, and the idle discharge receiver 288 is provided with an opening 289 along the nozzle row direction of the recording head 234 and the like.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 237 and pressed against the conveying belt 251 by the leading end pressing roller 249, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 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 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

  As described above, since the image forming apparatus includes the liquid discharge head according to the present invention as a recording head, a high-quality image can be formed.

  Although the serial type image forming apparatus is described here as the image forming apparatus, the liquid discharge head according to the present invention can also be mounted on the line type image forming apparatus.

  In the above-described embodiment, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this. In addition, as described above, the present invention can also be applied to an image forming apparatus using a liquid other than the narrowly defined ink or a fixing processing liquid.

DESCRIPTION OF SYMBOLS 1 Flow path plate 2 Vibrating plate member 3 Nozzle plate 4 Nozzle 5 Nozzle communication path 6 Pressurized liquid chamber (individual liquid chamber)
7 Fluid resistance portion 8 Introduction portion 10 Common liquid chamber 12 Piezoelectric member 12Am, 12B Piezoelectric element column 17 Frame member 30 Liquid chamber spacing wall 31 Top surface 32a, 32b Side wall surface 33 Convex portion 233 Carriage 234a, 234b Recording head 411y, 411m, 411c, 411k recording head

Claims (7)

A nozzle member formed with a plurality of nozzles for discharging droplets;
A flow path member in which a plurality of groove-like individual liquid chambers communicating with the nozzle are formed;
A wall surface member that forms one surface of the individual liquid chamber,
The individual liquid chamber is a triangle having a surface opposite to the wall member as a top surface and a partition wall between the plurality of individual liquid chambers as a side wall surface, and the top surface and the side wall surfaces as two surfaces. A liquid discharge head, wherein a convex portion having a truncated pyramid shape having a conical shape or two surfaces of the top surface and the side wall surface and having a surface parallel to the side wall surface is provided.   The liquid ejection head according to claim 1, wherein a plurality of the convex portions are provided in a direction along a top surface and a wall surface of the individual liquid chamber. The liquid ejecting head according to claim 2, wherein the convex portions are provided on both side wall surfaces of the individual liquid chamber and are alternately arranged in a liquid flow direction.   The liquid ejection head according to claim 2, wherein the plurality of convex portions are alternately arranged on both sides of a partition wall between adjacent individual liquid chambers in a liquid flow direction. The plurality of individual liquid chambers have the same shape,
The adjacent individual liquid chambers are arranged in a staggered manner in the nozzle arrangement direction,
3. The droplet discharge head according to claim 2, wherein the convex portions are arranged at the same position in the direction of liquid flow in each individual liquid chamber.   The liquid ejection head according to claim 1, wherein the convex portion is not in contact with the wall surface member.   An image forming apparatus comprising the liquid discharge head according to claim 1.

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