JP2013063535A - Liquid ejection head and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a bubble at the downstream side of a filter in a common liquid chamber from being moved a pressure chamber side.SOLUTION: The common liquid chamber 28 includes: a supply-side common liquid chamber 31 to which liquid is supplied from the outside; a discharge-side common liquid chamber 32 which discharges the liquid to the outside; and a common channel 30 communicating with a plurality of pressure chambers 6. The supply-side common liquid chamber 31 communicates with the common channel 30 via a first filter 41, the discharge-side common liquid chamber 32 communicates with the common channel 30 via a second filter 42, and the second filter 42 is positioned higher than the first filter 41 in a height direction.

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. Devices such as ink jet recording devices are known.

  In the liquid ejection head, in order to eject droplets from fine nozzles, if dust or bubbles are mixed in the head flow path, the droplet ejection characteristics become unstable or a droplet ejection failure occurs.

  In view of this, conventionally, a filter member (Patent Document 1) in which a filter member that collects foreign matters is disposed in a common liquid chamber (common flow path) is known.

  In addition, two plate members are placed in the liquid chamber on the downstream side of the filter at an interval, and a part of the two plate members are overlapped when viewed from the liquid flow direction, and are arranged obliquely, thereby introducing the bubbles obliquely upward to the outside. What was made to discharge | emit (patent document 2) is also known.

JP 2000-296613 A JP 2002-144550 A

  However, when the filter member is arranged in the common liquid chamber, it is easy for bubbles to collect on the downstream side of the filter, and since the flow rate is suppressed by the filter, it is difficult to discharge the accumulated bubbles, and the bubbles move to the pressure chamber and the nozzle. This causes drop ejection failure.

  In this case, since the plate member is disposed on the downstream side of the filter as in Patent Document 2, the pressure loss increases, and particularly when the high frequency driving is performed, the liquid supply to the pressure chamber is not in time, and the necessary discharge characteristics are obtained. There is a problem of disappearing.

  The present invention has been made in view of the above points, and an object thereof is to prevent bubbles on the downstream side of the filter member in the common liquid chamber from moving to the pressure chamber side.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
A plurality of nozzles for discharging droplets;
A plurality of pressure chambers communicating with the nozzle;
A common liquid chamber sharing a liquid with the plurality of pressure chambers;
A filter provided in the common liquid chamber and collecting foreign substances contained in the liquid,
The common liquid chamber is
A supply side common liquid chamber to which liquid is supplied from the outside;
A common liquid chamber on the discharge side for discharging liquid to the outside;
A common flow path leading to the plurality of pressure chambers,
The supply-side common liquid chamber communicates with the common flow path through a first filter,
The discharge side common liquid chamber communicates with the common flow path through a second filter,
The second filter is provided at a higher position in the height direction than the first filter.

  The liquid discharge head according to the present invention can prevent bubbles on the downstream side of the filter in the common liquid chamber from moving to the pressure chamber side.

FIG. 3 is an exploded perspective view of the liquid discharge head according to the first embodiment of the present invention. It is sectional explanatory drawing in alignment with the direction orthogonal to the nozzle arrangement direction of the head. It is a plane explanatory view of each member of the head. It is plane explanatory drawing with which it uses for description of the 1st example of a filter part. It is a plane explanatory view used for description of the 2nd example of a filter part. It is sectional explanatory drawing which shows the example from which the through-hole of a filter part differs. FIG. 6 is an exploded perspective view of a liquid discharge head according to a second embodiment of the present invention. It is sectional explanatory drawing in alignment with the direction orthogonal to the nozzle arrangement direction of the head. 1 is a schematic side view illustrating a mechanism unit of an example of an image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. A liquid discharge head according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view of the head, FIG. 2 is a sectional view along a direction orthogonal to the nozzle arrangement direction of the head, and FIG. 3 is a plan view of each member of the head.

  In the liquid discharge head, the nozzle plate 1, the flow path plate 2, and the vibration plate member 3 are joined.

  A plurality of nozzles 4 for discharging droplets are arranged in a staggered pattern on the nozzle plate 1 (only one nozzle row is shown in FIGS. 1 to 3). The nozzle plate 1 is formed of, for example, stainless steel (for example, SUS316) by press working, and the nozzle plate 1 is made of other resin such as Ni electroforming, polyimide resin film, silicon, and combinations thereof. Etc. can be used. Further, a liquid repellent film is formed on the nozzle surface by a known method such as a plating film or a liquid repellent coating. The nozzle plate 1 is bonded to the flow path plate 2 with an adhesive.

  The flow path plate 2 forms a pressure chamber 6 communicating with the nozzle 4, a fluid resistance portion 7 serving as a liquid supply path for supplying liquid to the pressure chamber 6, and a liquid introduction portion 8 upstream of the fluid resistance portion 7. Yes. The flow path plate 2 is formed by press working using, for example, stainless steel (SUS304 or the like), but is not limited to this, and may be formed by etching a silicon substrate.

  The diaphragm member 3 has a vibration region 3 a that can displace a part of the wall surface of the pressure chamber 6. The diaphragm member 3 has an opening 9 that faces a common flow path 30 constituting a common liquid chamber, which will be described later, and passes through the common flow path 30 and the liquid introduction portion 8 that is the inlet side of each pressure chamber 6. Has been. The diaphragm member 3 has a two-layer structure and is formed by Ni electroforming.

  A common flow path member 20, a first filter member 21, a second filter member 22, and a common liquid chamber member 23 that also serves as a frame of the head are laminated and bonded to the side opposite to the pressure chamber 6 of the diaphragm member 3. Thus, the common liquid chamber 28 having the first filter portions 41 and 42, which includes the common flow path 30 for supplying the liquid to each pressure chamber 6, the supply-side common liquid chamber 31, and the discharge-side common liquid chamber 32, is formed. . Details of the configuration related to the common liquid chamber 28 will be described later.

  In addition, a piezoelectric actuator 11 is arranged on the side of the vibration member 3 opposite to the pressure chamber 6 in the vibration region 3a. The piezoelectric actuator 11 is joined to a piezoelectric member 12 in which a columnar piezoelectric element (piezoelectric column) is formed on a base member 13. Each piezoelectric column of the piezoelectric member 12 is joined to the island-shaped convex portion 3b formed in the vibration region 3a of the diaphragm member 3, and a drive signal is given through the FPC 16 which is a wiring member.

  The piezoelectric member 12 is bonded and fixed to the base member 13 to form grooves that are not divided by groove processing (slit processing), thereby forming a plurality of piezoelectric columns 12A that are columnar piezoelectric elements. Further, as the piezoelectric member 12, zirconate titanate (PZT) having a thickness of 10 to 50 μm / layer and internal electrodes made of silver / palladium (AgPd) having a thickness of several μm / layer were alternately stacked. A laminated piezoelectric member is used.

  The piezoelectric actuator 11 is inserted and arranged in an actuator insertion hole 19 provided in the common flow path member 20, the first filter member 21, the second filter member 22, and the common liquid chamber member 23.

  In this liquid ejection head, for example, the voltage applied to the piezoelectric column 12A is lowered from the reference potential, the piezoelectric column 12A contracts, the vibration region 3a of the diaphragm member 3 deforms, and the volume of the pressure chamber 6 expands. Then, the liquid (ink) flows into the pressure chamber 6 and then the voltage applied to the piezoelectric column 12A is increased to extend the drive column 12A in the stacking direction, and the vibration region 3a is deformed in the nozzle 4 direction. Ink droplets are ejected from the nozzles 4 by pressurizing the ink.

  Then, by returning the voltage applied to the piezoelectric column 12A to the reference potential, the vibration region 3a is restored to the initial position, and the pressure chamber 6 expands to generate a negative pressure. 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 (drawing-pushing), and striking or pushing can be performed depending on the direction of the drive waveform.

  Next, the details of the common liquid chamber structure in the first embodiment of the present invention will be described.

  First, as described above, in order to form the common liquid chamber 28, the common flow path member 20 that forms the common flow path 30 communicating with each pressure chamber 6 through the opening 9, the common liquid chamber 31 on the supply side, It has the common liquid chamber member 23 which forms the discharge side common liquid chamber 32, and the 1st filter member 21 and the 2nd filter member 22 which are interposed between the common flow path member 20 and the common liquid chamber member 23.

  The common liquid chamber member 23 forms a supply-side common liquid chamber 31 and a discharge-side common liquid chamber 32 that are partitioned by a partition wall 34. The supply side common liquid chamber 31 and the discharge side common liquid chamber 32 have a shape that is long in the nozzle arrangement direction, and are partitioned by a partition wall 34 in a direction perpendicular to the nozzle arrangement direction.

  The common liquid chamber member 23 is provided with a liquid supply port 35 through which ink is supplied from the outside to the end of the supply side common liquid chamber 31. A liquid discharge port 36 for discharging ink to the outside is provided at the end of the discharge side common liquid chamber 32 opposite to the liquid supply port 35.

  Further, in the direction orthogonal to the nozzle arrangement direction, the supply-side common liquid chamber 31 is disposed on the side facing the liquid introduction portion 8 that is the inlet side of the pressure chamber 6 of the common flow path 30, and the discharge-side common liquid chamber 32 is It arrange | positions at the side which the liquid introduction part 8 does not face.

  The first filter member 21 is provided with a first filter portion 41 interposed between the supply-side common liquid chamber 31 and the common flow path 30. The second filter member 22 is provided with a second filter portion 42 interposed between the discharge side common liquid chamber 32 and the common flow path 30. The first filter member 21 has an opening 45 through the common flow path 30 and the second filter portion 42, and the second filter member 22 passes through the supply-side common liquid chamber 31 and the first filter portion 41. An opening 46 is formed.

  Here, in the arrangement at the time of liquid discharge in which the nozzle surface is arranged downward, the second filter member 22 is stacked on the upper side in the height direction on the first filter member 21, so that the first filter unit 41 Also, the second filter portion 42 is disposed at a higher position in the height direction by the thickness of the first filter member 21.

  In addition, a recess 38 serving as a bubble reservoir is provided on the wall surface of the common flow path 30 on the second filter portion 42 side formed by the first filter member 21. The recess 38 is formed so that the width of the opening 45 facing the second filter portion 42 of the first filter portion 41 in the direction orthogonal to the nozzle arrangement direction is larger than that of the second filter portion 42.

  With this configuration, when the ink is initially filled in the liquid discharge head, the ink is pressurized and supplied from the liquid supply port 35, the nozzle 4 is sealed with a suction cap (not shown), and the nozzle is sucked by suction means such as a suction pump. The ink is filled in the flow path in the head by performing suction from 4, and then the ink is discharged from the liquid discharge port 36 by supplying the pressure from the liquid supply port 35 by pressurizing the ink. Can be filled.

  Here, the ink supplied from the liquid supply port 35 passes through the first filter section 41 and flows from the common flow path 30 to the pressure chambers 6 through the openings 9, and from the common flow path 30 to the second filter section. It flows into the discharge side common liquid chamber 32 through 42.

  At this time, the air bubbles mixed downstream from the first filter part 41 move to the second filter part 42 side away from the inlet side (liquid introduction part 8 side) of the pressure chamber 6 of the common flow path 30 by buoyancy. In addition, bubbles that cannot pass through the second filter portion 42 are collected in the recess 38.

  In this way, the movement of bubbles from the common flow path 30 to each pressure chamber 6 is suppressed, and pressure loss due to bubble clogging can be reduced, so-called nozzle omission (droplet ejection failure or droplet ejection failure) does not occur. Stable droplet ejection can be performed.

  Next, different examples of the first filter on the supply side and the second filter on the discharge side will be described with reference to FIGS.

  The first example shown in FIG. 4 is an example in which a plurality of through holes 40 are arranged in a staggered manner. Further, the second example shown in FIG. 5 is an example in which a plurality of through holes 40 are arranged in a lattice shape.

  Here, the through hole 40 is formed in a taper shape as shown in FIG. 6A or a horn shape as shown in FIG. These shapes can be easily formed, for example, by manufacturing a filter member by a Ni electroforming method.

  The through-hole 40 is not limited to a circular shape in plan view, and may be a polygonal shape. The aperture ratio per unit area is also an element that greatly affects the fluid resistance, and the through holes 40 can be efficiently arranged by using a polygonal shape.

  The diameter of the through hole 40 is set to be equal to or smaller than the diameter of the nozzle 4 on the downstream side.

  As shown in FIGS. 4 and 5, the aperture ratio of the second filter portion 42 is made larger than the aperture ratio of the first filter portion 41. That is, the number of through holes 40 per unit area of the second filter portion 42 shown in each drawing (b) is larger than the number of through holes 40 per unit area of the first filter portion 41 shown in each drawing (a). There are many.

  As described above, since the opening ratio of the second filter section 42 on the discharge side is larger than the opening ratio of the first filter section 41 on the supply side, the flow to the discharge side common liquid chamber 32 is likely to occur, and bubbles are retained. Even in this case, the buoyancy of the bubbles makes it easier for the bubbles to move to the second filter portion 42 side or the bubble reservoir 38 side away from the inlet side of the pressure chamber 6.

  Further, the second filter part 42 is provided with liquid repellency. The liquid repellency is imparted by forming a liquid repellent film by a known method such as a plating film or a liquid repellent coating, similarly to the nozzle surface.

  In this way, by making the liquid repellency of the second filter part 42 on the discharge side higher (larger) than the liquid repellency of the first filter part 41 on the supply side, bubbles are formed on the second filter part 42 side on the discharge side. Makes it easier to stay. Thereby, it is possible to make the bubbles stay at a position away from the inlet side of the pressure chamber 6, and to reduce the entry of the bubbles into the pressure chamber 6 during discharge or suction operation from the nozzle surface.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is an exploded perspective view of the head, and FIG. 8 is a cross-sectional view along a direction orthogonal to the nozzle arrangement direction of the head.

  In the present embodiment, a single filter member 24 is used, and the filter 43 provided on the filter member 24 is disposed obliquely and interposed between the supply-side common liquid chamber 31 and the common flow path 30. A first filter part 41 and a second filter part 42 interposed between the discharge side common liquid chamber 32 and the common flow path 30 are formed, and the second filter part 42 is arranged in the height direction with respect to the first filter part 41. It is placed at a high position.

  In this case, the common liquid chamber member 23 is arranged in the order of the outer wall portion 23A outside the supply side common liquid chamber 31, the partition wall portion 34, and the outer wall portion 23B outside the discharge side common liquid chamber 32 in the direction orthogonal to the nozzle arrangement direction. The thickness is reduced.

  With this configuration, it is possible to obtain the same operational effects as those of the first embodiment, and it is possible to reduce costs by reducing the number of parts. In addition, since the first filter part 41 and the second filter part 42 are continuously inclined, the air bubbles on the downstream side of the first filter part 41 smoothly move to the second filter part 42 side. Bubbles can be moved to the side farther from the inlet side of the pressure chamber 6.

  Although the piezoelectric head is described in the above embodiment, the present invention is similarly applied to a thermal head using a substrate provided with a heating resistor as a wall surface member or other electrostatic head. can do.

  Also, a head-integrated liquid cartridge (cartridge-integrated head) can be obtained by integrating the above-described liquid discharge head and a tank that supplies liquid to the liquid discharge head.

  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 an explanatory side view of the mechanism portion of the apparatus, and FIG. 10 is an explanatory plan view of the 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 with an integrated tank is arranged in a sub-scanning direction orthogonal to the main scanning direction with a nozzle row composed of a plurality of nozzles, and is mounted with the ink droplet ejection direction facing downward.

  Each of the recording heads 234 has two nozzle rows, and one nozzle row of one recording head 234a has a black (K) droplet, the other nozzle row has a cyan (C) droplet, and the other nozzle row has the other nozzle row. One nozzle row of the recording head 234b discharges magenta (M) droplets, and the other nozzle row discharges yellow (Y) droplets. 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.

  A guide 245 for guiding the paper 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller 249 are used to feed the paper 242 fed from the paper feeding unit to the lower side of the recording head 234. And a holding 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 stably formed.

  In the present application, the “paper” is not limited to paper, but includes OHP, cloth, glass, a substrate, etc., and means a material to which ink droplets or other liquids can be attached. , Recording media, recording paper, recording paper, and the like. In addition, image formation, recording, printing, printing, and printing are all synonymous.

  The “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. “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 causing a droplet to land on the medium). ) Also means.

  The “ink” is not limited to an ink unless otherwise specified, but includes any liquid that can form an image, such as a recording liquid, a fixing processing liquid, or a liquid. Used generically, for example, includes DNA samples, resists, pattern materials, resins, and the like.

  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.

  Further, the image forming apparatus includes both a serial type image forming apparatus and a line type image forming apparatus, unless otherwise limited.

DESCRIPTION OF SYMBOLS 1 Nozzle plate 2 Flow path plate 3 Vibration board member 4 Nozzle 6 Pressure chamber 8 Liquid introduction part 11 Piezoelectric actuator 20 Common flow path member 21 1st filter member 22 2nd filter member 23 Common liquid chamber member 24 Filter member 28 Common liquid chamber DESCRIPTION OF SYMBOLS 30 Common flow path 31 Supply side common liquid chamber 32 Discharge side common liquid chamber 41 1st filter part 42 2nd filter part 43 Filter 233 Carriage 234a, 234b Recording head

Claims (8)

A plurality of nozzles for discharging droplets;
A plurality of pressure chambers communicating with the nozzle;
A common liquid chamber sharing a liquid with the plurality of pressure chambers;
A filter provided in the common liquid chamber and collecting foreign substances contained in the liquid,
The common liquid chamber is
A supply side common liquid chamber to which liquid is supplied from the outside;
A common liquid chamber on the discharge side for discharging liquid to the outside;
A common flow path leading to the plurality of pressure chambers,
The supply-side common liquid chamber communicates with the common flow path through the first filter section,
The discharge side common liquid chamber communicates with the common flow path through a second filter portion,
The liquid ejection head, wherein the second filter unit is provided at a higher position in the height direction than the first filter unit.   2. The liquid ejection head according to claim 1, wherein the first filter portion and the second filter portion are separate members and are arranged with a step in the height direction.   The said 1st filter part and the said 2nd filter part are one member, and it arrange | positions so that the said 2nd filter part may become high in a height direction, It is characterized by the above-mentioned. Liquid discharge head.   In the direction orthogonal to the nozzle arrangement direction, the supply-side common liquid chamber is disposed on the side of the common flow path facing the inlet side of the pressure chamber, and the discharge-side common liquid chamber is connected to the pressure chamber of the common flow path. 4. The liquid discharge head according to claim 1, wherein the liquid discharge head is disposed on a side where the inlet side does not face.   5. The liquid ejection head according to claim 1, wherein a bubble reservoir is formed on a wall surface of the common flow path on the second filter portion side.   6. The liquid ejection head according to claim 1, wherein an aperture ratio of the second filter portion is larger than an aperture ratio of the first filter portion.   The liquid discharge head according to claim 1, wherein the liquid repellency of the second filter portion is greater than the liquid repellency of the first filter portion.   An image forming apparatus comprising the liquid discharge head according to claim 1.

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