JP6701795B2 - Liquid ejection head, liquid ejection device, and image forming apparatus - Google Patents

Description

  The present invention relates to a liquid ejection head, a liquid ejection device, and an image forming apparatus.

  Recording devices using liquid ejection heads have been widely used in various applications in recent years with the spread of personal computers in general households due to cost reduction, high image quality, generalization, etc., but as a major technical problem, There are higher speed and higher image quality.

  As a solution to this, there are a method of increasing the drive frequency of the pressure generating means such as a piezoelectric element and a method of increasing the number of nozzles for each head. However, if the driving frequency of the pressure generating means is increased, the behavior of the pressure in the pressurized liquid chamber becomes complicated due to the reflection of the pressure propagating from the pressurized liquid chamber to the common liquid chamber, and the ink droplets can be accurately ejected. It gets harder. Therefore, it is necessary to suppress the pressure change in the common liquid chamber and suppress the propagation of the pressure from the common liquid chamber to the pressurized liquid chamber.

  However, a method of arranging a structure that prevents pressure propagation on the wall that divides the common liquid chamber has been proposed for some time, but for a head that requires a small size and high density, it must be enlarged to add a structure. There was a problem that it could not be applied.

  Patent Document 1 discloses a configuration in which a pressure wave propagation preventing member is arranged on a wall that defines the common liquid chamber for the purpose of reducing the influence of the pressure reflection of the common liquid chamber on the pressurized liquid chamber. There is. However, as described above, the problem that the configuration can be implemented without increasing the size of the head or changing the configuration (the structure can be produced more easily and the effect can be obtained) cannot be solved. Further, since the surface of the columnar wave diffusing member is formed in a concavo-convex shape, the pressure wave propagating to the common liquid chamber side easily returns to the pressurized liquid chamber side again.

  In Patent Document 2, in order to reduce the return of the pressure wave from the common liquid chamber to the pressurized liquid chamber, the pressure propagated from the pressurized liquid chamber on the wall surface of the common liquid chamber in the direction orthogonal to the nozzle arrangement direction. A plurality of pressure dispersing means for dispersing the are arranged along the nozzle arrangement direction. The pressure dispersion means has a shape in which a cross-sectional area in a direction orthogonal to the liquid flow direction increases in a direction opposite to the liquid flow direction in the liquid flow direction from the common liquid chamber to the individual flow paths. is doing. However, as described above, the problem that the configuration can be implemented without increasing the size of the head or changing the configuration (the structure can be produced more easily and the effect can be obtained) cannot be solved.

  Therefore, an object of the present invention is to provide a liquid ejection head that can easily and inexpensively suppress the pressure generated in the pressurized liquid chamber from returning to the pressurized liquid chamber and affecting the pressurized liquid chamber. To do.

In order to solve the above problems, a liquid ejection head according to the present invention includes a nozzle substrate in which a plurality of nozzles for ejecting a liquid are arranged, a plurality of pressurized liquid chambers communicating with the plurality of nozzles, and the plurality of applied liquid chambers. A liquid discharge head having a common liquid chamber communicating with a pressure liquid chamber, the flow path substrate being joined to the nozzle substrate, and pressure generating means for generating a pressure in the pressurized liquid chamber. The pressurized liquid chamber and the common liquid chamber communicate with each other through a fluid resistance portion, and the fluid resistance portion has a communication portion through which the liquid flows, and the common liquid is provided in a cross section in the plane direction of the flow path substrate. The chamber has one convex shape on a surface facing the pressurized liquid chamber and the communicating portion, the convex shape corresponding to one communicating portion, and the pressurized liquid chamber, the convex shape, and the communicating portion are the nozzles. Are arranged in the same direction as the row direction, and the communicating portion and the convex shape have a line segment connecting the vertex of the convex shape and the center of the communicating section in the direction in which the communicating portion is arranged. It is characterized in that it is arranged so as to overlap in the flowing direction of the liquid in the section .

  According to the present invention, it is possible to provide a liquid ejection head which can inexpensively and easily suppress the pressure generated in the pressurized liquid chamber from returning to the pressurized liquid chamber and affecting the pressurized liquid chamber.

FIG. 3 is a schematic side view of an example of a liquid ejection head according to the present invention. FIG. 3 is a schematic plan view of an example of a liquid ejection head according to the present invention. It is a cross-sectional schematic diagram which is perpendicular to the nozzle row installation direction which follows the AA line of FIG. It is a cross-sectional schematic diagram in the surface direction of the flow path substrate which follows the CC line of FIG. 11A to 11C are schematic cross-sectional views in the plane direction of the flow path substrate for explaining the reflection of pressure in the liquid ejection head according to the conventional example. 6A to 6C are schematic cross-sectional views in the plane direction of the flow path substrate for explaining the reflection of pressure in an example of the liquid ejection head according to the present invention. FIG. 9 is a schematic cross-sectional view of a flow path substrate in a plane direction in another example of the liquid ejection head according to the present invention. FIG. 9 is a schematic cross-sectional view in the plane direction of the flow path substrate in another example of the liquid ejection head according to the present invention. 7A to 7C are schematic cross-sectional views in the plane direction of the flow path substrate for explaining pressure reflection in another example of the liquid ejection head according to the present invention. FIG. 9 is a schematic cross-sectional view of a flow path substrate in a plane direction in another example of the liquid ejection head according to the present invention. FIG. 9 is a schematic cross-sectional view perpendicular to the nozzle row installation direction in another example of the liquid ejection head according to the present invention. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention including a liquid ejection device including a liquid ejection head according to the present invention. FIG. 9 is a schematic configuration diagram showing another example of an image forming apparatus including a liquid ejection apparatus according to the present invention. FIG. 6 is a schematic plan view of a main part showing another example of an image forming apparatus including a liquid ejection apparatus according to the present invention.

  Hereinafter, a liquid ejection head, a liquid ejection device, and an image forming apparatus according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and other embodiments, additions, modifications, deletions, and the like can be modified within the scope of those skilled in the art, and any mode Also, as long as the action and effect of the present invention are exhibited, it is included in the scope of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, an embodiment of a liquid ejection head according to the present invention will be described with reference to FIGS. 1 is a schematic side view of the same liquid discharge head, FIG. 2 is a schematic plan view of the same, and FIG. 3 is a schematic sectional view perpendicular to the nozzle array direction along the line AA of FIG.

  The liquid ejection head H of the present embodiment includes a flow channel substrate 1 formed of, for example, a SUS substrate, a vibration plate 2 bonded to the lower surface of the flow channel substrate 1, and a nozzle plate 3 bonded to the upper surface of the flow channel substrate 1. Have A pressurized liquid chamber (also referred to as a pressure chamber, a pressure chamber, a flow channel, etc.) 6 as an individual flow channel through which the nozzles 4 for ejecting the liquid communicate with each other, and an ink (liquid) in the pressurized liquid chamber 6 ( A fluid resistance part 7 having a communication part 5 through which the liquid flows and a common liquid chamber 8 for supplying the recording liquid to the plurality of pressurized liquid chambers 6 are formed, which also serves as a supply path for supplying the recording liquid). The common liquid chamber 8 is supplied with a recording liquid from a recording liquid tank (not shown) via a supply path.

  Here, the flow path substrate 1 is configured by adhering the restrictor plate 1A and the chamber plate 1B. The flow path substrate 1 is formed by forming an opening of each pressurizing liquid chamber 6, a fluid resistance portion 7, a common liquid chamber 8 or the like by etching the SUS substrate using an acidic etching liquid or performing mechanical processing such as punching. is doing. The fluid resistance portion 7 may be formed by opening the portion of the restrictor plate 1A and not opening the portion of the chamber plate 1B.

  The diaphragm 2 is adhesively bonded to the chamber plate 1B that constitutes the flow path substrate 1. The diaphragm 2 is formed by joining a convex portion 11B formed of a SUS substrate to a resin member 11A such as polyimide. Besides this, for example, one formed from a nickel metal plate can be used. As described above, by joining the chamber plate 1B of the fluid resistance portion 7 on the side of the vibration plate 2 to the vibration plate 2, the inside of the pressurized liquid chamber 6 is inserted through the resin member 11A of the vibration plate 2 such as thin polyimide. It is possible to prevent the pressure from escaping to the outside and to efficiently eject the droplets.

  The nozzle plate 3 forms a large number of nozzles 4 having a diameter of 10 to 30 μm corresponding to each pressurized liquid chamber 6, and is bonded to the restrictor plate 1A of the flow path substrate 1 with an adhesive. The nozzle plate 3 may be made of metal such as stainless steel or nickel, resin such as polyimide resin film, silicon, or a combination thereof. In addition, a water repellent film is formed on the nozzle surface (surface in the ejection direction: ejection surface) by a known method such as a plating film or a water repellent coating in order to ensure water repellency with ink.

  Then, a laminated piezoelectric element that constitutes pressure generating means (actuator means) corresponding to each pressurized liquid chamber 6 via the convex portion 11B on the outside of the surface of the vibration plate 2 (on the side opposite to the pressurized liquid chamber 6). 12 (sometimes referred to as piezoelectric elements) are bonded to each other, and these laminated piezoelectric elements 12 are bonded to the base member 13. The plurality of piezoelectric elements 12 are formed in one piezoelectric element member by groove processing (slit processing) without being divided, and the piezoelectric element members are fixed on the base member 13 along the arrangement direction of the plurality of piezoelectric elements 12. It is arranged. An FPC (Flexible printed circuits) cable 14 for applying a drive waveform is connected to one end surface of the piezoelectric element 12.

  The ink in the pressurized liquid chamber 6 may be pressurized by using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 12, or by using the displacement in the d31 direction as the piezoelectric direction of the piezoelectric element 12. It is also possible to adopt a configuration in which the ink inside 6 is pressurized. In this embodiment, a configuration using displacement in the d33 direction is used.

  The base member 13 is preferably made of a metal material. If the material of the base member 13 is metal, it is possible to prevent heat accumulation due to self-heating of the piezoelectric element 12. The piezoelectric element 12 and the base member 13 are adhesively bonded by an adhesive, but when the number of channels increases, the temperature rises to near 100° C. due to self-heating of the piezoelectric element 12, and the bonding strength significantly decreases. Further, the temperature inside the head rises due to self-heating and the ink temperature rises, but when the temperature of the ink rises, the viscosity of the ink decreases and the ejection characteristics are greatly affected. Therefore, by forming the base member 13 with a metal material to prevent heat accumulation due to self-heating of the piezoelectric element 12, it is possible to prevent deterioration of ejection strength due to decrease in joint strength and decrease in ink viscosity.

  Further, a frame member 17 is joined to the periphery of the diaphragm 2 with an adhesive. The frame member 17 is provided with a supply liquid chamber 16 adjacent to the common liquid chamber 8 via a vibration plate filter portion (supply opening portion) 19 as a deformable portion formed of the resin member 11A of the vibration plate 2. Has been formed. The diaphragm filter portion 19 forms wall surfaces of the common liquid chamber 8 and the supply liquid chamber 16. The diaphragm filter portion 19 as a deformable portion forming the wall portion between the supply liquid chamber 16 and the common liquid chamber 8 is formed of the member forming the diaphragm 2. It is also possible to use a separate member without being combined with.

  Further, the frame member 17 is formed with a communication passage 20 that connects the supply liquid chamber 16 and the outside (atmosphere). In this case, the communication passage 20 communicates with the atmosphere by opening on the side opposite to the surface on which the nozzle 4 is formed (the surface of the frame member 17). That is, if the nozzle surface is opened, the recording liquid may enter the supply liquid chamber 16 through the communication passage 20 when the nozzle surface is wiped (for this reason, the recording liquid may be covered by a so-called nozzle cover or the like). It is necessary to open), and the opening on the side opposite to the nozzle surface can prevent the recording liquid from entering the supply liquid chamber 16.

  Further, the communication passage 20 is formed at a position not facing the diaphragm filter portion 19. Accordingly, it is possible to prevent foreign matter from being inserted into the communication passage 20 and damaging the diaphragm filter portion 19.

  In addition, in the liquid ejection head of the present embodiment, the piezoelectric elements 12 are formed at intervals of 300 dpi and are arranged in two rows facing each other. Further, the pressurized liquid chamber 6 and the nozzle 4 are arranged, for example, in two rows in a zigzag pattern at intervals of one row of 150 dpi, and a resolution of 300 dpi can be obtained by one scan. In this case, the plurality of piezoelectric elements 12 arranged in one row are the piezoelectric elements 12 that are driven alternately and the piezoelectric elements 12 that are not driven and that are simply supporting columns.

  Further, as described above, in the liquid ejection head of the present embodiment, most of the members are formed of SUS and have the same thermal expansion coefficient, so that various problems due to thermal expansion during head assembly or during use. Can be avoided.

  In the liquid discharge head configured as described above, for example, by lowering the voltage applied to the piezoelectric element 12 from the reference potential, the piezoelectric element 12 contracts, the diaphragm 2 descends, and the volume of the pressurized liquid chamber 6 expands. .. As a result, the ink flows into the pressurized liquid chamber 6, and then the voltage applied to the piezoelectric element 12 is increased to extend the piezoelectric element 12 in the stacking direction, and the vibrating plate 2 is deformed in the nozzle 4 direction to apply the pressurized liquid. Shrink volume/volume of chamber 6. By contracting the volume/volume of the pressurized liquid chamber 6, the recording liquid in the pressurized liquid chamber 6 is pressurized and droplets of the recording liquid are ejected (jetted) from the nozzle 4.

  Then, by returning the voltage applied to the piezoelectric element 12 to the reference potential, the diaphragm 2 is restored to the initial position and the pressurized liquid chamber 6 expands to generate negative pressure. At this time, from the common liquid chamber 8 The recording liquid is filled in the pressurized liquid chamber 6. Therefore, after the vibration of the meniscus surface of the nozzle 4 is damped and stabilized, the operation for the next droplet ejection is started.

  The method for driving the head is not limited to the above example (pull-push ejection), and pull ejection or push ejection may be performed depending on how the drive waveform is applied.

  In such a liquid ejection head, when pressure is generated in the pressurized liquid chamber 6 in order to eject the liquid from the nozzle 4, the pressure is applied to the common liquid chamber 8 and the supply unit side (supply liquid) via the fluid resistance unit 7. It also propagates to the room 16 side). This pressure is reflected on the wall surface and returns to the pressurized liquid chamber 6, and the ejection state is changed by changing the meniscus state of the nozzle. Therefore, the ejection of the liquid is affected.

Next, details of the liquid ejection head of the present embodiment will be described.
In the liquid ejection head of this embodiment, the pressurized liquid chamber 6 and the common liquid chamber 8 communicate with each other through the fluid resistance portion 7, and the fluid resistance portion 7 has the communication portion 5 through which the liquid flows. Then, in the cross section in the plane direction of the flow path substrate 1, the common liquid chamber 8 has an uneven shape on the surface facing the pressurized liquid chamber 6, and has a convex shape on the area facing the communicating portion 5.

FIG. 4 shows a schematic view of a cross section of the liquid ejection head of the present embodiment in the plane direction of the flow path substrate 1. 4 is a schematic cross-sectional view taken along the line C-C in FIG.
As shown in FIG. 4, the common liquid chamber 8 has a concavo-convex shape on the surface facing the pressurized liquid chamber 6 and a convex shape on the region facing the communicating portion 5. With such a configuration, the direction in which the pressure is reflected by the reflecting wall surface can be changed (diffused to the surroundings), and the pressure can be prevented from being reflected in the pressurized liquid chamber 6, thus affecting the meniscus. Can be suppressed.

  Note that, in FIG. 4, the common liquid chamber 8 is a common liquid chamber 8 from the end of the wall surface of the pressurized liquid chamber 6 in at least a part of a region facing the communicating portion 5 among the wall faces facing the pressurized liquid chamber 6. It may be expressed as having a shape in which the distance to the facing wall surface in the chamber 8 is short. In the present embodiment, the liquid chamber width of the common liquid chamber 8 is shortened in at least a part of the region facing the communicating portion 5 (arrow in FIG. 4 ).

  Here, a comparison between the conventional example and this embodiment will be described. FIG. 5 shows a schematic cross-sectional view of the liquid discharge head according to the conventional example in the plane direction of the flow path substrate 1. Similarly, FIG. 6 shows a schematic cross-sectional view of the liquid ejection head according to the present embodiment in the plane direction of the flow path substrate 1. The arrows in FIGS. 5 and 6 indicate the direction of pressure propagation.

  As shown in FIG. 5A, when the liquid is ejected from the nozzle 4, the pressure passes through the communication portion 5 of the fluid resistance portion 7 and propagates to the common liquid chamber 8. As shown in FIG. 5B, the pressure propagated to the common liquid chamber 8 is reflected by the surface of the common liquid chamber 8 facing the pressurized liquid chamber 6, and as shown in FIG. It returns to the pressurized liquid chamber 6. For this reason, in the liquid ejection head of the conventional example, it is not possible to prevent the influence on the meniscus due to the pressure returning to the pressurized liquid chamber 6.

On the other hand, the liquid ejection head of this embodiment will be described with reference to FIG. Similar to FIG. 5A, the pressure generated in FIG. 6A passes through the communication portion 5 of the fluid resistance portion 7 and propagates to the common liquid chamber 8. In the present embodiment, as shown in FIG. 6B, the wall surface of the common liquid chamber 8 has an uneven shape, and the fluid resistance portion 7 has a convex shape in a region facing the communication portion 5. Therefore, the propagation direction of the pressure reflected by the wall surface of the common liquid chamber 8 can be changed, and as shown in FIG. 6C, the pressure returning to the pressurized liquid chamber 6 can be greatly reduced compared to the conventional case.
If the region of the fluid resistance portion 7 facing the communicating portion is concave, the structure will be such that the fluid wave converges to return the pressure wave.

  According to the present invention, by providing the concavo-convex shape on the wall surface of the common liquid chamber 8, it is possible to reduce the influence of the reflection of the pressure in the common liquid chamber 8 on the pressurized liquid chamber 6, thus increasing the size or The number of parts is increased, the configuration is complicated, and the design is not difficult and the cost is not high. Therefore, it is possible to inexpensively and easily suppress the pressure generated in the pressurized liquid chamber from returning to the pressurized liquid chamber and affecting the pressurized liquid chamber.

  In this embodiment, since the uneven shape is corrugated (also referred to as round shape, continuous change, etc.), the pressure from the arrangement direction of the pressurized liquid chambers 6 is less likely to return. In addition, the uneven shape in the present embodiment can be appropriately changed.

  Next, another embodiment according to the present invention is shown in FIG. FIG. 7 is a schematic view of a cross section in the plane direction of the flow path substrate 1 similarly to FIG. Although the uneven shape is wavy in the above embodiment, the uneven shape is triangular (also referred to as a discontinuous change) in this embodiment. Even with such a configuration, the same effect as that of the above-described embodiment can be obtained. Further, in the case of the triangular shape, it is easier to assume the pressure reflection path and to determine an appropriate uneven shape more easily than in the case of forming the round shape. In addition, the uneven shape in the present embodiment can be appropriately changed.

Further, in the above-described embodiment, since the peculiar configuration in the depth direction of the common liquid chamber 8 is not required, it is possible to form the uneven shape by a simple process. The shape (corrugation) of the embodiment according to FIG. 4 can be easily manufactured by pressing or etching, and the shape (triangle shape) of the embodiment according to FIG. 7 can be manufactured by etching.
When the triangular shape and the convex shape are corners as shown in FIG. 7, there is a point that a reflection path of pressure is easy to assume and preferable, but it is difficult to form the corner, and the anisotropy in the MEMS process or the like is high. It is considered that etching is a suitable construction method. On the other hand, the shape of FIG. 6 is easy to manufacture by the conventional method. In consideration of these, the uneven shape may be appropriately selected.

  Note that although Patent Document 1 describes sandblasting and pasting of mesh materials as examples, the above-mentioned processing and pasting of materials are performed in order to cope with a compact and high-density configuration and to cope with diversified inks. Very difficult to do. Further, there is a concern that the sticking adhesive may come into contact with the liquid, and immersion damage may increase due to an extreme increase in the surface area, leading to a reduction in the life of the head.

  Next, another embodiment according to the present invention will be described. FIG. 8 shows a liquid ejection head according to this embodiment. FIG. 8 is a schematic view of a cross section in the plane direction of the flow path substrate 1 similarly to FIG. As shown in FIG. 8, the pressurized liquid chamber 6 is partitioned by the partition wall portion, and the common liquid chamber 8 has an uneven shape having a convex shape in a region facing the partition wall portion. In the present embodiment, the uneven shape is wavy (round shape).

  Since the surface facing the partition wall also has a convex shape, the propagation of the pressure generated from the pressurized liquid chamber 6 is reflected by the convex shape of the surface facing the communicating portion 5 of the fluid resistance portion 7, and the addition of another row is performed. It is possible not to return to the pressure liquid chamber 6.

  Details of this embodiment will be described with reference to FIG. 9. Similarly to FIG. 5A, the pressure generated in FIG. 9A passes through the communication portion 5 of the fluid resistance portion 7 and propagates to the common liquid chamber 8. In the present embodiment, as shown in FIG. 9B, the wall surface of the common liquid chamber 8 has an uneven shape, and has a convex shape in a region facing the communicating portion 5 of the fluid resistance portion 7. Further, the surface of the fluid resistance portion 7 facing the communication portion 5 also has a convex shape.

  Therefore, the pressure reflected by the convex shape in the area facing the communicating portion 5 of the fluid resistance portion 7 is further reflected by the convex shape in the area facing the partition wall portion, and the pressure reflecting direction on the wall surface of the common liquid chamber 8 is further changed. It can be easily diffused. In addition, the effect of canceling out the reflected pressures can be expected. Thereby, the propagation direction of the pressure reflected by the wall surface of the common liquid chamber 8 can be directed toward the partition wall portion of the pressurized liquid chamber 6, and the pressure can be prevented from flowing into the pressurized liquid chambers 6 of the other rows. Therefore, the pressure returning to the pressurized liquid chamber 6 can be further reduced.

  Further, with respect to the embodiment according to FIG. 8, another embodiment in which the uneven shape is a triangular shape is shown in FIG. Also in this embodiment, the region facing the partition wall portion has a convex shape. Therefore, the propagation direction of the pressure reflected by the wall surface of the common liquid chamber 8 can be directed toward the partition wall portion of the pressurized liquid chamber 6, and the pressure can be prevented from returning to the pressurized liquid chamber 6 in the other row. The pressure returning to the pressurized liquid chamber 6 can be further reduced. As described above, the triangular shape has an advantage that it is easy to assume the reflection path, but it may be appropriately changed depending on the manufacturing method of the member.

  Next, another embodiment of the present invention will be described. A liquid ejection head according to this embodiment is shown in FIG. FIG. 11 is a schematic sectional view similar to FIG. 3, and is a schematic sectional view perpendicular to the nozzle array installation direction. As shown in FIG. 11, in this embodiment, the wall surface of the common liquid chamber 8 facing the fluid resistance portion 7 is inclined. When the pressure generated in the pressurized liquid chamber 6 propagates to the common liquid chamber 8 via the fluid resistance portion 7, the direction in which the pressure is reflected is changed by forming an angle (tilt) on the reflecting wall surface, It is possible to further suppress the pressure from being reflected by the pressurized liquid chamber 6. In this case, the pressure can be released to the supply unit side (supply liquid chamber 16 side), and the pressure return can be further suppressed.

Next, an example of an image forming apparatus including the liquid ejection apparatus according to the present invention including the liquid ejection head according to the present invention will be described with reference to FIG. Note that FIG. 12 is a schematic configuration diagram illustrating the overall configuration of the mechanical section of the same device.
This image forming apparatus is a line type image forming apparatus equipped with a recording head which is a full line type head having a nozzle row (in which nozzles 4 are arranged) having a length equal to or larger than a print area width of a medium.

  This image forming apparatus includes, for example, four full-line type liquid ejection heads according to the present invention that eject droplets of each color of black (K), cyan (C), magenta (M), and yellow (Y). The print heads 101b, 101c, 101m, and 101y configured (referred to as "print head 101" when colors are not distinguished) are provided, and each print head 101 is attached to a head holder (not shown) with the surface on which the nozzles 4 are formed facing downward. Further, a maintenance/recovery mechanism 102 for maintaining/restoring the performance of the head is provided corresponding to each recording head 101, and the maintenance/recovery mechanism 102 is maintained during the performance maintenance operation of the head such as a purging process and a wiping process. The mechanism 102 is moved relatively to face the nozzle surface of the recording head 101 with a capping member or the like constituting the maintenance/recovery mechanism 102.

  Note that, here, the recording head 101 is arranged to eject droplets of each color in the order of black, cyan, magenta, and yellow from the upstream side in the paper transport direction, but the arrangement and the number of colors are not limited to this. Further, as the line-type head, one or a plurality of heads in which a plurality of nozzle rows for ejecting droplets of each color are provided at a predetermined interval can be used, and the head and a recording liquid cartridge for supplying a recording liquid to the head. Can be integrated or can be separate.

  The paper feed tray 103 includes a bottom plate 105 on which the paper 104 is placed, and a paper feed roller (half-moon roller) 106 for feeding the paper 104. The bottom plate 105 is rotatable about a rotary shaft 109 attached to a base 108, and is biased toward the paper feed roller 106 by a pressure spring 107. A separation pad (not shown) made of a material having a large friction coefficient such as an artificial leather or a cork material is provided so as to face the paper feed roller 106 and prevent the paper 104 from being double-fed. Further, a release cam (not shown) that releases the contact between the bottom plate 105 and the paper feed roller 106 is provided.

  Further, guide members 110 and 111 for guiding the paper 104 fed in from the paper feed tray 103 are provided so as to feed the paper 104 between the transport roller 112 and the pinch roller 113.

  The conveyance roller 112 is rotated by a drive source (not shown), and conveys the fed sheet 104 toward the platen 115 arranged so as to face the recording head 101. The platen 115 may be a rigid structure as long as it can maintain the gap between the recording head 101 and the sheet 104, or a conveyor belt or the like can be used.

  On the downstream side of the platen 115, a paper discharge roller 116 for discharging the paper 104 on which an image is formed and a spur 117 facing the paper are arranged, and the paper 104 on which the image is formed is discharged by the paper discharge roller 116. The paper is discharged to the paper tray 118.

  A manual feed tray 121 for manually feeding the paper 104 and a paper feed roller 122 for feeding the paper 104 placed on the manual feed tray 121 are arranged on the opposite side of the paper discharge tray 118. The sheet 104 fed from the manual feed tray 121 is guided by the guide member 111 and fed between the transport roller 112 and the pinch roller 113.

  In this image forming apparatus, in the standby state, the release cam pushes down the bottom plate 105 of the paper feed tray 103 to a predetermined position to release the contact between the bottom plate 105 and the paper feed roller 106. Then, in this state, when the transport roller 112 is rotated, this rotational driving force is transmitted to the sheet feeding roller 106 and the release cam (not shown) by a gear (not shown) or the like, and the release cam is separated from the bottom plate 105 and the bottom plate 105. , The paper feed roller 106 and the paper 104 come into contact with each other, the paper 104 is picked up as the paper feed roller 106 rotates, and paper feeding is started, and the paper is separated one by one by a separation claw (not shown).

  Then, the sheet 104 is guided by the guide members 110 and 111 by the rotation of the feeding roller 106 and is sent between the transport roller 112 and the pinch roller 113, and the sheet 104 is sent out onto the platen 115 by the transport roller 112. Then, the trailing edge of the sheet 104 is released from the contact with the D-cut portion of the sheet feeding roller 106, and is conveyed onto the platen 115 by the conveying roller 112. Incidentally. A conveyance rotation pair may be additionally provided between the paper feed roller 106 and the conveyance roller 112.

  In this way, the recording head 1 ejects droplets onto the sheet 104 conveyed on the platen 115 to form an image, and the sheet 104 on which the image is formed is ejected to the ejection tray 118 by the ejection roller 116. The paper is ejected. The speed of paper conveyance and the timing of droplet ejection during image formation are controlled by a controller (not shown).

  Further, the platen 115 may be a rigid structure as long as it can maintain the gap between the recording head 101 and the sheet 104, or a conveyor belt or the like can be used.

  As described above, by providing the liquid ejection head according to the present invention, a high quality image can be formed at high speed.

Next, another example of the image forming apparatus including the liquid ejection apparatus according to the present invention including the liquid ejection head according to the present invention will be described with reference to FIGS. 13 and 14. Note that FIG. 13 is a schematic configuration diagram for explaining the overall configuration of the mechanical section of the same device, and FIG. 14 is a plan view of the principal parts of the mechanical section.
This image forming apparatus is a serial type image forming apparatus, in which a carriage 233 is slidably held in a main scanning direction by main and slave guide rods 231 and 232 which are guide members extending laterally on left and right side plates 221A and 221B. The main scanning motor moves and scans in the arrow direction (carriage main scanning direction) in FIG. 14 via the timing belt.

  On the carriage 233, recording heads 234a and 234b (which are liquid ejection heads according to the present invention for ejecting ink droplets of respective colors of yellow (Y), cyan (C), magenta (M) and black (K) ( When no distinction is made, a "recording head 234") is arranged such that a nozzle row composed of a plurality of nozzles is arranged in the sub-scanning direction orthogonal to the main scanning direction, and the ink droplet ejection direction is directed downward.

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

  Further, the carriage 233 is equipped with head tanks 235a and 235b (referred to as "head tank 235" when no distinction is made) for supplying ink of each color corresponding to the nozzle row of the recording head 234. The ink of each color is replenished and supplied from the ink cartridge 210 of each color to the head tank 235 via the supply tube 236 of each color.

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

  Then, in order to feed the paper 242 fed from the paper feeding unit to the lower side of the recording head 234, a guide member 245 that guides the paper 242, a counter roller 246, a conveyance guide member 247, and a leading end pressing roller. In addition to a holding member 248 having a holding belt 249, a feeding belt 251 which is a feeding unit for electrostatically attracting the fed sheet 242 and feeding it at a position facing the recording head 234 is provided.

  The conveyor belt 251 is an endless belt, is stretched between the conveyor roller 252 and the tension roller 253, and is configured to circulate in the belt conveying direction (sub-scanning direction). Further, a charging roller 256 which is a charging unit for charging the surface of the conveyor belt 251 is provided. The charging roller 256 is arranged so as to come into contact with the surface layer of the conveyor belt 251 and be driven to rotate by the rotation of the conveyor belt 251. The transport belt 251 is rotated in the belt transport direction of FIG. 14 by the transport roller 252 being rotationally driven by a sub-scanning motor (not shown) at a timing.

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

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

  Further, as shown in FIG. 14, in the non-printing area on one side of the carriage 233 in the scanning direction, the head maintenance/recovery according to the present invention includes a recovery unit for maintaining and recovering the nozzle state of the recording head 234. A maintenance/recovery mechanism 281 which is a device 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 the nozzle surfaces of the recording head 234, and the nozzle surface. A wiper blade 283, which is a blade member for wiping the recording medium, and an idle ejection receiver 284 for receiving a droplet when performing idle ejection for ejecting a droplet that does not contribute to recording in order to discharge the thickened recording liquid. ing.

  Further, as shown in FIG. 14, in the non-printing area on the other side in the scanning direction of the carriage 233, idle discharge is performed to discharge the liquid droplets that do not contribute to the recording in order to discharge the recording liquid thickened during recording. An ink recovery unit (empty ejection receiver) 288, which is a liquid recovery container for receiving the liquid droplets at this time, is arranged, and the ink recovery unit 288 is provided with an opening 289 along the nozzle row direction of the recording head 234.

  In the image forming apparatus thus configured, the paper 242 is separated and fed one by one from the paper feed tray 202, and the paper 242 fed substantially vertically upward is guided by the guide 245, and is conveyed by the conveyor belt 251 and the counter. The sheet is conveyed while being sandwiched between the roller 246, the leading end thereof is guided by the conveying guide 237, and the leading end pressing roller 249 presses the conveying belt 251 to change the conveying direction by about 90°.

  At this time, a positive output and a negative output are alternately repeated with respect to the charging roller 256, that is, an alternating voltage is applied, and the charging voltage pattern in which the conveyor belt 251 alternates, that is, in the sub-scanning direction which is the circulating direction. , Plus and minus are alternately charged in a belt shape with a predetermined width. When the sheet 242 is fed onto the positively and negatively charged conveying belt 251, the sheet 242 is attracted to the conveying belt 251, and the sheet 242 is conveyed in the sub-scanning direction by the circular movement of the conveying 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 ended and the paper 242 is discharged to the paper discharge tray 203.

  Even with such a serial type image forming apparatus, by providing the liquid ejection head according to the present invention, stable droplet ejection characteristics can be obtained, so that a high quality image can be recorded at high speed.

  In the above embodiment, the liquid ejecting apparatus according to the present invention is applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this. For example, an image forming apparatus such as a printer/fax/copier multifunction device. Can also be applied to. Further, the invention can be applied to a liquid ejecting apparatus or an image forming apparatus that uses a liquid other than the recording liquid.

1 Flow Substrate 1A Restrictor Plate 1B Chamber Plate 2 Vibration Plate 3 Nozzle Plate 4 Nozzle 5 Communication Port 6 Pressurized Liquid Chamber 7 Fluid Resistance Section 8 Common Liquid Chamber 11 Vibration Plate Island Section 11A Resin Member 11B Convex Section 12 Piezoelectric Element 13 Base member 14 FPC cable 16 Supply liquid chamber 17 Frame member 19 Diaphragm filter part (supply opening)
20 communication passage 40 driver IC
101, 101b, 101c, 101m, 101y Recording head 102 Maintenance recovery mechanism 103 Paper feed tray 104 Paper 105 Bottom plate 106 Half moon roller (paper feed roller)
107 Pressure Spring 108 Base 109 Rotating Shaft 110, 111 Guide Member 112 Conveying Roller 113 Pinch Roller 115 Platen 116 Paper Ejecting Roller 117 Spur 118 118 Paper Ejecting Tray 121 Manual Feed Tray 122 Paper Feeding Roll 202 Paper Feeding Tray 203 Paper Ejecting Tray 210 Ink Cartridge 221A, 221B Side plates 231, 232 Guide rod 233 Carriage 234, 234a, 234b Recording heads 235, 235a, 235b Head tank 236 Supply tube 237 Conveying guide 241 Paper stacking part (pressure plate)
242 Paper 243 Feeding roller 244 Separation pad 245 Guide member 246 Counter roller 247 Conveying guide member 248 Holding member 249 Tip pressure roller 251 Conveying belt 252 Conveying roller 256 Charging roller 261 Separation claw 262 Discharging roller 263 Discharging roller 271 Double-sided unit 272 Manual feed tray 281 Maintenance/recovery mechanism 282, 282a, 282b Cap 283 Wiper blade 284 Empty ejection receiver 288 Ink recovery unit (empty ejection receiver)
289 opening

Japanese Patent No. 2771670 JP, 2005-174419, A

Claims (7)

A nozzle substrate in which a plurality of nozzles for ejecting liquid are arranged in a row,
A flow path substrate having a plurality of pressurized liquid chambers communicating with the plurality of nozzles and a common liquid chamber communicating with the plurality of pressurized liquid chambers, and joined to the nozzle substrate;
A liquid discharge head having pressure generating means for generating a pressure in the pressurized liquid chamber,
The pressurized liquid chamber and the common liquid chamber communicate with each other through a fluid resistance portion, and the fluid resistance portion has a communication portion through which the liquid flows,
In a cross section in the surface direction of the flow path substrate, the common liquid chamber has one convex shape on a surface facing the pressurized liquid chamber and the communication portion, corresponding to one communication portion.
The pressurized liquid chamber, the convex shape, and the communicating portion are arranged in a row in the same direction as the row of the nozzles.
The communication part and the convex shape are arranged such that a line segment connecting the apex of the convex shape and the center of the communication part in the row direction of the communication part overlaps in the flowing direction of the liquid in the communication part. A liquid discharge head characterized by being provided . The liquid ejection head according to claim 1, wherein the convex shape is wavy. The liquid ejection head according to claim 1, wherein the convex shape is a triangular shape. The plurality of pressurized liquid chambers are partitioned by partition walls,
The liquid ejection head according to claim 1, wherein the common liquid chamber has a convex shape in a region facing the partition wall portion.   The liquid according to any one of claims 1 to 4, wherein a surface of the common liquid chamber facing the pressurized liquid chamber is inclined in a cross section perpendicular to the row direction of the plurality of nozzles. Discharge head.   A liquid ejecting apparatus for ejecting liquid droplets from a liquid ejecting head, wherein the liquid ejecting head is the liquid ejecting head according to any one of claims 1 to 5.   An image forming apparatus which forms an image by ejecting liquid droplets from a liquid ejection head, wherein the liquid ejection head is the liquid ejection head according to any one of claims 1 to 5.

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