JP4755120B2 - Liquid supply member for liquid discharge head, head unit, liquid discharge apparatus, and image forming apparatus - Google Patents

Description

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

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, and a multifunction machine of these, for example, a recording head constituted by a liquid ejection head (also referred to as a droplet ejection head) that ejects liquid droplets of a recording liquid (liquid) is included. Using a liquid ejection apparatus, while conveying a medium (hereinafter also referred to as “paper”, the material is not limited, and a recording medium, a recording medium, a transfer material, recording paper, and the like are also used synonymously). In some cases, liquid (hereinafter also referred to as ink) is attached to a sheet to form an image (recording, printing, printing, and printing are also used synonymously).

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

  As the liquid ejection head, a piezoelectric plate is provided with a diaphragm on a part of the wall of the liquid chamber filled with ink, and the diaphragm is displaced by a piezoelectric actuator or the like to change the volume in the liquid chamber to increase the pressure and eject droplets. There is known a thermal-type head in which a head or a heating element that generates heat when energized is provided in the liquid chamber, and the pressure in the liquid chamber is increased by bubbles generated by the heat generation of the heating element to discharge droplets.

  In such a liquid ejection type image forming apparatus, the number of nozzles and the number of heads are increased in order to increase the speed. Recently, a line-type image forming apparatus that forms a long head by joining a plurality of short heads and forms an image without scanning the head has been adopted.

  However, when the head becomes longer and the number of nozzles increases, the probability of occurrence of ejection failure increases, and one of the causes of ejection failure is the entry of bubbles in the liquid chamber of the head. That is, if bubbles enter the liquid chamber, ink is not supplied and ejection is not performed, or droplet ejection pressure is absorbed and abnormal ejection occurs. Even if a small bubble is attached to the vicinity of the nozzle, for example, the droplet bends and flies, resulting in an abnormal image.

  There are various forms in which bubbles enter the liquid chamber in the head. In some cases, the ink may flow from a flow path for supplying ink to the head, or may be sucked from a nozzle. Further, in a head that discharges droplets by boiling the ink using a heating element, minute bubbles may remain in the liquid chamber during the discharge process.

In this way, when bubbles enter the liquid chamber, discharge (not often referred to as idle discharge or preliminary discharge) unrelated to image formation is performed, or the negative pressure is formed by capping the nozzle surface. Thus, there is known a method of discharging air bubbles together with ink by suction or pressurizing an ink supply path with a pump or the like. When air bubbles are discharged by these methods, although there is a method of recycling the discharged ink, basically, a large amount of ink is used regardless of image formation and is wasted. In addition, there exists patent document 1 as a recycled thing.
JP 2005-212350 A

  There is no method other than discharging the air bubbles in the liquid chamber by the above-described method, but there is a method for removing the air bubbles in the ink supply path by circulating ink in the ink supply path. According to this method, it is possible to avoid bubbles in the ink supply path from entering the liquid chamber without discharging ink even when the head is elongated as described above. However, in the method of discharging bubbles in the ink supply path by circulating ink, there is a problem that the meniscus formed in the nozzle of the head is destroyed by the circulating pressure of ink, and ink oozes out or sucks bubbles from the nozzle. is there.

In view of this, there is an ink jet recording apparatus that seals the nozzle surface during ink circulation as described in Japanese Patent Application Laid-Open No. H10-228707. This is because the ink supply passage for guiding ink from the ink tank to the common liquid chamber of the recording head, the ink discharge passage for guiding ink from the common liquid chamber to the ink tank, and the discharge port sealing for sealing the discharge port communicating with the common liquid chamber And an ink pump for pressure-feeding ink from the ink tank to the common liquid chamber, and the ink pump is operated with the discharge port sealed by the discharge port sealing means so that the ink supply passage, the common liquid chamber, and the ink are supplied from the ink tank. By circulating the ink through the discharge passage, the air in the ink flow path is discharged into the ink tank together with the ink.
Japanese Patent No. 2821920

Further, as described in Patent Document 3, the ink supply path is divided by a partition having a plurality of communication paths into a side closer to and far from the individual liquid chamber of the head, and an ink inflow pipe and an ink outflow pipe are arranged on the far side. There is a head in which the ink circulation pressure does not affect the meniscus. This is a common liquid that has a circulation path between the thermal head and the ink tank, includes an ink pressure feeding means in the circulation path, and communicates with a plurality of liquid paths that respectively communicate with a plurality of ejection ports that eject ink. A first common liquid chamber that communicates directly with the plurality of liquid passages; and a first common liquid chamber that is adjacent to the first common liquid chamber and opposite to the plurality of liquid passage sides; And a plurality of communication passages therebetween, and a part of the circulation path, which is divided into a second common liquid chamber having an inflow port from the ink tank and an outflow port to the ink tank.
Japanese Patent Application Laid-Open No. 08-238772

  As described above, in the method of discharging the bubbles in the liquid supply path by circulating the liquid, the meniscus formed in the nozzle of the head is destroyed by the circulating pressure of the liquid, and the liquid oozes out or sucks the bubbles from the nozzle. Therefore, the measures described in Patent Documents 2 and 3 are taken.

  However, in the configuration in which the nozzle surface is sealed during the circulation of the liquid as described in Patent Document 2, it is difficult to completely seal the head when the head is elongated, and the liquid is discharged during the circulation of the liquid. Thus, there is a problem that an image cannot be formed.

  Further, as described in Patent Document 3, the liquid supply path is divided into a partition having a plurality of communication paths, the side near and far from the individual liquid chamber of the head, and a liquid inflow pipe and a liquid outflow pipe are provided on the far side. In the configuration in which the liquid circulation pressure does not affect the meniscus, it is effective to prevent the bubbles in the ink supply path from entering the individual liquid chamber, but the bubbles and nozzles generated in the individual liquid chamber Even when bubbles sucked from the air flow upstream due to buoyancy or the like, there is a problem that the partition stays near the individual liquid chamber by the partition wall and cannot be discharged to the outside by a circulating flow.

  The present invention has been made in view of the above-mentioned problems. The bubbles in the liquid supply path including bubbles flowing backward from the head are discharged without circulating the liquid to the outside by the circulation flow, and the meniscus is further circulated by the circulation pressure. An object of the present invention is to provide a liquid supply member for a liquid discharge head that does not have an adverse effect such as destroying the liquid, a head unit including the liquid supply member, a liquid discharge apparatus, and an image forming apparatus.

  In order to solve the above problems, a liquid supply member for a liquid discharge head according to the present invention has a plurality of independent common liquid chambers that supply liquid to a plurality of liquid chambers that communicate with a plurality of nozzles that discharge droplets. A liquid supply member that is connected to the liquid discharge head and supplies liquid to each common liquid chamber of the liquid discharge head. The liquid supply member flows inside the liquid discharge head along the direction in which the nozzles of the liquid discharge head are arranged. The liquid channel has a supply port for supplying liquid to the liquid channel and a discharge port for discharging liquid from the liquid channel at the end in the longitudinal direction of the liquid channel. The opening cross-sectional area of the region connected to the liquid chamber is larger than the opening cross-sectional area between the common liquid chambers.

  A liquid supply member for a liquid discharge head according to the present invention is connected to a liquid discharge head having a plurality of independent common liquid chambers that supply liquid to a plurality of liquid chambers that communicate with a plurality of nozzles that discharge droplets. A liquid supply member for supplying a liquid to each common liquid chamber of the liquid discharge head, the liquid supply member having a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. At the longitudinal end of the flow path, a supply port for supplying the liquid to the liquid flow path and a discharge port for discharging the liquid from the liquid flow path are provided, and the liquid flow path is a communication port connected to the common liquid chamber It was set as the structure by which the rib was provided in the circumference | surroundings.

  A liquid supply member for a liquid discharge head according to the present invention is connected to a liquid discharge head having a plurality of independent common liquid chambers that supply liquid to a plurality of liquid chambers that communicate with a plurality of nozzles that discharge droplets. A liquid supply member for supplying a liquid to each common liquid chamber of the liquid discharge head, the liquid supply member having a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A supply port for supplying liquid to the flow path and a discharge port for discharging liquid from the liquid flow path are provided, and at least one of the supply port and the discharge port is provided at a portion other than the longitudinal end of the liquid flow path. Corresponding to the port provided at the part other than the longitudinal end, a rectifying member is provided for adjusting the flow between the liquid chamber and the common liquid chamber, and the liquid flow path has the same opening cross-sectional area in the region connected to the common liquid chamber Open section between liquid chambers It was a larger configuration than.

  A liquid supply member for a liquid discharge head according to the present invention is connected to a liquid discharge head having a plurality of independent common liquid chambers that supply liquid to a plurality of liquid chambers that communicate with a plurality of nozzles that discharge droplets. A liquid supply member for supplying a liquid to each common liquid chamber of the liquid discharge head, the liquid supply member having a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A supply port for supplying liquid to the flow path and a discharge port for discharging liquid from the liquid flow path are provided, and at least one of the supply port and the discharge port is provided at a portion other than the longitudinal end of the liquid flow path. Corresponding to the port provided in the part other than the longitudinal end, a rectifying member is provided to adjust the flow between the common liquid chamber and the liquid flow path is formed around the communication port connected to the common liquid chamber. The structure where And the.

  A liquid supply member for a liquid discharge head according to the present invention is connected to a liquid discharge head having a plurality of independent common liquid chambers that supply liquid to a plurality of liquid chambers that communicate with a plurality of nozzles that discharge droplets. A liquid supply member for supplying a liquid to each common liquid chamber of the liquid discharge head, the liquid supply member having a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A supply port for supplying the liquid to the flow path and a discharge port for discharging the liquid from the liquid flow path are provided, and at least one of the supply port and the discharge port is a portion other than the longitudinal end of the liquid flow path. The liquid flow path provided between the common liquid chambers has a larger opening cross-sectional area than that between the common liquid chambers.

  A liquid supply member for a liquid discharge head according to the present invention is connected to a liquid discharge head having a plurality of independent common liquid chambers that supply liquid to a plurality of liquid chambers that communicate with a plurality of nozzles that discharge droplets. A liquid supply member for supplying a liquid to each common liquid chamber of the liquid discharge head, the liquid supply member having a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A supply port for supplying the liquid to the flow path and a discharge port for discharging the liquid from the liquid flow path are provided, and at least one of the supply port and the discharge port is a portion other than the longitudinal end of the liquid flow path. The liquid channel provided between them has a structure in which a rib is provided around a communication port connected to the common liquid chamber.

  The head unit according to the present invention has a configuration in which a plurality of liquid ejection heads are arranged in the longitudinal direction of the liquid supply member for the liquid ejection head according to the present invention, with the positions being shifted in a direction perpendicular to the longitudinal direction of the head. It was.

  The liquid ejection apparatus according to the present invention is configured to include the liquid supply member according to the present invention for supplying the liquid to the liquid ejection head or the head unit according to the present invention.

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

  According to the liquid supply member for a liquid discharge head according to the present invention, the liquid supply member for the liquid discharge head has a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A supply port for supplying the liquid to the liquid flow path and a discharge port for discharging the liquid from the liquid flow path are provided, and the liquid flow path has an opening cross-sectional area of the region connected to the common liquid chamber. Therefore, bubbles generated in the liquid discharge head and bubbles flowing into the liquid discharge head from the upstream side of the liquid supply path can be discharged by a circulating flow without destroying the meniscus of the liquid discharge head.

  According to the liquid supply member for a liquid discharge head according to the present invention, the liquid supply member for the liquid discharge head has a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A supply port for supplying liquid to the liquid flow path and a discharge port for discharging liquid from the liquid flow path, and the liquid flow path has a configuration in which a rib is provided around a communication port connected to the common liquid chamber; Therefore, bubbles generated in the liquid discharge head and bubbles flowing into the liquid discharge head from the upstream side of the liquid supply path can be discharged by a circulating flow without destroying the meniscus of the liquid discharge head.

  According to the liquid supply member for a liquid discharge head according to the present invention, the liquid supply member for supplying a liquid to the liquid flow path has a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A discharge port for discharging the liquid from the flow path is provided, and at least one of the supply port and the discharge port is provided in a part other than the longitudinal end of the liquid flow path, and is provided in a part other than the longitudinal end. Corresponding to the port, a rectifying member for regulating the flow between the common liquid chambers is provided, and the liquid flow path is configured such that the opening cross-sectional area of the region connected to the common liquid chamber is larger than the open cross-sectional area between the common liquid chambers Therefore, the bubbles generated in the liquid discharge head and the bubbles flowing into the liquid discharge head from the upstream of the liquid supply path can be discharged by circulating flow without destroying the meniscus of the liquid discharge head, It is possible to improve the foam discharging efficiency.

  According to the liquid supply member for a liquid discharge head according to the present invention, the liquid supply member for supplying a liquid to the liquid flow path has a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A discharge port for discharging the liquid from the flow path is provided, and at least one of the supply port and the discharge port is provided in a part other than the longitudinal end of the liquid flow path, and is provided in a part other than the longitudinal end. A flow straightening member is provided between the common liquid chamber corresponding to the port, and the liquid flow path has a rib provided around the communication port connected to the common liquid chamber. Bubbles generated in the discharge head and bubbles flowing into the liquid discharge head from upstream of the liquid supply path can be discharged by circulating flow without destroying the meniscus of the liquid discharge head, and the bubble discharge efficiency is improved. It can be.

  According to the liquid supply member for a liquid discharge head according to the present invention, the liquid supply member for supplying a liquid to the liquid flow path has a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A discharge port for discharging the liquid from the flow path is provided, and at least one of the supply port and the discharge port is provided between the common liquid chambers at a portion other than the end portion in the longitudinal direction of the liquid flow path. Since the opening cross-sectional area of the region connected to the liquid chamber is larger than the opening cross-sectional area between the common liquid chambers, bubbles generated in the liquid discharge head and bubbles flowing into the liquid discharge head from the upstream of the liquid supply path are liquidated. While being able to discharge by a circulation flow, without destroying the meniscus of a discharge head, bubble discharge | emission efficiency can be improved.

  According to the liquid supply member for a liquid discharge head according to the present invention, the liquid supply member for supplying a liquid to the liquid flow path has a liquid flow path through which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head. A discharge port for discharging the liquid from the flow path is provided, and at least one of the supply port and the discharge port is provided between the common liquid chambers at a portion other than the end portion in the longitudinal direction of the liquid flow path. Since a rib is provided around the communication port connected to the liquid chamber, bubbles generated in the liquid discharge head and bubbles flowing into the liquid discharge head from the upstream of the liquid supply path can be used to reduce the meniscus of the liquid discharge head. While being able to discharge | emit by a circulation flow, without destroying, bubble discharge | emission efficiency can be improved.

  According to the head unit of the present invention, the liquid supply member for the liquid discharge head according to the present invention has a plurality of liquid discharge heads arranged in the longitudinal direction of the head while being displaced in a direction perpendicular to the longitudinal direction of the head. Therefore, a long head capable of performing stable droplet discharge can be obtained.

  According to the liquid ejection apparatus according to the present invention, since the liquid supply member according to the present invention for supplying the liquid to the liquid ejection head or the head unit according to the present invention is provided, stable droplet ejection is performed. be able to.

  According to the image forming apparatus of the present invention, since the liquid supply member according to the present invention for supplying the liquid to the liquid discharge head or the head unit according to the present invention is provided, stable droplet discharge is performed. be able to.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. A first embodiment of a head unit including a liquid supply member for a liquid ejection head according to the present invention will be described with reference to FIGS. 1 is a perspective explanatory view showing a head unit in which a liquid supply member and a liquid discharge head according to the present invention are integrated, FIG. 2 is a longitudinal sectional view of the head unit, and FIG. 4 is a cross-sectional explanatory view taken along line BB in FIG. 4, FIG. 4 is a sectional view in the short direction of the head unit along line AA in FIG. 2, and FIG. FIG. Further, in FIG. 3, the liquid discharge head is illustrated by a broken line for the sake of simplicity (the same applies hereinafter).

  The head unit 100 is integrated with the liquid supply member 20 in a plurality of (here, six, but not limited to) short liquid discharge heads 1a to 1f (when not distinguished, “liquid discharge head 1”). Is a long head such as a line-type head, which is configured by shifting the position in a direction perpendicular to the longitudinal direction of the head and arranging it in the longitudinal direction of the head, that is, in a staggered arrangement. .

  The liquid discharge head 1 is a thermal head, and includes a heating element substrate 2 and a flow path substrate 3. The flow path substrate 3 is provided with a plurality of nozzles 5 for discharging droplets and a plurality of individual liquid chambers 6 with which the nozzles 5 communicate with each other, and the heating element substrate 3 corresponds to each individual liquid chamber 6 with a heating element. An element is provided. A current-carrying means such as an FPC (not shown) is connected to the heat-generating body substrate 2, and the heat-generating element 4 is driven by inputting a pulse voltage or the like to the heat-generating element 4 via the current-carrying means. Film boiling occurs in the liquid in the chamber 6, and liquid droplets (droplets) are ejected from the nozzle 5. In the present embodiment, as shown in FIGS. 4 and 5, two nozzle rows in which a plurality of nozzles 5 are arranged in the longitudinal direction of the head are formed, and the individual liquid chambers 6 corresponding to the nozzles 5 include As shown in FIGS. 2 to 4, the liquid is supplied from a common liquid chamber 7 provided at the center of the heating element substrate 2.

  The present invention supplies liquid to the common liquid chamber 7 as shown in FIGS. 2 and 3 corresponding to the openings forming the common liquid chamber 7 of the heating element substrate 2 of the six liquid discharge heads 1. The liquid supply member 20 according to the above is joined. In the present embodiment, the liquid supply member 20 is directly joined to each liquid ejection head 1, but a configuration in which another member such as a spacer plate is interposed therebetween may be used.

  The liquid supply member 20 has main flow paths 21 and 21 serving as two independent liquid flow paths (liquid circulation paths) through which the liquid flows along the longitudinal direction. One main channel (liquid channel) 21 corresponds to a row of liquid ejection heads 1a, 1b, 1c, and the other main channel (liquid channel) 21 corresponds to a row of liquid ejection heads 1d, 1e, 1f. To do. A supply port 12 for supplying a liquid and a discharge port 13 for discharging the liquid are formed at the longitudinal ends of the liquid flow paths 21 and 21, respectively.

  As will be described later, the liquid supply member 20 is disposed in a liquid supply path (not shown), and the liquid flows from the supply port 12 to the discharge port 13 through the main channel 21 to circulate the liquid. In FIG. 2 and the like, arrows directed toward the supply port 12 and arrows directed outward from the discharge port 13 indicate the inflow direction and the discharge direction of the liquid, respectively (the same applies below).

  A narrow communication channel 22 having a relatively smaller opening cross-sectional area (narrow cross section) than the main channel 21 is provided between the main channel 21 and the common liquid chamber 7 of the liquid discharge head 1. Yes. The narrow communication path 22 serves as a liquid communication port communicating with the common liquid chamber 7 of the liquid discharge head 1. The opening cross-sectional area is a direction (liquid supply member) orthogonal to the longitudinal direction of the liquid supply member 20 (the arrangement direction of the nozzles of the liquid discharge head 1 and the circulating flow generation direction) as shown in the cross-sectional explanatory view of FIG. The area in the cross section in the 20 short direction).

  Accordingly, the liquid to each liquid discharge head 1 enters the main flow path 21 from the supply port 12 and then is supplied to the common liquid reservoir 7 via the narrow communication flow path 22. When air bubbles are mixed into the liquid supply member 20 from the upstream side of the liquid discharge head 1 or the supply port 12, the air bubbles accumulate on the upper part (the top surface 21d) of the main flow channel 21 by the buoyancy. Therefore, by forming a flow from the supply port 12 toward the discharge port 13 in the main channel 21, bubbles are discharged from the discharge port 13. At this time, as shown in FIG. 4, since the narrow communication channel 22 communicating with the liquid ejection head 1 is narrowed with respect to the main channel 21, the flow of the main channel 21 flows in the narrow communication channel 22. Therefore, the influence on the liquid discharge head 1 by the circulation flow for discharging the bubbles can be eliminated.

  Further, the main channel 21 is configured such that the opening cross-sectional area of the portion 21 a corresponding to the upper portion of the liquid discharge head 1 is larger than that of the portion 21 b between the liquid discharge heads 1. That is, the main channel 21 serving as the liquid channel has a configuration in which the opening cross-sectional area of the region (part 21a) connected to the common liquid chamber 7 is larger than the opening cross-sectional area between the common liquid chambers (part 21b). Specifically, the height Hg and the width Wg of the common liquid chamber connection region portion 21a are set to be larger than the height Hh and the width Wh of the common liquid chamber inter-portion portion 21b (Hg> Hh, Wg> Wh).

  By configuring the main flow path 21 in this way, the flow velocity of the circulation flow is relatively slow near the liquid discharge head 1, so that meniscus destruction of the nozzle 5 of the liquid discharge head 1 is prevented, and the liquid discharge head 1. Since the flow rate is relatively high between 1, the bubble discharge performance can be enhanced. Here, both the height and width of the main channel 21 are made different, and the opening cross-sectional areas of the common liquid chamber connection region portion 21a and the common liquid chamber portion 21b are made different, but either one is made different. The same effect can be obtained by just

  In this embodiment, the liquid flow direction in the main flow path 21 corresponding to the liquid discharge heads 1a, 1b, and 1c and the main flow path 21 corresponding to the liquid discharge heads 1d, 1e, and 1f is reversed. However, it can also flow in the same direction. The liquid supply member 20 may be composed of a plurality of parts. In particular, when the member forming the narrow communication channel 22 is made of a material having a high thermal conductivity, the liquid discharge head 1 and the liquid inside can be efficiently used. Since heat can be dissipated, the droplet discharge stability can be further improved.

  As described above, the liquid flow path in which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head is provided, and a supply port that supplies the liquid to the liquid flow path is provided at the end in the longitudinal direction of the liquid flow path. A discharge port for discharging the liquid from the liquid flow path is provided, and the liquid flow path is configured such that the opening cross-sectional area of the region connected to the common liquid chamber is larger than the opening cross-sectional area between the common liquid chambers. Bubbles generated in the head and bubbles flowing into the liquid discharge head from upstream of the liquid supply path can be discharged by a circulating flow without destroying the meniscus of the liquid discharge head.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a longitudinal sectional view of the head unit in the embodiment.
Here, the supply port 12 is provided in the substantially central part of the main flow path 21 of the liquid supply member 20, and the discharge ports 13 and 13 are provided in the longitudinal direction end part. Thereby, even when the length of the main channel 21 (the length of the liquid supply member 20) becomes longer, the circulation channel (main channel 21) can be provided by appropriately providing a port in the middle of the main channel 21 in this way. Can be effectively shortened, the bubble discharge time can be shortened, and the bubble discharge efficiency is improved.

  In this embodiment, since the supply port 12 is located directly above the liquid discharge head 1, between the supply port 12 and the narrow communication channel 22 (the common liquid chamber 7 of the liquid discharge head 1), A rectifying member 18 that arranges the flow of the liquid supplied from the supply port 12 in a direction toward the discharge ports 13 and 13 is disposed. A surface of the rectifying member 18 facing the common liquid chamber 7 is an inclined surface 19, so that bubbles floating from the common liquid chamber 7 are not easily trapped by the rectifying member 18.

  As a result, the flow direction of the liquid flowing in from the supply port 12 is smoothly bent in the longitudinal direction of the main flow path 21 as indicated by an arrow, and the flow velocity is directly applied to the common liquid chamber 7 of the liquid discharge head 1. It is possible to prevent the flow from the large supply port 12 from moving toward the liquid discharge head 1 and to prevent the meniscus of the nozzle 7 of the liquid discharge head 1 from being adversely affected.

  That is, when the rectifying member 18 is not provided as in the first comparative example shown in FIG. 7, the flow of the liquid flowing in from the supply port 12 goes directly to the narrow communication channel 22 as indicated by the arrow, The flow effect is exerted on the common liquid chamber 7 of the liquid discharge head 1 and the meniscus of the nozzle 5 of the liquid discharge head 1 may be adversely affected. However, the rectifying member 18 is provided as in this embodiment. Thus, such inconvenience can be prevented.

  As described above, the liquid flow path in which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head is provided, and the supply port for supplying the liquid to the liquid flow path and the discharge port for discharging the liquid from the liquid flow path are provided. And at least one of the supply port and the discharge port is provided in a portion other than the longitudinal end portion of the liquid flow path, and is provided between the common liquid chamber and the port provided in the portion other than the longitudinal end portion. The flow path is provided with a flow regulating member, and the liquid flow path is configured such that the opening cross-sectional area of the region connected to the common liquid chamber is larger than the opening cross-sectional area between the common liquid chambers. In addition, bubbles flowing into the liquid discharge head from upstream of the liquid supply path can be discharged by a circulating flow without destroying the meniscus of the liquid discharge head, and the liquid discharge head has a negative effect on the meniscus. While preventing, it is possible to improve the bubble discharge efficiency by shortening the effective length of the liquid supplying member.

  Here, the example in which the supply port 12 is provided at a position facing the common liquid chamber at a portion other than the end portion in the longitudinal direction of the liquid supply member 20 has been described. However, instead of the supply port 12 or supply The same applies when the discharge port 13 is provided together with the port 12.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 8 is a longitudinal sectional view of the head unit in the same embodiment.
Here, a supply port is provided at a position other than the longitudinal end portion of the main flow path 21 of the liquid supply member 20 at a position that does not face the common liquid chamber 7 of the liquid ejection head 1 (position that faces the common liquid chamber portion 21b). 12 and a discharge port 13 are provided, and a supply port 12 and a discharge port 13 are also provided at the longitudinal ends. Thereby, even when the length of the main channel 21 (the length of the liquid supply member 20) becomes longer, the circulation channel (main channel 21) can be provided by appropriately providing a port in the middle of the main channel 21 in this way. Can be effectively shortened, the bubble discharge time can be shortened, and the bubble discharge efficiency is improved.

  Further, the supply port 12 and the discharge port 13 provided in a portion other than the longitudinal end portion of the main flow channel 21 are provided at positions corresponding to the common liquid chamber portion 21b and are separated from the liquid discharge head 1, Even if the rectifying member 18 as in the second embodiment is not provided, the flow of the liquid flowing in from the supply port 12 and the flow of the liquid flowing in and discharged into the discharge port 13 affect the meniscus of the nozzle 5 of the liquid discharge head 1. It can prevent giving.

  As described above, the liquid flow path in which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head is provided, and the supply port for supplying the liquid to the liquid flow path and the discharge port for discharging the liquid from the liquid flow path are provided. And at least one of the supply port and the discharge port is provided between the common liquid chambers at a portion other than the longitudinal end portion of the liquid flow path, and the liquid flow path has an opening cross-sectional area of a region connected to the common liquid chamber. Since the configuration is larger than the opening cross-sectional area between the common liquid chambers, the bubbles generated in the liquid discharge head and the bubbles flowing into the liquid discharge head from the upstream of the liquid supply path can be circulated without destroying the meniscus of the liquid discharge head. As a result, the effective length of the liquid supply member can be shortened and the bubble discharge efficiency can be improved while preventing adverse effects on the meniscus of the liquid discharge head.

  Here, the example in which the supply port 12 and the discharge port 13 are provided at positions facing the common liquid chambers at portions other than the end portion in the longitudinal direction of the liquid supply member 20 has been described. The present invention can be similarly applied even when any of the ports 13 is provided.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 9 is a longitudinal sectional view of the head unit in the same embodiment, FIG. 10 is a plane sectional explanatory view along the line DD of FIG. 11, and FIG. 11 is the same head unit along the line CC of FIG. FIG.
The liquid supply member 20 of this embodiment is provided on the wall surface facing the common liquid chamber 7 of the liquid ejection head 1 of the liquid supply member 20 instead of having the narrow communication channel 22 described in the above embodiments. A rib 16 is formed around the communication port 17 to be formed.

  In the liquid supply member 20 as well, when bubbles are mixed into the liquid supply member 20 from the upstream side of the liquid discharge head 1 or the supply port 12, the bubbles are accumulated on the upper part (the top surface 21d) of the main flow path 21 by the buoyancy. . Therefore, by forming a flow from the supply port 12 toward the discharge port 13 in the main channel 21, bubbles are discharged from the discharge port 13.

  At this time, the liquid flow on the side communicating with the liquid ejection head 1 in the common liquid chamber connection region portion 21a of the main flow path 21 has a contact area increased by the plurality of ribs 16, and thus flows due to the viscous resistance of the liquid. As in the configuration of the first embodiment, the substantial flow is only above the main channel 21. Therefore, since the flow in the common liquid chamber connection region portion 21a of the main channel 21 is not formed in the vicinity of the communication port 17, the influence on the meniscus of the nozzle 5 of the liquid discharge head 1 due to the circulation flow for discharging the bubbles is reduced. can do. In the present embodiment, the rib 16 is formed so that its main surface is parallel to the circulation flow, but may be provided so as to be perpendicular to the direction of the circulation flow.

  Also in this embodiment, the main channel 21 is such that the opening cross-sectional area of the portion 21 a corresponding to the upper portion of the liquid discharge head 1 is larger than the portion 21 b between the liquid discharge heads 1. That is, the main channel 21 serving as the liquid channel has a configuration in which the opening cross-sectional area of the region (part 21a) connected to the common liquid chamber 7 is larger than the opening cross-sectional area between the common liquid chambers (part 21b). By doing so, the flow velocity of the circulating flow is slowed down near the liquid ejection head 1 to prevent the meniscus destruction of the nozzle 5 of the liquid ejection head 1, and the flow velocity is increased between the liquid ejection heads 1 and 1 to discharge bubbles. Can increase the sex.

  As described above, the liquid flow path in which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head is provided, and a supply port that supplies the liquid to the liquid flow path is provided at the end in the longitudinal direction of the liquid flow path. Air bubbles generated in the liquid discharge head are provided by providing a discharge port for discharging liquid from the liquid flow path, and the liquid flow path is provided with a rib around the communication port connected to the common liquid chamber. In addition, bubbles that have flowed into the liquid discharge head from the upstream side of the liquid supply path can be discharged by a circulating flow without destroying the meniscus of the liquid discharge head.

Next, a fifth embodiment of the present invention will be described with reference to FIGS. 12 is a longitudinal sectional view of the head unit in the same embodiment, FIG. 13 is a plane sectional explanatory view taken along the line FF in FIG. 14, and FIG. 14 is the head unit along the line EE in FIG. FIG.
The liquid supply member 20 of this embodiment has a configuration in which one main channel 21 communicates with all six liquid ejection heads 1. With such a configuration, the internal space of the main channel 21 becomes large, so that it is easy to form a structure inside as needed.

  Therefore, here, the narrow communication channel 22 that communicates the liquid ejection head 1 from the main channel 21 is provided so as to protrude inside the main channel 21. With such a configuration, it is possible to reduce the size of the liquid supply member 20 and reduce the influence of the circulation flow on the meniscus of the nozzle 5 of the liquid discharge head 1 by the narrow communication flow path 22.

  However, in this configuration, the opening of the narrow communication flow path 22 is located at the center of the main flow path 21 where the flow velocity of the circulating flow is large, so that the narrow communication flow path 22 is surrounded by the opening of the narrow communication flow path 22. The rib 16 is provided up to a higher position. The ribs 16 are ribs 16a and 16a on the upstream and downstream sides in the liquid flow direction with respect to the opening of the narrow communication channel 22, and ribs along the liquid flow direction on the side of the opening of the narrow communication channel 22 16b and 16b. By this rib 16, the flow at the communication opening with the common liquid chamber 7 with respect to the circulating flow becomes gentle, and the adverse effect on the liquid discharge head 1 can be further effectively reduced.

  That is, as in Comparative Example 2 shown in FIG. 15 to FIG. 17, when the configuration without the rib 16 is used, the opening of the narrow communication channel 22 is located at the center of the main channel 21 where the flow velocity of the circulation flow is large. While the influence of the flow of the main flow path 21 reaches the common liquid chamber 7 of the liquid discharge head 1 through the narrow communication flow path 22 and the meniscus may collapse and liquid leakage may occur from the nozzle 5, a rib 16 is provided. Such a problem can be prevented by reducing the flow velocity in the vicinity of the opening.

  Here, a gap is formed between the rib 16 and the opening of the narrow communication channel 22, but the rib is integrally formed on the structure forming the opening so that there is no gap. You can also.

  As described above, the liquid flow path in which the liquid flows along the arrangement direction of the nozzles of the liquid discharge head is provided, and a supply port that supplies the liquid to the liquid flow path is provided at the end in the longitudinal direction of the liquid flow path. Air bubbles generated in the liquid discharge head are provided by providing a discharge port for discharging liquid from the liquid flow path, and the liquid flow path is provided with a rib around the communication port connected to the common liquid chamber. In addition, bubbles that have flowed into the liquid discharge head from the upstream side of the liquid supply path can be discharged by a circulating flow without destroying the meniscus of the liquid discharge head.

Next, a sixth embodiment of the present invention will be described with reference to FIGS. 18 is an explanatory diagram in the longitudinal direction of the head unit in the same embodiment, and FIG. 19 is an explanatory plan view.
The liquid supply member 20 of this embodiment is provided at a position that does not oppose the liquid discharge head 1 in the middle of the main flow path 21 by two supply ports 12 and two discharge ports 13 in addition to the end portion in the longitudinal direction. All of the supply port 12 and the discharge port 13 may be used simultaneously, or a plurality of ports may be selected and used in an appropriate combination. By providing a plurality of ports, it is possible to efficiently discharge bubbles in a wide flow path in various modes.

  Further, here, the port through which the liquid flows in and out is provided at a position not facing the liquid discharge head 1, and the narrow communication channel 22 communicating with the common liquid chamber 7 of the liquid discharge head 1 is narrowly communicated. Since the rib 16 is provided up to a position higher than the opening of the flow path 22, it does not adversely affect the meniscus of the nozzle 5 of the liquid discharge head 1 even for the circulation flow formed in various bubble discharge modes. Can be. Accordingly, it is possible to discharge bubbles while discharging droplets from the liquid discharge head 1.

  As described above, the liquid flow path in which the liquid flows along the nozzle arrangement direction of the liquid discharge head is provided, and the supply port for supplying the liquid to the liquid flow path and the discharge port for discharging the liquid from the liquid flow path are provided. In addition, either the supply port or the discharge port is provided at a position that does not face the common liquid chamber, and the liquid flow path is configured such that a rib is provided around the communication port connected to the common liquid chamber. The bubbles generated in the liquid discharge head and the bubbles flowing into the liquid discharge head from the upstream of the liquid supply path can be discharged by circulating flow without destroying the meniscus of the liquid discharge head, and the liquid discharge head has a negative effect on the meniscus. The bubble discharge efficiency can be improved by shortening the effective length of the liquid supply member while preventing the bubbles.

  In this embodiment, when either the supply port or the discharge port is provided at a position facing the common liquid chamber, the liquid discharge head is provided by providing a rectifying member as in the third embodiment. The bubble discharge efficiency can be improved by shortening the effective length of the liquid supply member while preventing adverse effects on the meniscus.

  Next, application to an image forming apparatus including a liquid ejection apparatus according to the present invention will be described. Here, an example will be described in which ink is ejected as a liquid and applied to an ink jet printer that can be applied to a facsimile machine, a copying machine, a multi-function machine thereof, or the like. However, the liquid ejection apparatus according to the present invention is not an ink. The present invention can also be applied to a liquid discharge head and a liquid discharge apparatus for discharging a liquid such as a DNA sample, a resist, and a pattern material, or an image forming apparatus including these.

First, a first embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS. 20 is a configuration diagram of the image forming apparatus, FIG. 21 is an explanatory diagram showing a state during maintenance and recovery of the apparatus, and FIG. 22 is a schematic explanatory diagram for explaining a liquid supply path.
In this image forming apparatus, four colors (black, cyan, magenta, and yellow) having different recording heads (100K, 100C, 100M, and 100Y) including a head unit 100 having a length corresponding to the maximum paper width to be conveyed are provided. 4 line printers are provided for each ink. The four recording heads 1 are fixed to a head frame 36, and the four heads 1 can be simultaneously moved up and down by a head lifting mechanism (not shown).

  A recording sheet on which an image is recorded with ink is conveyed immediately below the recording heads 100K, 100C, 100M, and 100Y. The recording sheets are stacked and held on the sheet feeding tray 38, and are fed one by one by a separation sheet feeding mechanism (not shown), conveyed by the sheet conveying belt 30, and discharged onto the sheet discharge tray 39 after recording is completed.

  The paper conveying belt 30 is stretched by a belt conveying roller 31 and a tension roller 32. The surface layer is a high resistance layer made of a resin material, and the back layer is a medium resistance layer obtained by controlling the resistance of the resin material with carbon. It has a two-layer structure. The paper conveying belt 30 is in contact with a charging roller 33 in which an intermediate resistance layer is formed on the outer layer of the metal roller and a thin high resistance layer is formed on the outermost layer.

  Therefore, by applying a high voltage to the charging roller 33, a discharge occurs in the air gap near the nip portion between the paper conveyance belt 30 and the charging roller 33, and charges are attached on the paper conveyance belt 30. When the voltage applied to the charging roller 33 is a positive and negative AC voltage, positive and negative charges are alternately attached in a stripe pattern on the paper transport belt 30. When the recording paper is supplied to the paper transport belt 30 thus charged, the recording paper is attracted to the paper transport belt 30 by electrostatic force. Since printing can be performed with the recording paper firmly held on the paper conveyance belt 30, stable printing quality can be obtained even when printing is performed while conveying the paper at high speed.

  Each of the liquid discharge heads 1 of the head unit 100 constituting the recording heads 100K, 100C, 100M, and 100Y is a thermal type that obtains discharge pressure by boiling the ink film by driving the heating element 4 as described in the first embodiment. A side shooter type configuration in which the flow direction of the ink to the ejection energy action portion (heating element) in the liquid chamber 6 and the opening central axis of the nozzle 5 are perpendicular to each other is employed.

  With this configuration, the energy from the heating element 4 can be more efficiently converted into the formation of ink droplets and the kinetic energy of the flight, and the meniscus can be quickly restored by supplying ink. Have. Further, the side shooter can avoid a so-called cavitation phenomenon in which the heat generating element 4 is gradually destroyed by an impact when bubbles that are problematic in the edge shooter method disappear. That is, when bubbles grow in the side shooter and the bubbles reach the nozzle 5, the bubbles are brought into the atmosphere, and the bubbles do not contract due to a temperature drop. Therefore, there is an advantage that the life of the recording head is long.

This liquid discharge head 1 can be manufactured as follows, for example. First, the heating element substrate 2 is formed by laminating HfB ₂ as a heating resistor layer by RF magnetron sputtering on a silicon wafer having a SiO 2 film formed by thermal oxidation, and further laminating Al as an electrode layer by EB vapor deposition. Next, the Al layer was etched with a phosphoric acid-nitric acid etching solution by photolithography. Next, the heating resistor layer is etched using RIE. In order to expose the heating element 4, a resist film is formed on a portion excluding the portion corresponding to the exposed portion, and the Al is removed from the portion where the resist is not formed by treatment with an etching solution, so A heating element 4 is provided between them. Finally, a SiO ₂ layer as a protective layer is provided on the electrothermal converter, and a polyimide layer is provided in a portion other than the heating element array portion to form the heating element substrate 2.

  Next, a polymethylisopropenyl ketone (ODUR-1010 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied onto PET as a soluble resin layer and dried to form a dry film on the heating element substrate 2 by laminating. Transcript. After pre-baking, pattern exposure corresponding to the individual liquid chamber 6 is performed, and development is performed using methyl isobutyl ketone / xylene = 2/1. Next, a resin composition comprising an epoxy resin, a cationic photopolymerization initiator, and a silane coupling agent is dissolved in a methyl isobutyl ketone / xylene mixed solvent at a concentration of 50 wt%, and a photosensitive coating resin layer is formed by spin coating. . Thereafter, pattern exposure and after baking corresponding to the nozzle 5 are performed, and then development is performed with methyl isobutyl ketone to form the nozzle 5.

  Further, it was immersed in methyl isobutyl ketone while applying ultrasonic waves, and the remaining soluble resin was eluted, and heated at 150 ° C. for 1 hour to completely cure the photosensitive coating material layer. Finally, the common liquid chamber 7 is formed by anisotropic etching of silicon with TMAH (tetramethylammonium hydroxide aqueous solution). At this time, the surface of the silicon substrate on which the nozzle 5 is formed is protected with a protective layer made of cyclized rubber so that the produced liquid chamber member 2 is not damaged.

  As described above, a short liquid discharge head 1 having 600 dpi / row, 1200 CH / row (meaning that 1200 nozzles 5 are arranged in one row), and a distance between nozzle rows of 240 μm can be manufactured.

  The liquid supply member 20 is the liquid supply member 20 according to the first embodiment, and the parts having the cross-sectional flow paths (the main flow path 21 and the narrow communication flow path 22) shown in FIGS. As shown in FIG. 1, six liquid discharge heads 1 are fixed to form a head unit 100, and the liquid discharge head 1 is used as a single unit. Double-width recording can be performed.

  The liquid supply member 20 has a supply port 12 and a discharge port 13 at both ends, and two flow paths 21 and 21 are formed as shown in FIG. Each of the flow paths 21 and 21 is composed of a narrow communication flow path 22 and a main flow path 21 communicating with the liquid discharge head 1, and the narrow communication flow path 22 is entirely formed in the common liquid chamber 7 of the head 1 as shown in FIG. 4. The shape is open and narrower than the main channel 21.

  The main channel 21 has a shape in which the region 21 a facing the narrow communication channel 22 has a larger width and depth than the region 21 b not facing the narrow communication channel 22. The specific dimensions in FIGS. 2 to 4 were Wg: 5 mm, Wf: 2.4 mm, Wh: 3 mm, Hg: 6 mm, Hf: 4 mm, Hh: 4 mm, Yh: 2 mm.

  The liquid supply member 20 is connected in a liquid supply path (ink supply system) as shown in FIG. In this liquid supply path (system), the head tank 70 has a function of supplying ink to the head unit 100 and receiving bubbles and discharging them to the outside, and the inside is open to the first ink chamber 71 and the upper part to the atmosphere. The ink is divided into a second ink chamber 72 provided with a port 73, and ink can be transferred from the second ink chamber 72 to the first ink chamber 71 by a pump P2. An ink cartridge 76 is connected to the second ink chamber 72 so that the ink filtered by the filter 75 can be replenished to the second ink chamber 72 of the head tank 70 by the pump P1.

  An ink port is provided on the bottom surface of the second ink chamber 72 of the head tank 70 and is connected to the discharge port 13 of the liquid supply member 20 of the head 1 via a normally open valve V2. The ink amount in the second ink chamber 72 is managed by the liquid level detection sensor 74 so that the water head difference Sh between the ink liquid level and the head 1 becomes a constant value (10 to 150 mm).

  Here, during normal image formation, the pumps P1 and P2 are stopped and only the valve V2 is opened. Ink is supplied from the second ink chamber 72 to the head unit 100 via the discharge port 13. When the liquid level in the second ink chamber 72 becomes lower than a predetermined position due to ink consumption, the liquid level detection sensor 74 detects. Accordingly, the valve V1 is opened, the pump P1 is operated, and the ink is replenished from the ink cartridge 76 to the second ink chamber 72. The replenishment stop is controlled by a detection signal from the liquid level detection sensor 74.

  Further, when the liquid discharge head 1 of the head unit 100 is clogged, the recovery operation of the liquid discharge head 1 is performed. The head unit 100 moves upward from the state of FIG. 20 and the maintenance unit 35 moves in the horizontal direction (from the state of FIG. 20 to the right in the figure: moved in the direction of the arrow) and is disposed directly below the head 1. Then, the head 1 is slightly lowered so that the nozzle surface 5a on which the nozzle 5 of the liquid ejection head 1 is formed is in close contact with the cap 40 of the maintenance unit 35 as shown in FIG. In this state, the valves V1 and V2 in FIG. 22 are closed and only the pump P2 is driven for a certain time.

  As a result, the ink in the first ink chamber 71 is pressurized and flows into the head unit 100. Since the valve V <b> 2 is closed, the ink is discharged from the nozzle 5 of the liquid discharge head 1. Together with the discharged ink, bubbles and foreign matters that have caused clogging of the liquid discharge head 1 are removed. Then, after stopping the pump P2, the head unit 100 is raised to a level at which the head unit 100 is not in contact with the cap 40, the maintenance unit 35 is moved in the horizontal direction (moved from the state in FIG. 23 to the right in the figure), 24, the nozzle surface 5a of the liquid discharge head 1 is wiped by the wiper blade 41. After a meniscus is formed on the nozzle 5 by wiping, the valve V2 is opened to hold the head 1 in a negative pressure state corresponding to the hydraulic head difference Sh.

  Since the ink discharged from the liquid discharge head 1 is stored in the cap 40, the ink is sucked by the pump 45 and discharged to the waste liquid tank 44. If the ink in the cap 40 is filtered using a filter, it is possible to reuse the sucked ink by returning it to the second ink chamber 72 of the head tank 70 instead of the waste liquid tank 44.

  Thereafter, the recording operation is performed in the state of FIG. 20 by moving the head unit 100 up and down and the horizontal movement of the maintenance unit 35, or waits until a recording instruction is issued in the state of FIG. By this recovery operation, clogging is eliminated and the liquid discharge head 1 of the head unit 100 can be maintained in a good state.

  Here, in the liquid supply system shown in FIG. 22, since the flow paths 80 and 81 that connect the liquid supply member 20 and the head tank 70 are usually resin tubes, air bubbles are gradually formed inside over time due to the air permeability of the tube material itself. Mixed. If a large amount of bubbles are accumulated inside the liquid supply member 20, the ink flows along the flow of ink during the recording operation and enters the liquid discharge head 1 to cause ink droplet discharge failure. In order to discharge the bubbles from the liquid supply member 20, in FIG. 22, only the pump P <b> 2 is driven with the valve V <b> 2 opened, and ink flows from the second ink chamber 72 to the first ink chamber 71. The ink enters the supply port 12 of the liquid supply member 20 from the first ink chamber 71, is discharged from the discharge port 13 together with the bubbles inside the liquid supply member, and returns to the second ink chamber 72. Bubbles in the ink rise in the second ink chamber 72 and are discharged from the atmosphere opening port 73.

  In order to evaluate the bubble discharge property when the liquid supply member 20 according to the present invention is used in this image forming apparatus, a three-way valve is attached upstream of the liquid supply member 20 to inject bubbles into the tube, and the liquid supply member While observing the inside of the pump 20, the pump P <b> 2 was operated to mix bubbles in the liquid supply member 20. After waiting until the flow inside the liquid supply member 20 stopped, the pump V2 was operated again to circulate ink at a flow rate of 60 ml / min. As a result, although small bubbles remained in the upper corner portion in the liquid supply member 20, it was confirmed that the bubbles could be discharged almost satisfactorily. Further, when the nozzle surfaces of the respective liquid discharge heads 1 of the head unit 100 were observed, there was no problem such as ink bleeding from the nozzles 5, and good image formation could be performed without discharge defects.

  On the other hand, as a comparison, for comparison, the main channel 21 has a uniform cross section, and the liquid supply is Wg: 5 mm, Wf: 2.4 mm, Wh: 5 mm, Hg: 6 mm, Hf: 4 mm, Hh: 6 mm, Yh: 2 mm When a member was prepared and a head unit similar to the above was constructed and bubble discharge evaluation was performed, the bubble was discharged, but the region 21a facing the narrow communication channel 22 described above became the narrow communication channel 22. Compared with the case where the width and depth dimensions are larger than those of the non-facing region 21b, it took a longer time to discharge.

  Next, as the liquid supply member 20 of the image forming apparatus, a supply port 12 is provided directly above the liquid discharge head 1 as in Comparative Example 1 (FIG. 7), and discharge ports 13 and 13 are provided at both ends in the longitudinal direction. The liquid supply member 20 was manufactured, and bubble discharge evaluation was performed. As a result, the time required for discharging the bubbles was shortened and the effect of improving the discharge efficiency was confirmed. However, the liquid level of the head tank 70 connected to the liquid supply member 20 is high, and the nozzle surface 5a of the head unit 100 and the liquid level When the water head difference Sh on the surface was small, there was a problem that the ink oozed out of the meniscus.

  Therefore, as shown in the second embodiment (FIG. 6), a liquid supply member 20 that is changed to a configuration in which a rectifying member 18 is provided at a position facing the supply port 12 in the main channel 21 was manufactured. The upper surface of the rectifying member 18 is formed as a curved surface so that the supplied ink can be smoothly diverted in the direction of the two discharge ports 13, 13, and the lower surface (bottom surface) does not retain bubbles floating from the liquid ejection head 1. Thus, the inclined surface 19 was obtained. When the same evaluation as described above was performed using the liquid supply member 20, it was possible to discharge the bubbles in a short time without causing the above-described problem of ink bleeding from the meniscus.

  Next, as the liquid supply member 20, all the communication ports (narrow communication channels 22) for supplying ink to the individual liquid ejection heads 1 as in Comparative Example 2 (FIGS. 15 to 17) have one main channel 21. The head unit 100 is configured by manufacturing a liquid supply member 20 having a configuration in which one supply port 12 and one discharge port 13 are connected to different ends in the longitudinal direction. Here, a narrow communication flow path 22 communicating with each liquid discharge head 1 is protruded on the main flow path 21 side, and a structure suitable for high-speed printing in which the space ratio of the main flow path 21 to the outer dimension of the liquid supply member 20 is large. It was. The main dimensions in FIGS. 15 to 17 are Wa: 8 mm, Wf: 1.6 mm, Ha: 6 mm, Hi: 2 mm, Yh: 1.5 mm.

  The liquid supply member 20 of Comparative Example 2 was connected to the apparatus having the ink supply system of FIG. In order to discharge the bubbles in the liquid supply member 20 satisfactorily, it was necessary to circulate the ink at a flow rate of 200 ml / min or more. However, when it was circulated under the conditions, a failure of ejection failure occurred in the subsequent ink ejection operation.

  Therefore, as in the fifth embodiment (FIGS. 12 to 14), the liquid supply member 20 provided with the ribs 16 (16a, 16b) extending to a position higher than the opening around the narrow communication channel 22 is provided. The head unit 100 was constructed by manufacturing. As the ribs 16, first, three ribs 16 a having a thickness of 0.4 mm are provided at both ends in the longitudinal direction of the narrow communication flow path 22 at a 0.9 mm pitch, and a thickness of 0.6 mm is formed in the width direction of the narrow communication flow path 22. One rib 16b was provided on each side. Each of the ribs 16a and 16b is 2 mm higher than the opening of the narrow communication channel 22 (Hr: 4 mm). When the same bubble discharge evaluation as described above was performed using this liquid supply member 20, even when the ink was circulated at a flow rate of 200 ml / min or more, the problem of ink ejection failure did not occur, and the bubbles could be discharged well.

  Next, in order to improve bubble discharge efficiency over the fifth embodiment, two supply ports 12 are provided on the top surface 21d of the liquid supply member 20, as in the sixth embodiment (FIGS. 18 and 19). The head unit 100 was configured by manufacturing the liquid supply member 20 in which a total of four ports were added. The supply port 12 and the discharge port 13 on the top surface are provided at positions where there is no communication port (narrow communication channel 22) to the liquid discharge head 1 immediately below. Further, all the ports are set so that the supply port 12 and the discharge port 13 are alternately arranged.

  As described above, since the plurality of ports are provided and the distance between the ports is shortened, the bubbles can be discharged in a shorter time than when the liquid supply member of the fifth embodiment is used. Furthermore, since a plurality of ports were provided, it was possible to circulate partially. That is, when printing on a small-sized sheet with respect to the long head unit 100, all the short liquid discharge heads 1 (1a to 1f) are not driven. For example, printing can be performed by driving only the three heads (1a, 1d, 1e) in the right half of FIGS. In this case, it is not necessary to discharge bubbles with respect to the unused heads (1b, 1c, 1f). Therefore, in this case, it is only necessary to circulate ink using only the ports around the heads (1a, 1d, 1e) being used to discharge the bubbles.

  In this way, by providing a plurality of ports and partially circulating them, it was possible to efficiently discharge bubbles without consuming unnecessary power. Thus, by providing a plurality of ports, ink circulation can be performed in various combinations depending on the situation, so that the stability of the long head and the recording apparatus having the liquid supply part material is further improved.

Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to FIG.
The liquid supply path (ink supply system) of this image forming apparatus is different from the ink supply system of FIG. 22 described above in that a flow rate adjusting valve V3 is provided on the downstream side of the discharge port 13 of the liquid supply member 20. Further, as the liquid supply member 20, a member provided with a supply port 12 at a portion other than the end portion in the longitudinal direction and with discharge ports 13 and 13 at the end portion in the longitudinal direction is used.

  Thus, by providing the flow rate adjustment valve V3 downstream of the discharge port 13, the flow rate (Qc) of the ink discharged from the discharge port 13 can be adjusted. Therefore, the main flow is reduced by reducing the flow rate Qc. Ink can be pumped from the path 21 to the liquid ejection head 1. Thereby, it is possible to simultaneously discharge the bubbles in the main channel 21 and discharge the bubbles in the liquid discharge head 1.

  As described above, in the present invention, the influence of the circulating flow is prevented from reaching the meniscus of the nozzle. Accordingly, a circulating flow can be formed during the recording operation. By performing the recording while circulating the ink, bubbles are not accumulated, and the recording operation is not interrupted to discharge the bubbles, thereby improving the recording throughput.

  The present invention can be applied to various liquid ejection type heads, but the thermal type heads described in the above-described embodiments are particularly suitable because they easily increase the temperature including ink. Among the thermal type heads, the above-described side shooter type head is more preferable because bubbles are easily generated inside the head and the generated bubbles easily flow into the common liquid chamber.

FIG. 3 is a perspective explanatory view showing a first embodiment of a head unit including a liquid supply member for a liquid ejection head according to the present invention. It is longitudinal direction sectional drawing of the head unit. It is a plane cross-section explanatory drawing which follows the BB line of FIG. FIG. 3 is an enlarged sectional view in the short direction of the head unit along the line AA in FIG. 2. FIG. 4 is an enlarged explanatory view of a main part along the short direction of the liquid discharge head. It is a longitudinal direction sectional view of a head unit in a 2nd embodiment of the present invention. 6 is a longitudinal sectional view of a head unit of Comparative Example 1. FIG. It is a longitudinal direction sectional view of a head unit in a 3rd embodiment of the present invention. It is longitudinal direction explanatory drawing of the head unit in 4th Embodiment of this invention. It is a plane cross-sectional explanatory drawing which follows the DD line of FIG. FIG. 10 is an enlarged cross-sectional view in the short-side direction of the head unit taken along line CC in FIG. 9. FIG. 10 is an explanatory longitudinal sectional view of a head unit according to a fifth embodiment of the invention. It is a plane cross-section explanatory drawing which follows the FF line of FIG. FIG. 13 is an enlarged cross-sectional view of the head unit in the short direction along the line EE in FIG. 12. FIG. 6 is a longitudinal cross-sectional explanatory view of a head unit of Comparative Example 2. It is a plane cross-sectional explanatory drawing which follows the HH line of FIG. FIG. 16 is an enlarged cross-sectional view of the head unit in the short direction along the line GG in FIG. 15. It is longitudinal direction explanatory drawing of the head unit in 6th Embodiment of this invention. It is a plane explanatory drawing similarly. 1 is a configuration diagram for explaining a first embodiment of an image forming apparatus according to the present invention; It is explanatory drawing which shows the state at the time of the maintenance recovery of the apparatus. FIG. 3 is a schematic explanatory diagram for explaining a liquid supply path of the apparatus. FIG. 6 is an explanatory diagram for explaining a maintenance / recovery operation of the image forming apparatus. It is explanatory drawing similarly used for description of a maintenance recovery operation | movement. FIG. 5 is a schematic explanatory diagram for explaining a liquid supply path of the image forming apparatus according to the second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid discharge head 2 ... Heat generating body substrate 3 ... Flow path formation member 5 ... Nozzle 6 ... Liquid chamber 7 ... Common liquid chamber 20 ... Liquid supply member 21 ... Main flow path 21a ... Common liquid chamber connection area | region part 22b ... Common liquid Inter-chamber portion 16, 16a, 16b ... rib 18 ... rectifying member 100 ... head unit 100K, 100C, 100M, 100Y ... recording head

Claims (9)

Connected to a liquid discharge head having a plurality of independent common liquid chambers for supplying a liquid to a plurality of liquid chambers through which a plurality of nozzles for discharging droplets communicate, and the liquid is supplied to each common liquid chamber of the liquid discharge head A liquid supply member for supplying,
This liquid supply member has a liquid flow path through which the liquid flows along the direction in which the nozzles of the liquid discharge head are arranged,
At the end in the longitudinal direction of the liquid channel, a supply port for supplying the liquid to the liquid channel and a discharge port for discharging the liquid from the liquid channel are provided,
The liquid supply member for a liquid discharge head, wherein the liquid flow path has an opening cross-sectional area of a region connected to the common liquid chamber larger than an opening cross-sectional area between the common liquid chambers. Connected to a liquid discharge head having a plurality of independent common liquid chambers for supplying a liquid to a plurality of liquid chambers through which a plurality of nozzles for discharging droplets communicate, and the liquid is supplied to each common liquid chamber of the liquid discharge head A liquid supply member for supplying,
This liquid supply member has a liquid flow path through which the liquid flows along the direction in which the nozzles of the liquid discharge head are arranged,
At the end in the longitudinal direction of the liquid channel, a supply port for supplying the liquid to the liquid channel and a discharge port for discharging the liquid from the liquid channel are provided,
The liquid supply member for a liquid discharge head, wherein the liquid channel is provided with a rib around a communication port connected to the common liquid chamber. Connected to a liquid discharge head having a plurality of independent common liquid chambers for supplying a liquid to a plurality of liquid chambers through which a plurality of nozzles for discharging droplets communicate, and the liquid is supplied to each common liquid chamber of the liquid discharge head A liquid supply member for supplying,
This liquid supply member has a liquid flow path through which the liquid flows along the direction in which the nozzles of the liquid discharge head are arranged,
A supply port for supplying liquid to the liquid flow path and a discharge port for discharging liquid from the liquid flow path are provided, and at least one of the supply port and the discharge port is other than a longitudinal end of the liquid flow path A rectifying member is provided to adjust the flow between the common liquid chamber corresponding to the port provided in the portion other than the longitudinal end portion,
The liquid supply member for a liquid discharge head, wherein the liquid flow path has an opening cross-sectional area of a region connected to the common liquid chamber larger than an opening cross-sectional area between the common liquid chambers. Connected to a liquid discharge head having a plurality of independent common liquid chambers for supplying a liquid to a plurality of liquid chambers through which a plurality of nozzles for discharging droplets communicate, and the liquid is supplied to each common liquid chamber of the liquid discharge head A liquid supply member for supplying,
This liquid supply member has a liquid flow path through which the liquid flows along the direction in which the nozzles of the liquid discharge head are arranged,
A supply port for supplying liquid to the liquid flow path and a discharge port for discharging liquid from the liquid flow path are provided, and at least one of the supply port and the discharge port is other than a longitudinal end of the liquid flow path A rectifying member is provided to adjust the flow between the common liquid chamber corresponding to the port provided in the portion other than the longitudinal end portion,
The liquid supply member for a liquid discharge head, wherein the liquid channel is provided with a rib around a communication port connected to the common liquid chamber. Connected to a liquid discharge head having a plurality of independent common liquid chambers for supplying a liquid to a plurality of liquid chambers through which a plurality of nozzles for discharging droplets communicate, and the liquid is supplied to each common liquid chamber of the liquid discharge head A liquid supply member for supplying,
This liquid supply member has a liquid flow path through which the liquid flows along the direction in which the nozzles of the liquid discharge head are arranged,
A supply port for supplying liquid to the liquid flow path and a discharge port for discharging liquid from the liquid flow path are provided, and at least one of the supply port and the discharge port is other than a longitudinal end of the liquid flow path Part, provided between the common liquid chambers,
The liquid supply member for a liquid discharge head, wherein the liquid flow path has an opening cross-sectional area of a region connected to the common liquid chamber larger than an opening cross-sectional area between the common liquid chambers. Connected to a liquid discharge head having a plurality of independent common liquid chambers for supplying a liquid to a plurality of liquid chambers through which a plurality of nozzles for discharging droplets communicate, and the liquid is supplied to each common liquid chamber of the liquid discharge head A liquid supply member for supplying,
This liquid supply member has a liquid flow path through which the liquid flows along the direction in which the nozzles of the liquid discharge head are arranged,
A supply port for supplying liquid to the liquid flow path and a discharge port for discharging liquid from the liquid flow path are provided, and at least one of the supply port and the discharge port is other than a longitudinal end of the liquid flow path Part, provided between the common liquid chambers,
The liquid supply member for a liquid discharge head, wherein the liquid channel is provided with a rib around a communication port connected to the common liquid chamber.   7. A liquid supply member for a liquid discharge head according to claim 1, wherein a plurality of liquid discharge heads are arranged in the longitudinal direction of the head while being displaced in a direction perpendicular to the longitudinal direction of the head. Characteristic head unit.   8. A liquid ejection apparatus for ejecting liquid droplets from a liquid ejection head, comprising the liquid supply member according to any one of claims 1 to 6 or the head unit according to claim 7. A liquid discharge apparatus characterized by comprising:   The liquid supply member according to claim 1, or a liquid supply member according to claim 7, wherein a liquid is supplied to the liquid discharge head in an image forming apparatus that forms an image by discharging liquid droplets from the liquid discharge head. An image forming apparatus comprising the head unit.

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