JP2012192712A - Liquid ejection head, image forming apparatus, and method for cleaning liquid ejection head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate a cleaning step of cleaning the inside of a common liquid chamber and to prevent the bubble retention in the common liquid chamber.SOLUTION: In a common liquid chamber member, a first member 21, a second member 22, and a third member, that is, an elastic member 23 lying between the first and second members 21 and 22 are laminated. In the elastic member 23, a communication hole 24 communicating between the inside of the common liquid chamber 10 and the outside is provided in a direction perpendicular to the ink flow direction (arrow direction). When the cleaning is carried out, the communication hole 24 is opened to discharge a cleaning liquid therefrom and the communication hole 24 is closed after the cleaning.

Description

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

  As an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, a plotter, and a complex machine of these, for example, an ink jet recording apparatus is known as an image forming apparatus of a liquid discharge recording method using a recording head for discharging ink droplets. . This liquid discharge recording type image forming apparatus ejects ink droplets from a recording head onto a conveyed paper to form an image (recording, printing, printing, and printing are also used synonymously). Serial type image forming device that forms an image by ejecting droplets while the recording head moves in the main scanning direction, and a line type that forms images by ejecting droplets without the recording head moving There is a line type image forming apparatus using a head.

  In the present application, “image forming apparatus” means an apparatus for forming an image by landing ink on a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. "Image formation" is not only the application of images with meanings such as characters and figures to the medium, but also the addition of images with no meaning such as patterns to the medium (simply applying droplets to the medium) Also means landing). The term “ink” is not limited to what is referred to as ink, but is used as a general term for all liquids that can perform image formation, such as recording liquid, fixing processing liquid, liquid, and resin. . The term “paper” is not limited to paper, but includes the above-described OHP sheet, cloth, and the like, and means that ink droplets adhere to the recording medium, recording medium, recording paper, recording It is used as a general term for what includes what is called paper. In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  The liquid ejection head includes a plurality of nozzles that eject droplets, a plurality of individual liquid chambers (individual flow paths) that communicate with each nozzle, and a common liquid chamber that supplies liquid (ink) to each individual liquid chamber. There is something.

  By the way, when the head is assembled, a cleaning process for cleaning the inside of the head is performed in order to remove foreign matters such as dust adhering to a flow path such as a liquid chamber inside the head. In other words, if foreign matter such as dust attached in the assembly process remains in the head, nozzle clogging may occur, resulting in a drop ejection failure, so that it adheres to the final stage of the assembly process. In-head cleaning is performed to remove the foreign matter.

  As described above, when the cleaning process is performed at the end of the head assembly process, the head is almost completed at this stage, and it is necessary to secure a discharge path for discharging the cleaning liquid.

  Therefore, conventionally, for example, by using a frame member provided with a small opening dedicated as a cleaning port in advance, a stainless steel spherical plug is fitted into the cleaning port after cleaning, and then the caulking is further performed, followed by cleaning. The port is being blocked.

  There is also a common liquid chamber member divided. In this case, since the liquid chambers need to be connected to each other after the cleaning operation, the opening area where each component (member) is joined is cleaned so that dust and the like are not mixed again after cleaning. Some are provided smaller than the cross-sectional area.

JP 2007-021996 A

  However, as described above, in the configuration in which press fitting and thermal caulking of a stainless steel spherical plug are performed, the cost increases due to the increase in the number of parts, the press fitting and caulking man-hours increase, and dust attached to the spherical plug, etc. There is a problem that it is necessary to remove foreign matter.

  Further, in the configuration in which the common liquid chamber member is divided, it is necessary to reduce the opening area in order to prevent dust from entering from the opening again after cleaning. The opening is provided in the common liquid chamber of the head and forms a part of the route for supplying ink from the tank to the nozzle. Therefore, if there is a portion where the opening area is narrowed, the fluid resistance increases accordingly. Therefore, there is a possibility that ink supply at the time of droplet ejection is insufficient.

  In addition, when the ink is initially filled in the completed head, the narrowed area corresponds to the water stop area, and thus it takes a lot of labor to find the optimum filling condition in order to fill the ink in the flow path. .

  Furthermore, after the initial ink filling is completed, the remaining bubbles inside the flow path and the bubbles contained in the ink supplied from the tank for filling the ink consumed by the droplet discharge and recovery operations are narrowed. If the air bubbles staying in the nozzle reaches the nozzle in the end, there is a problem that non-ejection of ink is caused.

  The present invention has been made in view of the above-described problems, and it is an object of the present invention to prevent a shortage of liquid supply and air bubbles due to an increase in fluid resistance in a common liquid chamber, and to simplify a cleaning process during head assembly. And

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
A common liquid chamber member that forms a common liquid chamber that supplies liquid to a plurality of liquid chambers that communicate with a plurality of nozzles that discharge droplets, respectively;
The common liquid chamber member is composed of a plurality of members,
Of the plurality of members, at least one member is an elastic member having elasticity,
The elastic member is configured to have a communication hole that communicates the common liquid chamber with the outside.

  Here, the communication hole of the elastic member may be closed in a pressurized state.

  Further, the elastic member may be integrally formed with other members constituting the common liquid chamber member.

  An image forming apparatus according to the present invention includes the liquid ejection head according to the present invention.

The method for cleaning a liquid discharge head according to the present invention includes:
A liquid discharge head cleaning method for cleaning a liquid discharge head according to the present invention,
With the communication hole of the elastic member of the common liquid chamber member opened,
Supplying cleaning liquid into the common liquid chamber and discharging it from the communication hole;
After completion of the cleaning, the communication hole of the elastic member of the common liquid chamber member is closed.

  According to the liquid ejection head according to the present invention, the common liquid chamber member is composed of a plurality of members, and at least one member of the plurality of members is an elastic member having elasticity, Since the communication hole that connects the liquid chamber and the outside is provided, the cleaning process at the time of assembling the head can perform cleaning with the communication hole of the elastic member opened, and the cleaning process and cleaning equipment In addition, by closing the communication hole of the elastic member when completed, the fluid resistance in the common liquid chamber and the retention of bubbles are prevented, and initial filling is facilitated. And drop defects caused by bubbles can be reduced.

  Since the image forming apparatus according to the present invention includes the liquid ejection head according to the present invention, a high quality image can be formed by performing stable droplet ejection.

  According to the method for cleaning a liquid discharge head according to the present invention, the communication hole of the elastic member of the common liquid chamber member is opened, the cleaning liquid is supplied into the common liquid chamber and is discharged from the communication hole, and the common liquid after the cleaning is finished. Since the communication hole of the elastic member of the chamber member is closed, the cleaning process and the cleaning equipment can be simplified.

FIG. 3 is an explanatory cross-sectional view along a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head in the first embodiment of the liquid discharge head according to the present invention. It is principal part sectional explanatory drawing of the common liquid chamber member part of the head in 2nd Embodiment of the liquid discharge head which concerns on this invention. (A) is sectional explanatory drawing provided to description of the example from which the member structure of the common liquid chamber member in each embodiment differs, (b) is side explanatory drawing. (A) is sectional explanatory drawing used for description of the 1st example of integral molding of components, (b) is side explanatory drawing similarly. (A) is sectional explanatory drawing used for description of the 2nd example of integral molding of components, (b) is side explanatory drawing similarly. FIG. 3 is an explanatory cross-sectional view for explaining the first embodiment of the liquid ejection head cleaning method according to the present invention. FIG. 7 is a cross-sectional explanatory diagram of the process following FIG. 6. FIG. 8 is an explanatory cross-sectional view of the process following FIG. 7. FIG. 6 is a cross-sectional explanatory diagram for explaining a second embodiment of the method for cleaning a liquid discharge head according to the present invention. FIG. 10 is an explanatory cross-sectional view for explaining a third embodiment of the method for cleaning a liquid discharge head according to the present invention. It is a section explanatory view of a common liquid chamber member part used for explanation of a bubble discharge method in a 3rd embodiment of a liquid discharge head concerning the present invention. FIG. 12 is a cross-sectional explanatory diagram of the process following FIG. 11. (A) is sectional explanatory drawing with which it uses for description of the 1st example of the shape of the elastic member in the liquid discharge head which concerns on each embodiment, and a communicating hole, (b) is side explanatory drawing. (A) is sectional explanatory drawing similarly used for description of a 2nd example, (b) is side explanatory drawing. (A) is sectional explanatory drawing similarly provided for description of a 3rd example, (b) is side explanatory drawing. (A) is sectional explanatory drawing similarly used for description of a 4th example, (b) is side explanatory drawing. (A) is sectional explanatory drawing similarly provided for description of a 5th example, (b) is side explanatory drawing. FIG. 4 is a side explanatory view illustrating a mechanism unit of the image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a first embodiment of a liquid discharge head according to the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional explanatory view along a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head in the embodiment.

  The liquid discharge head includes a flow path plate (flow path member, liquid chamber substrate) 1, a vibration plate member 2 bonded to one surface of the flow path plate 1, and a nozzle plate 3 bonded to the other surface of the flow path plate 1. A plurality of liquid chambers (pressurized liquid chamber, pressure chamber, pressure chamber, flow path, etc.) as individual flow paths through which a plurality of nozzles 4 for discharging liquid droplets (liquid drops) communicate with each other. 6) forming a fluid resistance portion 7 that also serves as a supply path for supplying ink to the liquid chamber 6 and a liquid introduction portion 8 that communicates with the liquid chamber 6 via the fluid resistance portion 7; Ink is supplied from the common liquid chamber 10 formed in the frame member 20, which is a common liquid chamber member, through the supply port 9 formed in the diaphragm member 2.

  A laminated piezoelectric member 12 as an actuator means (also referred to as a driving means, a driving element, a pressure generating means, etc.) is joined to each vibration region (diaphragm portion) 2A which is a thin part of the diaphragm member 2, and the laminated piezoelectric element is joined. The member 12 is joined to the base member 13. Although not shown, the multilayer piezoelectric member 12 is formed in a columnar shape by processing a groove by half-cut dicing in the lateral direction of the liquid chamber.

  The piezoelectric member 12 is connected to an FPC 15 as a flexible wiring board for giving a drive signal.

  Further, a common liquid chamber member 20 composed of a plurality of members is disposed on the outer peripheral side of the piezoelectric actuator constituted by the piezoelectric member 12, the base member 13, the FPC 15, and the like. The common liquid chamber 10 is formed in the common liquid chamber member 20. Further, a filter unit 32 having a filter 31 for filtering ink supplied from the outside to the common liquid chamber 10 is provided on the upstream side of the common liquid chamber member 20.

  In the liquid discharge head configured as described above, for example, the voltage applied to the piezoelectric member 12 is lowered from the reference potential, the piezoelectric member 12 contracts, the vibration region 2A of the vibration plate member 2 is lowered, and the volume of the liquid chamber 6 is reduced. Is expanded, for example, flows into the liquid chamber 6, and then the voltage applied to the piezoelectric member 12 is increased to extend in the stacking direction, and the vibration region 2 </ b> A is deformed in the nozzle 4 direction to reduce the volume of the liquid chamber 6. By contracting, the ink in the liquid chamber 6 is pressurized and an ink droplet is ejected from the nozzle 4.

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

  Note that the driving method of the head is not limited to the above example (drawing-pushing), and striking or pushing can be performed depending on the direction of the drive waveform.

Next, details of the common liquid chamber member 20 in the liquid discharge head will be described.
The common liquid chamber member 20 is configured by laminating a first member 21, a second member 22, and an elastic member 23 that is a third member interposed between the first and second members 21 and 22. . The first member 21 and the second member 22 are formed by injection molding of a thermoplastic resin such as epoxy resin or polyphenylene sulfite, for example. The elastic member 23 is made of an elastomer.

  The elastic member 23 is provided with a communication hole 24 that communicates the internal common liquid chamber 10 with the outside in a direction orthogonal to the direction of ink flow (arrow direction).

Next, a cleaning process at the time of assembling the liquid discharge head will be described.
Since the cleaning process in the common liquid chamber 10 is intended to remove dust adhering in the assembly work process, this cleaning process is performed in the latter half of the head assembly process. At this stage, the above-described filter unit 32 is assembled.

  Therefore, the nozzle surface of the nozzle plate 3 (the surface on which the nozzle 4 is formed) is capped with a cap member, and the cleaning liquid is pressurized and injected from the nozzle 4 into the head flow path by supplying the cleaning liquid into the cap member at a high pressure. To do. The injected cleaning liquid reaches the common liquid chamber 10 through the nozzle 4, the pressurized liquid chamber (individual liquid chamber) 6, etc., the inside of the common liquid chamber 10 is cleaned with the cleaning liquid, and the communication hole in which the elastic member 23 is formed. Foreign matter such as dust that has been discharged to the outside from 24 and adhered to the common liquid chamber 10 is discharged together with the discharge of the cleaning liquid.

  Thus, the common liquid chamber member is composed of a plurality of members, and at least one of the plurality of members is an elastic member having elasticity, and the elastic member communicates the common liquid chamber with the outside. In the cleaning process at the time of assembling the head, the cleaning can be performed with the communication hole of the elastic member being opened, and the cleaning process and the cleaning equipment can be simplified. it can.

  Further, when completed, the elastic member can be pressed by means not shown to close the communication hole. As described above, since the cleaning liquid can flow out to the outside during cleaning and the communication hole 24 can be easily closed, an opening area is provided in the common liquid chamber in order to prevent dust mixed in when connecting the common liquid chamber members. There is no need to provide a narrowed area. Therefore, increase of fluid resistance in the common liquid chamber and retention of bubbles can be prevented, initial filling can be performed easily, and drop ejection defects due to bubbles can be reduced.

Next, a second embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 2 is an explanatory cross-sectional view of the main part of the common liquid chamber member portion of the head in the same embodiment.
In the present embodiment, the claw portion 25 is integrally formed on the outer peripheral surface of the first member 21 in the first embodiment, and the protrusion portions 26 a and 26 b that lock the claw portion 25 on the outer peripheral surface of the second member 22. Are integrally formed at intervals in the ink flow direction.

  Since it comprised in this way, as shown to Fig.2 (a), in the state in which the nail | claw part 25 of the 1st member 21 was latched by the projection part 26a of the 2nd member 22, the 1st member 21 and 2nd By pressing the member 22 from above and below (from the direction in which the elastic member 23 is crushed by the first member 21 and the second member 23), the elastic member 23 is crushed by the first member 21 and the second member 23, As shown in FIG. 2 (b), the claw portion 25 gets over the protrusion 26b and is crushed until the communication hole 24 of the elastic member 23 is closed. The state where the communication hole 24 is closed by being held by the protrusion 23b is maintained.

  In this way, the ink flowing into the common liquid chamber 10 is communicated through the communication hole 18 by closing the communication hole 24 of the elastic member 23 by pressurizing the first and second members 21 and 22 after the cleaning process is completed. Will not be discharged from. In addition, a sufficient opening of the common liquid chamber 10 can be formed, and an increase in fluid resistance and retention of bubbles in the common liquid chamber can be prevented, so that initial filling can be easily performed. Also, droplet discharge defects due to the retention of water are reduced.

  Next, an example in which the member configuration of the common liquid chamber member in each of the above embodiments is different will be described with reference to FIG. FIG. 3 is an explanatory cross-sectional view showing a state before assembly of the components of the common liquid chamber member.

  In the example of FIG. 3A, the first member 21, the second member 22, and the elastic member 23 that is the third member are each configured as a three-part configuration.

  The example of FIG. 3B has a two-part configuration of a first member 21 and a member (part) 120 in which the second member 22 and the elastic member 23 that is the third member are integrated.

  The example of FIG. 3C has a two-part configuration of a first member 21 and a member (part) 121 in which the elastic member 23 that is the third member is integrated, and a second member 22.

  Here, the number of component parts of the common liquid chamber member 20 is preferably smaller from the viewpoint of assembly man-hours and parts management, and the configurations of FIGS. 3B and 3C are more preferable than the configuration of FIG. Is preferred.

  Next, different examples of integral molding of components will be described with reference to FIGS. In addition, each figure (a) is sectional explanatory drawing with which it uses for description of the same body shaping | molding, (b) is side explanatory drawing similarly. Here, an example of the two-part configuration in FIG. 3B will be described.

  In the example shown in FIG. 4, in order to mold the first member 21 that has been molded in advance into the rubber as the elastic member 23 in the next process, the first member 21 is set in a rubber mold and subjected to a vulcanization process. And the elastic member 23 as an integral part.

  The example shown in FIG. 5 is an example in which the first member 21 and the elastic member 23 are simultaneously molded by two-color molding. In the case of two-color molding, after the first member 21 is molded, the cavity for the first member 21 and the cavity for the elastic member 23 are switched and injection is performed again to perform molding. For this reason, it has a form in which a die structure is formed so that it can be molded by two-color molding.

Next, a first embodiment of the liquid discharge head cleaning method according to the present invention will be described with reference to FIGS. 6 and 7 are cross-sectional explanatory views for explaining the cleaning method.
As shown in FIG. 6A, the claw portion 25 of the first member 21 is engaged with the protruding portion 26b of the second member 22, and the elastic member 23 is crushed. Until just before this state, the inside of the common liquid chamber 10 communicates with the outside air, and dust is mixed in due to rubbing between parts in the process of assembly, but the common liquid chamber 10 in the common liquid chamber member 20 is mixed. There is no more foreign dust inside.

  Further, at this stage, the filter unit 32 is assembled in the middle of the path on the connection port side with the ink tank (not shown), and the dust from the ink tank side is not mixed.

  Therefore, as shown in FIG. 6B, the pressure cap 51 is sealed in close contact with the nozzle surface 3a. A pressure pump 52 is connected to the pressure cap 51.

  At the same time, the communication hole 24 is opened by the restoring force of the elastic member 23 by changing the claw portion 25 of the first member 21 from the protruding portion 26b of the second member 22 to the protruding portion 26a. Communicates with outside air (outside).

  Then, as shown in FIG. 7A, a waste liquid tube 53 is connected to the communication hole 24 of the elastic member 23, and the cleaning liquid is pressurized and injected by the pressure pump 52. As a result, the cleaning liquid is injected into the head from the nozzle 4 and injected into the common liquid chamber 10 through the pressurized liquid chamber 6 and the cleaning waste liquid that has cleaned the common liquid chamber 10 is collected through the waste liquid tube 53. The

  After cleaning with the cleaning liquid, air is pressurized and injected from the pressure cap 51 to collect the cleaning liquid so that no cleaning waste liquid remains in the common liquid chamber 10.

  Thereafter, as shown in FIG. 7B, in order to finish the cleaning process, the waste liquid tube 53 is removed, and the nail of the first member 21 is immediately removed in order to prevent dust from entering the cleaned common liquid chamber 10. The communication hole 24 is closed by pressurizing and crushing the elastic member 23 by changing the portion 25 from the protruding portion 26a of the second member 22 to the protruding portion 26b.

  And as shown in FIG. 8, the pressurization cap member 51 is removed and a series of washing | cleaning processes are complete | finished.

  As described above, the communication hole of the elastic member of the common liquid chamber member is opened, the cleaning liquid is supplied into the common liquid chamber and discharged from the communication hole, and the communication hole of the elastic member of the common liquid chamber member is closed after the cleaning is completed. By adopting a configuration in which the state is maintained, the cleaning process and the cleaning equipment can be simplified. When the communication hole 24 is closed with a general plug-shaped member, the plug-shaped member needs to be sufficiently washed, and dust may be newly generated by attaching the member. However, if the cleaning portion is pressed as in the present embodiment, no new dust is generated, and even if dust is generated, it is pressed and embedded by the elastic member 23. Never invade.

Next, a second embodiment of the liquid ejection head cleaning method according to the present invention will be described with reference to FIG. FIG. 9 is an explanatory cross-sectional view for explaining the cleaning method.
In the first embodiment, since the cleaning liquid is injected under pressure from the nozzle side, the cleaning liquid flows from the nozzle 4 toward the communication hole 24. At this time, the entire common liquid chamber 10 is filled with the cleaning liquid, but the flow of the cleaning liquid is slow (small) in a region corresponding to the upstream side of the flow path from the communication hole 24 in the common liquid chamber 10. Therefore, there is a possibility that the cleaning effect of the region corresponding to the upstream side is weaker than the region corresponding to the downstream side of the flow path from the communication hole 24 in the common liquid chamber 10.

  Therefore, in the present embodiment, when the common liquid chamber 10 is cleaned, the opening of the filter unit 32 is sealed with the pressure caps 51 and 51, and the cleaning liquid starts from the filter unit 32 side (upstream side of the common liquid chamber 10). The waste liquid of the cleaning liquid is collected from the waste liquid tube 53 connected to the communication hole 24.

  By doing so, the flow of the cleaning liquid in the region corresponding to the upstream side of the flow path from the communication hole 24 in the common liquid chamber 10 is not reduced, and the upstream side of the flow path from the communication hole 24 in the common liquid chamber 10 is ensured. The area corresponding to can be cleaned.

Next, a third embodiment of the liquid ejection head cleaning method according to the present invention will be described with reference to FIG. FIG. 10 is an explanatory cross-sectional view for explaining the cleaning method.
This embodiment combines the cleaning methods of the first embodiment and the second embodiment, and injects the cleaning liquid from both the nozzle 4 and the filter unit 32 at the same time, so that the cleaning liquid flows in the entire common liquid chamber 10. Thus, cleaning can be performed more efficiently. In order to further improve the cleaning power, it is preferable to drive the two pumps 52 alternately to cause pulsation in the cleaning liquid in the common liquid chamber 10.

  The procedure of the cleaning method is the same as that described in the first embodiment.

Next, a third embodiment of the liquid ejection head according to the present invention will be described with reference to FIGS. 11 and 12 are cross-sectional explanatory views of the common liquid chamber member portion used for explaining the bubble discharging method in the same embodiment.
When air (bubbles) is mixed into the common liquid chamber 10, if the bubbles enter the pressurized liquid chamber 6 or the nozzle 4, the droplet discharge becomes unstable or cannot be discharged. When air of a certain amount or more in 10 is mixed, it is necessary to quickly discharge and remove bubbles. In addition, air mixing into the common liquid chamber 10 may be caused by air bubbles contained in an ink tank (not shown) being supplied into the common liquid chamber 10 together with ink, or by the common liquid chamber member 20 (elasticity from outside air). This may be caused by mixing through the member 23 or the like.

  Therefore, here, the bubble detection means 55 is provided on the side wall surface of the second member 22. The bubble detection means 55 is composed of two electrodes, and detects the presence or absence of bubbles by determining the presence or absence of energization between these electrodes (a state where conductive ink immerses the electrodes). Can do.

  Here, when the control unit of the apparatus main body detects air mixing into the common liquid chamber 10 from the energized state of the bubble detection means 55, for example, as shown in FIG. When the region 61 and the air region 62 are generated, the apparatus main body moves the head to the maintenance position (maintenance recovery position). At the maintenance position, although not shown, an opening / closing means for opening and closing the communication hole 24 of the elastic member 23 is provided, thereby opening the communication hole 24 of the elastic member 23.

  Then, as shown in FIG. 11 (b), the ink liquid level in the common liquid chamber 10 is raised by pressurizing and supplying the ink into the common liquid chamber 10 by a pressurizing means (not shown). When the electrode part of the detection means 55 is immersed in ink, the ink supply is stopped.

  Then, as shown in FIG. 12, by closing the communication hole 24 of the elastic member 23 by pressing the first member 22 and the second member 23 with an opening / closing means (not shown) and crushing the elastic member 23, Complete the bubble discharge operation.

  Since the ink supply stop position is below the communication hole, the position of the communication hole 24 is arranged above the common liquid chamber 10 in order to discharge air mixed in the common liquid chamber 10 as much as possible. It is preferable. Further, by performing this ink supply operation with the above-described waste liquid tube 53 attached, ink can be filled up to the height of the communication hole 24, and the residual air can be further reduced.

  Next, examples in which the shape of the elastic member and the communication hole in the liquid ejection head according to each of the above embodiments are different will be described with reference to FIGS. In addition, each figure (a) is sectional explanatory drawing, (b) is side explanatory drawing.

  The first example in FIG. 13 is an example in which the communication hole 24 is trapezoidal, and the second example in FIG. 14 is an example in which the communication hole 24 is rectangular. The thickness of the elastic member 23 (width in the liquid flow direction) ) Is thinned at the portion of the communication hole 24. That is, the elastic member 23 has a thin portion 23 a where the communication hole 24 is formed and a thick portion 23 b where the communication hole 24 is not formed.

  The third example of FIG. 15 is an example in which the thickness of the elastic member 23 is the same including the portion corresponding to the communication hole 24. That is, the elastic member 23 has the same thickness as the portion where the communication hole 24 is not formed by forming the convex portion 23 c in the portion where the communication hole 24 is formed.

  The fourth example of FIG. 16 is also an example in which the thickness of the elastic member 23 is the same including the portion corresponding to the communication hole 24. That is, the elastic member 23 has the same thickness as the portion where the communication hole 24 is not formed by forming the projections 23 c and 23 d in the portion where the communication hole 24 is formed.

  The fifth example of FIG. 17 is an example in which the thickness of the elastic member 23 is made thicker at the portion corresponding to the communication hole 24 than at the portion where the communication hole 24 is not formed. That is, the elastic member 23 is made thicker than the portion where the communication hole 24 is not formed by forming the convex portion 23 e in the portion where the communication hole 24 is formed.

  In the first to fifth examples, in the case of the shapes as in the first and second examples, the crushing amount of the thick portion increases, and it may be difficult to close the communication hole 24 without a gap. On the other hand, by making the thickness of the region of the communication hole 24 the same as the thickness of the other regions as in the third example and the fourth example, or the thickness of the region of the communication hole 24 as in the fifth example. By making it thicker than the thickness of the other region, the communication hole 24 by pressurization can be reliably closed.

Next, an example of the image forming apparatus according to the present invention including the liquid discharge head according to the present invention will be described with reference to FIGS. 18 is an explanatory side view of the mechanism of the apparatus, and FIG. 19 is an explanatory plan view of the main part.
This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 221A and 221B. The main scanning motor that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 includes a plurality of recording heads 234 including the liquid ejection head according to the present invention for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). Nozzle rows composed of nozzles are arranged in the sub-scanning direction orthogonal to the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.

  The recording head 234 is configured by attaching liquid ejection heads 234a and 234b each having two nozzle rows to one base member, and one nozzle row of one head 234a has a black (K) droplet. The other nozzle row ejects cyan (C) droplets, the other nozzle row of the other head 234b ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. . Note that, here, a two-head configuration is used to eject four color droplets, but a liquid ejection head for each color may be provided.

  The carriage 233 is equipped with sub tanks 235a and 235b (referred to as “sub tank 235” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 234. The sub tank 235 is supplied with ink of each color from the ink cartridge 210 of each color by the supply unit 224 via the supply tube 236 of each color.

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

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

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

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

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

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

  In addition, in the non-printing area on the other side of the carriage 233 in the scanning direction, idle ejection that receives droplets when performing idle ejection that ejects droplets that do not contribute to recording in order to discharge ink that has been thickened during recording or the like. A receiver 288 is disposed, and the idle discharge receiver 288 is provided with an opening 289 along the nozzle row direction of the recording head 234 and the like.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 247 and pressed against the conveying belt 251 by the leading end pressure roller 249, and the conveying direction is changed by approximately 90 °.

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

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

  Thus, since the image forming apparatus includes the liquid discharge head according to the present invention as a recording head, stable droplet discharge characteristics can be obtained, and a high-quality image can be stably formed.

  In the above embodiment, a serial type image forming apparatus is described as an example of the image forming apparatus of the present invention. However, the present invention can be similarly applied to a line type image forming apparatus. Further, the present invention can be applied to an image forming apparatus using a liquid other than the narrowly defined ink, a fixing processing liquid, or the like.

DESCRIPTION OF SYMBOLS 1 Flow path plate 2 Vibration board member 3 Nozzle plate 4 Nozzle 6 Liquid chamber 10 Common liquid chamber 12 Piezoelectric member 20 Common liquid chamber member 21 1st member 22 2nd member 23 3rd member (elastic member)
24 Communication hole 25 Claw part 26a, 26b Projection part 233 ... Carriage 234 ... Recording head

Claims (5)

A common liquid chamber member that forms a common liquid chamber that supplies liquid to a plurality of liquid chambers that communicate with a plurality of nozzles that discharge droplets, respectively;
The common liquid chamber member is composed of a plurality of members,
Of the plurality of members, at least one member is an elastic member having elasticity,
The elastic member is provided with a communication hole that communicates the common liquid chamber with the outside.   The liquid ejection head according to claim 1, wherein the communication hole of the elastic member is closed in a pressurized state.   The liquid ejection head according to claim 1, wherein the elastic member is integrally formed with another member constituting the common liquid chamber member.   An image forming apparatus comprising the liquid discharge head according to claim 1. A method for cleaning a liquid discharge head for cleaning the liquid discharge head according to any one of claims 1 to 3,
With the communication hole of the elastic member of the common liquid chamber member opened,
Supplying cleaning liquid into the common liquid chamber and discharging it from the communication hole;
A cleaning method of a liquid discharge head, wherein after completion of cleaning, the communication hole of the elastic member of the common liquid chamber member is closed.

Images