JP3993765B2 - Liquid supply / discharge mechanism and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid supply / discharge mechanism that supplies liquid to a liquid discharge head and collects waste liquid discharged from the liquid discharge head, and an image forming apparatus incorporating the liquid supply / discharge mechanism.
[0002]
In this specification, “print” or “record” is not only used to form significant information such as characters and figures, but also manifests so that it can be perceived visually by humans regardless of significance. Regardless of whether or not it is, it is widely used to form images, patterns, patterns, etc. on a print medium, or to include processing such as etching.
[0003]
The “print medium” is not only a piece of paper used in a general printing apparatus, but also a cloth, a plastic film, a metal plate, glass, ceramics, wood, leather, etc. that can accept ink, and is in a sheet form. Three-dimensional solids other than objects, such as spheres and cylinders, are also targets.
[0004]
Further, the term “liquid” should be broadly interpreted in the same way as the definition of “print (or recording)”, and is applied to a print medium to form an image, a pattern, a pattern, or the like. And the like that are used for the etching process of the above, or the treatment of the ink (for example, solidification or insolubilization of the coloring material in the ink applied to the print medium).
[0005]
[Prior art]
Image formation by an ink jet method in which a droplet of liquid such as ink is ejected from a discharge port formed in a liquid discharge head and attached to a print medium such as paper to form a desired image on the print medium is disclosed in US Pat. No. 4,723,129. The principle and technology are described in the issue.
[0006]
In such an ink jet printer, as the amount of liquid such as ink increases, a liquid tank that stores a large amount of liquid in advance, that is, a main tank is replaceable, and is assembled to the main tank and the liquid discharge head. Japanese Patent Application Laid-Open No. 10-157155 discloses a technique for connecting a small-capacity liquid tank, i.e., a sub-tank, via a liquid supply pipe and supplying liquid from the main tank to the sub-tank according to the amount of liquid consumed in the sub-tank. Has been proposed in
[0007]
On the other hand, in such an ink jet type liquid discharge head, the liquid present in the liquid passage communicating with the discharge port formed in the liquid discharge head is dried and thickened, and dust or the like adheres to the discharge port. There is a problem of clogging. Similarly, there is a problem that bubbles are generated in the liquid intervening in the liquid passage and the liquid is not normally ejected normally, and a smooth ejection operation is difficult or impossible. For this reason, the discharge port is clogged by reducing the pressure inside the liquid discharge head using a suction pump and sucking and removing the thickened liquid or bubbles intervening in the liquid path formed in the liquid discharge head from the discharge port. In general, it is common to recover from discharge defects.
[0008]
An example of a conventional liquid suction / discharge mechanism for an ink jet type liquid discharge head is schematically shown in FIG. That is, the ink jet head 101 as a liquid discharge head and the sub liquid tank 102 for storing the liquid L supplied to the ink jet head 101 are connected via the liquid supply pipe 103.
[0009]
The sub liquid tank 102 and the main liquid tank 106 for storing the liquid L supplied to the sub liquid tank 102 are connected via a liquid supply pipe 107, and a liquid supply pump provided in the middle of the liquid supply pipe 107. By the operation of 108, the liquid L in the main liquid tank 106 is replenished into the sub liquid tank 102.
[0010]
The capping member 110 capable of covering the ejection port surface 109 of the inkjet head 101 in which a large number of ejection ports (not shown) open downward is in close contact with the waste liquid L from the inkjet head 101. _W A waste liquid tank 111 is connected through a waste liquid suction pipe 112. A waste liquid suction pump 113 is provided in the middle of the waste liquid suction pipe 112, and by operating the waste liquid suction pump 113, the capping member 110 from the discharge port removes thickened liquid or bubbles intervening in a liquid path (not shown) of the inkjet head 101. Then, it is further collected from here into the waste liquid tank 111 through the waste liquid suction pipe 112.
[0011]
[Problems to be solved by the invention]
In the conventional liquid suction / discharge mechanism as shown in FIG. 6 for the ink jet type liquid discharge head, the liquid replenishment pump 108 and the waste liquid suction pump 113 are required for one ink jet head 101. If three or more ink jet heads 101 are incorporated, at least two pumps are required for each ink jet head 101, which increases the cost of parts and increases the size of the liquid supply / discharge mechanism itself. There was a problem that hindered compactness.
[0012]
OBJECT OF THE INVENTION
SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid supply / discharge mechanism capable of reducing the cost of parts and reducing the size by giving two functions to one pump, and an image forming apparatus incorporating the liquid supply / discharge mechanism. There is to do.
[0013]
[Means for Solving the Problems]
According to a first aspect of the present invention, a first liquid tank that stores liquid supplied to a liquid discharge head, a waste liquid tank that stores waste liquid discharged from the liquid discharge head, A waste liquid guide pipe for guiding the waste liquid discharged from the liquid discharge head at one end thereof to the waste liquid tank; A common pipe having one end communicating with the first liquid tank, a common pump provided on the other end of the common pipe, and a first reservoir for storing the liquid supplied to the common pump and the first liquid tank. A liquid supply pipe that communicates with the two liquid tanks, a first on-off valve that is provided in the liquid supply pipe and that can open and close the liquid supply pipe, and the common pump and the waste liquid tank communicate with each other to provide the waste liquid. A suction pipe for sucking air in the tank; and a second opening / closing valve provided on the suction pipe and capable of opening and closing the suction pipe. The common pump sucks air in the waste liquid tank through the suction pipe and depressurizes the waste liquid tank, so that the waste liquid from the liquid discharge head flows into the waste liquid tank through the waste liquid guide pipe. To be sucked into The liquid supply / discharge mechanism is characterized by the above.
[0014]
In the first embodiment of the present invention, when the first liquid tank needs to be replenished with the supply of liquid from the first liquid tank to the liquid discharge head, the first on-off valve is opened. By closing the second on-off valve and driving the common pump, the liquid in the second liquid tank is supplied from the liquid supply pipe into the first liquid tank through the common pipe. When the waste liquid is drawn into the waste liquid tank from the liquid discharge head, the first on-off valve is closed and the second on-off valve is opened, and the common pump is driven so that the air in the waste liquid tank passes through the suction pipe and the common pipe. As a result, the waste liquid tank is depressurized as a result of being sucked into the first liquid tank, and the waste liquid is discharged from the liquid discharge head. Through the waste liquid guide tube It is sucked into the waste liquid tank.
[0015]
According to a second aspect of the present invention, there is provided a mounting portion of a liquid discharge head that discharges liquid onto a print medium, a print medium conveying means for the liquid discharge head attached to the mounting portion, and the above-described first aspect of the present invention. An image forming apparatus including a liquid supply / discharge mechanism according to a form.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
In the liquid supply / discharge mechanism according to the first aspect of the present invention, both the first on-off valve and the second on-off valve are in a closed state, or the other is closed while one is open. It is preferable that it exists in.
[0017]
It is preferable to locate the open end of the suction pipe that opens into the waste liquid tank at the upper end of the waste liquid tank.
[0018]
Receiving container for receiving waste liquid discharged from the liquid discharge head More , The other end of the waste liquid guide tube This acceptance In a vessel Communicate Have It may be a thing. In this case, a defoaming promoting member that promotes defoaming of bubbles contained in the waste liquid drawn into the waste liquid tank from the open end of the waste liquid guide pipe that opens into the waste liquid tank is disposed immediately below the open end of the waste liquid guide pipe. Preferably, this may be a porous or fibrous liquid holding member capable of holding waste liquid, or a plate-like member fixed inside the waste liquid tank.
[0019]
The open end of the waste liquid guide pipe that opens into the waste liquid tank may be inclined with respect to the axis of the waste liquid guide pipe.
[0020]
It is also possible to provide a liquid level detection sensor in the waste liquid tank for defining a storage amount of the waste liquid sucked into the waste liquid tank.
[0021]
In the image forming apparatus according to the second aspect of the present invention, the liquid discharge head may be of a line type that can discharge liquid onto a print medium. In this case, a plurality of liquid ejection heads can be arranged in parallel, and these can be arranged in a direction crossing the print medium conveyance direction by the conveyance means.
[0023]
Liquid, ink Or Treatment liquid for adjusting the printability of ink on a print medium Or ink and processing liquid It may be.
[0024]
【Example】
An embodiment in which a liquid supply / discharge mechanism and an image forming apparatus incorporating the same according to the present invention are applied to a full-line type ink jet printer will be described in detail with reference to FIGS. 1 to 5. The present invention is not limited to the examples, and these may be further combined, or any change or modification included in the concept of the present invention described in the scope of the claims may be made. Therefore, other techniques belonging to the spirit of the present invention are naturally applicable. Can be applied.
[0025]
The appearance of the ink jet printer in this embodiment is schematically shown in FIG. 1, and the ink supply / discharge system for one of the ink jet heads is schematically shown in FIG. That is, as shown in FIG. 1, a plurality (four in the illustrated example) of inkjet heads 11 in which discharge ports (not shown) are opened downward at a predetermined interval along a width direction orthogonal to the conveyance direction of the print medium P A yellow ink, a magenta ink, a cyan ink, and a black ink are sequentially ejected from the downstream side in the transport direction of the print medium P, respectively, along the transport direction of P. On the other hand, color printing can be performed. Each ink-jet head 11 incorporates ejection energy generating means for ejecting ink I from individual ejection ports, and the driving of the ejection energy generating means is performed by a head driver 13 based on a command from the control device 12. It is switched by. These inkjet heads 11 are opposed to the platen 15 with a predetermined interval across the endless conveying belt 14, and the platen 15 is moved by the head moving means 16 for recovery processing whose operation is controlled by the control device 12. It can be moved up and down in the opposite direction. Prior to the printing operation on the print medium P, old ink intervening in an ink path (not shown) communicating with the discharge port of the inkjet head 11 is discharged to the side of each inkjet head 11 (upstream in the conveyance direction of the print medium P). A head cap 17 for discharging the ink jet head 11 from the outlet and performing the recovery process of the ink jet head 11 is arranged as a receiving container of the present invention with a half-pitch shift with respect to the arrangement interval of the ink jet heads 11, and the operation is controlled by the control device 12. The waste ink I is moved directly below the inkjet head 11 by the cap moving means 18 and discharged from the discharge port. _W Have come to receive.
[0026]
The conveying belt 14 for conveying the print medium P is wound around a driving roller 20 connected to a belt driving motor 19, and its operation is switched by a motor driver 21 connected to the control device 12. Further, on the upstream side of the conveyance belt 14, a charger 22 is provided for charging the conveyance belt 14 to bring the print medium P into close contact with the conveyance belt 14. The electrification driver 23 connected to the control device 12 is switched on / off. A pair of paper feed rollers 24 for supplying the print medium P onto the transport belt 14 is connected to a paper feed motor 25 for driving and rotating the pair of paper feed rollers 24. The operation of 25 is switched by the motor driver 26 connected to the control device 12.
[0027]
Accordingly, prior to the printing operation on the print medium P, the inkjet head 11 is lifted away from the platen 15, and then the head cap 17 is moved directly below the inkjet head 11 to perform the recovery process of the inkjet head 11. The head cap 17 is moved to the original standby position, and the inkjet head 11 is further moved to the platen 15 side to the printing position. At the same time as the charger 22 is operated, the transport belt 14 is driven, and the print medium P is placed on the transport belt 14 by the paper feed roller 24, and a predetermined color image is printed by each inkjet head 11. Printed on P.
[0028]
As shown in FIG. 2, a sub ink tank 27 is connected to each inkjet head 11 via an ink supply pipe 28. The sub ink tank 27 and the main ink tank 31 for storing the ink I supplied to the sub ink tank 27 have a common pipe 32 having one end opened upward at the upper end portion of the sub ink tank 27 and one end of the main ink tank. The ink I in the main ink tank 31 is replenished into the sub ink tank 27 by the operation of the common pump 34 that is connected through the ink replenishment pipe 33 drawn into the pipe 31 and provided in the middle of the common pipe 32. It is like that. In this case, the pressure in the sub ink tank 27 fluctuates due to the change in the amount of ink stored in the sub ink tank 27, so that the smooth circulation supply of the ink I to the inkjet head 11 is not hindered. At the upper end portion, an air communication hole 35 is provided. The common pump 34 has a structure that does not block the flow of ink or air intervening in the common pipe 32 even when its operation is stopped.
[0029]
The main ink tank 31 in this embodiment has a flexible ink containing bag 36 for containing the ink I in a sealed state, and a casing 37 for protecting it, and the sub ink tank 27 is supplied with the ink I. When the volume of the ink containing bag 36 is reduced in accordance with the operation, if the casing 37 has a sealed structure, the inside of the casing 37 is in a depressurized state to prevent the smooth replenishment operation of the ink I from being difficult. Therefore, an air communication hole 38 is formed in the casing 37.
[0030]
The head cap 17 that can cover the ejection port surface 39 formed by the ejection ports formed in the inkjet head 11 in a close contact state has a waste ink I from the inkjet head 11. _W Are connected via a waste ink guide pipe 41. Further, one end of the waste ink tank 40 and the common pump 34 communicate with each other via a suction pipe 42 that opens to the upper end of the waste ink tank 40, and the inside of the waste ink tank 40 is activated by operating the common pump 34. As the pressure is reduced, a thickening liquid or bubbles intervening in an ink path (not shown) communicating with the ejection port of the inkjet head 11 are drawn into the head cap 17 from the ejection port, and from here through the waste ink guide tube 41. Then, it is collected in the waste ink tank 40.
[0031]
In the middle of the waste ink guide pipe 41 and the suction pipe 42, a detachable joint 43 is incorporated, and the waste ink I stored in the waste ink tank 40 is stored. _W Can be replaced with a new waste ink tank 40 at a time when the amount reaches a predetermined amount. For this reason, the waste ink tank 40 has a waste ink I. _W A liquid level detection sensor 44 is provided for defining the storage amount of the liquid, and a detection signal is output to the control device 12. In this embodiment, since the ink absorber 45 described later is incorporated in the waste ink tank 40, the waste ink I is moved when the waste ink tank 40 is moved along with the replacement of the waste ink tank 40. _W , And liquid leakage from the waste ink guide tube 41 and the suction tube 42 can be suppressed.
[0032]
As described above, since the other ends of the ink supply pipe 33 and the suction pipe 42 communicate with the other end of the common pipe 32, the other end side of the common pipe 32 drawn out of the sub ink tank 27 is bifurcated. One of them is an ink supply pipe 33 that communicates with the main ink tank 31 and the other is a suction pipe 42 that communicates with the waste ink tank 40. For this reason, when the common pump 34 is operated, replenishment of ink I or waste ink I _W In the middle of the ink supply pipe 33 and the suction pipe 42, electromagnetic open / close valves 46 and 47 are respectively installed in the middle of the ink supply pipe 33 and the suction pipe 42 so that both are closed simultaneously or one of them is opened. These opening / closing operations are controlled by the control device 12 so that the other valve is closed in the valve state.
[0033]
As shown in FIG. 3 in which the portion of the waste ink tank 40 is extracted and enlarged, the waste ink I is sucked into the waste ink tank 40 from the opening on the other end side of the waste ink guide pipe 41. _W An ink absorber 45 for defoaming and holding bubbles intervening therein is accommodated as a defoaming promoting member of the present invention, and this ink absorber 45 is a textile such as foamed resin or felt having an open cell body. Etc. can be adopted.
[0034]
When the opening on the other end side of the waste ink guide tube 41 drawn into the waste ink tank 40 is completely brought into contact with the upper end surface of the ink absorber 45 or embedded in the ink absorber 45, the ink On the contrary, bubbles are generated by the mesh structure of the absorber 45 itself, or the opening on the other end side of the waste ink guide tube 41 is the waste ink I. _W The waste ink tank 40 is simply depressurized, and the waste ink I is discharged from the head cap 17 side. _W Therefore, the opening of the waste ink guide tube 41 is disposed with a predetermined gap from the upper end surface of the ink absorber 45, and the waste ink is reduced depending on the decompressed state in the waste ink tank 40. Waste ink I sucked out from the other end of the guide tube 41 _W Consideration is made so that the ink penetrates quickly into the ink absorber 45.
[0035]
From this point of view, as shown in FIG. 4 showing the internal structure of the waste ink tank 40 in another embodiment of the present invention, the opening of the waste ink guide tube 41 is inclined with respect to the axis thereof. The opening of the waste ink guide pipe 41 may be made to reliably face the space 48 formed at the upper end portion of the waste ink tank 40. When the ink absorber 45 is not incorporated in the waste ink tank 40, as shown in FIG. 5 showing the internal structure of the waste ink tank 40 in still another embodiment of the present invention, A plate-like member 49 made of resin or the like is provided in an inclined state immediately below the opening of the waste ink guide tube 41, and the waste ink I is provided on the inclined surface 50 of the plate-like member 49. _W It is also possible to obtain an antifoaming effect by guiding.
[0036]
The ink suction / discharge system described above is provided for each inkjet head 11, but the waste ink I collected in the waste ink tank 40 is used. _W Since it is not necessary to avoid color mixing, one waste ink tank 40 may be connected to the head caps 17 of all the inkjet heads 11 via the waste ink guide pipes 41, respectively. Further, it is possible to further incorporate an ink jet head that discharges a treatment liquid for adjusting the printability of ink on the print medium P. In this case, the treatment liquid supply / discharge system can be the same as the ink supply / discharge system described above for the treatment liquid discharge inkjet head.
[0037]
Since the ink I in the sub ink tank 27 is consumed as the printing operation for the print medium P progresses, it is necessary to replenish the sub ink tank 27 with the ink I from the main ink tank 31 as needed. In this case, the electromagnetic open / close valve 46 on the ink supply pipe 33 side is switched to the open state and the electromagnetic open / close valve 47 on the suction pipe 42 side is closed, and then the common pump 34 is driven, whereby the ink is discharged from the main ink tank 31. A predetermined amount of ink I is supplied into the sub ink tank 27 through the supply pipe 33 and the common pipe 32.
[0038]
On the other hand, with the progress of this printing work, the print quality deteriorates due to adverse effects such as paper dust or dust adhering to the ejection opening of the ink jet head 11, bubbles accumulating in the ink path, and ink thickening. In order to avoid this, the recovery process of the inkjet head 11 is performed at a timing determined in advance by sequence control. In this recovery process, the head moving means 16 and the cap moving means 18 are operated, the head cap 17 is pressed against the discharge port surface 39 of the inkjet head 11, and the electromagnetic on-off valve 46 on the ink supply pipe 33 side is closed. At the same time, after the electromagnetic on-off valve 47 on the suction pipe 42 side is switched to the open state, the common pump 34 is driven so that the air in the waste ink tank 40 is sucked into the sub ink tank 27 through the suction pipe 42. As a result, the inside of the waste ink tank 40 is depressurized and a thickening liquid or bubbles intervening in an ink path (not shown) communicating with the ejection port of the inkjet head 11 are drawn into the head cap 17 from the ejection port. The ink is then permeated and held in the ink absorber 45 in the waste ink tank 40 through the waste ink guide tube 41.
[0039]
Waste ink I guided into the waste ink tank 40 _W Bubbles are contained in the waste ink tank 40, which tends to foam in the waste ink tank 40 in a reduced pressure atmosphere, but the waste ink I sucked into the waste ink tank 40 from the opening of the waste ink guide tube 41. _W Can be suppressed by promptly contacting and penetrating the ink absorber 45. The air sucked into the sub ink tank 27 is discharged outside from the atmosphere communication hole 35, and the waste ink I is put into the sub ink tank 27. _W There will be no inconvenience that is absorbed.
[0040]
In order to suck the waste ink from the discharge port of the inkjet head 11 by the negative pressure generated by the shared pump 34, it is necessary to completely block the periphery of the discharge port with the head cap 17. However, when a pressure pump is provided in the middle of the ink supply pipe 28 or the like that communicates between the inkjet head 11 and the sub ink tank 27, the pressure pump is operated during the recovery process to discharge the inkjet head 11 It is also possible to apply a positive pressure to the head cap 17 and push out the waste ink to the head cap 17 side. In the present invention, even when such a configuration is adopted, the ink supply from the ink absorbing bag 36 to the sub ink tank 35 and the waste liquid transport from the head cap 17 to the waste ink tank 40 are performed as one common pump. 34. In the case of incorporating such a pressure pump, the ink jet head 11 and the sub ink tank 27 are further connected via an ink return pipe, thereby being included in the ink supply path from the ink supply pipe 28 to the ink jet head 11. The air bubbles generated can be removed and discharged to the sub ink tank 27 through the ink return pipe.
[0041]
The present invention includes means (for example, an electrothermal converter or a laser beam) that generates thermal energy as energy used for discharging the liquid, and causes a change in the state of the liquid by the thermal energy. In the image forming apparatus using the ink jet type liquid discharge head, an excellent effect is brought about. This is because according to such a method, high density and high definition of the print can be achieved.
[0042]
As for the typical configuration and principle, for example, those performed using the basic principle disclosed in US Pat. No. 4,723,129 and US Pat. No. 4,740,796 are preferable. This method can be applied to both a so-called on-demand type and a continuous type. In particular, in the case of the on-demand type, an electric circuit arranged corresponding to a sheet or a channel holding a liquid is used. Applying at least one drive signal that gives a rapid temperature rise exceeding the nucleate boiling corresponding to the print information to the thermal converter to generate thermal energy, causing film boiling on the heat acting surface of the liquid discharge head, As a result, it is effective because bubbles in the liquid corresponding to the drive signals on a one-to-one basis can be formed. Due to the growth and contraction of the bubbles, the liquid is discharged through the discharge port to form at least one droplet. It is more preferable that the drive signal has a pulse shape, since the bubble growth and contraction is performed immediately and appropriately, and thus it is possible to achieve liquid discharge with particularly excellent responsiveness. As this pulse-shaped drive signal, those described in US Pat. No. 4,463,359 and US Pat. No. 4,345,262 are suitable.
[0043]
If the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface are employed, further excellent printing can be performed.
[0044]
As a configuration of the liquid ejection head, a combination configuration of an ejection port, a liquid path, and an electrothermal transducer as disclosed in each of the above specifications (a linear shape in which the electrothermal transducer is disposed along the liquid path) US Pat. No. 4,558,333 which discloses a configuration in which a liquid passage or an electrothermal transducer is disposed in a region where the heat acting portion bends in addition to a liquid passage or a right-angle liquid passage facing the discharge port across the liquid passage) A configuration using US Pat. No. 4,459,600 is also included in the present invention. In addition, for a plurality of electrothermal transducers, Japanese Patent Application Laid-Open No. Sho 59-123670 that discloses a configuration in which a common slit is used as a discharge portion of the electrothermal transducer, or an aperture that absorbs pressure waves of thermal energy The effect of the present invention is effective even if the configuration is based on Japanese Patent Application Laid-Open No. 59-138461 which discloses a configuration corresponding to the discharge section. That is, whatever the form of the liquid ejection head is, according to the present invention, printing can be performed reliably and efficiently.
[0045]
As a full-line type liquid discharge head having a length corresponding to the maximum width of the print medium that can be printed by the image forming apparatus, a configuration satisfying the length by a combination of a plurality of liquid discharge heads or integrally formed Any configuration as one liquid discharge head may be used.
[0046]
As the configuration of the image forming apparatus of the present invention, it is possible to further stabilize the effect of the present invention by adding a recovery means for making the liquid discharge state from the liquid discharge head appropriate, a preliminary auxiliary means, etc. It is preferable. Specifically, a capping unit, a cleaning unit, a pressurizing or sucking unit for the liquid discharge head, a preheating unit for heating using an electrothermal converter, a heating element different from this, or a combination thereof, A preliminary discharge unit that discharges separately from the printing operation can be given.
[0047]
As for the type and number of liquid discharge heads to be mounted, for example, only one corresponding to a single color ink is provided, and also corresponding to a plurality of types of inks having different print colors and densities (lightness). A plurality of them may be provided. That is, for example, the print mode of the image forming apparatus is not limited to a print mode of only a mainstream color such as black, but the liquid discharge head may be configured integrally or a plurality of combinations. The present invention is also very effective for an image forming apparatus having at least one of full-color print modes using color or mixed colors. In this case, it is also effective to discharge a processing liquid (printability improving liquid) for adjusting the printability of ink according to the type of print medium and the print mode from a dedicated or common liquid discharge head to the print medium.
[0048]
As the form of the image forming apparatus according to the present invention, it is used as an image output terminal of information processing equipment such as a computer, a copying apparatus combined with a reader, etc., a facsimile apparatus or a textile printing apparatus having a transmission / reception function, or etching. The print medium may be in the form of a device, and as a print medium, in addition to sheet-like or long paper or fabric, plate-like wood or leather, stone, resin, glass, metal, etc., 3 Dimensional three-dimensional structures can be mentioned.
[0049]
【The invention's effect】
According to the liquid supply / discharge mechanism of the present invention, the common pump is provided on the other end side of the common pipe whose one end communicates with the first liquid tank, and the liquid supply pipe that communicates the common pump and the second liquid tank is provided. Since the first on-off valve is provided and the second on-off valve is provided in the suction pipe for sucking the air in the waste liquid tank by communicating the shared pump and the waste liquid tank, one of these two on-off valves is opened. During the valve state, the other pump is closed so that the common pump can supply the liquid from the second liquid tank to the first liquid tank and Via waste liquid induction tube It becomes possible to share the waste liquid suction operation to the waste liquid tank, and the liquid supply / discharge mechanism can be made compact and the cost of its parts can be reduced.
[0050]
When the open end of the suction pipe that opens into the waste liquid tank is positioned at the upper end of the waste liquid tank, the waste liquid sucked into the waste liquid tank from the liquid discharge head is drawn into the first liquid tank from the suction pipe. Such a problem can be prevented.
[0051]
Receiving container for receiving waste liquid discharged from the liquid discharge head More , The other end of the waste liquid guide tube This acceptance In a vessel Communicate Have In this case, the waste liquid from the liquid discharge head can be sucked into the waste liquid tank through the waste liquid guide pipe from the receiving container.
[0052]
When a defoaming promoting member is provided directly under the open end of the waste liquid guide pipe that opens into the waste liquid tank, bubbles contained in the waste liquid drawn into the waste liquid tank from the open end of the waste liquid guide pipe are quickly removed. It is possible to eliminate the bubbles, and it is possible to prevent a problem that a part of the waste liquid sucked into the waste liquid tank is drawn into the first liquid tank from the suction pipe.
[0053]
In the case where the defoaming promoting member is a porous or fibrous liquid holding member capable of holding waste liquid, the waste liquid drawn into the waste liquid tank from the open end of the waste liquid guide pipe is used as a liquid holding member using capillary force. By permeating and holding, bubbles contained in the waste liquid can be smoothly eliminated.
[0054]
When the defoaming promoting member is a plate-like member fixed inside the waste liquid tank, it is contained in the waste liquid by guiding the waste liquid drawn into the waste liquid tank from the open end of the waste liquid guide pipe to the plate-like member. Air bubbles can be smoothly eliminated.
[0055]
When the open end of the waste liquid guide pipe that opens into the waste liquid tank is inclined with respect to the axis of the waste liquid guide pipe, this open end is prevented from being blocked by the antifoam promoting member. can do.
[0056]
When a liquid level detection sensor for defining the amount of waste liquid to be sucked into the waste liquid tank is provided in the waste liquid tank, it is possible to reliably grasp the replacement timing of the waste liquid tank.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a schematic structure of an embodiment in which an image forming apparatus according to the present invention is applied to a full-line type ink jet printer.
FIG. 2 is a conceptual diagram of a liquid supply / discharge mechanism related to one liquid discharge head in the embodiment shown in FIG.
FIG. 3 is an enlarged view of extraction of a waste liquid tank portion in the embodiment shown in FIG. 2;
FIG. 4 is a cross-sectional view showing a schematic structure of another embodiment of the waste liquid tank in the liquid supply / discharge mechanism according to the present invention.
FIG. 5 is a cross-sectional view showing a schematic structure of still another embodiment of the waste liquid tank in the liquid supply / discharge mechanism according to the present invention.
FIG. 6 is a conceptual diagram illustrating an example of a conventional liquid supply / discharge mechanism related to a liquid discharge head.
[Explanation of symbols]
P Print media
I ink
I _W Waste ink
11 Inkjet head
12 Control device
13 Head driver
14 Conveyor belt
15 Platen
16 Head moving means
17 Head cap
18 Cap moving means
19 Belt drive motor
20 Drive roller
21 Motor driver
22 Charger
23 Charger driver
24 Paper feed roller
25 Paper feed motor
26 Motor driver
27 Secondary ink tank
28 Ink supply pipe
31 Main ink tank
32 Common piping
33 Ink supply tube
34 Common pump
35 Air communication hole
36 Ink bag
37 Casing
38 Air communication hole
39 Discharge port surface
40 Waste ink tank
41 Waste ink guide tube
42 Suction tube
43 Fitting
44 Liquid level detection sensor
45 Ink absorber
46, 47 solenoid valve
48 spaces
49 Plate member
50 Inclined surface 50

Claims (14)

A first liquid tank for storing liquid supplied to the liquid discharge head;
A waste liquid tank for storing waste liquid discharged from the liquid discharge head;
A waste liquid guide pipe for guiding the waste liquid discharged from the liquid discharge head at one end thereof to the waste liquid tank;
A common pipe having one end communicating with the first liquid tank;
A common pump provided on the other end of the common pipe;
A liquid supply pipe that communicates the shared pump with a second liquid tank that stores liquid supplied to the first liquid tank;
A first on-off valve provided in the liquid supply pipe and capable of opening and closing the liquid supply pipe;
A suction pipe for communicating the common pump and the waste liquid tank to suck air in the waste liquid tank;
A second on-off valve provided on the suction pipe and capable of opening and closing the suction pipe, and the shared pump sucks air in the waste liquid tank through the suction pipe to depressurize the waste liquid tank. Accordingly , the liquid supply / discharge mechanism is characterized in that the waste liquid from the liquid discharge head is sucked into the waste liquid tank through the waste liquid guide pipe .   2. The first on-off valve and the second on-off valve are both in a closed state, or the other is in a closed state while one is in an open state. Liquid supply / discharge mechanism.   The liquid supply / discharge mechanism according to claim 1, wherein an opening end of the suction pipe that opens into the waste liquid tank is located at an upper end portion of the waste liquid tank. Further comprising a receiving vessel for receiving the waste liquid discharged from the liquid discharge head, according to claim 3 and the other end of the waste liquid derived tubes claim 1, characterized in that communicates with the receiving container Liquid supply / discharge mechanism.   Defoaming that is arranged directly under the open end of the waste liquid guide pipe that opens into the waste liquid tank, and promotes defoaming of bubbles contained in the waste liquid drawn into the waste liquid tank from the open end of the waste liquid guide pipe The liquid supply / discharge mechanism according to claim 4, further comprising a promotion member.   6. The liquid supply / discharge mechanism according to claim 5, wherein the defoaming promoting member is a porous or fibrous liquid holding member capable of holding a waste liquid.   The liquid supply / discharge mechanism according to claim 5, wherein the defoaming promoting member is a plate-like member fixed inside the waste liquid tank.   8. The liquid according to claim 4, wherein an opening end of the waste liquid guide pipe that opens into the waste liquid tank is inclined with respect to an axis of the waste liquid guide pipe. Supply / discharge mechanism.   9. The liquid level detection sensor according to claim 1, further comprising a liquid level detection sensor that is provided in the waste liquid tank and defines a storage amount of the waste liquid sucked into the waste liquid tank. Liquid supply / discharge mechanism. A mounting portion of a liquid discharge head for discharging liquid onto a print medium;
Means for transporting the print medium to the liquid ejection head attached to the attachment portion;
An image forming apparatus comprising: the liquid supply / discharge mechanism according to claim 1.   The image forming apparatus according to claim 10, wherein the liquid discharge head is of a line type capable of discharging liquid onto a print medium.   The image forming apparatus according to claim 11, wherein a plurality of liquid discharge heads are arranged in parallel.   The image forming apparatus according to claim 12, wherein the liquid discharge heads are arranged in a direction intersecting a transport direction of the print medium by the transport unit.   14. The image forming apparatus according to claim 10, wherein the liquid is ink, a processing liquid for adjusting the printability of ink on a print medium, or an ink and a processing liquid. .

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