JP2023071230A - Ink jet recording device - Google Patents

Abstract

To provide an ink jet recording device which can reduce ununiformity of ink discharge condition with a simple mechanism.SOLUTION: An ink jet recording device 100 comprises a sub tank 2 having a storage chamber 20 for accommodating an ink, a recording head 1, and a communication part 3. The recording head 1 has: an inflow port 11 into which the ink from the sub tank 2 flows; a nozzle array 14 which is configured in such a manner that a plurality of nozzles for discharging the ink flown in from the inflow port 11 to a medium 9 to be recorded are arranged; and a discharge port 13 which discharges the ink flown in from the inflow port 11. The communication part 3 has one end 3d connected to the discharge port 13, and the other end 3u which is positioned above a liquid level S of the ink accommodated in the storage chamber 20 in a vertical position. The sub tank 2 is positioned above the recording head 1. A negative pressure is applied to each of internal spaces 20s, 3s of the storage chamber 20 and communication part 3.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inkjet recording apparatus.

For example, Japanese Patent Application Laid-Open No. 2002-200002 describes an inkjet recording apparatus that includes a recording head that ejects ink from nozzle rows in the horizontal direction. The nozzle row is configured by arranging a plurality of nozzles in the vertical direction, and ink is supplied to each nozzle from a common liquid chamber in the print head.

If no countermeasures are taken in the above configuration, the water pressure of the ink in each nozzle constituting the nozzle row changes according to the height of the nozzle, so there is a problem that the ink ejection state becomes uneven. In order to deal with this problem, the apparatus described in Japanese Patent Application Laid-Open No. 2002-200011 has a liquid feeding means that circulates the ink between the ink tank and the recording head so that the ink in the common liquid chamber moves from the upper end side to the lower end side of the common liquid chamber. By generating a flow toward the direction of the ink, the ink ejection state is made uniform.

JP 2013-103485 A

Problems similar to those described above may occur regardless of whether the direction of ink ejection is horizontal. However, in the technique described in Patent Document 1, liquid feeding means and a configuration for controlling this are essential, and there is a risk of complicating the mechanism.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet recording apparatus capable of reducing non-uniformity in the ink ejection state with a simple mechanism.

In order to achieve the above object, an inkjet recording apparatus according to the present invention comprises:
an ink tank having a storage chamber for storing ink;
an inlet into which the ink from the ink tank flows, a nozzle row configured by arranging a plurality of nozzles for ejecting the ink that has flowed in from the inlet onto a recording medium, and discharging the ink that has flowed in from the inlet a recording head having an outlet for
a communicating portion communicating with the outlet,
one end of the communication portion is connected to the discharge port, and the other end is positioned vertically above the liquid surface of the ink contained in the containing chamber;
The ink tank is positioned above the recording head,
Negative pressure is applied to the internal space of each of the storage chamber and the communication portion.

According to the present invention, it is possible to reduce non-uniformity in the ink ejection state with a simple mechanism.

1 is a diagram showing the configuration of an inkjet recording apparatus according to one embodiment of the present invention; FIG. FIG. 2 is a partial perspective view of the recording head according to the embodiment; 4 is a flowchart of cleaning processing according to the embodiment;

An embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, an inkjet recording apparatus 100 according to one embodiment of the present invention includes a recording head 1, a sub-tank 2, a communication section 3, a main tank 4, a refilling pump 5, and a pressure adjusting A pump 6 , a control unit 7 and a waste liquid tank 8 are provided.

The inkjet recording apparatus 100 is a horizontal ejection type apparatus that prints on the recording medium 9 by ejecting ink droplets horizontally from the recording head 1 onto the recording medium 9 . In FIG. 1, the horizontal direction corresponds to the horizontal direction, and the vertical direction corresponds to the vertical direction. Moreover, the up-down direction used in the following description refers to the up-down direction along the vertical direction. FIG. 1 mainly schematically shows each configuration of the inkjet recording apparatus 100 so that the positional relationship between the recording head 1, the sub-tank 2, and the three-way valve 30, which will be described later, can be easily grasped. Of course, the size, shape, etc. of each part shown in FIG. 1 are not limited to the illustrated mode.

At least one of the recording head 1 and the recording medium 9 can be moved by a moving means (not shown). and control relative movement. For example, as moving means for moving the recording head 1, a ball screw, a linear motor, a robot arm, or the like can be used. Further, for example, as a moving means for moving the recording medium 9, a table, a conveyor, a roll-to-roll conveying machine, a robot arm, etc. to which a driving means is connected can be adopted. This inkjet printing apparatus 100 can be applied to either a multi-pass system (also called a serial head system) or a single-pass system (also called a line head system). The recording medium 9 is, for example, various base materials and materials such as paper, film, sheet, steel plate, wood, glass plate, other plate materials, cans, bottles, other cylindrical objects, boxes, containers, etc. Not limited.

The recording head 1 includes a housing 10 , an inlet 11 , an ink chamber 12 , an outlet 13 and a nozzle array 14 .

The housing 10 has a rectangular parallelepiped shape, and has a first side surface 10a and a second side surface 10b as two side surfaces along its longitudinal direction. A nozzle row 14 is provided on the first side surface 10a, and an inlet 11 and an outlet 13 are provided on the second side 10b. The inlet 11 is a cylindrical portion into which ink from the sub-tank 2 flows. The ink chamber 12 is provided inside the housing 10 and accommodates ink that has flowed in from the inlet 11 . One end of the ink chamber 12 is connected to the inlet 11 and the other end is connected to the outlet 13 . The ink chamber 12 has an ink channel 12a positioned behind the nozzle row 14. As shown in FIG. The discharge port 13 is a tubular portion for discharging the ink inside the ink chamber 12 to the outside of the recording head 1 . For example, the inlet 11 and the outlet 13 are each provided to protrude from the second side surface 10b.

As shown in FIG. 2, the nozzle row 14 is configured by arranging a plurality of nozzles 14a for ejecting onto the recording medium 9. As shown in FIG. The nozzle row 14 is planarly configured along the first side surface 10a. The plurality of nozzles 14a are arranged, for example, at a constant pitch. In this embodiment, the nozzle row 14 facing the recording medium 9 extends in the vertical direction. Each of the plurality of nozzles 14 communicates with the ink flow path 12a. Ink is supplied to the plurality of nozzles 14a from the ink flow path 12a. Under the control of the control unit 7 , the recording head 1 ejects ink droplets from the nozzles 14 a to land on the recording medium 9 .

The print head 1 of this embodiment is vertically arranged such that one nozzle 14a constituting the nozzle row 14 is positioned higher than the other one nozzle 14a. In this state where the recording head 1 is arranged vertically (that is, the state in which the nozzle array 14 of the recording head 1 faces the recording medium 9), the inlet 11 is positioned at the lower end of the second side surface 10b. The discharge port 13 is positioned at the upper end of the second side surface 10b. That is, in this state, the outlet 13 is located above the inlet 11 . Due to this positional relationship, bubbles in the ink and the ink chamber 12 are easily removed when the recording head 1 is filled with ink.

The sub-tank 2 contains ink to be supplied to the recording head 1 . The sub-tank 2 is connected to a storage chamber 20 , a supply port 21 connected to the inflow port 11 by a supply pipe 25 , a connection port 22 connected to the discharge port 13 via the communicating portion 3 , and a pressure adjusting pump 6 . and a replenishment port 24 connected to the main tank 4 via the replenishment pump 5.

The storage chamber 20 is formed inside the sub-tank 2 and communicates with each of the supply port 21 , the connection port 22 , the pressure adjustment port 23 and the replenishment port 24 . When the operating state of the inkjet recording apparatus 100 is a normal operating state in which ink can be ejected from the nozzle arrays 14 onto the recording medium 9, the internal space 20s of the storage chamber 20 has a negative pressure (a state lower than the atmospheric pressure). is given. 20 s of this internal space is a space located above the liquid surface S of the said ink, when the ink is accommodated in the accommodation chamber 20. As shown in FIG. The supply port 21, the connection port 22, the pressure adjustment port 23, and the replenishment port 24 are each cylindrical. The supply port 21 is provided at the bottom of the sub-tank 2 . The connection port 22 , the pressure adjustment port 23 and the replenishment port 24 are provided on the top surface of the sub-tank 2 . The supply port 21, the connection port 22, the pressure adjustment port 23, and the replenishment port 24 can be installed at arbitrary locations as long as their respective functions are not impaired.

The communicating portion 3 is configured to allow the inside of the discharge port 13 of the recording head 1 and the inner space 20s of the sub-tank 2 to communicate with each other. The communicating portion 3 has one end 3 d connected to the discharge port 13 and the other end 3 u connected to the connection port 22 . The communicating portion 3 includes a three-way valve 30 , a first pipe 31 and a second pipe 32 .

The three-way valve 30 is positioned above the liquid surface S and includes a first valve 30a, a second valve 30b and a third valve 30c. The first valve 30 a is connected to the discharge port 13 of the recording head 1 via the first pipe 31 . The second valve 30 b is connected to the connection port 22 of the sub-tank 2 via the second pipe 32 . In this embodiment, the first pipe 31 is connected to the discharge port 13 at one end 3d of the communicating portion 3, and the second pipe 32 is connected to the connecting port 22 at the other end 3u of the communicating portion 3. be. The third valve 30 c is connected to a waste liquid pipe 8 a for flowing ink to the waste liquid tank 8 .

The three-way valve 30 is composed of, for example, an electromagnetic valve, a control valve, etc., and its state is controlled by the control of the controller 7 . The states are the first state in which the first valve 30a and the second valve 30b are opened and the third valve 30c is closed, the first state in which the first valve 30a and the third valve 30c are opened, and at least a second state in which the second valve 30b is closed. The three-way valve 30 in the first state opens the first flow path from the discharge port 13 to the storage chamber 20, and blocks the second flow path from the discharge port 13 to the waste liquid pipe 8a. The three-way valve 30 in the second state blocks the first flow path while opening the second flow path. When the inkjet recording apparatus 100 is in the normal operating state described above, the three-way valve 30 is controlled to the first state. As a result, the discharge port 13 of the recording head 1 and the internal space 20s of the sub-tank 2 are brought into communication with each other.

The main tank 4 contains ink for replenishing the sub-tank 2 .

The replenishment pump 5 is interposed between the flow paths connecting the sub-tank 2 and the main tank 4 . The replenishing pump 5 is operated under the control of the control section 7 to replenish the sub-tank 2 with the ink in the main tank 4 . Based on a signal from a liquid surface sensor (not shown) that detects the position of the ink surface S in the subtank 2, the control unit 7 controls the amount of ink in the subtank 2 to be maintained at a set level. Ink is replenished from the main tank 4 to the sub-tank 2 by driving the replenishment pump 5. - 特許庁

The pressure adjusting pump 6 is configured to adjust the pressure in the internal space 20 s of the storage chamber 20 and operates under the control of the control section 7 . When the inkjet recording apparatus 100 is in the above-described normal operating state, the controller 7 drives the pressure adjusting pump 6 to apply negative pressure to the internal space 20s.

The control unit 7 controls the overall operation of the inkjet recording apparatus 100, and is composed of a computer such as a PLC (Programmable Logic Controller). Specifically, the control unit 7 controls (i) the relative position and relative movement control of the recording head 1 and the recording medium 9 via the moving means, (ii) ejection operation control of the recording head 1, and (iii) replenishment. (iv) operation control of the pressure adjusting pump 6; (v) state control of the three-way valve 30; The control unit 7 executes a program stored in a built-in memory to perform these various controls, cleaning processing to be described later, and the like.

For example, the control unit 7 is connected to an input device (not shown) including a keyboard, mouse, touch panel, and the like. In response to an instruction from the input device, the control unit 7 puts the inkjet recording apparatus 100 into a normal operation state, and enables ink to be ejected from the recording head 1 onto the recording medium 9 . The control unit 7 controls the relative position and relative movement of the recording head 1 and the recording medium 9 based on the recording data prepared in the memory and indicating the contents of recording on the recording medium 9 . to perform recording (printing) on the recording medium 9 . Note that the control unit 7 is not limited to one computer, and may be composed of a plurality of cooperating computers.

For example, the control unit 7 controls as follows when controlling the inside of the storage chamber 20 of the sub-tank 2 to a negative pressure. The inkjet recording apparatus 100 further includes a pressure sensor 6a for detecting the pressure inside the storage chamber 20, as shown in FIG. The control unit 7 executes feedback control using the difference between the target negative pressure value and the detected pressure as the deviation so that the pressure detected by the pressure sensor 6a (hereinafter referred to as the detected pressure) becomes a predetermined target negative pressure value. do. The target negative pressure value is determined in advance through experiments so that the water pressure of ink in the vicinity of the inlet 11 (including the inside of the inlet 11) is a desired value (for example, about 0.5 kPa). This target negative pressure value is set to a value that allows the ink filled in each nozzle 14a of the recording head 1 to maintain an appropriate meniscus shape for stable ejection from the openings of the nozzles 14a. Also, the target negative pressure value is set to a value that can prevent ink from dripping from each nozzle 14 a of the recording head 1 .

As described above, the control unit 7 controls the inside of the storage chamber 20 to a constant negative pressure in the normal operation state. Controlling the negative pressure to a constant value means controlling the negative pressure so as to approach the target negative pressure value, and is not limited to the fact that the measured value of the negative pressure is always constant. As the feedback control executed by the control unit 7, well-known methods such as P control, PI control, PID control, etc. can be used. Further, although FIG. 1 shows an example in which the pressure sensor 6a is provided near the pressure adjustment port 23, the installation position of the pressure sensor 6a can be arbitrarily changed as long as the pressure inside the storage chamber 20 can be detected.

Here, in the horizontal ejection method in which ink is ejected horizontally from the recording head 1, if no countermeasures are taken, the water pressure of the ink in each nozzle 14a constituting the nozzle row 14 will increase as described above. As a result, there is a problem that the ink ejection state becomes non-uniform. In other words, the water pressure difference between the lower nozzles 14a and the upper nozzles 14a in the nozzle row 14 causes a problem that the ink is more difficult to reach the upper nozzles 14a than the lower nozzles 14a. In order to deal with this problem, the control unit 7 of this embodiment controls the interior of the storage chamber 20 of the sub-tank 2 to a negative pressure in the normal operation state, and controls the three-way valve 30 to the first state to open the communication portion. 3, the discharge port 13 of the recording head 1 and the storage chamber 20 are communicated with each other.

By controlling the interior of the storage chamber 20 to a negative pressure and controlling the three-way valve 30 to the first state, the internal space 3 s of the communicating portion 3 has the same negative pressure as the internal space 20 s of the storage chamber 20 , and the discharge port 13 The liquid surface S 1 of the ink discharged to the communicating portion 3 (specifically, the first pipe 31 ) is at the same height as the liquid surface S of the ink in the storage chamber 20 . Therefore, not only the ink in the sub-tank 2 is supplied to the recording head 1 through the inlet 11 , but also the ink in the first tube 31 is supplied through the outlet 13 . In other words, the discharge port 13 of this embodiment not only serves to discharge ink from the recording head 1 but also serves to supply the ink in the first tube 31 to the recording head 1 . As a result, the conditions for supplying ink to the upper nozzles 14a in the nozzle row 14 are the same as those for the lower nozzles 14a. Further, the negative pressure space extending from the internal space 3s of the communicating portion 3 to the internal space 20s of the storage chamber 20 functions as a so-called air damper, and dampens fluctuations in the water pressure of the ink filled on the discharge port 13 side of the recording head 1. can be absorbed.

Further, in the inkjet recording apparatus 100 configured such that the sub-tank 2 is located above the recording head 1 and the connection port 22 is located above the liquid surface S of the ink, the negative pressure space is generated as described above. By doing so, the height of the ink surface S in the storage chamber 20 and the ink surface S1 in the communicating portion 3 can be kept the same. In other words, with this configuration, the ink discharged from the discharge port 13 to the communicating portion 3 does not reach the storage chamber 20 . Here, if the ink reaches the accommodation chamber 20 through the communicating portion 3, the liquid surface S of the ink in the accommodating chamber 20 and the liquid surface S1 of the ink in the communicating portion 3 are kept at the same height. As a result, there is a risk that the water pressure of the ink in the recording head 1 will fluctuate.

According to the inkjet recording apparatus 100 of this embodiment, the negative pressure space generated as described above can make the water pressure condition of the ink for each nozzle 14a of the nozzle row 14 substantially uniform. Non-uniformity in the ejection state can be reduced.

The control unit 7 not only controls the inside of the storage chamber 20 to a negative pressure and controls the three-way valve 30 to the first state in the normal operation state, but also executes the cleaning process shown in FIG. 3 as necessary. The trigger for starting the execution of the cleaning process may be determined in advance, and can be set arbitrarily. For example, the control unit 7 may start the cleaning process in response to an instruction from the input device, or may automatically start the cleaning process each time a predetermined period elapses. The cleaning process will be described below.

(cleaning process)
When the cleaning process is started, the controller 7 switches the three-way valve 30, which was in the first state in the normal operation state, to the second state (step S1). As a result, the first flow path from the discharge port 13 to the storage chamber 20 is blocked, while the second flow path from the discharge port 13 to the waste liquid pipe 8a is opened. Transition. A check valve (not shown) is provided in the path of the waste liquid pipe 8a. This check valve prevents the ink remaining in the waste liquid pipe 8a during the previous cleaning process from flowing back to the communicating portion 3 between step S1 and step S2 which will be described next. can be done.

Subsequently, the control unit 7 controls the operation of the pressure adjusting pump 6 to pressurize the storage chamber 20 of the sub-tank 2 (step S2), and after a predetermined period of time has passed from the start of pressurization, the pressure in the storage chamber 20 is increased. Pressurization is stopped (step S3). As a result, the ink in the sub-tank 2 and the recording head 1 is discharged from the discharge port 13 to the first pipe 31, and discharged from the first pipe 31 to the waste liquid tank 8 through the waste liquid pipe 8a. In other words, the processing from steps S1 to S3 corresponds to the waste liquid processing of discharging the ink from the waste liquid pipe 8a.

Subsequently, the controller 7 switches the three-way valve 30 from the second state to the first state (step S4). As a result, the first flow path from the discharge port 13 to the storage chamber 20 is opened, while the second flow path from the discharge port 13 to the waste liquid pipe 8a is blocked. becomes.

Subsequently, the control unit 7 opens the storage chamber 20 of the sub-tank 2 to the atmosphere (step S5). For example, the control unit 7 opens the atmosphere to the atmosphere by controlling an atmosphere relief valve provided in the pressure regulating pump 6 to an open state. This step S5 is a step for preparing to shift from the state in which positive pressure is applied to the internal space 20s by pressurization to step S6 for applying negative pressure to the internal space 20s as described below.

Subsequently, the controller 7 controls the storage chamber 20 to have a negative pressure (step S6). For example, the control unit 7 controls the operation of the pressure regulating pump 6, closes the atmospheric release valve, and then monitors the pressure detected by the pressure sensor 6a to achieve a predetermined target negative pressure value. It controls the pressure inside the containment chamber 20 .

Subsequently, the control unit 7 controls the operation of the replenishing pump 5 to replenish ink from the main tank 4 to the sub-tank 2, thereby supplying ink from the sub-tank 2 to the recording head 1 (step S7). The controller 7 monitors the signal from the liquid level sensor and drives the replenishment pump 5 so that the amount of ink in the sub-tank 2 reaches the set level. In other words, the processing from steps S4 to S7 corresponds to the supply processing for supplying ink to the sub-tank 2 (an example of an ink tank).

Subsequently, the control unit 7 performs wiping of the recording head 1 (step S8), and ends the cleaning process. Specifically, the control unit 7 that performs wiping operates a wiper (not shown) made of rubber, non-woven fabric, or the like to wipe off the ink adhering to the nozzle row 14 . The description of the cleaning process is above. After executing the cleaning process, the control unit 7 returns to the normal operating state.

In addition, this invention is not limited by the above embodiment and drawing. Modifications (including deletion of components) can be made as appropriate without changing the gist of the present invention.

Although an example in which the communication portion 3 connects the discharge port 13 and the storage chamber 20 has been described above, the communication portion 3 does not have to be connected to the storage chamber 20 . For example, one end 3d of the communicating portion 3 is connected to the discharge port 13, and the other end 3u is located above the liquid surface S of the ink contained in the containing chamber 20 in the vertical direction. By applying the same negative pressure as the negative pressure applied to the internal space 20s of the storage chamber 20 to the internal space 3s of the communicating portion 3 provided in this way, the ink ejection state can be controlled by the same principle as described above. Non-uniformity can be reduced. Further, regardless of whether or not the communicating portion 3 is connected to the storage chamber 20, the liquid surface S1 of the ink discharged to the communicating portion 3 is at a height corresponding to the liquid surface S of the ink stored in the storage chamber 20. as long as it is maintained The corresponding height is not necessarily limited to the height of the liquid surface S1 that is the same as the height of the liquid surface S, and includes the case where the height of the liquid surface S1 with respect to the liquid surface S fluctuates or displaces. The relative heights of the liquid surface S1 and the liquid surface S are such that the internal space 3s of the communicating portion 3 and the internal space 20s of the storage chamber 20, both of which are applied with negative pressure, function as air dampers as described above. Optional as far as possible.

To facilitate the understanding of the description, the example in which the nozzle row 14 of the recording head 1 is composed of one row has been described above, but it is a matter of course that the nozzle row 14 may be composed of a plurality of rows. Any well-known configuration can be applied as the recording head 1 . For example, a configuration may be adopted in which a plurality of nozzle rows 14 are provided in the recording head 1 that ejects ink of one color, and the ink of the one color is ejected from the plurality of nozzle rows 14 . Further, for example, four nozzle arrays 14 of the recording head 1 may be provided corresponding to each color ink of C (Cyan), M (Magenta), Y (Yellow), and K (Key plate). When the nozzle rows 14 corresponding to each color of ink are provided in this way, the number of sub-tanks 2 and main tanks 4 corresponding to each color are provided in the inkjet recording apparatus 100, and the inside of each sub-tank 2 is controlled to a negative pressure. The space controlled to be the same as that of FIG.

Although an example in which the recording head 1 ejects ink in the horizontal direction has been described above, the direction in which ink is ejected from the recording head 1 can be arbitrarily changed and is not limited. For example, the recording head 1 may be configured to eject ink in a direction oblique to the vertical direction. Even in this configuration, the problem of non-uniform ink ejection occurs, so the above technique is useful. Note that even if the recording head 1 is configured to eject ink in a direction oblique to the vertical direction, one nozzle 14a constituting the nozzle row 14 is arranged to be positioned higher than the other one nozzle 14a. Moreover, it is preferable that the outlet 13 is located above the inlet 11 . This is because, as described above, when the recording head 1 is filled with ink, air bubbles in the ink and the ink chamber 12 are easily removed. Furthermore, the recording head 1 may be configured to eject ink upward or downward along the vertical direction. In this configuration, the nozzles 14a forming the nozzle row 14 do not have height differences, but the internal structure of the recording head 1 may cause fluctuations in the water pressure of the ink in each nozzle 14a. In such cases, the above technique is useful.

The pressure regulating pump 6 only needs to have a negative pressure and positive pressure regulating function, and may be composed of, for example, a combination of a negative pressure pump and a positive pressure pump.

By additionally providing a damper at a position corresponding to at least one of the inlet 11 and the outlet 13 of the print head 1, the non-uniformity of the ink ejection state may be reduced more satisfactorily. As the damper, a well-known configuration such as an air chamber, tube damper, membrane damper, etc. can be appropriately adopted.

An example in which the state of the three-way valve 30 is controlled by the control unit 7 has been described above, but the state of the three-way valve 30 may be controlled manually. Moreover, although the example in which the cleaning process can be performed using the three-way valve 30 has been described above, the three-way valve 30 and the cleaning process may be omitted. In this case, for example, the communication section 3 can be configured by one pipe, and the inkjet recording apparatus 100 can be configured more simply.

The order of some of the processes constituting the cleaning process described above may be partially changed, or some of the processes may be omitted. For example, the order of steps S1 and S2 may be changed, or the process of step S5 may be omitted. Also, the process of step S8 may be omitted.

The inkjet recording apparatus 100 described above has the following effects.

(1) The inkjet recording apparatus 100 includes a sub-tank 2 (an example of an ink tank) having a storage chamber 20 for storing ink, an inlet 11 into which ink flows from the sub-tank 2, and the ink flowing in from the inlet 11 to be recorded. A recording head 1 having a nozzle row 14 configured by arranging a plurality of nozzles 14a for ejecting onto a medium 9, an outlet 13 for discharging ink flowing in from the inlet 11, and a communicating portion communicating with the outlet 13. 3 and . One end 3 d of the communication portion 3 is connected to the discharge port 13 , and the other end 3 u of the communication portion 3 is positioned above the liquid surface S of the ink stored in the storage chamber 20 in the vertical direction. The sub-tank 2 is located above the print head 1, and negative pressure is applied to the internal spaces 20s and 3s of the storage chamber 20 and the communication portion 3, respectively.
According to the above configuration (1), as described above, it is possible to make the water pressure condition of the ink for each nozzle 14a of the nozzle row 14 substantially uniform, and as a result, the non-uniformity of the ink ejection state is reduced. be able to. In addition, the mechanism is simple because the nonuniformity of the ink ejection state can be reduced only by applying the negative pressure to the internal spaces 20s and 3s of the storage chamber 20 and the communication portion 3, respectively.

(2) In addition, in a state in which negative pressure is applied to the internal spaces 20s and 3s of the storage chamber 20 and the communication portion 3, the liquid surface S1 of the ink discharged from the discharge port 13 to the communication portion 3 is The height corresponding to the liquid surface S of the ink contained in 20 is maintained.
According to the configuration (2) above, it is possible to prevent the water pressure of the ink in the recording head 1 from fluctuating as described above.

(3) The recording head 1 is arranged such that one nozzle 14a constituting the nozzle row 14 is positioned higher than the other one nozzle 14a, and the outlet 13 is positioned higher than the inlet 11. may be located in
According to the configuration (3) above, as described above, when the recording head 1 is filled with ink, air bubbles in the ink and the ink chamber 12 are easily removed.

(4) Further, the communicating portion 3 may be connected to the storage chamber 20 at the other end 3u so that the inside of the discharge port 13 and the internal space 20s of the storage chamber 20 are communicated with each other.
According to the configuration (4) above, it is only necessary to connect the discharge port 13 to the storage chamber 20 to which the negative pressure is applied through the communicating portion 3, so the mechanism is simpler.

(5) Further, the communicating section 3 may include a three-way valve 30 positioned above the liquid surface S of the ink contained in the containing chamber 20 . One valve (third valve 30c) of the three-way valve 30 is connected to the waste liquid pipe 8a branched from the communicating portion 3, and opens the first flow path from the discharge port 13 to the storage chamber 20, while opening the discharge port 13. to the waste liquid pipe 8a, and a second state in which the second flow path is opened and the first flow path is blocked. When the negative pressure is applied to 20s, it is controlled to the first state.
According to the configuration (5) above, it is possible to create a route for flowing the ink of the recording head 1 to the waste liquid pipe 8a when the ink is discharged. In addition, since the three-way valve 30 is positioned above the liquid surface S of the ink, excess ink is prevented from entering above the three-way valve 30 (specifically, the second pipe 32) in the communicating portion 3. can.

(6) The inkjet recording apparatus 100 controls the state of the three-way valve 30, the pressure of the internal space 20s of the storage chamber 20, and the supply of ink to the sub-tank 2. After the ink in the recording head 1 is discharged, the sub-tank 2 is A control unit 7 (an example of a control unit) capable of executing a post-drainage supply process for supplying ink to the ink may be further provided. In the post-drainage supply process, the three-way valve 30 is switched from the first state to the second state, and the internal space 20s of the storage chamber 20 is pressurized to drain the ink from the waste liquid pipe 8a. from the second state to the first state, apply a negative pressure to the internal space 20s of the storage chamber 20, and supply ink to the sub-tank 2.
According to the configuration (6) above, the ink can be discharged and supplied automatically under the control of the controller 7 . It should be noted that the post-drainage supply process is included in the aforementioned cleaning process.

In the above description, descriptions of well-known technical matters are omitted as appropriate in order to facilitate understanding of the present invention.

The present invention is capable of various embodiments and modifications without departing from the broader spirit and scope of the invention. Moreover, the embodiment described above is for explaining the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims rather than the embodiments. Various modifications made within the scope of the claims and within the meaning of equivalent inventions are considered to be within the scope of the present invention.

DESCRIPTION OF SYMBOLS 100... Inkjet recording apparatus 1... Recording head 10... Housing, 10a... 1st side surface, 10b... 2nd side surface, 11... Inlet, 12... Ink chamber, 12a... Ink channel, 13... Outlet, 14... Nozzle row, 14a Nozzle 2 Sub-tank (an example of an ink tank)
DESCRIPTION OF SYMBOLS 20... Storage chamber, 20s... Internal space 21... Supply port, 22... Connection port, 23... Pressure adjustment port, 24... Replenishment port, 25... Supply pipe 3... Communication part, 3s... Internal space, 3d... One end, 3u... Other end 30... Three-way valve, 30a to 30c... First to third valves, 31... First pipe, 32... Second pipe 4... Main tank 5... Replenishment pump 6... Pressure adjustment pump, 6a... Pressure sensor 7 Control section 8 Waste liquid tank 8a Waste liquid pipe 9 Recording medium S Level of ink contained in storage chamber S1 Level of ink discharged to communication section

(1) In order to achieve the above object, the inkjet recording apparatus according to the first aspect of the present invention comprises:
An ink having a storage chamber for storing ink, a connection port positioned vertically above the liquid surface of the ink stored in the storage chamber, and a pressure adjustment port positioned above the liquid surface of the ink. a tank;
an inlet into which the ink from the ink tank flows, a nozzle row configured by arranging a plurality of nozzles for ejecting the ink that has flowed in from the inlet onto a recording medium, and discharging the ink that has flowed in from the inlet a recording head positioned below the ink tank in the vertical direction ;
a communicating portion having one end connected to the discharge port and the other end connected to the connection port ;
a negative pressure applying means for applying a negative pressure from the pressure adjustment port to the internal space of the storage chamber located above the liquid surface of the ink stored in the storage chamber;
In a state in which the nozzle array of the recording head is capable of ejecting ink, the communicating portion communicates the interior of the discharge port with the interior space of the storage chamber,
The liquid surface of the ink discharged from the discharge port to the communication portion and in the communication portion is lowered by the negative pressure applied to the internal space of the storage chamber by the negative pressure applying means. It is maintained downward and at a height corresponding to the liquid level of the ink stored in the storage chamber.
(2) In order to achieve the above object, the inkjet recording apparatus according to the second aspect of the present invention comprises:
an ink tank having a storage chamber for storing ink;
an inlet into which the ink from the ink tank flows, a nozzle row configured by arranging a plurality of nozzles for ejecting the ink that has flowed in from the inlet onto a recording medium, and discharging the ink that has flowed in from the inlet a recording head having an outlet for
a communicating portion communicating with the outlet,
one end of the communication portion is connected to the discharge port, and the other end is positioned vertically above the liquid surface of the ink contained in the containing chamber;
The ink tank is positioned above the recording head,
Negative pressure is applied to the internal space of each of the storage chamber and the communication section,
The recording head is arranged such that one nozzle constituting the nozzle row is positioned above the other nozzle, and the discharge port is positioned above the inlet.
(3) In order to achieve the above object, the inkjet recording apparatus according to the third aspect of the present invention comprises:
an ink tank having a storage chamber for storing ink;
an inlet into which the ink from the ink tank flows, a nozzle row configured by arranging a plurality of nozzles for ejecting the ink that has flowed in from the inlet onto a recording medium, and discharging the ink that has flowed in from the inlet a recording head having an outlet for
a communicating portion including a three-way valve positioned vertically above the liquid level of the ink contained in the containing chamber and communicating with the discharge port;
A post-drainage supply for controlling the state of the three-way valve, the pressure in the internal space of the storage chamber, and the supply of ink to the ink tank, and supplying the ink to the ink tank after the ink in the recording head has been discharged. a control means capable of executing a process;
The communication portion has one end connected to the discharge port and the other end connected to the storage chamber, is positioned above the liquid surface of the ink contained in the storage chamber, and is located above the liquid surface of the ink stored in the storage chamber. Communicate with the internal space of the storage chamber,
The ink tank is positioned above the recording head,
Negative pressure is applied to the internal space of each of the storage chamber and the communication section,
The three-way valve is
one valve is connected to a waste liquid pipe branching from the communicating portion;
a first state in which a first flow path from the discharge port to the storage chamber is opened while a second flow path from the discharge port to the waste liquid pipe is blocked; controlled to a second state of blocking the first flow path,
is controlled to the first state in a state in which a negative pressure is applied to the internal space of the storage chamber;
The supply processing after the waste liquid includes:
a waste liquid treatment of switching the three-way valve from the first state to the second state and pressurizing the internal space of the storage chamber to discharge the ink from the waste liquid pipe;
a supply process of switching the three-way valve from the second state to the first state, applying negative pressure to the internal space of the storage chamber, and supplying ink to the ink tank.

Claims (6)

an ink tank having a storage chamber for storing ink;
an inlet into which the ink from the ink tank flows, a nozzle row configured by arranging a plurality of nozzles for ejecting the ink that has flowed in from the inlet onto a recording medium, and discharging the ink that has flowed in from the inlet a recording head having an outlet for
a communicating portion communicating with the outlet,
one end of the communication portion is connected to the discharge port, and the other end is positioned vertically above the liquid surface of the ink contained in the containing chamber;
The ink tank is positioned above the recording head,
Negative pressure is applied to the internal space of each of the storage chamber and the communication section,
Inkjet recording device. In a state in which negative pressure is applied to the internal spaces of the storage chamber and the communication portion, the liquid level of the ink discharged from the discharge port to the communication portion is equal to the liquid level of the ink stored in the storage chamber. is maintained at a height corresponding to
The inkjet recording apparatus according to claim 1. The recording head is arranged such that one nozzle constituting the nozzle row is positioned above the other nozzle, and the discharge port is positioned above the inlet.
The inkjet recording apparatus according to claim 1 or 2. The communication part has the other end connected to the storage chamber, and communicates the inside of the discharge port and the internal space of the storage chamber.
The inkjet recording apparatus according to any one of claims 1 to 3. the communicating portion includes a three-way valve positioned above the liquid surface of the ink contained in the containing chamber;
The three-way valve is
one valve is connected to a waste liquid pipe branching from the communicating portion;
a first state in which a first flow path from the discharge port to the storage chamber is opened while a second flow path from the discharge port to the waste liquid pipe is blocked; controlled to a second state of blocking the first flow path,
Controlled to the first state when negative pressure is applied to the internal space of the storage chamber,
The inkjet recording apparatus according to claim 4. A post-drainage supply for controlling the state of the three-way valve, the pressure in the internal space of the storage chamber, and the supply of ink to the ink tank, and supplying the ink to the ink tank after the ink in the recording head has been discharged. further comprising control means capable of executing a process;
The supply processing after the waste liquid includes:
a waste liquid treatment of switching the three-way valve from the first state to the second state and pressurizing the internal space of the storage chamber to discharge the ink from the waste liquid pipe;
a supply process of switching the three-way valve from the second state to the first state, applying negative pressure to the internal space of the storage chamber, and supplying ink to the ink tank;
The inkjet recording apparatus according to claim 5.

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