WO2016051826A1

WO2016051826A1 - Inkjet printer

Info

Publication number: WO2016051826A1
Application number: PCT/JP2015/059388
Authority: WO
Inventors: 孝紀吉澤
Original assignee: 株式会社沖データ・インフォテック
Priority date: 2014-09-30
Filing date: 2015-03-26
Publication date: 2016-04-07

Abstract

Provided is an inkjet printer that makes it possible to keep a nozzle surface clean and in which the discharge of ink having a large amount of air dissolved therein from a recording head is prevented by eliminating a part of an ink flow path in which the proportion of dissolved air is high. The inkjet printer is provided with a wiper that wipes the nozzle surface, a branching path between a sub-tank and a recording head, and a flow path that is formed so as to return ink from the branching path to the sub-tank. Increases in the proportion of dissolved air within the ink flow path are minimized by returning ink to the sub-tank when the ink remains within the ink flow path for a certain length of time or longer and reducing the proportion of dissolved air within the ink.

Description

inkjet printer

The present invention relates to an ink jet printer that records an image by ejecting ink.

2. Related Art Inkjet printers that record images by ejecting ink from an inkjet recording head onto a recording medium such as paper or resin film are known. Ink jet printers are known in which a sub tank is provided in an ink flow path from an ink cartridge for storing ink to a recording head, and the head of the sub tank is controlled to apply a certain range of negative pressure to the recording head. Yes. A tube pump is widely used to supply ink to the sub tank.

Also, ink jet printers are required to improve performance such as high image quality, durability, and reliability. If a large amount of air is dissolved in the ink ejected from the recording head, bubbles may be generated due to high-frequency vibration during ejection, which may cause ejection failure such as non-ejection. Also, there may be a discharge failure in which ink scatters around, and the scattered ink may adhere to other nozzles, destroying the meniscus, and causing a discharge failure.

Therefore, in a general ink jet printer, the ink adhering to the nozzle surface of the recording head is periodically wiped with an elastic wipe blade to remove the adhering matter. In addition, there is one that suppresses the generation of bubbles by using degassed ink. In addition, in order to remove thickened ink and foreign matter in the nozzle, a mechanism is known in which the nozzle surface is sealed with a cap and the inside of the cap is made negative pressure to suck ink and foreign matter from the nozzle. For example, Japanese Patent Application Laid-Open No. 2007-29679 discloses a mechanism for sucking ink from a recording head using a suction cap.

JP 2007-296679 A

In the conventional technology, there is a possibility that sufficient ink cannot be sucked when there is a gap between the nozzle surface and the cap due to ink adhering to the nozzle surface and fixing on the nozzle surface. In the prior art, a separate cleaning head is provided so that the suction cap can be cleaned. This can prevent ink adhering to the cap, but the edge of the cap is not wiped off, so that the ink may remain attached. For this reason, there is a problem that the suction of the ink by the cap is inferior in accuracy. Therefore, instead of removing ink with a cap, a method of extruding ink from a recording head and removing problematic ink has been considered. In this case, although the ink is pushed out by the pump, a tube pump having a relatively simple configuration is used. However, since the tube pump handles the tube with a roller and moves the ink, it is necessary to use a flexible tube. Therefore, a tube having a low air blocking property is used. If the ink stays in the tube pump, air dissolves in the ink, and if the ink in which a large amount of air reaches the recording head causes ejection failure and becomes a problem.

In order to solve such a problem, the present invention eliminates a portion where the ratio of dissolved air is high in the ink flow path, prevents a large amount of dissolved air from being ejected from the recording head, and further reduces the nozzle surface. An ink jet printer that can be kept clean is provided.

An ink jet printer according to the present invention includes a recording head including a plurality of nozzles that eject ink onto a recording medium, a wiper that wipes a nozzle surface on which the nozzles of the recording head are disposed, and ink that supplies ink to the recording head. A subtank disposed in an ink flow path between the cartridge and the recording head, wipes off the deposits on the nozzle surface by the wiper, supplies ink from the subtank to the recording head, and the recording medium. In an ink jet printer that records an image by discharging the ink from the recording head to a desired position, the ink is moved between the ink cartridge and the sub tank and the ink flow path is opened or closed. A first pump is disposed between the sub tank and the recording head; A first valve that opens or closes the ink flow path is disposed on the sub tank side of the ink flow path, and a second valve that opens or closes the ink flow path is disposed on the recording head side; The ink flow path between the sub-tank and the first pump and the ink flow path between the first valve and the second valve are connected to move the ink and open the ink flow path. A second pump to be closed is disposed, and by driving the first pump, ink is supplied from the ink cartridge to the sub tank, the first valve is opened, and the second valve is closed. The second pump is driven in reverse to move the ink in the second pump to the sub tank.

According to the present invention, an ink jet printer capable of eliminating a portion having a high ratio of dissolved air in the ink flow path, preventing ink with a large amount of dissolved air from being ejected from the recording head, and further keeping the nozzle surface clean. Can provide.

FIG. 1 is a schematic diagram illustrating an ink flow path. FIG. 2 is a diagram illustrating the first pump. FIG. 3 is a diagram illustrating the second pump. FIG. 4 is a block diagram of the ink jet printer. FIG. 5 is a flowchart of the operation of returning the ink in the second pump to the sub tank. FIG. 6 is a flowchart of the operation of filling the recording head with ink. FIG. 7 is a flowchart of the ink supply operation during recording. FIG. 8 is a schematic diagram of an ink jet printer.

Embodiments of the present invention will be described with reference to the drawings. First, the ink jet printer will be described with reference to FIG. FIG. 8 is a schematic diagram of an ink jet printer. As shown in FIG. 8, the inkjet printer 1 according to the present embodiment arranges the recording medium 7 horizontally, conveys it from the back of the sheet of FIG. 8, ejects ink from the recording head 3, and records the recording medium 7. Images, characters, etc. corresponding to the recording data are recorded on the surface of the. The recording medium 7 is paper, a resin film, or the like. This paper conveyance direction is called the sub-scanning direction.

The ink jet printer 1 includes a transport unit that transports the recording medium 7. In addition, a plurality of recording heads 3 are mounted for color recording, and the direction intersecting the conveyance direction of the recording medium 7, here, the horizontal direction in FIG. 8, that is, the direction orthogonal to the conveyance direction of the recording medium 7 A wiper unit 10 for wiping the recording head 3, a capping unit 5 for capping the recording head 3, and a spit unit 8 for receiving ink discharged from the recording head 3. The moving direction of the reciprocating scanning is called a main scanning direction. The ink jet printer 1 includes control means for controlling the entire apparatus including reception of recording data and control of recording operation.

The conveying means includes a plurality of conveying roller pairs 16 driven by a motor on a substantially flat platen 6 extended in the depth direction of the sheet of FIG. The transport roller pair 16 includes a grid roller whose rotation axis is parallel to the platen 6 and a pinch roller that is energized by the grid roller. The recording medium 7 is conveyed while being sandwiched between the grid roller and the pinch roller. The grid roller is rotated by driving the motor 11, and the recording medium 7 is conveyed from the depth direction to the near side.

The carriage 2 is provided so as to be movable along a carriage rail 13 that extends in a direction perpendicular to the conveyance direction of the recording medium 7 above the conveyance means, the wipe unit 10, the spit unit 8, and the capping unit 5. Yes. In addition, a motor 15 that reciprocates the carriage 2 on the carriage rail 13 so as to be capable of position control and speed control is provided. The motor 15 is connected to the endless belt 12 to which the carriage 2 is fixed, and drives the endless belt 12. A linear scale 14 is provided in parallel with the carriage rail 13. A sensor for detecting the scale of the linear scale 14, that is, a carriage position detection sensor 17 is provided in the carriage 2. The position of the carriage 2 can be detected, and the positions of the plurality of recording heads 3 fixed to the carriage 2 can be calculated by the control unit accordingly.

In the present embodiment, four recording heads 3 are provided corresponding to four color inks of black, yellow, magenta, and cyan for performing color recording. An ink cartridge 4 is provided for each color and is supplied to each recording head 3 through a tube 18.

Although details of the recording head 3 are not shown, a plurality of nozzles for ejecting ink are arranged in a line, and the supplied ink is ejected by an ejection mechanism such as a piezoelectric element. The ink jet printer 1 causes the spit unit 8 to eject ink from the nozzles outside the image forming range, and ejects thickened ink or ejects to adjust the meniscus. Further, the spit unit 8 can receive ink from a plurality of recording heads 3 at the same time. For example, when the recording head 3 is filled with ink, the spit unit 8 receives excess ink that is discharged.

Position control and speed control of the motor 15 that drives the carriage 2 are performed according to control signals from the control means. During the recording operation, the motor 15 is controlled so that the recording head 3 reciprocates over the recording medium 7 at a predetermined speed. Further, the motor 15 moves the recording head 3 to a predetermined wiping position of the wipe unit 10 during the cleaning operation. Further, when capping, it is moved onto the capping unit 5, and when spitting, it is moved onto the spit unit 8.

The wipe unit 10 wipes and cleans the nozzle surface of the recording head 3 by moving the wipe blade relative to the nozzle surface of the recording head 3 with the recording head 3 moved above the wipe unit 10. To do. The capping unit 5 covers the nozzle surface on which the nozzles for ejecting ink of the recording head 3 are arranged to prevent drying. The schematic configuration of the capping unit 5 includes a cap, elevating means for raising and lowering the cap, a spit unit 8, and a waste ink bottle 9 for storing waste ink. A cap is provided for each recording head 3. The lifting / lowering means performs a vertical movement for selectively switching the position of the cap in the vertical direction, and includes, for example, appropriate mechanical / electromagnetic / fluid lifting / lowering means.

FIG. 1 is a schematic diagram illustrating an ink flow path. The ink flow path for one color from the ink cartridge 4 to the recording head 3, that is, the ink flow path of one recording head 3 will be described. Other ink colors also have the same ink flow path configuration. The ink cartridge 4 and the recording head 3 are connected by a tube 18, and a sub tank 20, a valve, and a pump are arranged in the middle of the flow path of the tube 18 in order to control the flow of ink.

A sub tank 20 is disposed in the ink flow path. By managing the amount of ink stored in the sub tank 20, a suitable negative pressure can be applied to the recording head 3 based on suitable water head value management. It is possible to make a meniscus suitable for the nozzle. In addition, two pumps of the first pump 21 and the second pump 22 are provided, so that the ink can be moved in the ink flow path. In addition, the first valve 23 and the second valve are provided, and the ink flow path can be controlled by controlling the opening and closing of each valve. Further, a pressure detection sensor 25 is provided, and the pressure between the second valve 24 and the recording head 3 can be measured.

The first pump 21 moves the ink in the forward direction indicated by the arrow, moves it in the reverse direction, and when the pump is stopped, the ink flow path is either closed or opened. Can be. The second pump 22 can close the ink flow path when the ink is moved in the forward direction indicated by the arrow, moved in the reverse direction, and the pump is stopped. The first valve 23 and the second valve 24 can be in either a closed state or an open state. For example, an electromagnetic valve that can be controlled by a control means. Since the 1st pump 21 and the 2nd pump 22 play a different role, they are pumps of a different mechanism. Control is easy to understand by using a pump according to the role.

If the second pump 22 is in an open state, the head value cannot be managed by the sub-tank 20 and a discharge failure may occur. Therefore, a pump that always closes the flow path is used as the second pump 22. In some cases, ink is supplied from the ink cartridge 4 to the recording head 3 without passing through the sub tank 20 and is discharged. This is because the first pump 21 is opened, the first valve 23 is closed, the second valve 24 is opened, and the second pump 22 is driven in the forward direction, and the ink in the second pump 22 is transferred to the sub tank 20. It is a case where it discharges without putting. When the ink has not been used for a long time, it is necessary to discharge the ink in the second pump 22. At this time, it is preferable not to put the ink in the second pump 22 into the sub tank 20. This is because there is a possibility of staying in the sub tank 20. In this way, since different pumps are arranged in the flow path, they can be used depending on the situation and can be controlled easily.

FIG. 2 is a diagram illustrating the first pump. An internal configuration of the first pump 21 is shown. The case 30 is provided with a U-shaped outer wall 31, and a tube 32 is disposed along the outer wall 31. A first connector 36 and a second connector 37 are connected to both ends of the tube 32. The first connector 36 is connected to the ink cartridge 4. The second connector 37 is connected to the sub tank 20 and the second pump 22. The rotor 33 has one arm and a roller 34 connected to the tip. The roller 34 is rotated around the shaft 35, the tube 32 is squeezed, and the ink in the tube 32 is moved. When the roller 34 is rotated from the first connector 36 toward the second connector 37 (this is called forward rotation), ink flows in the forward direction. When the roller 34 is rotated from the second connector 37 toward the first connector 36 (this is referred to as reverse rotation), ink flows in the reverse direction. Further, the first pump 21 includes a first position detection sensor 38 and a second position detection sensor 39 as roller position detection means, and can detect the position of the roller 34. The position of the roller 34 is known from the detection results of these sensors. That is, the position detected by the first position detection sensor 38 is a position for closing the flow path, and the position detected by the second position detection sensor 39 is a position for opening the flow path. These are used for control by the control means described later. For example, when the roller 34 is at the position of the second position detection sensor 39, the flow path is open, and the ink moves according to the pressure on the first connector 36 side and the second connector 37 side. The control means performs control so that the desired control is possible even in such a state.

FIG. 3 is a diagram illustrating the second pump. An internal configuration of the second pump 22 is shown. The case 40 is provided with a U-shaped outer wall 41, and a tube 42 is disposed along the outer wall 41. A first connector 46 and a second connector 47 are connected to both ends of the tube 42. The first connector 46 is connected to the ink cartridge 4 and the sub tank 20. The second connector 47 is connected to the first valve 23 and the second valve 24. The rotor 43 is provided with two arms, and a roller 44 and a roller 45 connected to the tip of the rotor 43 are rotated around a shaft 48 to squeeze the tube 42 and move the ink in the tube 42. When the rollers 44 and 45 are rotated from the first connector 46 toward the second connector 47 (this is referred to as normal rotation), ink flows in the forward direction. When the rollers 44 and 45 are rotated from the second connector 47 toward the first connector 46 (this is referred to as reverse rotation), ink flows in the opposite direction. The arms are arranged on a straight line around the axis 48. As a result, regardless of the angle of the rotor 43, either the roller 44 or the roller 45 always closes the tube 42. For example, the tube 42 can be kept closed by stopping the rotor 43 at the position of the roller 49 indicated by the dotted line. The other roller is not in contact with the tube 42.

Since the tube 42 is squeezed by the rollers 44 and 45, flexibility and durability are required. Therefore, it becomes a product made of soft resin and does not have much barrier property against air. Therefore, air dissolves into the ink inside through the tube 42. The ink in which a large amount of air is dissolved becomes bubbles when ejected in the recording head 3 and adversely affects the ejection. In the worst case, the bubbles cannot be discharged. Therefore, it is necessary not to retain the specific ink in which a large amount of air is dissolved in the tube 42. The tube connecting the parts does not need to be very flexible, so a material having a high barrier property against air can be used. From this point, air does not dissolve in the ink to the extent that it affects ejection. For example, since the flow path is always closed, the ink can always be moved in a desired direction and is used for such a flow path. The control means performs control so that the desired control is possible even in such a state. In this way, the ink flow path is controlled using two types of pumps having different configurations according to the purpose, thereby facilitating the control. Although the second pump 22 has been described with two rollers of the roller 44 and the roller 45, a tube pump using three rollers arranged at an angle of 120 degrees with each other and four rollers arranged at an angle of 90 degrees with each other may be used. .

FIG. 4 is a block diagram of the ink jet printer. The control unit 50 is a control unit including a CPU that executes processing operations such as calculation, control, determination, and setting. The control means 50 operates according to a control program stored in the ROM 51. The RAM 52 is used as a temporary storage area for data and a work area for processing by the control means 50. The carriage movement motor drive circuit 53 operates under the control of the control means 50 and drives the motor 15 that moves the carriage 2.

The carriage position detection sensor 17 is a linear sensor that detects the scale of the linear scale 14. It is mounted on the carriage 2. Based on this sensor output, the position of the carriage 2 is calculated and acquired. The head drive circuit 54 is controlled by the control means 50. The recording head 3 is operated via the head driving circuit 54. When a plurality of recording heads 3 are mounted, the control unit 50 and the head driving circuit 54 can drive each recording head 3 individually. The head drive circuit 54 generates ink ejection timing or non-ejection timing for each recording head 3 based on information input from the control unit 50, and drives the recording head 3. When ink ejection is performed, an ON waveform is generated, and when ink ejection is not performed, an OFF waveform is generated and transferred to each recording head 3. The ejection timing is calculated according to the position of the carriage 2.

The roller position detection means 55 includes a first position detection sensor 38 and a second position detection sensor 39 that detect the position of the roller 34 of the first pump 21. The control means 50 receives the output from these sensors and acquires the position of the roller 34. Based on the acquired information, the first pump driving means 58 can be controlled.

The first valve driving means 56 opens and closes the first valve 23. The first valve driving means 55 operates under the control of the control means 50. The second valve driving means 57 opens and closes the second valve 24. The second valve drive means 57 operates under the control of the control means 50.

The first pump drive means 58 operates under the control of the control means 50. The first pump driving means 58 rotates the rotor of the first pump 21. Perform forward rotation, reverse rotation, and stop. Since the position of the roller 34 can be detected and controlled to stop, the tube 32 can be opened or closed.

The second pump drive means 59 operates under the control of the control means 50. The second pump drive unit 59 rotates the rotor of the second pump 22. Perform forward rotation, reverse rotation, and stop. When stopped, the tube 42 is closed.

The pressure detection sensor 25 is controlled by the control means 50, and the control means 50 acquires the detected pressure value. By determining whether or not the pressure applied to the recording head 3 is within a preset value range when the ink is moved by driving the first pump 21 and the second pump 22, Abnormal pressure can be detected, pumps and valves can be controlled, and flow path failure can be prevented. The set value is obtained by experiment and stored in the ROM 51.

The capacity detection sensor 60 is a sensor that detects the capacity of the ink in the sub tank 20, and the detected value is acquired by the control means 50. For example, the minimum and maximum allowable amounts are detected, and control is performed to maintain the range.

FIG. 5 is a flowchart of the operation of returning the ink in the second pump to the sub tank. First, in step S1, the first valve 23 is opened, the second valve 24 is closed, the first pump 21 is stopped at the closed position, and the second pump 22 is driven in the reverse direction. The ink is reversely driven for a first predetermined time period when only the ink in the second pump 22 is put into the sub tank 20.

Next, in step 2, the first valve 23 is closed, the second valve 24 is opened, the first pump 21 is stopped at the closed position, and the second pump 22 is driven forward for a second predetermined time. The ink flow path between the sub tank 20 and the recording head 3 is brought into a pressurized state. In some cases, ink is discharged from the recording head 3.

By this operation, the ink in which the air in the second pump 22 is dissolved is put into the sub tank 20, so that the ratio of the remaining air can be reduced and the generation of bubbles during recording can be reduced. The ink in the subtank 20 having a high gas barrier property is in a state where it is difficult for outside air to enter and the ratio of residual air is low. Further, the amount of ink in the sub tank 20 is larger than the amount of ink in the second pump 22. The ink in the second pump 22 is mixed with the ink in the sub tank 20 to prevent the ink having a high residual air ratio from remaining in a specific place. If ink with a high proportion of residual air in a specific location is supplied to the recording head 3, there is a high possibility that bubbles will be generated in the recording head 3 to cause ejection failure. Discharge failure occurs.

For example, the amount of ink in the sub-tank 20 is 100 ml, and the amount of ink in the second pump 22 is about 2 ml, which is 50 times larger, so that the dissolved air can be reduced to a satisfactory level. Although it varies depending on the capacity in the sub tank 20 or the capacity in the pump, if the capacity of the sub tank 20 is increased, the effect is great, but since the mounting space is limited, a capacity difference of about 20 to 500 times is preferable.
This operation is performed every predetermined time. For example, it is performed every 6 hours, and the portion where ink with a high ratio of residual air is distributed is eliminated. It is possible to prevent bubbles from being generated and causing defective discharge.

Furthermore, if this operation is continued without newly supplying ink from the ink cartridge 4, the concentration of residual air in the ink in the sub tank 20 increases and bubbles may be generated during recording. In order to prevent this, when the ratio of the remaining air of the ink in the sub tank 20 becomes equal to or higher than a predetermined concentration, all of the ink is discharged or a predetermined amount of ink such as half is discharged, and a new sub tank 20 is discharged from the ink cartridge 4. It is preferable to reduce the concentration of residual air. The first pump 21 is closed, the first valve 23 and the second valve 24 are opened, and ink is discharged from the recording head 3. Thereafter, the first valve 23 and the second valve 24 are closed, and the first pump 21 supplies ink to the sub tank 20.

FIG. 6 is a flowchart of the operation of filling the recording head with ink. First, in step S10, the first valve 23 is closed, the second valve 24 is opened, the first pump 21 is stopped in the closed position, the second pump 22 is driven forward, and the sub-tank 20 The air is removed and the second pump 22 is stopped. The time for forward driving of the second pump 22 is a predetermined time determined in advance by experiment and stored in the ROM 52.

Next, in step S11, the second pump 22 is stopped, and the first pump 21 is rotated forward until the ink in the sub tank 20 reaches a predetermined amount. The detection value of the capacity detection sensor 60 that detects the ink amount in the sub tank 20 is determined, and ink is filled from the ink cartridge 4 to the maximum value of the allowable amount, for example.

Next, in step S12, the first pump 21 is stopped in the closed position, and the second pump 22 is rotated forward until the ink is filled in the flow path. A predetermined time determined in advance by an experiment or the like is stored in the ROM 52 and operated for that time. Thereby, ink can be filled from the sub tank 20 to the recording head 3.

Next, in step S13, the first valve 23 is opened, the second valve 24 is closed, the second pump 22 is operated in reverse, and the air and ink between the sub tank 20 and the first valve 23 are supplied to the second pump. 22 and then stop. Since there is a possibility that air is mixed in the flow path where the ink is not flowed in step S12, the flow is once taken into the second pump 22 in order to discharge it. A predetermined time determined in advance by an experiment or the like is stored in the ROM 52 and operated for that time. This is because the capacity of the flow path from the sub tank 20 to the branch portion between the first valve 23 and the second valve 24 passes through the second pump 22 side from the branch portion, the first pump 21, the second pump 22, and the sub tank. This is possible because the capacity of the channel up to 20 branches is smaller. Preferably, it is desired to once take in the flow path to the inside of the second pump 22. This is because when the bubbles flow toward the first pump 21, it is necessary to consume more ink for the exclusion.

Next, in step S14, the first valve 23 is closed, the second valve 24 is opened, the second pump 22 is rotated forward, ink containing air is discharged from the recording head 3, and then stopped. . A predetermined time determined in advance by an experiment or the like is stored in the ROM 52 and operated for that time.

Next, in step S15, it is confirmed whether step S13 and step S14 have been executed a predetermined number of times. For example, since there is a possibility that the air cannot be exhausted once, it is preferably executed a plurality of times such as twice or three times. This is also determined in advance by an experiment or the like, stored in the ROM 52, and ends when the predetermined number of times is executed.

FIG. 7 is a flowchart of the ink supply operation during recording. At the time of recording, the ink in the sub tank 20 is consumed. The sub tank 20 always stores the amount of ink in a predetermined range, so that a suitable negative pressure can be ensured by suitable head value management of the recording head 3. Therefore, the ink amount in the sub tank 20 is controlled.

First, in step S20, the first valve 23 is opened, the second valve 24 is opened, the first pump 21 is stopped in the closed position, and the second pump 22 is stopped. In this state, ink is ejected from the recording head 3.

Next, in step S21, based on the detection result of the capacity detection sensor 60, it is determined whether or not a volume of ink in a predetermined range is stored in the sub tank 20. If ink of a predetermined range of capacity has been stored, the process ends. Otherwise, the process proceeds to step S22.

In step S <b> 22, the first pump 21 is driven forward to supply ink from the ink cartridge 4 to the sub tank 20. This supply is performed until the detection result of the capacitance detection sensor 60 reaches the upper limit of the shared range. By these operations, the ink in the sub tank 20 can keep a certain range of ink volumes.
The operation described with reference to FIGS. 5 to 7 can prevent generation of bubbles in the ink flow path, maintain a suitable negative pressure for the recording head 3, and prevent ejection failure.

The present invention can be used for an ink jet printer.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Carriage 3 Recording head 4 Ink cartridge 5 Capping unit 6 Platen 7 Recording medium 8 Spit unit 10 Wipe unit 13 Carriage rail 14 Linear scale 17 Carriage position detection sensor 18 Tube 20 Sub tank 21 1st pump 22 2nd pump 23 1st 1 valve 24 2nd valve

Claims

A recording head comprising a plurality of nozzles for ejecting ink onto a recording medium;
A wiper for wiping the nozzle surface on which the nozzles of the recording head are disposed;
A subtank disposed in an ink flow path between the recording head and an ink cartridge that supplies ink to the recording head, and wipes off deposits on the nozzle surface by the wiper. In an ink jet printer for recording an image by supplying ink to and discharging the ink from the recording head to a desired position of the recording medium,
A first pump that moves the ink and opens or closes the ink flow path is disposed between the ink cartridge and the sub tank.
A first valve that opens or closes the ink flow path is disposed on the sub tank side of the ink flow path between the sub tank and the print head, and the ink flow path is opened or closed on the print head side. A second valve is arranged,
The ink flow path between the sub-tank and the first pump and the ink flow path between the first valve and the second valve are connected to move the ink and open the ink flow path. A second pump to be closed is arranged,
By driving the first pump, ink is supplied from the ink cartridge to the sub tank,
An ink jet printer that moves the ink in the second pump to the sub-tank by opening the first valve, closing the second valve, and driving the second pump in a reverse direction. .
The ink jet printer according to claim 1, wherein the movement of the ink in the second pump to the sub tank is performed by operating the second pump for a predetermined time every predetermined time.
When the ink in the ink cartridge is filled in the ink channel, the ink and air in the ink channel from the sub tank to the recording head in the ink channel are discharged from the recording head. 3. The ink jet printer according to claim 1, wherein the ink is then filled from the ink cartridge into the ink flow path.
The volume of the first portion when the ink flow path from the outlet of the sub tank to the branch portion of the second pump between the first valve and the second valve is the first portion is the first volume. The volume of the ink flow path in the two pumps and the total volume of the second part when the ink flow path from the second pump to the branching part is the second part are smaller, and the second valve is With the first valve open, the second pump is driven in reverse, the ink in the first part is moved to the second part, the first valve is closed, and the second valve is 4. The inkjet according to claim 1, wherein the second pump is driven to rotate forward in an opened state, and the ink in the second portion is discharged from the recording head. 5. printer.
In the second pump, the ink flow path composed of a flexible tube is disposed inside, and the ink is moved by handling the tube with two or more rollers, and at least one of the rollers is moved. The inkjet printer according to any one of claims 1 to 4, wherein the tube is always closed by one of the two.