JP6564333B2 - inkjet printer - Google Patents

Description

  The present invention relates to an inkjet printer that records an image by discharging ink from a recording head.

  2. Related Art Inkjet printers that record images by ejecting ink from an ink jet recording head onto a recording medium such as paper or a resin film have become widespread. Ink jet printers are known in which a subtank is provided in the ink flow path from the ink cartridge for storing ink to the recording head, and the head of ink in the subtank is managed to apply a certain range of negative pressure to the recording head. ing. In addition, a pump such as a tube pump is used to supply ink from the ink cartridge to the recording head.

  Inkjet printers are also required to improve the image quality of recorded images. When the recording head has ejection failure such as ink ejection failure, a streaky pattern appears in the recorded image. For example, when air bubbles, dust, thickened ink, or the like is present in the ink flow path, the nozzles of the recording head are clogged, resulting in ejection failure.

  Therefore, in a general inkjet printer, degassed ink is used or dust in the flow path is captured by a filter so that bubbles are not generated in the ink flow path. However, when the ink is first filled in the ink channel when the printer is first used, bubbles may remain in the ink channel.

  For example, in Japanese Patent Application Laid-Open No. 2010-52194, a filter for capturing foreign matter is provided in the ink flow path. When the ink is passed through the filter during the initial filling of the ink, there is a problem that the air contained therein becomes bubbles when passing through the filter. Therefore, when the ink is initially filled, the flow path to the recording head is closed, and the ink is circulated sufficiently between the ink tank, the filter, and the sub tank, so that the bubbles are dissolved in the ink or released from the sub tank to the atmosphere. It has been removed. Thereafter, a method of opening a flow path to the recording head and supplying ink to the recording head is employed.

JP 2010-52194 A

  However, in the conventional technique, the ink is dissolved in the ink or bubbles are collected in the sub tank. The air dissolved in the ink may become bubbles due to high frequency vibration of the recording head, which may cause clogging in the recording head. For this reason, contact between the ink and air and dissolution of air in the ink should be avoided. For example, it is necessary that the ink flow path be sealed with respect to the outside and that no air bubbles exist. Therefore, it is necessary to discharge the bubbles in the ink flow path to the outside during the initial filling of the ink.

  In order to solve such a problem, the present invention provides an ink jet printer that discharges bubbles in an ink flow path to the outside, reduces or prevents the generation of bubbles, and enables suitable ink discharge by a recording head. .

  An ink jet printer according to the present invention includes a recording head having a plurality of nozzles that eject ink to a recording medium, and a sub tank disposed in an ink flow path from an ink cartridge that supplies ink to the recording head to the recording head. An inkjet printer that supplies ink from the sub-tank to the recording head, discharges the ink from the recording head, and records an image on the recording medium, and is disposed between the ink cartridge and the sub-tank, A first pump that supplies the ink to the ink flow path; a first valve that is disposed between the sub tank and the recording head and on the sub tank side of the ink flow path; and opens and closes the ink flow path; A second valve disposed on the recording head side for opening and closing the ink flow path; and the first valve; A bypass passage connecting the branch portion provided in the ink passage between the second valves and a branch portion provided in the ink passage between the sub tank and the first pump, and disposed in the bypass passage A second pump that moves the ink through the bypass flow path during operation, the first valve, the second valve, the first pump, and the second pump. Control means for controlling the operation of the pump, the ink inlet / outlet on the first pump side of the sub tank, the ink inlet / outlet on the first valve side, the first valve, and the second valve in this order. The ink flow path between the first valve and the second valve is formed such that the water head gradually increases in the direction of the second valve, and the control means includes: Open or close the first valve Control, whether the second valve is opened or closed, and the first pump is stopped with the ink flow path closed, or is opened and stopped. Or whether to perform the operation of flowing the ink in the direction of the sub tank or the operation of flowing the ink in the direction of the ink cartridge, and stopping the second pump, or supplying the ink in the direction of the ink cartridge. And control whether to perform the operation of flowing the ink in the direction of the recording head, and the control means, when the ink is initially filled from the ink cartridge into the ink flow path, The sub tank is filled with the ink, and then the first valve is opened, the second valve is closed, the first pump is closed, and the second pump is reversed to reverse the bypass. The air and the ink in the subtank are allowed to flow from the subtank into the flow path, and then the first valve is closed, the second valve is opened, the first pump is closed and the first pump is stopped. Two pumps are operated to cause the ink to flow in the direction of the recording head, and control is performed to discharge the ink mixed with the air flowing into the bypass flow path from the recording head.

  According to the present invention, when the ink is initially filled in the ink flow path, the air in the ink flow path is discharged to the outside, and the ink flow path is filled with the ink, thereby preventing the recording head from being clogged. A discharge failure caused by bubbles can be prevented, and recording with a suitable image quality becomes possible.

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 filling the recording head with ink. FIG. 6 is a schematic diagram of an inkjet printer.

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

  First, the ink jet printer of this embodiment will be described with reference to the schematic diagram of the ink jet printer of FIG. The recording medium 73 is arranged horizontally, conveyed from the back of the sheet of FIG. 6 toward the front, ink is ejected from the recording head 62, and images, characters, and the like corresponding to the recording data are recorded on the surface of the recording medium 73. The recording medium 73 is paper, a resin film, or the like. This paper conveyance direction is called the sub-scanning direction.

  The ink jet printer 60 includes a transport unit that transports the recording medium 73. In addition, a plurality of recording heads 62 are mounted for color recording, and the direction intersecting the conveyance direction of the recording medium 73, here, the left-right direction in FIG. A carriage 61 for reciprocating scanning is provided. Further, a wipe unit 67 for wiping the recording head 62, a capping unit 65 for capping the recording head 62, and a spit unit 66 for receiving ink discharged from the recording head 62 are provided. The direction in which the carriage 61 reciprocates is called the main scanning direction. Further, the ink jet printer 60 includes a control unit that controls the entire apparatus including reception of recording data and control of a recording operation.

  A substantially flat platen 77 that flatly supports the transported recording medium 73 is arranged along the movement direction of the carriage 61. The transport unit includes a plurality of transport rollers 75 and pinch rollers 74 that transport the recording medium 73 onto the platen 77. The pinch roller 74 is pressed in the direction of the transport roller 75 and rotates with the rotation of the transport roller 75. The recording medium 73 is conveyed by a roller pair of a plurality of conveyance rollers 75 and pinch rollers 74 driven by a motor 76.

  The carriage 61 is movably provided along a carriage rail 72 that extends in a direction orthogonal to the conveyance direction of the recording medium 73. Further, a motor 71 is provided for reciprocating the carriage 61 so as to be capable of position control and speed control in the moving direction. The motor 71 is connected to an endless belt 70 to which the carriage 61 is fixed, and drives the endless belt 70. A linear scale 69 is provided in parallel with the carriage rail 72. A sensor 68 for detecting the scale of the linear scale 69 is provided in the carriage 61. As a result, the position of the carriage 61 can be detected, and the position of the carriage 61 and the plurality of recording heads 62 fixed to the carriage 61 can be controlled by the control means.

  In the present embodiment, four recording heads 62 are provided corresponding to four color inks of black, yellow, magenta, and cyan for performing color recording. In addition, an ink cartridge 63 is provided for each color and is supplied to each recording head 62 via a tube 64.

  Although details of the recording head 62 are not shown, a plurality of nozzles that eject ink are arranged in a row, and the supplied ink is ejected by an ejection mechanism such as a piezoelectric element. The ink jet printer 60 can eject the ink from the nozzles to the spit unit 66 outside the image forming range, and can eject the thickened ink or to adjust the meniscus. Further, the spit unit 66 can receive ink from a plurality of recording heads 62 at the same time. For example, when the recording head 62 is filled with ink, the spit unit 66 receives excess ink that is discharged.

  Position control and speed control of the motor 71 that drives the carriage 61 are performed in accordance with control signals from the control means. During the recording operation, the motor 71 is controlled so that the recording head 62 reciprocates over the recording medium 73 at a predetermined speed. Further, the motor 71 moves the recording head 62 to a predetermined wiping position of the wipe unit 67 during the cleaning operation. Further, when capping, it is moved on the capping unit 65, and when spitting, it is moved on the spit unit 66.

  The wipe unit 67 moves the wipe blade relative to the nozzle surface on which the nozzles for ejecting ink of the recording head 62 are moved in a state where the recording head 62 is moved above the wipe unit 67. The nozzle surface of the recording head 62 is wiped and cleaned. The capping unit 65 covers the nozzle surface on which the nozzles for ejecting ink of the recording head 62 are arranged to prevent drying. The schematic configuration of the capping unit 65 includes caps corresponding to the respective recording heads 62 and elevating means for elevating and lowering the caps. 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. The spit unit 66 has a waste ink bottle that stores waste ink.

  An image can be recorded by moving the carriage 61 to a desired position on the recording medium 73 supported by the platen 77 and transporting it by a transport means, and ejecting ink from the nozzles of the recording head 62 to the desired position.

  FIG. 1 is a schematic diagram illustrating an ink flow path. An ink flow path for one color from the ink cartridge 10 to one recording head 12 will be described. Other ink colors also have the same ink flow path configuration. A first tube 17 connects the ink cartridge 10 to the sub tank 11. The first pump 13 is disposed in the middle of the flow path of the first tube 17. Further, the sub-tank 11 and the recording head 12 are connected by the second tube 18. A first valve 15 and a second valve 16 are arranged in the middle of the flow path of the second tube 18. Further, the flow path between the first pump 13 and the sub tank 11 of the first tube 17 and the flow path between the first valve 15 and the second valve 16 of the second tube 18 are connected, and the second pump 14 is interposed therebetween. Is arranged. That is, the flow path between the first pump 13 of the first tube 17 and the sub tank 11 is branched, and the flow path between the first valve 15 and the second valve 16 of the second tube 18 is branched. Each of the branched portions is connected, and is an ink path from the ink cartridge 10 to the recording head 12, and includes a bypass path that does not pass through the sub tank 11.

  By managing the amount of ink stored in the subtank 11, a suitable negative pressure can be applied to the recording head 12 based on the water head of the ink in the subtank 11, and a meniscus suitable for the nozzle can be created. The ink can be moved in the ink flow path by the two pumps of the first pump 13 and the second pump 14. In addition, the first valve 15 and the second valve 16 are provided, and the opening and closing of each valve can be controlled to control the direction of ink flow.

  The first pump 13 moves the ink in the forward direction indicated by the arrow, moves it in the reverse direction, and when the pump is stopped, either the closed state or the open state of the ink flow path Can be. The second pump 14 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 15 and the second valve 16 can be in either a closed state or an open state. For example, an electromagnetic valve that can be controlled by a control means. The first pump 15 and the second pump 16 need different functions, and pumps having different mechanisms are used. Control is made easy and easy to understand by using a pump according to the purpose of use.

  If the second pump 14 may be in an open state, the sub-tank 11 cannot manage the water head and a discharge failure may occur. Therefore, a pump that always closes the flow path is used as the second pump 14. In some cases, ink is supplied from the ink cartridge 10 to the recording head 12 without passing through the subtank 11 and discharged. This is because the first pump 13 is opened, the first valve 15 is closed, the second valve 16 is opened, and the second pump 14 is driven in the forward direction so that ink is discharged without entering the sub tank 11. can do. In this way, since different pumps are arranged in the flow path, they can be used according to the situation and control becomes easy.

  FIG. 2 is a diagram illustrating the first pump. An internal configuration of the first pump 13 is shown. The case is provided with a U-shaped outer wall 23, and a tube 22 is disposed along the outer wall 23. The first connector 20 and the second connector 21 are connected to both ends of the tube 22. The first connector 20 is connected to the ink cartridge 10. The second connector 21 is connected to the sub tank 11 and the second pump 14. The rotor 26 is provided with an arm and a roller 24 connected to the tip thereof. The rotor 26 is rotated around the shaft 25 to squeeze the tube 22 and move the ink in the tube 22. When the roller 24 is rotated from the first connector 20 toward the second connector 21 along the outer wall 23 (this is referred to as normal rotation), ink flows in the forward direction. When the roller 24 is rotated from the second connector 21 toward the first connector 20 along the outer wall 23 (this is referred to as reverse rotation), ink flows in the opposite direction. The first pump 21 is configured so that the control means can grasp the position of the roller 24 by a roller position detecting means described later. For example, a position detection sensor (not shown) is provided, and the position of the roller 24 can be detected as a position 27 for closing the flow path indicated by a dotted line and a position 28 for opening the flow path. These positions are detected and used for control by the control means described later.

  FIG. 3 is a diagram illustrating the second pump. An internal configuration of the second pump 14 is shown. The case is provided with a U-shaped outer wall 33, and a tube 32 is disposed along the outer wall 33. The first connector 30 and the second connector 31 are connected to both ends of the tube 32. The first connector 30 is connected to the first pump 13 and the sub tank 11. The second connector 31 is connected to the first valve 15 and the second valve 16. The rotor 38 is provided with two arms, and a roller 34 and a roller 35 connected to the tip of the rotor 38 are rotated around a shaft 37 to squeeze the tube 32 and move ink in the tube 32. When the rollers 34 and 35 are rotated along the outer wall 33 in the direction from the first connector 30 to the second connector 31 (this is referred to as normal rotation), ink flows in the positive direction. When the rollers 34 and 35 are rotated along the outer wall 33 in the direction from the second connector 31 to the first connector 30 (this is called reverse rotation), the ink flows in the opposite direction. The arms are arranged on a straight line with the axis 37 as the center. The rollers 34 and 35 are arranged on the opposite side to the shaft 37, that is, at a position where the angle is 180 degrees apart. As a result, regardless of the angle of the rotor 38, either the roller 34 or the roller 35 always closes the tube 32. For example, the tube 32 can be kept closed by stopping the rotor 38 at the position of the roller 36 indicated by the dotted line. The other roller is in a position not in contact with the tube 32.

  Although the second pump 14 has been described as having two rollers, 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. If such a tube pump is used, the flow path is always closed, and control that allows the ink to be moved in a desired direction is possible.

  FIG. 4 is a block diagram of the ink jet printer. The control means 40 is a control circuit including a CPU that executes processing operations such as calculation, control, determination, and setting. The control means 40 operates according to a control program stored in the ROM 41. The RAM 42 is a memory used for temporary storage of data, a work area for processing by the control means 40, and the like. The carriage movement motor drive circuit 43 operates under the control of the control means 40 and drives a motor 71 that moves the carriage 61.

  The carriage position detection sensor 68 is a linear sensor that detects the scale of the linear scale 69. It is mounted on the carriage 61. The carriage position detection sensor 68 is connected to the control means 40 and controlled. The control means 40 can calculate and acquire the position of the carriage 61 based on the sensor output.

  The head drive circuit 44 is controlled by the control means 40. The recording head 62 is operated via the head driving circuit 44. When a plurality of recording heads 62 are mounted, the control unit 40 and the head driving circuit 44 can individually control and drive each recording head 62. The head driving circuit 44 generates ink ejection timing or non-ejection timing for each recording head 62 based on information input from the control means 40 and drives the recording head 62. When ink ejection is performed, an ON waveform is generated. When ink ejection is not performed, an OFF waveform is generated and transferred to each recording head 62. The ejection timing is calculated according to the position of the carriage 61. The position of the carriage 61 can be obtained by counting the scale of the linear scale 69 based on a signal from the carriage position detection sensor 68.

  The roller position detection unit 45 includes a sensor that detects the position of the roller 24 of the first pump 13. The control means 40 receives the output from this sensor and acquires the position of the roller 24. The control means 40 can perform various controls based on the acquired information.

  The first valve driving means 46 opens and closes the first valve 15. The first valve driving means 46 operates under the control of the control means 40. The second valve driving means 47 opens and closes the second valve 16. The second valve drive means 47 operates under the control of the control means 40.

  The first pump drive means 48 operates under the control of the control means 40. The first pump driving means 48 rotates the rotor of the first pump 13. Perform forward rotation, reverse rotation, and stop. Since the control of detecting and stopping the position of the roller 24 can be performed, the tube 22 can be opened or closed.

  The second pump drive means 49 operates under the control of the control means 40. The second pump driving means 49 rotates the rotor of the second pump 14. Perform forward rotation, reverse rotation, and stop. When stopped, the tube 32 is closed.

  The capacity detection sensor 50 is a sensor that detects the capacity of the ink in the sub tank 11, and the detected value can be acquired by the control means 40. Based on the detected value, the control means 40 can perform various controls. For example, the minimum amount and the maximum amount that can be tolerated are detected, and control can be performed to maintain the range. The capacity detection sensor 50 can detect that the ink capacity is equal to or lower than the lower limit indicating ink end and equal to or higher than the upper limit indicating ink full.

  FIG. 5 is a flowchart of the operation of filling the recording head with ink. A process of initially filling ink in the ink flow path from the ink cartridge 10 to the recording head 12 without ink in the ink flow path will be described. In the example, one recording head 12 will be described, but the ink flow paths corresponding to the respective color inks are similarly filled with ink and then recorded.

  First, in step S1 to step S3, the state of the sub tank 11 is set to a predetermined state. The sub tank 11 before ink filling is filled with air and swells, or conversely collapses, and various states exist. If the state is unknown, there is a risk of incorrect control. Therefore, it is necessary to start the control after setting the state of the sub tank 11 to a predetermined state.

  In step S <b> 1, the internal air is removed regardless of the state of the sub tank 11. The first valve 15 is closed, the second valve 16 is opened, and the first pump 13 is stopped at the closed position. Then, the second pump 14 is operated in the forward direction. The air inside the sub tank 11 is discharged from the recording head 12. This is performed until the capacity detection sensor 50 of the sub tank 11 detects the ink end. When the ink end is detected, the process proceeds to step S2.

  In step S2, the second pump 14 that has been operated in the forward direction is operated in the reverse direction. The capacity detection sensor 50 supplies air from the recording head 12 side into the sub tank 11 until the ink end is not detected from the state where the ink end is detected. When the ink end is not detected, the process proceeds to step S3.

  In step S3, the second pump 14 that has been operated in the reverse direction is operated in the forward direction. This operation is performed for a predetermined time. For example, it is performed for 60 seconds. By performing the predetermined time, the air is sufficiently removed from the state where the sub tank 11 is filled with air so that the ink end is not detected. After operation for a predetermined time, the process proceeds to step S4. The predetermined time is obtained by experiments in advance, and the value of the operating time is stored in a memory such as the ROM 41, and taken out and controlled at the time of implementation.

  In step S4, the first valve 15 is closed and the second valve 16 is kept open. The second pump 14 is stopped. Then, the first pump 13 is operated in the forward direction. The operation of the first pump 13 is such that the capacity detection sensor 50 sends ink from the ink cartridge 10 toward the sub tank 11 until the ink end is not detected, and the first pump 13 is closed when the ink end is not detected. And stop. In this state, air remains in the ink tank near the second pump 15 inside the sub tank 11. Further, the ink is filled in the first tube 17 and the first pump 13 from the ink cartridge 10 to the sub tank 11. The sub tank 11 is mixed with ink and air. Next, the process proceeds to step S5.

  In step S5, the first valve 15 is closed and the second valve 16 is opened. The first pump 13 remains stopped in the closed state. The second pump 14 is operated in the positive direction for a predetermined time, for example, 5 seconds. As a result, the ink in the sub tank 11 is moved toward the recording head 12 via the second pump 14 and the second valve 16. The predetermined time is an operation time necessary for the leading edge of the ink to reach a position beyond the second valve 16. It is obtained by experiment in advance, the set value is stored in the ROM 41, and is taken out and controlled during operation. At this time, the arrangement of the sub tank 11 is important. The opening that connects the sub tank 11 to the ink cartridge 10 side is at a lower position in the vertical line direction than the opening that connects to the head side. The bubbles in the sub tank 11 move to the higher vertical direction of the sub tank 11 so that the bubbles in the sub tank 11 do not enter the first tube 17 from the opening on the ink cartridge 10 side. That is, the opening on the ink cartridge 10 side has a lower water head.

  In the state up to this processing, bubbles still remain between the sub tank 11 and the sub tank 11 to the first valve 15. Next, the process proceeds to step S6. The predetermined time is obtained by experiments in advance, and the value of the operating time is stored in a memory such as the ROM 41, and taken out and controlled at the time of implementation.

  In step S6, the first valve 15 is closed, the second valve 16 is opened, the second pump 14 is stopped, and the first pump 13 is operated in the forward direction. Then, the ink is sent from the ink cartridge 10 toward the sub tank 11 until the capacity detection sensor 50 of the sub tank 11 detects ink full. That is, the sub tank 11 is filled with ink. When filling is completed, the process proceeds to step S7.

  In step S <b> 7, the air in the sub tank 11 is once pulled in the direction of the second pump 14. The first valve 15 is opened, the second valve 16 is closed, and the first pump 13 is closed. The second pump is operated in the reverse direction. Perform for a predetermined time. For example, it is performed for 5 seconds. The air remaining in the sub tank 11 is moved in the direction of the second pump 14. At this time, control is performed so that air does not enter the second pump 14. When air enters the second pump 14, when the second pump 14 is operated, ink and bubbles are squeezed and moved at the same time, so that many bubbles are generated, and this is avoided. The predetermined time is obtained by experiments in advance, and the value of the operating time is stored in a memory such as the ROM 41, and taken out and controlled at the time of implementation. Next, the process proceeds to step S8.

  In step S8, the first valve 15 is closed, the second valve 16 is opened, and the second pump 14 is stopped. The first pump 13 is stopped in the closed state. That is, the first valve 15 is closed, the second pump 14 is stopped, and waits for 10 seconds, for example. By providing the weight for this predetermined time, it waits for the bubbles in the path to move toward the second valve 16. From the 2nd pump 14 to the 2nd valve 16, it arrange | positions so that it may become high gradually. The first valve 15 to the second valve 16 are arranged so as to gradually increase. By arranging in this way, it is possible to prevent bubbles from moving from the second pump 14 toward the first valve 15. At the branch portion from the second pump 14, the direction of the first valve 15 is low and the direction of the second valve 16 is high, so that bubbles move in the direction of the second valve. That is, the second valve 16 has a higher head than the first valve 15, the second valve 16 has a higher head than the second pump 14, and the first valve has a higher head than the second pump 14. High placement. Further, by providing the wait time, the fluctuation of the internal pressure in the tube due to driving of the pump or the like is eliminated, and it is possible to wait for a steady state. This time is obtained in advance by experiments and the like, stored in a memory such as the ROM 41, and taken out and controlled at the time of implementation. Next, the process proceeds to step S9.

  In step S9, the first valve 15 is closed, the second valve 16 is opened, and the first pump 13 is stopped in a closed state. The second pump 14 is operated in the forward direction for a predetermined time. For example, it is operated for 5 seconds. The ink on the first tube 17 side passes through the second pump 14 and moves the air drawn in the direction of the second pump 14 toward the second valve 16. The air between the branch portion between the first valve 15 and the second valve 16 and the second pump 14 is carried to the ink path after the second valve 16. From the 2nd pump 14 to the 2nd valve 16, it arrange | positions so that it may become high gradually. The first valve 15 to the second valve 16 are arranged so as to gradually increase. By arranging in this way, it is possible to prevent bubbles from moving from the second pump 14 toward the first valve 15. That is, at the branch portion from the second pump 14, the direction of the first valve 15 is low and the direction of the second valve 16 is high, so that the bubbles move in the second valve direction. This predetermined time is obtained in advance through experiments or the like, stored in a memory such as the ROM 41, and taken out and controlled at the time of implementation. Next, the process proceeds to step S10.

  In step S10, the first valve 15 is opened, the second valve 16 is closed, and the first pump 13 is closed and stopped. The second pump 14 is operated in the reverse direction for a predetermined time. This predetermined time is, for example, 5 seconds. The ink and bubbles are sucked from the sub tank 11 toward the second pump 14 by operating for a short time. Control is performed so that air does not enter the second pump 14. The predetermined time is obtained by an experiment in advance, the value of the operating time is stored in a memory such as the ROM 41, and taken out and controlled at the time of implementation. The same process is performed in step 7, but the air can be surely removed by performing the process again. Also, the second time can be less than the first time. For example, 4 seconds. Since most of the air is removed at the first time, the second time can be done in a short time to perform preliminary. Next, the process proceeds to step S11.

  In step S11, the first valve 15 is closed, the second valve 16 is opened, the first pump 13 is stopped in a closed state, and the second pump 14 is stopped. That is, by providing a weight for this predetermined time, the process waits for bubbles in the path to move toward the second valve 16. From the 2nd pump 14 to the 2nd valve 16, it arrange | positions so that it may become high gradually. The first valve 15 to the second valve 16 are arranged so as to gradually increase. Further, by providing the wait time, the fluctuation of the internal pressure in the tube due to driving of the pump or the like is eliminated, and it is possible to wait for a steady state. And it becomes easy to move a bubble. This time is obtained in advance by experiments and the like, stored in a memory such as the ROM 41, and taken out and controlled at the time of implementation. In step S11, the same wait time as in step S8 may be used. Next, the process proceeds to step S12.

  In step S12, the first valve 15 is closed, the second valve 16 is opened, and the first pump 13 is stopped in the open state. Then, the second pump 14 is operated in the forward direction. Ink is made to flow in the direction of the recording head 12, and ink is filled into the ink flow path including the inside of the recording head 10. The second pump 14 is operated for a predetermined time and supplies ink sufficiently. This time is obtained in advance by experiments and the like, stored in a memory such as the ROM 41, and taken out and controlled at the time of implementation. Next, the process proceeds to step S13.

  In step S13, the first valve 15 is closed, the second valve 16 is opened, and the first pump 13 is stopped in a closed state. Then, the second pump 14 is operated in the forward direction. Further, the recording head 12 is driven to discharge ink. The bubbles in the recording head 10 are discharged to the outside. Driving operations such as the operation of the second pump 14 and the number of ejection dots of the recording head 12 are obtained in advance through experiments and the like, stored in a memory such as the ROM 41, and taken out and controlled at the time of implementation. Next, the process proceeds to step S14.

  In step S14, the first valve 15 is opened, the second valve 16 is opened, and the second pump 14 is stopped. Further, the first pump 13 is operated in the forward direction, and ink filling is performed until the capacity detection sensor 50 of the sub tank 11 detects ink full.

  The initial filling process is completed. Bubbles in the ink flow path can be discharged out of the flow path so that there are no air bubbles in the ink flow path, and ink can be filled. The sub tank 11 is filled with an appropriate amount of ink, that is, between the lower limit and the upper limit of the detection value of the capacity detection sensor 50, the first valve 15 is opened, the second valve 16 is opened, and the second pump 14 is stopped. Thus, a suitable negative pressure can be applied to the recording head 3 by the sub tank 11.

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

DESCRIPTION OF SYMBOLS 10 Ink cartridge 11 Sub tank 12 Recording head 13 1st pump 14 2nd pump 15 1st valve 16 2nd valve 17 1st tube 18 2nd tube 60 Inkjet printer 61 Carriage 62 Recording head 63 Ink cartridge 64 Tube 65 Capping unit 66 Spit Unit 67 Wipe unit 68 Sensor 69 Linear scale 70 Endless belt 71 Motor 72 Carriage rail 73 Recording medium 74 Pinch roller 75 Transport roller 76 Motor 77 Platen

Claims (4)

A recording head comprising a plurality of nozzles for ejecting ink onto a recording medium;
A sub tank disposed in an ink flow path from an ink cartridge for supplying ink to the recording head to the recording head, supplying ink from the sub tank to the recording head, and discharging the ink from the recording head. In an inkjet printer that records an image on the recording medium,
A first pump disposed between the ink cartridge and the sub tank and supplying the ink to the ink flow path ;
Said sub-tank and said is a between the recording head disposed on the sub-tank side of the ink passage, a first valve for opening and closing of said ink channel, the arranged recording head side, the opening and closing of said ink channel A second valve for performing
A bypass passage connecting the branch portion provided in the ink flow path between the first valve and the second valve, and the branch portion provided in the ink flow path between the sub tank and the first pump;
A second pump that is disposed in the bypass flow path, closes the bypass flow path when stopped, and moves the ink through the bypass flow path during operation;
Control means for controlling operations of the first valve, the second valve, the first pump, and the second pump ,
The sub-tank is arranged so that the water head becomes higher in the order of the ink inlet / outlet on the first pump side, the ink inlet / outlet on the first valve side, the first valve, and the second valve. The ink flow path between one valve and the second valve is formed such that the head gradually increases in the direction of the second valve ,
The control means controls whether the first valve is opened or closed, whether the second valve is opened or closed, and the first pump, Control whether the ink flow path is closed and stopped, opened or stopped, the operation of flowing the ink in the sub-tank direction, or the operation of flowing the ink in the ink cartridge direction; and Controlling whether to stop the second pump, to perform the operation of flowing the ink in the direction of the ink cartridge, or to perform the operation of flowing the ink in the direction of the recording head,
When the ink is initially filled from the ink cartridge into the ink flow path, the control means fills the sub tank with the ink, then opens the first valve, closes the second valve, 1 pump is closed and stopped, the second pump is reversed, and the air and the ink in the sub tank are allowed to flow from the sub tank to the bypass flow path, and then the first valve is closed, The second valve is opened, the first pump is closed and stopped, the ink is caused to flow through the second pump in the direction of the recording head, and the air that has flowed into the bypass channel is mixed. An ink jet printer that performs control to discharge the ink from the recording head .   The inkjet printer according to claim 1, wherein the second valve is disposed at a position having a higher water head than the second pump. The control means closes the first valve, opens the second valve, stops the first pump in a closed state, and causes the second pump to flow the ink toward the recording head. Before, the first valve is closed, the second valve is opened, the first pump is closed and stopped, the second pump is stopped for a predetermined time, and the air in the ink flow path is removed. The inkjet printer according to claim 1, wherein the inkjet printer is moved . After the ink mixed with the air that has flowed into the bypass channel is discharged from the recording head, the first valve is opened , the second pump is stopped, and the first pump is moved toward the sub tank. 4. The ink jet printer according to claim 1 , wherein an ink flow operation is performed to fill the sub tank with the ink of the ink cartridge. 5.

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