JP6557289B2 - Liquid circulation device and liquid discharge recording device - Google Patents

Description

Embodiment, the liquid circulating apparatus for circulating the liquid to be supplied to the liquid discharge portion, and relates to a liquid discharge recording equipment.

  There is a liquid circulation type liquid ejection device that circulates liquid between a liquid tank and a liquid ejection head to remove bubbles generated in the nozzles of the inkjet head and foreign matters mixed in the nozzles from the vicinity of the nozzles. In the conventional liquid ejecting apparatus, when the ink in the liquid tank is detected to be low, the printing operation is stopped, the ink is replenished from the replenishing liquid tank, and the printing operation is resumed when the ink refilling to the liquid tank is completed. . For this reason, in the conventional liquid ejecting apparatus, printing cannot be performed when ink is replenished, and the productivity of the liquid ejecting apparatus may be reduced. In particular, when the volume of the liquid tank is small, there is a risk that the replenishment operation of the ink from the replenishment liquid tank to the liquid tank frequently occurs to further reduce the production efficiency of the liquid ejection device.

JP 2005-125670 A

The problem to be solved by the present invention is to prevent the liquid discharge operation from being stopped for replenishment of a new liquid to the liquid tank that circulates the liquid between the liquid discharge unit and to improve the productivity by the liquid discharge. liquid circulation device for improved, and to provide a liquid discharge recording equipment.

In order to achieve the above object, a liquid circulation apparatus according to an embodiment can circulate the liquid between a liquid ejection unit that ejects liquid and collects the liquid from the liquid ejection unit; A liquid casing constituting a liquid chamber having the liquid supply chamber for supplying the liquid to the liquid discharge section, a liquid level sensor for detecting the liquid level of the liquid recovery chamber and the liquid level of the liquid supply chamber, respectively. , said liquid replenishing unit for replenishing the new liquid to the liquid casing, which is connected directly to the liquid supply chamber, and a gas material replenishment unit that replenishes the gas into the liquid casing, the liquid casing in the liquid replenishing unit and said replenishing the fresh liquid, and supplementing the gas into the liquid casing in the gas replenishing unit, the pressure in the liquid casing adjusted pressure, the liquid surface of the liquid supply chamber predetermined in of If the liquid level in the liquid supply chamber is lower than a predetermined height, the pressure in the liquid supply chamber is adjusted by the gas replenishing unit. The pressure of the liquid recovery chamber or the liquid supply chamber is adjusted by the unit.

1 is a schematic front view showing an ink jet recording apparatus of an embodiment. 1 is a schematic plan view showing an ink jet recording apparatus according to an embodiment. 1 is a schematic configuration diagram illustrating an inkjet head according to an embodiment. Schematic explanatory drawing which shows the state in which an ink stays at a nozzle with the inkjet head of embodiment. Schematic explanatory drawing which shows discharge of the ink droplet from the nozzle of embodiment. 1 is a schematic configuration diagram illustrating an ink circulation device according to an embodiment. Schematic explanatory drawing which shows the circulation and pressure adjustment of the ink of embodiment. FIG. 2 is a schematic block diagram illustrating a control system that controls the ink jet recording apparatus according to the embodiment. The timing chart which shows adjustment of the pressure concerning the nozzle of embodiment. The flowchart which shows control of adjustment of the pressure concerning the nozzle of embodiment.

  An ink jet recording apparatus 1 that is a liquid discharge recording apparatus of an embodiment will be described with reference to FIGS. 1 to 10. 1 and 2 show an example of an ink jet recording apparatus 1. The ink jet recording apparatus 1 includes an image forming unit 6, a recording medium moving unit 7 that is a transport unit, and a maintenance unit 310. The image forming unit 6 includes an inkjet recording unit 4, a carriage 100 that supports the inkjet recording unit 4, a conveyance belt 101 that reciprocates the carriage 100 in the direction of arrow A, and a carriage motor 102 that drives the conveyance belt 101.

  The inkjet recording unit 4 includes an inkjet head 2 that is a liquid ejection unit and an ink ejection unit, and an ink circulation device 3 that is a circulation unit. The ink circulation device 3 is formed above the inkjet head 2 and is integrally formed with the inkjet head 2. The ink jet recording unit 4 ejects ink onto the recording medium S to form a desired image.

  The inkjet recording unit 4 includes, for example, inkjet recording units 4a, 4b, 4c, 4d, and 4e that discharge cyan ink, magenta ink, yellow ink, black ink, and white ink, respectively. The color or characteristics of the ink used by each of the inkjet recording units 4a, 4b, 4c, 4d, and 4e is not limited. For example, the inkjet recording unit 4e can eject transparent glossy ink, special ink that develops color when irradiated with infrared rays or ultraviolet rays, instead of white ink. The ink jet recording units 4a, 4b, 4c, 4d, and 4e have the same configuration although different inks are used. Therefore, description will be made using common reference numerals.

  The ink jet recording unit 4 can be narrowed by stacking the ink circulation device 3 above the ink jet head 2. Therefore, the width of the carriage 100 that supports the plurality of inkjet recording units 4a to 4e in parallel can be reduced. The image forming unit 6 can reduce the conveyance distance of the carriage 100 by reducing the width of the carriage 100, can achieve downsizing of the inkjet recording apparatus 1, and can increase the printing speed.

  The image forming unit 6 includes an ink cartridge 81 for replenishing the ink circulation device 3 with new ink. 81a, 81b, 81c, 81d, and 81e of the ink cartridge 81 hold cyan ink, magenta ink, yellow ink, black ink, and white ink, respectively. The ink cartridges 81a, 81b, 81c, 81d, and 81e have the same configuration although different inks are held. Therefore, description will be made using common reference numerals. The ink cartridge 81 communicates with the ink circulation device 3 of the inkjet recording unit 4 via the tube 82. The ink cartridge 81 is disposed relatively below the ink circulation device 3 in the direction of gravity.

  The recording medium moving unit 7 includes a table 103 that holds the recording medium S by suction. The table 103 is mounted on the slide rail device 105 and reciprocates in the arrow B direction. The table 103 sucks and fixes the recording medium S from the small-diameter hole 110 on the upper surface by applying a negative pressure inside the table 104. While the inkjet recording unit 4 reciprocates along the conveyance belt 101 in the direction of arrow A, the distance h between the nozzle plate 52 of the inkjet head 2 and the recording medium S is maintained constant. The inkjet head 2 includes 300 nozzles 51 that are 300 liquid ejection units in the longitudinal direction of the nozzle plate 52. The longitudinal direction of the nozzle plate 52 is the same as the conveyance direction of the recording medium S.

  The image forming unit 6 forms an image on the recording medium S while reciprocating the inkjet head 2 in a direction orthogonal to the conveyance direction of the recording medium S. The inkjet head 2 forms an image on the recording medium S by ejecting ink I from the nozzles 51 provided on the nozzle plate 52 in accordance with the image forming signal. The inkjet recording unit 4 forms an image on the recording medium S with a width of, for example, 300 nozzles.

  The maintenance unit 310 is disposed at a position outside the moving range of the table 103 in the scanning range in the arrow A direction of the inkjet recording unit 4. The inkjet head 2 faces the maintenance unit 310 at the standby position Q. The maintenance unit 310 is a case whose upper side is open, and is provided so as to be movable up and down (in the directions of arrows C and D in FIG. 1).

  When the carriage 100 moves in the direction of arrow A to print an image, the maintenance unit 310 moves downward (in the direction of arrow C) and moves away from the nozzle plate 52. When the printing operation is completed, the maintenance unit 310 moves upward (in the direction of arrow D). When the printing operation is completed and the inkjet head 2 returns to the standby position Q, the maintenance unit 310 moves upward to cover the nozzle plate 52 of the inkjet head 2. The maintenance unit 310 prevents ink from evaporating from the nozzle plate 52 and prevents dust and paper dust from adhering to the nozzle plate 52. The maintenance unit 310 has a cap function for the nozzle plate 52.

  The maintenance unit 310 includes a rubber blade 120 and a waste ink receiver 130. The rubber blade 120 removes ink, dust, paper dust, and the like attached to the nozzle plate 52 of the inkjet head 2. The waste ink receiving unit 130 receives waste ink, dust, paper dust, and the like generated during the maintenance operation. The maintenance unit 310 includes a mechanism that moves the blade 120 in the direction of arrow B, and wipes the surface of the nozzle plate 52 with the blade 120.

  The ink jet head 2 performs maintenance (spit function) for forcibly ejecting ink from the nozzles 51 in order to remove the deteriorated ink in the vicinity of the nozzles. The inkjet head 2 performs maintenance (purging function) in which ink is slightly discharged from the nozzle 51 to take in paper dust and dust adhering to the surface of the inkjet head 2 into the discharged ink film and wiped with the blade 120. The waste ink receiver 130 collects waste ink generated by the spit function or the purge function.

  The ink jet recording apparatus 1 ejects ink from the nozzles 51 while reciprocating the ink jet head 2 in a direction perpendicular to the conveyance direction of the recording medium S by the recording medium moving unit 7, thereby forming an image on the recording medium S. Form.

  The structure of the inkjet recording apparatus 1 is not limited. For example, instead of using the table 103 for moving the recording medium, a device that moves by winding a roll-shaped recording medium in a direction perpendicular to the moving direction of the inkjet recording unit 4 may be used. Alternatively, a device that moves a sheet-like recording medium by a platen roller in a direction perpendicular to the moving direction of the inkjet recording unit 4 may be used.

  The ink jet recording unit 4 will be described in detail. For example, as shown in FIG. 3, the inkjet head 2 of the inkjet recording unit 4 includes a nozzle plate 52 including nozzles 51, a substrate 60 including actuators 54, and a manifold 61 connected to the substrate 60. The substrate 60 includes an ink flow path 180 through which ink flows between the nozzle 51 and the actuator 54. The actuator 54 faces the ink flow path 180 and is provided corresponding to each nozzle 51.

  The substrate 60 includes a boundary wall 190 between the adjacent nozzles 51 so that the pressure generated in the ink in the ink flow path 180 by the actuator 54 is concentrated on the nozzles 51. The ink flow path 180 surrounded by the nozzle plate 52, the actuator 54, and the boundary wall 190 becomes the ink pressure chamber 150. A plurality of ink pressure chambers 150 are provided corresponding to the respective nozzles 51a of the first nozzle row 57a and the respective nozzles 51b of the second nozzle row 57b. Each of the first nozzle row 57a and the second nozzle row 57b includes 300 nozzles 51a and 51b.

  The substrate 60 includes a common ink supply chamber 58 that supplies ink to the ink flow paths 180 of the plurality of ink pressure chambers 150, and a common ink chamber 59 that collects ink from the plurality of ink flow paths 180 and the first nozzle row 57 a side. It is provided on each of the two nozzle rows 57b.

  The manifold 61 includes an ink supply port 160 through which ink flows in the direction of arrow F and an ink discharge port 170 through which ink is discharged in the direction of arrow G. The ink supply port 160 is supplied with the ink I from the ink circulation device 3, and the ink discharge port 170 returns the ink to the ink circulation device 3. The manifold 61 has an ink distribution passage 62 that communicates from the ink supply port 160 to the common ink supply chamber 58. The manifold 61 has an ink return passage 63 that communicates from the common ink chamber 59 to the ink discharge port 170.

  Ink I flowing in the direction of arrow F through the ink distribution passage 62 flows from the common ink supply chamber 58 into the plurality of ink pressure chambers 150. The ink I that has not been ejected from the nozzle 51 in the ink pressure chamber 150 flows into the common ink chamber 59 and returns to the ink reflux path 63.

  The actuator 54 of the ink jet head 2 is configured by a unimorph type piezoelectric diaphragm in which a piezoelectric element 55 and a diaphragm 56 are laminated, for example. The piezoelectric element 55 is made of a piezoelectric ceramic material such as PZT (lead zirconate titanate). The diaphragm 56 is made of, for example, SiN (silicon nitride).

  As shown in FIGS. 4 and 5, the piezoelectric element 55 includes electrodes 55a and 55b on the upper and lower sides. When no voltage is applied to the electrodes 55a and 55b, the piezoelectric element 55 does not deform as shown in FIG. 4, so the actuator 54 does not deform. When the actuator 54 is not deformed, a meniscus 290 that is an interface between the ink I and air is formed in the nozzle 51 by the surface tension of the ink. The ink I in the ink pressure chamber 150 remains in the nozzle 51 by the meniscus 290.

  When voltage (V) is applied to the electrodes 55a and 55b, the piezoelectric element 55 is deformed and the actuator 54 is deformed as shown in FIG. Due to the deformation of the actuator 54, the pressure applied to the meniscus 290 becomes higher than the air pressure (positive pressure), and the ink I breaks the meniscus 290 to become an ink droplet ID and is ejected from the nozzle 51.

  The structure of the inkjet head 2 is not limited as long as it causes pressure fluctuations in the ink in the ink pressure chamber. The ink jet head may have, for example, a structure that discharges ink droplets by deforming a vibration plate with static electricity, or a structure that discharges ink droplets from nozzles using thermal energy of a heater or the like. Further, since the viscosity of the ink changes depending on the temperature and the discharge characteristics from the nozzles change, the ink jet head may be provided with a temperature sensor in order to control the ink discharge well.

  For example, as shown in FIGS. 6 and 7, the ink circulation device 3 of the ink jet recording unit 4 includes an ink casing 70 that is a liquid chamber and an ink chamber, an ink circulation unit 76, and a pressure adjustment unit 90 that is a gas replenishment unit. Prepare. The ink circulation device 3 circulates and supplies ink to the inkjet head 2 and adjusts the pressure in the ink pressure chamber 150 of the inkjet head 2. The ink circulation device 3 adjusts the pressure of the ink pressure chamber 150 to adjust the pressure of the meniscus 290 of the nozzle 51. The ink circulation device 3 circulates and supplies ink to the inkjet head 2 to absorb bubbles contained in the ink I or remove foreign matters.

  In the inkjet head 2, if the pressure applied to the meniscus 290 of the nozzle 51 is higher than the air pressure (positive pressure), the ink I leaks from the nozzle 51. If the pressure applied to the meniscus 290 is lower than the air pressure (negative pressure), the ink I maintains the meniscus 290 and remains in the nozzle 51. For example, when the pressure in the ink pressure chamber 150 is adjusted to −0.5 to −4.0 kPa, the inkjet head 2 maintains the meniscus 290 and does not eject ink from the nozzles 51.

  For example, when the nozzle 51 is arranged so that the ink I is ejected in the direction of gravity (downward), when the pressure in the ink pressure chamber 150 is greater than −0.5 to −4.0 kPa (positive pressure side), it is slightly Ink I leaks from the nozzles 51 due to the vibration. In addition, when the pressure in the ink pressure chamber 150 is lower than −0.5 to −4.0 kPa (negative pressure side), bubbles are sucked from the nozzle 51 to cause ink ejection failure. The ink circulation device 3 maintains the pressure of the meniscus 290 in the range of −0.5 to −4.0 kPa to prevent unnecessary ink leakage or air bubble suction.

  The ink casing 70 includes an ink collection chamber 71 that collects the ink I from the inkjet head 2, and an ink supply chamber 72 that supplies the ink I to the inkjet head 2. The ink recovery chamber 71 and the ink supply chamber 72 are adjacent to each other through a common wall 73. The ink casing 70 is sealed against the outside air. The ink recovery chamber 71 and the ink supply chamber 72 hold the ink I downward via the first liquid level α1 or the second liquid level α2, respectively. The ink recovery chamber 71 and the ink supply chamber 72 form a first air chamber β1 or a second air chamber β2 upward via the first α1 or the second liquid level α2, respectively.

  The ink collection chamber 71 includes an ink return pipe 71 a that communicates with the ink discharge port 170 of the inkjet head 2 and returns the ink I from the inkjet head 2 to the ink collection chamber 71. The ink collection chamber 71 includes an ink supply pump 71 b for replenishing new ink from the ink cartridge 81 via the tube 82. The ink supply pump 71b is a liquid replenishment unit and constitutes an ink replenishment unit. The ink recovery chamber 71 includes a liquid supply hole 71 c for supplying ink to the ink circulation unit 76. The ink recovery chamber 71 includes a first communication hole 71 d that communicates with the first pressure adjustment unit 91 of the pressure adjustment unit 90.

  The ink supply chamber 72 includes an ink supply pipe 72 a that communicates with the ink supply port 160 of the inkjet head 2 and flows the ink I into the inkjet head 2. The ink supply chamber 72 includes a discharge hole 72 b through which the ink I fed from the ink circulation unit 76 is discharged. The ink supply chamber 72 includes a second communication hole 72 c that communicates with the second pressure adjustment unit 92 of the pressure adjustment unit 90.

  The structure of the ink recovery chamber or the ink supply chamber is not limited as long as ink can be circulated favorably with the ink jet head. For example, a heater for heating the ink may be provided so as to keep the temperature of the ink within a predetermined range.

  By disposing the ink cartridge 81 relatively below the ink circulation device 3 in the gravity direction, the water head pressure of the ink in the ink cartridge 81 is kept lower than the set pressure of the ink recovery chamber 71. By disposing the ink cartridge 81 below the ink circulation device 3, the ink cartridge 81 supplies new ink to the ink collection chamber 71 only when the ink supply pump 71b is driven.

  The ink supply pump 71b is, for example, a piezoelectric pump. The ink supply pump 71b periodically changes the volume in the pump (volume of the pump chamber) by bending of the piezoelectric vibration plate in which the piezoelectric element and the metal plate are bonded. The ink supply pump 71b has the volume of the pump chamber Ink is transferred from the ink cartridge 81 to the pump chamber due to the change. The ink supply pump 71 b causes the ink conveyance direction to be one direction from the ink cartridge 81 to the ink collection chamber 71 by a check valve. In the ink supply pump 71b, when the pump chamber expands due to the deflection of the piezoelectric diaphragm, ink flows into the pump chamber. Ink supply pump 71b causes ink to flow out of the pump chamber when the pump chamber contracts due to the deflection of the piezoelectric diaphragm. The ink supply pump 71b repeats expansion and contraction of the pump chamber and sends ink from the ink cartridge 81 to the ink recovery chamber 71.

  The arrangement position of the ink cartridge 81 is not limited. For example, when the ink cartridge 81 is arranged at a position higher than the ink circulation device 3, the water head pressure of the ink in the ink cartridge 81 becomes higher than the set pressure of the ink recovery chamber 71. When the ink cartridge 81 is arranged at a position higher than the ink circulation device 3, ink can be supplied from the ink cartridge 81 to the ink collection chamber 71 by opening and closing the electromagnetic valve using the water head difference.

  The ink circulation unit 76 of the ink circulation device 3 includes a circulation path 76 a that reaches the discharge hole 72 b of the ink supply chamber 72 from the liquid supply hole 71 c of the ink recovery chamber 71 as shown in FIG. 7. The ink circulation unit 76 includes a circulation pump 77 and a filter 78 on the circulation path 76a. The circulation pump 77 is provided across the adjacent ink recovery chamber 71 and ink supply chamber 72. The circulation pump 77 circulates the ink I from the ink recovery chamber 71 to the ink recovery chamber 71 through the ink supply chamber 72 and the inkjet head 2 as indicated by an arrow J. The ink circulation unit 76 sucks ink from the liquid feeding hole 71c, and sends the ink I to the ink supply chamber 72 through the discharge hole 72b. As the circulation pump 77, for example, a tube pump, a diaphragm pump, or a piston pump is used.

  The filter 78 is, for example, downstream of the circulation pump 77 in the circulation path 76a in the circulation direction, and removes foreign matters mixed in the ink I. As the filter 78, for example, a mesh filter such as polypropylene, nylon, polyphenylene sulfide, or stainless steel is used.

  While ink is circulated from the ink collection chamber 71 to the ink supply chamber 72 by the ink circulation section 76, the bubbles in the ink I rise in the direction opposite to the gravity direction (upward) due to buoyancy. Bubbles rising due to buoyancy reach the air chambers β1 and β2 above the first liquid surface α1 of the ink recovery chamber 71 or the second liquid surface α2 of the ink supply chamber 72 and are removed.

  As shown in FIG. 7, the ink circulation device 3 includes a first ink amount sensor (liquid level sensor) 88 a that measures the ink amount in the ink collection chamber 71 and a second ink that measures the ink amount in the ink supply chamber 72. A quantity sensor (liquid level sensor) 88b is provided. The first ink level sensor (liquid level sensor) 88a or the second ink level sensor (liquid level sensor) 88b, for example, vibrates a piezoelectric diaphragm with an alternating voltage, thereby causing the ink recovery chamber 71 or the ink supply chamber 72 to move. The amount of ink is measured by detecting the vibration of the transmitted ink. The structure of the ink amount sensor is not limited, and may be a structure that measures the height of the first liquid level α1 or the second liquid level α2.

  As shown in FIG. 7, the ink circulation device 3 is connected to a first pressure sensor 91 b that communicates with the first communication hole 71 d of the ink recovery chamber 71 and a second communication hole 72 c of the ink supply chamber 72. Pressure sensor 92b. The first pressure sensor 91b detects the pressure of the first air chamber β1 of the ink recovery chamber 71. The second pressure sensor 92b detects the pressure of the second air chamber β2 of the ink supply chamber 72. The structure of the pressure sensors 91b and 92b is not limited. The pressure sensors 91b and 92b output the air pressure of the first air chamber β1 or the second air chamber β2 as an electrical signal using, for example, a semiconductor piezoresistive pressure sensor. The semiconductor piezoresistive pressure sensor includes a diaphragm that receives pressure from the outside and a semiconductor strain gauge formed on the surface of the diaphragm, and an electric due to the piezoresistive effect generated in the strain gauge as the diaphragm is deformed by the pressure from the outside. A change in resistance is converted into an electrical signal to detect pressure.

  The first pressure adjusting unit 91 of the ink circulation device 3 includes a first pressure adjusting pump 91a, and the second pressure adjusting unit 92 includes a second pressure adjusting pump 92a. The pressure adjusting pumps 91a and 92a send air to the ink recovery chamber 71 or the ink supply chamber 72, respectively, to increase the pressure in the circulation path 76a. The first or second pressure adjusting pumps 91a and 92a release the air in the ink collection chamber 71 or the ink supply chamber 72 to the outside, respectively, to reduce the pressure in the circulation path 76a. For example, a tube pump or a bellows pump can be used as the pressure adjusting pumps 91a and 92a.

  A control system 200 for controlling the operation of the inkjet recording apparatus 1 will be described with reference to the block diagram shown in FIG. The control board 500 of the control system 200 is a control unit, which is a microcomputer 510 that controls the entire inkjet recording apparatus 1, a recording unit drive circuit 540 that drives the inkjet recording apparatus 1, an amplification circuit 541, and a recording medium moving unit 7. Is provided with a moving unit driving circuit 542. The microcomputer 510 includes a memory 520 that stores a program or various data, and an AD conversion unit 530 that captures an output voltage from the inkjet recording unit 4.

  The control board 500 is connected to a power source 550, a display device 560 that displays the status of the inkjet recording apparatus 1, and a keyboard 570 as an input device. The control substrate 500 is connected to the drive unit and the detection unit of the inkjet recording unit 4. The control board 500 is connected to the pump 104 and the slide rail device 105 of the recording medium moving unit 7, the drive unit of the maintenance unit 310, and the carriage motor 102 of the conveyance belt 101.

  When the ink jet recording apparatus 1 is first printed, the ink I is filled into the ink jet recording unit 4 from the ink cartridge 81. In order to fill the ink I, the microcomputer 510 returns the ink jet recording unit 4 to the standby position, raises the maintenance unit 310 in the arrow D direction, and covers the nozzle plate 52. The microcomputer 510 drives the ink supply pump 71 b to send ink from the ink cartridge 81 to the ink collection chamber 71. When the ink I reaches the liquid feed hole 71 c in the ink recovery chamber 71, the microcomputer 510 adjusts the pressure of the ink casing 70 by the pressure adjusting unit 90 and drives the circulation pump 77. When the ink I reaches the liquid feed hole 71c of the ink recovery chamber 71 and the discharge hole 72b of the ink supply chamber 72, the microcomputer 510 completes the initial filling of the ink I.

  The inkjet recording apparatus 1 initially uses the cyan ink, magenta ink, yellow ink, black ink, and white ink of the respective ink cartridges 81a, 81b, 81c, 81d, and 81e to the inkjet recording units 4a, 4b, 4c, 4d, and 4e, respectively. Fill.

  When the initial filling of the ink I is completed, the pressure in the ink casing 70 is maintained at a negative pressure so that the ink I does not leak from the nozzle 51 of the inkjet head 2 and air bubbles are not sucked from the nozzle 51. The negative pressure of the ink casing 70 causes the nozzle 51 to maintain a negative meniscus 290. Negative pressure is the pressure when the atmospheric pressure is zero. Even when the power supply 550 of the inkjet recording apparatus 1 is turned off in the state where the initial filling of the ink I is completed, the ink casing 70 is in a sealed state, and the meniscus 290 in the nozzle 51 is maintained at a negative pressure to prevent ink leakage. .

  When printing is started, the microcomputer 510 controls the recording medium moving unit 7 to attract and fix the recording medium S to the table 103, and reciprocates the table 103 in the arrow B direction. The microcomputer 510 moves the maintenance unit 310 in the direction of arrow C, controls the carriage motor 102 to convey the carriage 100 in the direction of the recording medium S, and reciprocates in the direction of arrow A.

  For example, the microcomputer 510 selectively drives the actuator 54 of the inkjet head 2 by an image signal corresponding to the image data stored in the memory 520 and ejects the ink droplet ID from the nozzle 51 to the recording medium S. The microcomputer 510 drives the circulation pump 77 to circulate the ink I returned from the inkjet head 2 to the inkjet head 2 through the ink recovery chamber 71, the filter 78, and the ink supply chamber 72. The ink jet recording unit 4 circulates the ink I, thereby removing bubbles and foreign matters mixed in the ink I, maintaining good ink ejection performance, and improving the print image quality of the ink jet recording unit 4.

  The pressure of the ink casing 70 varies due to the discharge of the ink droplet ID from the nozzle 51 or the driving of the circulation pump 77. The microcomputer 510 adjusts the pressure of the ink casing 70 in order to maintain the pressure of the ink casing 70 in a stable range where ink leaks from the nozzles 51 or bubbles are not sucked from the nozzles 51. The microcomputer 510 adjusts the pressure of the ink casing 70 by switching the driving of the pressure adjusting unit 90 and the ink supply pump 71b.

  For example, when the ink droplet ID is ejected from the nozzle 51 during printing, the ink amount in the ink casing 70 is instantaneously reduced, and the pressure in the ink recovery chamber 71 is reduced. When the first pressure sensor 91b detects a decrease in the pressure in the ink recovery chamber 71, the microcomputer 510 causes the first pressure sensor 91b, the second pressure sensor 92b, the first ink amount sensor (liquid level sensor) 88a, and Based on the detection result of the second ink amount sensor (liquid level sensor) 88b, the pressure adjusting unit 90 or the ink supply pump 71b is driven. When the pressure applied to the nozzle 51 is not in the stable range, the microcomputer 510 takes outside air into the ink casing 70 or ink recovery chamber according to the height of the first liquid level α1 or the second liquid level α2. The pressure applied to the nozzle 51 is adjusted by switching whether or not new ink is supplied to 71.

  The adjustment control of the pressure applied to the nozzle 51 will be described with reference to FIGS. In the ink jet recording unit 4, the lower limit value of the stable range of the pressure value P of the nozzle 51 that does not leak ink from the nozzle 51 or suck air bubbles from the nozzle 51 is set to Pt1 and the upper limit value is set to Pt2, for example. After the power source 550 is turned on at time t1, as shown in FIG. 9, when the pressure value P of the nozzle 51 is lower than the lower limit value Pt1, the microcomputer 510 adjusts the pressure inside the ink casing 70.

  The pressure adjustment is performed by switching whether to take outside air into the ink casing 70 or to replenish new ink from the ink cartridge 81 to the ink collection chamber 71. When the pressure value P of the nozzle 51 reaches the range between the lower limit value Pt1 and the upper limit value Pt2 at time t2, the microcomputer 510 stops pressurization adjustment. In order to adjust the pressure of the nozzle 51, new ink is replenished to the ink casing 70. That is, the ink jet recording unit 4 replenishes the ink recovery chamber 71 with new ink when adjusting the pressure of the nozzle 51 during printing by discharging the ink I from the nozzle 51.

  When the pressure value P of the nozzle 51 becomes higher than the upper limit value Pt2 at time t3 in FIG. 9, the microcomputer 510 discharges the air in the ink casing 70 to the outside and adjusts the nozzle 51 to reduce the pressure. When the pressure value P of the nozzle 51 reaches the range between the lower limit value Pt1 and the upper limit value Pt2 at time t4, the microcomputer 510 stops the pressure reduction adjustment.

  When the power supply 550 of the inkjet recording apparatus 1 is turned on, the microcomputer 510 starts the pressure adjustment of the nozzle 51 according to the flowchart of FIG. The microcomputer 510 determines whether the pressure value P of the nozzle 51 is in the range of Pt1 ≦ P ≦ Pt2 from the detection results of the first pressure sensor 91b and the second pressure sensor 92b (ACT100). The determination of the range of the pressure value P of the nozzle 51 may be determined from the detection result of either the first pressure sensor 91b or the second pressure sensor 92b.

  When the pressure value P of the nozzle 51 is not in the range of Pt1 ≦ P ≦ Pt2 (No in ACT100), the microcomputer 510 determines whether the pressure value P of the nozzle 51 is larger than the upper limit value Pt2 (ACT101). When the pressure value P of the nozzle 51 is less than the upper limit value Pt2 (No in ACT101), the microcomputer 510 determines whether the first liquid level α1 and the second liquid level α2 are higher than the height f (ACT103). . The height f is arbitrary and may be higher than the liquid feeding hole 71c and the discharge hole 72b of the ink casing 70. Further, the determination of the height f of the ACT 103 is arbitrary, such as determination based on the height of one of the first liquid level α1 and the second liquid level α2.

  If the first liquid level α1 and the second liquid level α2 are higher than the height f (Yes in ACT103), the microcomputer 510 proceeds to (ACT104). In ACT 104, the microcomputer 510 pressurizes and adjusts the pressure of the nozzle 51 by driving the first pressure adjusting pump 91a and the second pressure adjusting pump 92a to take outside air into the ink casing 70. When the pressure value P of the nozzle 51 reaches the range of Pt1 ≦ P ≦ Pt2 in ACT 104, the microcomputer 510 ends the pressure adjustment of the nozzle 51. When adjusting the pressure of the ACT 104, the pressure of the nozzle 51 may be adjusted by taking outside air from either the first pressure adjusting pump 91a or the second pressure adjusting pump 92a.

  When the first liquid level α1 and the second liquid level α2 are not more than the height f (No in ACT103), the microcomputer 510 proceeds to (ACT105). In ACT 105, the microcomputer 510 pressurizes and adjusts the pressure of the nozzle 51 by driving the ink supply pump 71 b to replenish new ink I from the ink cartridge 81 into the ink collection chamber 71. When the pressure value P of the nozzle 51 reaches the range of Pt1 ≦ P ≦ Pt2 in ACT 105, the microcomputer 510 ends the pressure adjustment of the nozzle 51.

  That is, when the pressure value P of the nozzle 51 is less than the lower limit value Pt1 (No in ACT101), the microcomputer 510 performs the first pressure adjustment pump 91a and the second pressure adjustment according to the amount of ink in the ink casing 70. By switching between driving of the pump 92a and driving of the ink supply pump 71b, the pressure value P of the nozzle 51 is pressurized and adjusted. If the amount of ink in the ink casing 70 is reduced during pressure adjustment, the microcomputer 510 replenishes the ink casing 70 with new ink I from the ink cartridge 81. By increasing the volume of the ink I in the ink casing 70, the pressure value P of the nozzle 51 is adjusted by pressurization. The ink I in the ink casing 70 maintains the height f. The ink jet recording unit 4 can replenish the ink collection chamber 71 with new ink by adjusting the pressure of the nozzle 51 without stopping the printing operation.

  In ACT101, when the pressure value P of the nozzle 51 is equal to or higher than the upper limit value Pt2 (Yes in ACT101), the microcomputer 510 proceeds to ACT102. In ACT 102, the microcomputer 510 drives the first pressure adjustment pump 91 a and the second pressure adjustment pump 92 a to discharge the air in the ink casing 70, thereby reducing the pressure of the nozzle 51. When the pressure value P of the nozzle 51 reaches the range of Pt1 ≦ P ≦ Pt2, the microcomputer 510 ends the pressure adjustment of the nozzle 51.

  The ink jet recording unit 4 maintains the pressure value P of the nozzle 51 in the range of Pt1 ≦ P ≦ Pt2, maintains the good ink ejection characteristics of the nozzle 51, and improves the image quality. The ink jet recording unit 4 maintains the pressure value P of the nozzle 51 in the range of Pt1 ≦ P ≦ Pt2 to prevent unnecessary ink leakage from the nozzle 51 or air bubble suction.

  The pressure adjustment of the nozzle 51 shown in FIG. 10 is always performed at an arbitrary timing designated by the microcomputer 510.

  According to the embodiment, the ink jet recording unit 4 circulates the ink I by the ink circulation device 3 to remove bubbles or foreign matters contained in the ink I. The ink ejection performance of the ink jet head 2 is maintained well, and the print image quality of the ink jet recording unit 4 is improved.

  According to the embodiment, in order to pressurize and adjust the pressure value P of the nozzle 51, the inkjet recording unit 4 drives the first pressure adjusting pump 91a and the second pressure adjusting pump 92a and the ink supply pump 71b. Switch between driving. The driving of the first pressure adjusting pump 91 a and the second pressure adjusting pump 92 a and the driving of the ink supply pump 71 b are switched according to the height of the ink I in the ink casing 70. When the pressure value P of the nozzle 51 is less than the lower limit value Pt1, and the height of the ink I in the ink casing 70 is higher than f, the first pressure adjusting pump 91a and the second pressure adjusting pump 92a are driven. If the height of the ink I in the ink casing 70 is higher than f, outside air is taken into the ink casing 70 and the pressure value P of the nozzle 51 is pressurized and adjusted.

  When the pressure value P of the nozzle 51 is less than the lower limit value Pt1, if the height of the ink I in the ink casing 70 is f or less, the ink supply pump 71b is driven. If the height of the ink I in the ink casing 70 is equal to or less than f, the ink collection chamber 71 is replenished with new ink, and the pressure value P of the nozzle 51 is pressurized and adjusted. The ink jet recording unit 4 can replenish new ink I from the ink cartridge 81 into the ink casing 70 even during pressure adjustment during the printing operation. The ink jet recording unit 4 can replenish the ink I in the ink casing 70 while adjusting the pressure value P of the nozzle 51 without stopping the printing operation, thereby preventing the print production efficiency of the ink jet recording apparatus 1 from being lowered. it can.

  The configuration of the liquid circulation device according to the embodiment described above is not limited. For example, if the liquid can be circulated while replenishing the liquid in the liquid chamber, the liquid chamber and the liquid discharge portion may not be formed integrally. The liquid circulation device can also discharge liquids other than ink. As a liquid ejection device that ejects materials other than ink, for example, a device that ejects liquid containing conductive particles for forming a wiring pattern of a printed wiring board may be used.

  Although the embodiment of the present invention has been described, the embodiment is presented as an example, and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Inkjet recording device 2 ... Inkjet head 3 ... Ink circulation device 4 ... Inkjet recording part 70 ... Ink casing 71 ... Ink collection chamber 71b ... Ink supply pump 72 ... Ink supply chamber 77 ... Circulation pump 81 ... Ink cartridge 90 ... Pressure adjustment Part 510: Microcomputer

Claims (6)

A liquid recovery chamber for recovering the liquid from the liquid discharge section, the liquid supply chamber for supplying the liquid to the liquid discharge section; A liquid casing constituting a liquid chamber having
A liquid level sensor for detecting the liquid level in the liquid recovery chamber and the liquid level in the liquid supply chamber,
A liquid replenishing unit for replenishing the liquid casing with a new liquid;
A gas replenishment unit that is directly connected to the liquid supply chamber and replenishes the liquid casing with a gas;
Replenishing the liquid casing with the new liquid in the liquid replenishing unit;
And supplemented child the gas to the liquid casing in the gas replenishment unit,
To adjust the pressure in the liquid casing by pressurization ,
When the liquid level in the liquid supply chamber is higher than a predetermined height, the pressure in the liquid supply chamber is adjusted by the gas replenishment unit, and the liquid level in the liquid recovery chamber or the liquid level in the liquid supply chamber is predetermined. A liquid circulation device that adjusts the pressure in the liquid recovery chamber or the liquid supply chamber under pressure by the liquid replenishing unit .   The liquid circulation device according to claim 1, wherein the liquid casing is formed on the liquid discharge unit and is formed integrally with the liquid discharge unit. A pressure sensor for detecting a pressure value of the liquid ejection unit;
3. The pressure in the liquid casing is pressurized and adjusted by the gas replenishing unit or the liquid replenishing unit when the pressure value of the liquid ejection unit is less than a predetermined value. The liquid circulation apparatus as described. A liquid recovery chamber for recovering the liquid from the liquid discharge section, the liquid supply chamber for supplying the liquid to the liquid discharge section; A liquid casing constituting a liquid chamber having
A liquid replenishing unit for replenishing the liquid casing with a new liquid;
A gas replenishment unit that is directly connected to the liquid supply chamber and replenishes the liquid casing with a gas;
The liquid casing is provided on the liquid discharge section;
Replenishing the liquid casing with the new liquid in the liquid replenishing unit;
Replenishing the liquid casing with the gas at the gas replenishment section;
A liquid circulation device that pressurizes and adjusts the pressure in the liquid casing. The liquid circulation device according to claim 4, wherein the liquid casing is formed integrally with the liquid discharge unit. A liquid circulation device according to any one of claims 1 to 5 ,
A liquid discharge recording apparatus comprising: a transport unit that transports a recording medium to a position at which the liquid is discharged from the liquid discharge unit.

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