JP2017114091A - Inkjet recording device - Google Patents

Abstract

An ink jet recording apparatus capable of smoothly supplying ink to a circulation channel while circulating the ink through the circulation channel.
An ink jet recording apparatus includes a main tank, an ink jet head, a circulation flow channel, a liquid feeding unit, a replenishment flow channel, and a replenishment valve. The circulation channel circulates the supplied ink from the main tank through the supply channel. The circulation channel includes a first supply channel 61, a second supply channel 62, a first manifold 65, a first recovery channel 67, a second recovery channel 68, a second manifold 70, and a connection channel 75. The ink that has flowed through the first recovery flow path flows into the second manifold, and the ink that has flowed through the second recovery flow path flows into the second manifold. The liquid feeding part is provided in a connection channel that connects the second manifold and the first manifold. In the second manifold, the channel cross-sectional area of the common channel of the second manifold is larger than the channel cross-sectional area of the connection channel, and the supply channel connects the main tank and the common channel.
[Selection] Figure 1

Description

  The present invention relates to an ink jet recording apparatus.

  A technique related to an ink jet recording apparatus has been proposed. For example, Patent Document 1 discloses an ink jet printing apparatus. In the ink jet printing apparatus, the upper ink tank and the ink supply chamber are connected via an ink supply path. The ink recovery chamber, the lower ink tank, the pump, the temperature controller, and the upper ink tank are connected via an ink recovery path. When the lower ink tank is maintained at atmospheric pressure, the height position of the lower ink tank is determined so as to obtain an appropriate pressure at which a meniscus is generated in the nozzle due to a difference in water head between the lower ink tank and the nozzle of the inkjet head. A pressure adjusting unit provided in the lower ink tank depressurizes the air layer in the upper part of the lower ink tank. The ink in the upper ink tank is supplied into the ink supply chamber through the ink supply path. The ink is distributed from the ink supply chamber to a plurality of ink jet heads, and is ejected from each ink jet head onto the printing paper. Excess ink is temporarily stored in the lower ink tank from the ink recovery chamber through the ink recovery path, and is supplied to the upper ink tank via the temperature controller. The lower ink tank is connected to the ink bottle, and the ink in the ink bottle is supplied to the lower ink tank by turning on the third electromagnetic valve.

Japanese Patent No. 5406778

  In an ink jet recording apparatus, ink is ejected from nozzles of an ink jet head. According to the ink jet recording apparatus, an image can be recorded on a recording medium with high quality. The inventor studied an ink jet head having a structure formed by a plurality of head portions. In that case, the inventor considered the structure which provides a sub tank with respect to each head part. The sub tank stores the ink supplied from the main tank. The ink stored in the sub tank flows out of the sub tank and is supplied to the head unit. In the ink jet recording apparatus, by forming a stable meniscus on the nozzles of each head unit, it is possible to realize preferable ink discharge and to stabilize the quality of the recorded image. In order to stabilize the meniscus, for example, the amount of ink stored in the sub tank is adjusted to a predetermined range in a state where the space in which the ink is stored in the sub tank is maintained at a pressure lower than atmospheric pressure (negative pressure). There is a need.

  The ink is formed by, for example, dispersing predetermined components such as a colorant and an additive in a solvent. The contained component has a predetermined specific gravity. All or some of the contained components have a specific gravity greater than that of the solvent. Therefore, sedimentation of contained components may occur in the ink existing inside the ink jet recording apparatus. Such sedimentation is likely to occur, for example, when an ink jet recording apparatus does not record an image and the ink continuously stagnates in a certain place. When the contained component settles, the density changes, and quality deterioration such as density unevenness or distortion and deterioration of color reproducibility may occur in the ejection result.

  In the ink jet recording apparatus, when image recording is executed, the ink stored in the sub tank decreases. In an ink jet recording apparatus, ink may be forcibly ejected from nozzles formed in each head portion. Such ink ejection is performed to prevent nozzle clogging. When ink is forcibly ejected from the nozzle of the head unit, the ink stored in the sub tank decreases. The inventor is able to supply ink to the circulation channel in order to adjust the amount of ink stored in the sub-tank while circulating the ink through the circulation channel to suppress sedimentation of the ink-containing components. Study was carried out.

  An object of the present invention is to provide an ink jet recording apparatus capable of smoothly supplying ink to a circulation channel while circulating the ink through the circulation channel.

  In one aspect of the present invention, an ink jet head including a main tank for storing ink, a first nozzle and a second nozzle for discharging the ink, and the ink replenished from the main tank flows, and the first nozzle A circulation channel for circulating the ink ejected from the second nozzle, a liquid feeding unit that is provided in the circulation channel and flows the ink through the circulation channel, the main tank, and the circulation channel A replenishing passage through which the ink replenished from the main tank to the circulation passage flows, and a replenishing valve provided in the replenishing passage to open and close the replenishing passage. Is a first head part in which the first nozzle is formed, a first sub tank for storing the ink supplied to the first head part, and a second head in which the second nozzle is formed. And a second sub tank that stores the ink supplied to the second head portion, and the circulation channel is connected to the first sub tank, and the ink supplied to the first sub tank flows through the second sub tank. A first supply channel, the second sub-tank, the second supply channel through which the ink supplied to the second sub-tank flows, the first supply channel and the second supply channel, The ink that flows out from the first head portion is connected to the first manifold and the first head portion, which causes the ink to flow out to the first supply passage and the ink to flow out to the second supply passage. A first recovery channel, a second recovery channel that is connected to the second head portion and through which the ink flowing out from the second head portion flows, and the first recovery channel and the second recovery channel are connected. The first recovery channel The ink that has flowed in, the ink that has flowed through the second recovery flow path, and the second manifold, the second manifold, and the first manifold are connected, and the second manifold is connected to the first manifold. A liquid flow path, the liquid supply section is provided in the flow path, and the second manifold flows from the first recovery flow path and the second recovery flow path. The flow passage cross-sectional area of the common flow passage of the second manifold through which the ink flowing out to the connection flow passage flows is larger than the flow passage cross-sectional area of the connection flow passage. The inkjet recording apparatus is connected to the common flow path at an end opposite to the tank side.

  For example, the connection position of the replenishment flow path with respect to the circulation flow path can be a predetermined position of the connection flow path between the liquid feeding unit and the first manifold. In such a configuration (comparative example), when ink flows from the main tank into the connection channel via the replenishment channel, the pressure of the ink increases, and the ink may flow into the first manifold all at once. As a result, it is assumed that a large amount of ink flows from the first manifold to the first supply channel and the second supply channel and is supplied to the first sub tank and the second sub tank in a short time. When a large amount of ink is supplied to the first sub tank in a short time, the pressure in the first sub tank may fluctuate. When the pressure in the first subtank fluctuates, the meniscus formed in the first nozzle becomes unstable, and ink ejection from the first nozzle may be hindered. When a large amount of ink is supplied to the second sub tank in a short time, the pressure in the second sub tank may fluctuate. When the pressure in the second subtank fluctuates, the meniscus formed in the second nozzle becomes unstable, and ink ejection from the second nozzle may be hindered.

  In the above-described ink jet recording apparatus, the increase in ink pressure associated with ink replenishment can be suppressed by connecting the replenishment flow path to the common flow path of the second manifold having a flow path cross-sectional area larger than that of the connection flow path. it can. Furthermore, since the replenished ink is then fed through the connecting flow path via the liquid feeding unit, the amount of ink flowing into the first manifold can be maintained in a constant state. Therefore, according to the above-described ink jet recording apparatus, the pressure in the first sub tank and the pressure in the second sub tank can be reduced when ink is supplied from the main tank to the circulation flow path without separately providing a configuration for suppressing an increase in ink pressure. It can suppress that a pressure fluctuates. The configuration of the ink jet recording apparatus can be simplified. The distance that the replenished ink flows before reaching the first head portion and the second head portion can be made longer than the configuration of the comparative example. Before the ink reaches the first head portion and the second head portion, the temperature of the ink can be naturally increased.

  The inkjet recording apparatus is provided in the first sub tank and heats the ink stored in the first sub tank, and the ink provided in the second sub tank and stored in the second sub tank. And a second heating unit that heats. Furthermore, the inkjet recording apparatus may include a third heating unit that is provided in the first manifold and heats the ink that has flowed into the first manifold. According to this configuration, the ink supplied to the first head unit is heated by the first sub tank and / or the first manifold, and the temperature of the ink can be adjusted to a temperature suitable for ejection from the first nozzle. it can. The ink supplied to the second head portion is heated by the second sub tank and / or the first manifold, and the temperature of the ink can be adjusted to a temperature suitable for ejection from the second nozzle.

  According to the present invention, it is possible to obtain an ink jet recording apparatus capable of smoothly supplying ink to the circulation channel while circulating the ink through the circulation channel.

It is sectional drawing which shows an example of schematic structure of an inkjet recording device.

  Embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the configurations described below, and various configurations can be employed in the same technical idea. For example, some of the configurations shown below may be omitted or replaced with other configurations. Other configurations may be included.

<Inkjet recording apparatus>
In the ink jet recording apparatus 10, images are recorded on various recording media. Examples of the recording medium include fabric or building materials. Inks used for image recording are, for example, four colors of black, magenta, yellow, and cyan. However, you may make it use the ink of a different color from these inks of each color. The number of ink colors may be three or less or five or more. The embodiment will be described without distinguishing ink colors. In FIG. 1, the illustration regarding each part 15, 20, 60, 77, 80, 81 for every color is simplified. Hatching indicates a cross-sectioned portion.

  The inkjet recording apparatus 10 includes a main tank 15, an inkjet head 20, a circulation channel 60, a liquid feeding unit 77, a supply channel 80, a supply valve 81, and a control device 90. The main tank 15 stores ink. The inkjet head 20 includes a plurality of nozzles 24, 25, and 26. The inkjet head 20 ejects ink from a plurality of nozzles 24, 25, and 26. The ink supplied (supplied) from the main tank 15 flows through the circulation channel 60. The ink ejected from the plurality of nozzles 24, 25, 26 is circulated by the circulation channel 60. Other description regarding the inkjet head 20 and the circulation flow path 60 will be described later. The liquid feeding unit 77 is provided in the circulation channel 60 and causes ink to flow through the circulation channel 60. The ink is circulated through the circulation channel 60 by the liquid feeding unit 77. As the liquid feeding unit 77, a known pump is exemplified. However, a known mechanism different from the pump can be employed as the liquid feeding unit 77.

  The supply channel 80 connects the main tank 15 and the circulation channel 60. Ink supplied from the main tank 15 to the circulation channel 60 flows through the supply channel 80. The supply valve 81 is provided in the supply flow path 80. The supply valve 81 is an electromagnetic valve and opens and closes the supply flow path 80. The replenishing valve 81 is opened when ink is replenished from the main tank 15 to the circulation channel 60. The replenishment valve 81 is closed when stopping the replenishment of ink from the main tank 15 to the circulation flow path 60.

  The control device 90 includes a control unit 91, a connection interface 92, and a power source 93. In the embodiment, the connection interface 92 is described as “connection I / F 92”. The control unit 91 controls various operations executed by the inkjet recording apparatus 10. For example, the control unit 91 controls the ejection of ink from the inkjet head 20. The controller 91 controls the opening and closing of the replenishing valve 81. The control unit 91 includes, for example, a CPU, a storage unit, and a RAM. The CPU executes arithmetic processing. The storage unit is, for example, a nonvolatile memory and / or a hard disk. The storage unit stores programs for various operations executed by the inkjet recording apparatus 10. The RAM serves as a work area when the CPU executes the program stored in the storage unit.

  A replenishment valve 81 is connected to the connection I / F 92. In addition, detectors 49, 50, and 51 are connected to the connection I / F 92. An opening signal and a closing signal output from the control unit 91 are output from the connection I / F 92 to the supply valve 81. The liquid level signal output from each of the detectors 49, 50 and 51 is input to the control device 90 via the connection I / F 92. The liquid level signal is output from the connection I / F 92 to the controller 91. Heating units 52, 53, 54 and 55 are connected to the power source 93. The power source 93 supplies power to the heating units 52, 53, 54, and 55. The detectors 49, 50, 51 and the liquid level signal and the heating units 52, 53, 54, 55 will be described later. In FIG. 1, the connection I / F 92, the detectors 49, 50, 51 and the replenishment valve 81 are connected, and the illustration of the electrical wiring connecting the power source 93 and the heating units 52, 53, 54, 55 is omitted.

<Inkjet head>
The inkjet head 20 includes a plurality of head portions, a carriage 42, and a plurality of sub tanks. In the inkjet head 20, one sub tank is provided for one head portion. In the embodiment, the number of head portions provided in one inkjet head 20 is three. Therefore, the number of sub tanks provided in one inkjet head 20 is three. The three head portions are referred to as “head portion 21”, “head portion 22”, and “head portion 23”. The three sub tanks are referred to as “sub tank 43”, “sub tank 44”, and “sub tank 45”. The sub tank 43 is provided for the head unit 21. The sub tank 44 is provided for the head unit 22. The sub tank 45 is provided for the head portion 23. The number of head portions and the number of sub-tanks included in one inkjet head 20 may be two or four or more. The number of head portions and the number of sub-tanks included in one inkjet head 20 are appropriately determined in consideration of various conditions.

  The head parts 21, 22, and 23 have the same configuration. The sub tanks 43, 44, and 45 have the same configuration. In the embodiment, the sub tank 43 is attached to the upper side of the head portion 21 in the vertical direction. The sub tank 44 is attached to the upper side of the head portion 22 in the vertical direction. The sub tank 45 is attached to the upper side of the head portion 23 in the vertical direction. The head portions 21, 22, and 23 are mounted on the carriage 42 with the sub tanks 43, 44, and 45 attached thereto. In the head portion 21, a plurality of nozzles 24, an inlet 27, an outlet 30, and an internal flow path 33 are formed. In the head portion 22, a plurality of nozzles 25, an inlet 28, an outlet 31, and an internal channel 34 are formed. A plurality of nozzles 26, inlets 29, outlets 32, and internal flow paths 35 are formed in the head portion 23. In the inkjet head 20, ink is ejected from nozzles 24, 25, and 26 formed in the head portions 21, 22, and 23, respectively. In FIG. 1, the number of nozzles 24, 25, and 26 is four each. The number and arrangement of the nozzles 24, 25, and 26 are appropriately determined in consideration of various conditions.

  The ink supplied from the sub tank 43 to the head unit 21 flows into the head unit 21 from the inflow port 27. The ink supplied to the head unit 21 is ejected from the nozzle 24 or flows out from the outlet 30. The internal flow path 33 includes a main flow part 36 and a plurality of branch parts 39. The main flow part 36 connects the inlet 27 and the outlet 30. The branch portion 39 branches from the main flow portion 36 and is connected to the nozzle 24. That is, the ink flows into the head portion 21 from the inlet 27, flows through the main flow portion 36 toward the outlet 30, and then flows out from the outlet 30 to the circulation channel 60. A part of the ink flowing through the main flow part 36 flows into the branch part 39 and flows toward the nozzle 24.

  The ink supplied from the sub tank 44 to the head unit 22 flows into the head unit 22 from the inflow port 28. The ink supplied to the head unit 22 is ejected from the nozzle 25 or flows out from the outflow port 31. The internal flow path 34 includes a main flow part 37 and a plurality of branch parts 40. The main flow part 37 connects the inlet 28 and the outlet 31. The tributary portion 40 branches from the main flow portion 37 and is connected to the nozzle 25. That is, the ink flows into the head portion 22 from the inflow port 28, flows through the main flow portion 37 toward the outflow port 31, and then flows out from the outflow port 31 to the circulation channel 60. Part of the ink flowing through the main flow portion 37 flows into the branch portion 40 and flows toward the nozzle 25.

  The ink supplied from the sub tank 45 to the head unit 23 flows into the head unit 23 from the inflow port 29. The ink supplied to the head unit 23 is ejected from the nozzle 26 or flows out from the outflow port 32. The internal flow path 35 includes a main flow part 38 and a plurality of branch parts 41. The main flow part 38 connects the inlet 29 and the outlet 32. The branch portion 41 branches from the main flow portion 38 and is connected to the nozzle 26. That is, the ink flows into the head portion 23 from the inflow port 29, flows through the main flow portion 38 toward the outflow port 32, and then flows out from the outflow port 32 to the circulation channel 60. A part of the ink flowing through the main flow part 38 flows into the branch part 41 and flows toward the nozzle 26.

  The sub tank 43 stores the ink supplied to the head unit 21. The sub tank 44 stores the ink supplied to the head unit 22. The sub tank 45 stores the ink supplied to the head unit 23. In the embodiment, the space formed inside the sub tank 43 is referred to as a “reservoir chamber 46”. In the sub tank 43, the ink is stored in the storage chamber 46. A space formed inside the sub tank 44 is referred to as a “reservoir chamber 47”. In the sub tank 44, the ink is stored in the storage chamber 47. A space formed inside the sub tank 45 is referred to as a “reservoir chamber 48”. In the sub tank 45, the ink is stored in the storage chamber 48.

  The sub tanks 43, 44, and 45 are connected to the atmospheric pressure adjustment system, respectively. The atmospheric pressure adjustment system includes a vacuum pump and a compressor. The vacuum pump sets the pressure in the storage chambers 46, 47, and 48 to a pressure (negative pressure) lower than the atmospheric pressure. The compressor sets the pressure in the storage chambers 46, 47, and 48 to a pressure higher than the atmospheric pressure. That is, in the sub tanks 43, 44, and 45, the air pressure in the storage chambers 46, 47, and 48 in a state where ink is stored is adjusted by the air pressure adjustment system. In FIG. 1, illustration of the atmospheric pressure adjustment system is omitted.

  In the inkjet recording apparatus 10, when an image is recorded on a recording medium, the storage chambers 46, 47, and 48 are in a state of communicating with a vacuum pump. In the inkjet recording apparatus 10, when the inkjet head 20 forcibly ejects ink from the plurality of nozzles 24 of the head unit 21, the plurality of nozzles 25 of the head unit 22, and the plurality of nozzles 26 of the head unit 23, for example, The chambers 46, 47, and 48 are in communication with the compressor.

  The sub tank 43 is provided with a detector 49 and a heating unit 52. The detector 49 detects the amount of ink stored in the sub tank 43. The heating unit 52 heats the ink stored in the sub tank 43. The sub tank 44 is provided with a detector 50 and a heating unit 53. The detector 50 detects the amount of ink stored in the sub tank 44. The heating unit 53 heats the ink stored in the sub tank 44. The sub tank 45 is provided with a detector 51 and a heating unit 54. The detector 51 detects the amount of ink stored in the sub tank 45. The heating unit 54 heats the ink stored in the sub tank 45.

  As the detectors 49, 50, 51, known sensors that can detect the amount of ink stored in the sub tanks 43, 44, 45 are employed. For example, as the detectors 49, 50, 51, known liquid level sensors are employed. The type of sensor employed as the detectors 49, 50, 51 is appropriately determined in consideration of various conditions. In the embodiment, the detection of the amount of ink by the detectors 49, 50, 51 is performed by detecting the liquid level of the ink stored in the sub tanks 43, 44, 45.

  The detectors 49, 50, 51 output a liquid level signal. The liquid level signal is a detection signal indicating the level of the ink level detected by each of the detectors 49, 50, 51. The liquid level signal output from the detectors 49, 50, 51 when the amount of ink is the first amount or when the amount of ink is less than the first amount is referred to as a “lower limit value signal”. The liquid level signal output from the detectors 49, 50, 51 when the amount of ink is the second amount or when the amount of ink exceeds the second amount is referred to as an “upper limit signal”. The first amount is determined in advance as a lower limit value of the amount of ink stored in the sub tanks 43, 44, 45. For example, the first amount is set to about 5 to 20% of the volume of the storage chambers 46, 47, and 48. In the ink jet recording apparatus 10, the air pressure in the storage chambers 46, 47, 48 is increased, and the ink stored in the sub tanks 43, 44, 45 is forced from the plurality of nozzles 24, 25, 26 of the head units 21, 22, 23. When the ink is discharged, the amount of ink stored in the sub tanks 43, 44, and 45 becomes the first amount or less. The second amount is determined in advance as an upper limit value of the amount of ink stored in the sub tanks 43, 44, 45. For example, the second amount is set to about 60 to 80% of the volume of the storage chambers 46, 47, and 48.

  As the heating units 52, 53, and 54, known electric heaters are employed. For example, as the heating units 52, 53, and 54, a known sheet-shaped rubber heater is employed. When a sheet-like rubber heater is employed as the heating units 52, 53, and 54, the rubber heater is affixed to the entire circumference of the outer peripheral surfaces of the sub tanks 43, 44, and 45, respectively. The heat of the sheet-like rubber heater conducts heat to the sub tanks 43, 44, and 45, respectively, and the sub tanks 43, 44, and 45 are heated by this heat. Accordingly, the ink stored in the sub tanks 43, 44, 45 is heated.

<Circulation channel>
The circulation channel 60 includes supply channels 61, 62, 63, a first manifold 65, recovery channels 67, 68, 69, a second manifold 70, and a connection channel 75. In FIG. 1, an arrow shown in the vicinity or inside of each part forming the circulation channel 60 indicates the direction in which ink flows in that part. In the embodiment, the supply flow paths 61, 62, 63, the first manifold 65, the recovery flow paths 67, 68, 69, and the second manifold 70 are formed by a circular member. Therefore, in the supply flow paths 61, 62, 63, the first manifold 65, the recovery flow paths 67, 68, 69, and the second manifold 70, the cross section of the region where the ink flows is circular.

  The supply flow path 61 is connected to the sub tank 43. Ink supplied to the sub tank 43 flows through the supply channel 61. The supply flow path 62 is connected to the sub tank 44. Ink supplied to the sub tank 44 flows through the supply flow path 62. The supply flow path 63 is connected to the sub tank 45. Ink supplied to the sub tank 45 flows through the supply flow path 63. Supply passages 61, 62, and 63 are connected to the first manifold 65. The first manifold 65 causes ink to flow out to the supply channel 61, causes ink to flow out to the supply channel 62, and causes ink to flow out to the supply channel 63. That is, the first manifold 65 distributes the ink in the circulation channel 60 to the supply channels 61, 62, and 63, respectively.

  The first manifold 65 is provided with a heating unit 55. For example, as the heating unit 55, a known sheet-like rubber heater similar to the heating units 52, 53, and 54 is employed. When a sheet-like rubber heater is employed as the heating unit 55, the rubber heater is attached to the entire circumference of the outer peripheral surface of the first manifold 65 excluding the portion to which the supply flow paths 61, 62, 63 are connected. It is done. The heat of the sheet-like rubber heater is conducted to the first manifold 65, and the first manifold 65 is warmed by this heat. As a result, the ink flowing into the first manifold 65 and heated in the common flow channel 66 of the first manifold 65 is heated. The common flow channel 66 is a flow channel formed by the first manifold 65 through which ink flowing from the connection flow channel 75 and flowing out to the supply flow channels 61, 62, 63 flows.

  The recovery flow path 67 is connected to the head unit 21 and the ink flowing out from the head unit 21 flows. The recovery flow path 68 is connected to the head unit 22, and the ink flowing out from the head unit 22 flows. The recovery channel 69 is connected to the head unit 23, and the ink flowing out from the head unit 23 flows. Recovery passages 67, 68, and 69 are connected to the second manifold 70. Ink that has flowed through the recovery flow path 67 flows into the second manifold 70, ink that has flowed through the recovery flow path 68 flows in, and ink that flows through the recovery flow path 69 flows in. Regarding the illustration of the supply channels 62 and 63 and the second manifold 70, in FIG. 1, the supply channels 62 and 63 and the second manifold 70 are arranged in a state where the second manifold 70 is provided on the back side with respect to the supply channels 62 and 63. Two manifolds 70 are shown superimposed.

  The connection channel 75 connects the second manifold 70 and the first manifold 65. The connection channel 75 causes ink to flow from the second manifold 70 to the first manifold 65. That is, the ink that flows out from the second manifold 70 and flows into the first manifold 65 flows through the connection channel 75. The ink flowing out from the second manifold 70 flows through the connection channel 75 and flows into the first manifold 65. The connection channel 75 is provided with a liquid feeding part 77. Regarding the illustration of the connection flow path 75 and the replenishment flow path 80, in FIG. 1, the connection flow path 75 and the replenishment flow path 80 are overlapped in a state where the replenishment flow path 80 is provided on the back side with respect to the connection flow path 75. It is shown in the figure.

  Regarding the connection between the circulation channel 60 and the supply channel 80, the supply channel 80 is connected to the common channel 71 of the second manifold 70 at the end opposite to the main tank 15 side. The common flow path 71 is a flow path formed by the second manifold 70 through which the ink that flows in from the recovery flow paths 67, 68, 69 and flows out to the connection flow path 75 flows. The ink that flows from the main tank 15 through the replenishment flow path 80 and is supplied to the common flow path 71 flows out from the second manifold 70 to the connection flow path 75 and is circulated through the circulation flow path 60 through the liquid feeding unit 77. . The liquid feeding unit 77 is in a driving state in both cases where the replenishing valve 81 is closed and in an opened state. Therefore, the ink circulation is continuously executed.

  In the circulation channel 60, the second manifold 70 is in a state where the channel cross-sectional area of the common channel 71 is larger than the channel cross-sectional area of the connection channel 75. That is, the second manifold 70 is in a state where the inner diameter φA of the common flow path 71 is larger than the inner diameter φB of the connection flow path 75. For example, the inner diameter φA is set to a dimension that is twice or more larger than the inner diameter φB. The channel length of the common channel 71 is set to a dimension of about 10 to 25% with respect to the entire length of the circulation channel 60, for example. The volume of the common flow path 71 (the volume of the second manifold 70) is set larger than the volume of the connection flow path 75. The first manifold 65 has the same configuration as the second manifold 70.

<Opening and closing operation of refill valve>
The opening / closing operation of the supply valve 81 provided in the supply flow path 80 will be described. Opening and closing of the replenishing valve 81 is controlled by the control unit 91 (CPU). The amount of ink stored in the sub tanks 43, 44, 45 is larger than the first amount in any of the sub tanks 43, 44, 45, and the supply of ink from the main tank 15 to the circulation flow path 60 is stopped. The refill valve 81 is in a closed state. By repeating the recording of the image on the recording medium or forcibly ejecting the ink from the plurality of nozzles 24, 25, 26 of the heads 21, 22, 23, all or one of the sub tanks 43, 44, 45 is recorded. Suppose that the amount of ink stored in the section becomes the first amount or falls below the first amount. In this case, a lower limit value signal is output from the detector of the sub tank in which the amount of ink is equal to or less than the first amount among the detectors 49, 50, 51. The lower limit signal is input to the control device 90 via the connection I / F 92. The control unit 91 acquires a lower limit signal. The control unit 91 outputs an opening signal to the replenishing valve 81 when acquiring the lower limit value signal. The release signal is output from the connection I / F 92 to the supply valve 81. The supply valve 81 is switched to the opened state. Along with this, the ink stored in the main tank 15 flows through the supply channel 80 and is supplied to the circulation channel 60. That is, the aforementioned ink flows into the common flow path 71 of the second manifold 70.

  The supply valve 81 is opened, and the ink stored in the main tank 15 is stored in all or part of the sub tanks 43, 44, 45 in a state where the ink flows through the supply channel 80 and is supplied to the circulation channel 60. When the amount of the ink thus obtained becomes the second amount or exceeds the second amount, among the detectors 49, 50 and 51, from the detector of the sub tank in which the amount of ink is equal to or larger than the second amount, An upper limit signal is output. The upper limit value signal is input to the control device 90 via the connection I / F 92. The control unit 91 acquires an upper limit value signal. When acquiring the upper limit signal, the control unit 91 outputs a closing signal to the supply valve 81. The closing signal is output from the connection I / F 92 to the supply valve 81. The replenishing valve 81 switches to a closed state. Accordingly, the supply of ink from the main tank 15 to the circulation flow path 60 is stopped.

<Effect of embodiment>
According to the embodiment, the following effects can be obtained.

  (1) In the inkjet recording apparatus 10, the circulation flow path 60 includes the supply flow paths 61, 62, 63, the first manifold 65, the recovery flow paths 67, 68, 69, the second manifold 70, and the connection flow path. 75. The connection channel 75 connects the second manifold 70 and the first manifold 65. The connection channel 75 is provided with a liquid feeding part 77. The ink that flows out from the second manifold 70 and flows into the first manifold 65 flows through the connection channel 75. In the circulation channel 60, the second manifold 70 is in a state where the channel cross-sectional area of the common channel 71 is larger than the channel cross-sectional area of the connection channel 75. In the inkjet recording apparatus 10, the replenishment flow path 80 is connected to the common flow path 71 of the second manifold 70 at the end opposite to the main tank 15 side.

  The ink jet recording apparatus can be configured as follows (comparative example). That is, in the inkjet recording apparatus of the comparative example, the connection position of the replenishment flow path with respect to the circulation flow path can be set to a predetermined position of the connection flow path between the liquid feeding unit and the first manifold, for example. In this case, when ink flows from the main tank into the connection channel via the replenishment channel, the ink pressure increases, and the ink may flow into the first manifold all at once. As a result, it is assumed that a large amount of ink flows out from the first manifold to the plurality of supply channels, and is supplied to the plurality of sub tanks in a short time. When a large amount of ink is supplied to a plurality of sub tanks in a short time, the pressure in the storage chamber may fluctuate in each sub tank. When the pressure in the storage chamber fluctuates in each sub tank, the meniscus formed in the nozzle of the corresponding head unit becomes unstable, and ink ejection from the nozzle may be hindered.

  In the inkjet recording apparatus 10, the supply flow path 80 is connected to the common flow path 71 of the second manifold 70 having a flow path cross-sectional area larger than that of the connection flow path 75, thereby suppressing an increase in ink pressure due to ink replenishment. can do. Furthermore, since the replenished ink is then fed through the connection channel 75 via the liquid feeding unit 77, the amount of ink flowing into the first manifold 65 can be maintained in a constant state. . Therefore, according to the inkjet recording apparatus 10, the storage chambers 46, 44, 45 of the sub tanks 43, 44, 45 can be provided at the time of replenishing ink from the main tank 15 to the circulation flow path 60 without separately providing a configuration for suppressing an increase in ink pressure. It can suppress that the pressure of 47 and 48 fluctuates. The configuration of the inkjet recording apparatus 10 can be simplified. The distance that the replenished ink flows until it reaches the heads 21, 22, and 23 can be made longer than that of the ink jet recording apparatus of the comparative example. Before the ink reaches the head portions 21, 22, and 23, the temperature of the ink can be naturally increased.

  (2) In the inkjet head 20, the heating unit 52 is provided in the sub tank 43, the heating unit 53 is provided in the sub tank 44, and the heating unit 54 is provided in the sub tank 45. In the circulation channel 60, the heating unit 55 is provided in the first manifold 65. Therefore, the ink supplied from the first manifold 65 to the sub tanks 43, 44, 45 can be heated. Furthermore, the ink supplied from the sub tank 43 to the head unit 21 can be heated, and the temperature of the ink can be adjusted to a temperature suitable for ejection from the nozzle 24. The ink supplied from the sub tank 44 to the head unit 22 can be heated, and the temperature of the ink can be adjusted to a temperature suitable for ejection from the nozzle 25. The ink supplied from the sub tank 45 to the head unit 23 can be heated, and the temperature of the ink can be adjusted to a temperature suitable for ejection from the nozzle 26.

<Modification>
The embodiment can also be performed as follows. Some configurations of the modifications shown below can be appropriately combined and employed. Hereinafter, points different from the above will be described, and description of similar points will be omitted as appropriate.

  (1) Although not described above, the inkjet recording apparatus 10 may be either a serial type or a line type. That is, the circulation channel 60 can be employed regardless of the type of the inkjet recording apparatus 10. When the inkjet recording apparatus 10 is a serial type, the inkjet recording apparatus 10 includes a moving unit that reciprocates the carriage 42 in the main scanning direction. Image recording on the recording medium is performed while the carriage 42 is reciprocated in the main scanning direction. When the inkjet recording apparatus 10 is a line type, the plurality of nozzles 24, 25, and 26 are arranged in the direction of the width of the recording medium that coincides with the main scanning direction. Serial type or line type ink jet recording apparatuses are already in practical use and both are well known. Therefore, the other description regarding these is abbreviate | omitted.

  (2) The heating unit 52 is provided in the sub tank 43, the heating unit 53 is provided in the sub tank 44, the heating unit 54 is provided in the sub tank 45, and the heating unit 55 is provided in the first manifold 65. In the ink jet head, the heating units 52, 53, and 54 may be omitted. The heating unit 55 for the first manifold 65 may be omitted. In addition, for example, a heating unit may be provided in the connection channel 75 in the circulation channel 60 to heat the ink flowing through the connection channel 75.

DESCRIPTION OF SYMBOLS 10 Inkjet recording device, 15 Main tank 20 Inkjet head, 21, 22, 23 Head part 24, 25, 26 Nozzle, 27, 28, 29 Inlet 30, 31, 32 Outlet, 33, 34, 35 Internal flow path 36 , 37, 38 Main stream part, 39, 40, 41 Tributary part, 42 Carriage 43, 44, 45 Sub tank, 46, 47, 48 Storage chamber 49, 50, 51 Detector, 52, 53, 54, 55 Heating part 60 Circulation Flow path, 61, 62, 63 Supply flow path, 65 First manifold 66 Common flow path, 67, 68, 69 Recovery flow path, 70 Second manifold 71 Common flow path, 75 Connection flow path, 77 Liquid feed section, 80 Supply flow path 81 Supply valve, 90 control device, 91 control unit 92 connection interface (connection I / F), 93 power supply, φA, φB inside diameter

Claims (3)

A main tank for storing ink;
An ink jet head including a first nozzle and a second nozzle for discharging the ink;
A circulation flow path through which the ink replenished from the main tank flows and circulates the ink discharged from the first nozzle and the second nozzle;
A liquid feeding section that is provided in the circulation flow path and that causes the ink to flow through the circulation flow path;
A replenishment flow path for connecting the main tank and the circulation flow path, through which the ink replenished from the main tank to the circulation flow path flows;
A replenishment valve provided in the replenishment flow path and opening and closing the replenishment flow path,
The inkjet head is
A first head portion on which the first nozzle is formed;
A first sub-tank for storing the ink supplied to the first head portion;
A second head portion on which the second nozzle is formed;
A second sub tank for storing the ink supplied to the second head portion,
The circulation channel is
A first supply flow path connected to the first sub tank and through which the ink supplied to the first sub tank flows;
A second supply flow path connected to the second sub tank and through which the ink supplied to the second sub tank flows;
A first manifold that connects the first supply channel and the second supply channel, causes the ink to flow out to the first supply channel, and causes the ink to flow out to the second supply channel;
A first recovery flow path connected to the first head portion and through which the ink flowing out of the first head portion flows;
A second recovery flow path connected to the second head portion and through which the ink flowing out of the second head portion flows;
A second manifold in which the first recovery flow path and the second recovery flow path are connected, the ink flowing through the first recovery flow path flows in, and the ink flowing through the second recovery flow path flows in When,
A connection channel that connects the second manifold and the first manifold, and causes the ink to flow from the second manifold to the first manifold,
The liquid feeding part is provided in the connection channel,
The second manifold has a flow path cross-sectional area of a common flow path of the second manifold through which the ink flowing from the first recovery flow path and the second recovery flow path and flowing out to the connection flow path flows. It is in a state larger than the channel cross-sectional area of the connection channel,
The ink jet recording apparatus, wherein the replenishment flow path is connected to the common flow path at an end opposite to the main tank. A first heating unit that is provided in the first sub tank and heats the ink stored in the first sub tank;
The inkjet recording apparatus according to claim 1, further comprising: a second heating unit that is provided in the second sub tank and heats the ink stored in the second sub tank.   The inkjet recording apparatus according to claim 1, further comprising a third heating unit that is provided in the first manifold and heats the ink that has flowed into the first manifold.

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