JP5823231B2 - Ink jet recording apparatus and ink recovery method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and an ink recovery method.

  Conventionally, an inkjet recording apparatus has been used for image recording, and proposals relating to this have been made (for example, see Patent Documents 1 to 4). Patent Document 1 discloses an ink jet recording apparatus that prints a part of ink droplets ejected from a nozzle on a recording material and collects remaining ink droplets that have not been printed in an ink circulation system and reuses them. Yes. In the ink jet recording apparatus, the density of the ink in the ink circulation system is detected by a natural vibration measurement type density meter, and a replenisher is added to the ink circulation system in accordance with the difference between the detected density and a preset reference density. Control is performed so that the ink density in the circulation system is set to the reference density. In Patent Document 2, a maintenance unit recovers a recording head that applies a liquid containing an ionic liquid as a solvent to a recording medium, regenerates the recovered liquid using a reproducing unit, and supplies the recovered liquid to the recording head again. A recording apparatus used for recording is disclosed.

  Patent Document 3 discloses an ink jet recording apparatus that includes a recording head, an ink storage tank, an ink receiving member, a first ink path, a second ink path, and an operation control unit. ing. The first ink path connects the ink receiving member and the ink storage tank, and the drainage return path that forms a path for collecting the discharged ink discharged from the recording head to the ink storage tank via the ink receiving member, and the first ink path. And a pump. The second ink path is configured as a path independent of the drainage return path, and connects the ink storage tank and one end of the recording head, and forms an ink supply path that forms a path for supplying ink from the ink storage tank to the recording head. And a second pump. The operation control unit performs recording by supplying ink to the recording head via the second ink path and collecting the ink from the recording head via the ink receiving member to the ink storage tank via the first ink path. In the head recovery operation, the ink supply amount of the second ink path and the ink recovery amount of the first ink path are substantially the same, or the ink recovery amount of the first ink path is larger than the ink supply amount of the second ink path. The driving of the first pump and the second pump is controlled so that

  Patent Document 4 discloses an ink supply device for an ink jet printer. In the ink supply device, the ink in the ink bottle communicates with the air trap through the ink supply pipe. The ink pressurized by the pump reaches the nozzle through the filter and the electromagnetic valve, and is controlled by a necessary electric signal to eject ink particles and is used for printing. Ink that is not used for printing is collected by a gutter and returned to the ink bottle through a collection tube by a collection pump. There is an air vent pipe above the ink bottle, and the internal pressure of the ink bottle is released to the atmosphere via an air trap. Above the air trap is open to the atmosphere. The air trap is used as a place for removing bubbles in the ink and a place for measuring the liquid level.

JP-A-7-117233 JP 2006-212788 A Japanese Patent No. 3630978 Japanese Patent Publication No. 64-255

  By the way, in an ink jet recording apparatus, there is a case where ink ejected from a nozzle of a recording head and not used for image recording is collected and reused. The ink contains a colorant. Each of the components such as the coloring material has a predetermined specific gravity. Accordingly, when ink is continuously stored (stagnation) in a certain place, a component such as a colorant may settle (precipitate). When collecting ink that is not used for image recording, sedimentation is likely to occur in the collected place (configuration) and / or the ink collecting flow path for collection. When the contained component settles, for example, the concentration of the contained component of the ink to be ejected may change, and quality deterioration such as density unevenness and / or distortion, and deterioration in color reproducibility may occur in the ejection result.

  An object of the present invention is to provide an ink jet recording apparatus and an ink recovery method that can suitably recover and reuse ink ejected from a recording head that is not used for image recording.

  One aspect of the present invention made in view of the above conventional problems is an ink jet recording apparatus that ejects ink and records an image on a recording medium, the recording head having nozzles for ejecting ink formed thereon, and the recording head Receiving and receiving a supply side reservoir for storing ink supplied to the recording medium, an ink supply channel for supplying ink from the supply side reservoir to the recording head, and ink discharged from the nozzles of the recording head. A recovery-side storage unit that stores the contained ink, and the recovery-side storage unit and the supply-side storage unit are connected, and the ink stored in the recovery-side storage unit is allowed to flow into the supply-side storage unit An ink recovery channel, and a first position in the middle of the ink recovery channel, branched from the ink recovery channel, connected to the recovery side storage unit, and the ink that has flowed out of the recovery side storage unit, An ink circulation channel for flowing into the collection side storage unit and a recovery state provided at the first position, where the ink flows through the ink recovery channel and flows into the supply side storage unit, A switching unit that switches between a circulation state of flowing through the ink circulation channel and flowing into the recovery side storage unit, and a midway of the ink recovery channel that is closer to the recovery side storage unit than the first position When the switching unit is in the recovery state, the ink stored in the recovery side storage unit is fed to the supply side storage unit side, and the switching unit is in the circulation state. If it is, it is an ink jet recording apparatus provided with the liquid feeding part for sending the ink stored in the said collection | recovery side storage part to the said collection | recovery side storage part side.

  According to this, after being ejected from the nozzles of the recording head, the ink stored in the recovery side storage section can be circulated until it flows into the supply side storage section. For this reason, it is possible to suppress sedimentation of the contained components in the ink.

  This ink jet recording apparatus can also be configured as follows. A detection unit that detects the amount of ink stored in the recovery-side storage unit, and the switching unit is in the recovery state when the amount of ink detected by the detection unit is an upper limit amount, When the amount of ink detected by the detection unit reaches the lower limit amount, the circulation state may be set. According to this, a collection state and a circulation state can be switched suitably. In this case, the lower limit amount can exist in all the flow paths through which the ink that has flowed out of the recovery side storage portion flows into the recovery side storage portion when the switching portion is in the circulating state. The amount may be larger than the amount of ink. According to this, in the circulated state, the ink that has flowed out of the collection side storage unit is prevented from entering the entire flow path through which the ink passes until it flows into the collection side storage unit, and the liquid supply unit Occurrence of biting can be prevented.

  The collection-side storage unit receives an ink tray that receives ink ejected from the nozzles of the recording head, and ink received by the ink tray flows into the supply-side storage unit through the ink collection channel. A relay tank that stores the ink that flows in, and the ink recovery flow path connects the ink tray, the relay tank, and the supply side storage unit, and the ink flowing out from the ink tray is The ink flowing into the relay tank and flowing out from the relay tank is allowed to flow into the supply side reservoir, the ink circulation channel is connected to the relay tank, and the ink flowing out from the relay tank is transferred to the relay tank. You may make it flow in. According to this, ink can be suitably stored in the relay tank, and ink circulation can be suitably performed.

  A detection unit configured to detect the amount of ink stored in the relay tank, and the switching unit is set to the recovery state when the amount of ink detected by the detection unit reaches an upper limit amount; When the amount of ink detected by the portion reaches the lower limit amount, the circulation state may be set. According to this, a collection state and a circulation state can be switched suitably. In this case, the lower limit amount is the amount of ink that can exist in all the flow paths through which the ink flowing out of the relay tank flows before flowing into the relay tank when the switching unit is in the circulating state. The amount may be large. According to this, in a circulating state, the ink that has flowed out of the relay tank is prevented from entering the entire flow path through which the ink passes until it flows into the relay tank, and the air feeding is generated in the liquid feeding section. Can be prevented.

  In any of the inkjet recording apparatuses described above, the ink may be an active energy curable ink, and the active energy curable ink may be ejected to record an image on a recording medium. According to this, it is possible to suppress the occurrence of sedimentation in an ink jet recording apparatus that uses an active energy curable ink that is liable to cause sedimentation of components such as colorants for image recording. Examples of the active energy curable ink include ultraviolet curable ink and electron beam curable ink. The active energy curable ink is used for inkjet recording of images in industrial applications such as processing production. The active energy curable ink is obtained by dispersing a component such as a pigment as a colorant in a solvent. Therefore, in the active energy curable ink, sedimentation of contained components occurs over time. The pigment as the component contained in the active energy curable ink includes an inorganic pigment and an organic pigment. Among these, the specific gravity of the inorganic pigment is larger than that of the organic pigment. Therefore, in particular, in an active energy curable ink containing an inorganic pigment, precipitation of the inorganic pigment with time tends to occur. For example, when an active energy curable ink containing an inorganic pigment having a specific gravity of 3.0 to 6.0 is used, the pigment concentration of the discharged active energy curable ink changes, resulting in density unevenness and / or Quality deterioration such as distortion and deterioration of color reproducibility tends to occur. In the ink jet recording apparatus as described above, ink circulation is executed as described above. Therefore, after the active energy curable ink ejected from the nozzles of the recording head is stored in the recovery side reservoir, the active energy curable ink that does not flow into the supply side reservoir is circulated, thereby precipitating the inorganic pigment. Can be suppressed. Note that an active energy curable ink such as an ultraviolet curable ink or an electron beam curable ink is more expensive than an ink used for personal use. Therefore, it is effective to collect active energy curable ink that is not used for image recording.

  Another aspect of the present invention is an ink jet recording apparatus that ejects ink and records an image on a recording medium, and stores a recording head on which nozzles that eject ink are formed, and ink supplied to the recording head. A supply side reservoir, an ink supply channel for supplying ink from the supply side reservoir to the recording head, an ink tray that receives ink ejected from the nozzles of the recording head, and an ink tray that receives the ink. The contained ink flows in, connects the relay tank that stores the introduced ink, the ink tray, the relay tank, and the supply-side storage unit, and the ink that flows out from the ink tray is connected to the relay tank. And an ink recovery flow path for allowing the ink flowing out from the relay tank to flow into the supply side reservoir, and the supply from the relay tank. A liquid supply section provided at a position in the middle of the ink recovery flow path on the side storage section, for supplying the ink stored in the relay tank to the supply storage section side; An inkjet recording apparatus is provided.

  According to this, when the ink received by the ink tray is allowed to flow into the supply side storage unit, the ink can be stored in the relay tank. It is also possible to connect the ink tray and the supply-side storage part by an ink recovery flow path, and recover the ink using the difference between the water heads. However, in such a configuration, it is necessary that the recording head and the ink tray are located above the supply-side reservoir, and the supply-side reservoir is provided directly below or near the ink tray. Therefore, an inkjet recording apparatus that realizes recovery due to a water head difference is likely to be subject to design restrictions such as an increase in size of the apparatus and difficulty in securing a space for a maintenance operation. In the maintenance operation, the recording head is cleaned and ink is ejected from the nozzles. The ejected ink is not used for image recording. The inventor considered the configuration in which the supply side storage unit is disposed in a space in consideration of workability and / or the configuration of the entire apparatus, a liquid feeding unit is provided in the ink recovery flow path, and the ink is fed. At this time, the inventor transfers the ink received in the ink tray to the supply-side storage unit by the liquid supply unit, so that the ink existing in the ink recovery channel gradually decreases, and the air is supplied to the liquid supply unit. It has been found that biting may occur. According to the configuration in which the relay tank is provided, it is possible to suppress the entry of air in the ink recovery flow path after the relay tank and prevent the occurrence of air entrapment in the liquid feeding unit. In this ink jet recording apparatus, the “position in the middle of the ink recovery flow path, which is closer to the supply side storage part than the relay tank” provided with the liquid feeding part is the ink jet recording according to one aspect of the present invention described above. It corresponds to the second position in the device.

According to still another aspect of the present invention, ink is supplied from a supply-side reservoir that stores ink, flows through an ink supply channel to a recording head, and is ejected from nozzles formed in the recording head. A receiving step of storing the collected ink in the collection side storage unit, the ink connects the collection side storage unit and the supply side storage unit, and the ink stored in the collection side storage unit is stored in the supply side storage The ink is collected from the ink collection flow path at a first position in the middle of the ink collection flow path. And a circulation state that is connected to the recovery-side storage unit and flows into the recovery-side storage unit through an ink circulation channel for allowing the ink that has flowed out of the recovery-side storage unit to flow into the recovery-side storage unit Or cut A switching step in which the switching unit is set to the collection state or the circulation state, and the ink collection which is closer to the collection side storage unit than the first position when the switching unit is in the collection state. Ink flown out of the recovery-side storage section through the ink recovery flow path by a liquid-feeding section that is provided at a second position in the middle of the flow path and that feeds ink stored in the recovery-side storage section. An ink recovery step for flowing into the supply side reservoir,
An ink circulation step in which, when the switching unit is in the circulation state, the liquid feeding unit causes the ink that has flowed out of the recovery side storage unit to flow into the recovery side storage unit via the ink circulation channel; And an ink recovery method.

  According to this, the same function as the above realized by the ink jet recording apparatus according to one aspect of the present invention can be realized. In addition, this ink recovery method is similar to the ink jet recording apparatus according to one aspect of the present invention described above, and the ink recovery method executed using the ink jet recording apparatus including another element as described above, or other It can also be specified as an ink recovery method executed using the ink jet recording apparatus according to the aspect. Even with such an ink recovery method, the same function as described above, which is realized by the above-described ink jet recording apparatus, including similar elements, can be realized.

  According to the present invention, it is possible to obtain an ink jet recording apparatus and an ink recovery method that can suitably recover and reuse ink ejected from a recording head that is not used for image recording.

It is a figure which shows an example of an inkjet recording device, Comprising: It is a top view of an inkjet recording device. It is a figure explaining the ink flow path with which an inkjet recording device is provided. FIG. 6 is a diagram (No. 1) for describing a first control for an ink recovery method executed during image recording or standby. The upper stage is the first stage of the first control, and the lower stage is the second stage of the first control. It is FIG. (2) explaining 1st control. The upper stage is the third stage of the first control, and the lower stage is the fourth stage of the first control. It is a figure which shows the relationship between the drive state of the collection | recovery side pump and the state of the collection | recovery side switching part in each step of 1st control. FIG. 6 is a diagram (part 1) illustrating a second control for the ink recovery method that is executed when the initial ink is introduced into the ink jet recording apparatus. The upper stage is the first stage of the second control, and the lower stage is the second stage of the second control. It is FIG. (The 2) explaining 2nd control. The upper stage is the third stage of the second control, and the lower stage is the fourth stage of the second control. It is FIG. (The 3) explaining 2nd control. The upper stage is the fifth stage of the second control, and the lower stage is the sixth stage of the second control. It is a figure which shows the relationship between the drive state of a collection | recovery side pump and the state of a collection | recovery side switching part in each step of 2nd control. It is a figure explaining the other ink flow path with which an inkjet recording device is provided.

  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 1, a full color image is recorded (formed). As a recording medium on which an image is recorded, industrial materials 3 used in processing production are exemplified in addition to recording paper widely used in personal use. In this embodiment, the industrial material 3 will be described as an example of the recording medium. The industrial material 3 includes, for example, a fabric and a building material. Building materials include concrete blocks, ceramic siding materials, and the like. In the inkjet recording apparatus 1 for industrial use, active energy curable ink is used for recording an image. Examples of the active energy curable ink include ultraviolet curable ink and electron beam curable ink. The active energy curable ink contains a pigment, a reactive monomer and / or a reactive oligomer, a photopolymerization initiator, and further contains an additive as necessary. Examples of ink colors include yellow, magenta, cyan, and black.

  The pigment includes an organic pigment and an inorganic pigment. For example, an inorganic pigment is used when light resistance or the like is required. Examples of inorganic pigments used for image recording include the following. Examples of yellow pigments include yellow lead, yellow iron oxide, cadmium yellow, and titanium yellow. Examples of red pigments include red bean paste, cadmium red, and cadmium lithopon red. Examples of blue pigments include cobalt blue, cerulean blue, and cobalt aluminum chrome blue. Examples of the black pigment include carbon. In addition, in order to realize a vivid color expression, the base may be colored white. Examples of the white pigment contained in the white active energy curable ink include lithopone, titanium dioxide, precipitated barium sulfate, barite powder, and antimony oxide. A red inorganic pigment tends to settle more easily than other inorganic pigments.

  As shown in FIG. 1, the inkjet recording apparatus 1 includes a transport unit 10, a recording head 20, an irradiation unit 30, a maintenance unit 40, a control box 50, an ink tank 60, and an ink flow path 70. . The ink jet recording apparatus includes a serial type ink jet recording apparatus and a line type ink jet recording apparatus. In this embodiment, the case where the inkjet recording apparatus 1 is a line type inkjet recording apparatus will be described as an example. The conveyance unit 10 is configured by a conveyor or the like. The transport unit 10 transports the industrial material 3 placed on the transport surface 12 from one end side of the transport unit 10 to the other end side of the transport unit 10 through the recording head 20 and the irradiation unit 30.

  For example, when active energy curable inks of yellow, magenta, cyan, and black are used, the recording head 20 includes the recording heads 20Y, 20M, 20C, and 20K for these colors. The recording head 20Y is a yellow recording head. The recording head 20M is a recording head for magenta. The recording head 20C is a cyan recording head. The recording head 20K is a black recording head. The recording heads 20Y, 20M, 20C, and 20K are arranged in the order of the recording head 20K, the recording head 20C, the recording head 20M, and the recording head 20Y in the transport direction. The recording heads 20Y, 20M, 20C, and 20K have the same configuration. In this embodiment, when the recording heads 20Y, 20M, 20C, and 20K are not distinguished from each other (when ink colors are not distinguished from each other), or when they are collectively referred to, they are simply referred to as “recording head 20”. The recording head 20 is formed with a plurality of nozzles (not shown) that discharge active energy curable ink. The nozzle is formed to face the recording surface 5 of the industrial material 3 conveyed by the conveying unit 10, and the active energy curable ink ejected from the nozzle lands on the recording surface 5. The active energy curable ink that has landed on the recording surface 5 forms ink dots. As a result, an image is recorded on the recording surface 5 and the recording surface 5 is patterned.

  A sub tank 22 (see FIG. 2) is mounted on the recording head 20 in an integrated state. The active energy curable ink supplied through the ink flow path 70 is stored in the sub tank 22 and then supplied to the recording head 20. The sub tank 22 is a tank for temporarily storing the active energy curable ink discharged from the nozzle. The capacity of the sub tank 22 is set as appropriate. For example, it is set in a range of 30 g to 40 g. A pressure increasing / decreasing mechanism 24 (see FIG. 2) is connected to the sub tank 22 via a predetermined air line 26 (see FIG. 2). The pressurizing / depressurizing mechanism 24 depressurizes and pressurizes the inside of the sub tank 22. Specifically, when the active energy curable ink is ejected from the recording head 20, the pressure increasing / decreasing mechanism 24 reduces the pressure inside the sub tank 22 to a pressure lower than the atmospheric pressure. Thereby, a meniscus can be generated suitably. On the other hand, when a maintenance operation described later is performed, the pressure increasing / decreasing mechanism 24 makes the inside of the sub tank 22 have a pressure higher than the atmospheric pressure. The internal pressure of the sub tank 22 is increased by sending compressed air into the sub tank 22. Accordingly, the active energy curable ink can be suitably discharged (discharged) from the nozzle. The air line 26 is provided with a solenoid valve 28 (see FIG. 2). The solenoid valve 28 is constituted by a two-way solenoid valve, for example. When the inside of the sub tank 22 is depressurized and pressurized by the pressure increasing / decreasing mechanism 24, the electromagnetic valve 28 is opened. When the sub tank 22 and the pressure increasing / decreasing mechanism 24 are not in communication, the electromagnetic valve 28 is closed.

  The irradiation unit 30 irradiates active energy rays. For example, when ultraviolet curable ink is used for image recording, the irradiation unit 30 emits ultraviolet rays as active energy rays. When the electron beam curable ink is used, the irradiation unit 30 emits an electron beam as an active energy ray. The irradiation unit 30 is installed at a predetermined position downstream of the recording head 20 in the transport direction. For example, when ultraviolet curable ink is used, the irradiation unit 30 includes an ultraviolet lamp installed toward the conveyance surface 12 of the conveyance unit 10 and irradiates ultraviolet rays in the direction of the conveyance surface 12. For example, the active energy ray is irradiated by a detection sensor (not shown) provided at a predetermined position downstream of the recording head 20 in the transport direction and upstream of the irradiation unit 30 in the transport direction. Is started on the condition that is detected. Irradiation of active energy rays indicates that it is detected that the industrial material 3 has passed through the irradiation unit 30 by a detection sensor (not shown) provided at a predetermined position downstream of the irradiation unit 30 in the transport direction. Stopped as a condition.

  In the maintenance unit 40, a maintenance operation for the recording head 20 is performed. When the maintenance operation is performed, the recording head 20 (the entire recording heads 20Y, 20M, 20C, and 20K for each color) is moved to a position where the maintenance unit 40 is provided by a predetermined moving mechanism. The maintenance unit 40 includes an ink tray 78 (see FIG. 2). The ink tray 78, together with the relay tank 80 (see FIG. 2), constitutes a collection side storage unit. The ink tray 78 and the relay tank 80 will be described later. In the maintenance unit 40, for example, the ejection surface, which is the surface on which the nozzles are formed in the recording head 20, is cleaned. In the maintenance unit 40, the active energy curable ink is forcibly ejected from the recording head 20 to the ink tray 78. This discharge is performed for the purpose of eliminating nozzle clogging, air clogging, and the like. When the maintenance operation as described above is completed, the recording head 20 moved to the maintenance unit 40 is returned to the position shown in FIG. 1 by a predetermined moving mechanism. In the inkjet recording apparatus 1 in which the recording head 20 has returned to the position shown in FIG. 1, for example, the conveyance of the industrial material 3 is started and image recording is resumed.

  The control box 50 includes, for example, a control unit (not shown) and a connection interface (not shown). The control unit controls the inkjet recording apparatus 1. For example, the control unit controls an ink jet recording method related to image recording and the like and an ink recovery method. The control unit includes a circuit board on which electronic components are mounted, electrical wiring, and the like. Note that at least a part of the configuration included in the control unit may be installed above the recording head 20. The connection interface is an interface for connecting the inkjet recording apparatus 1 (control box 50) and an external apparatus (not shown) such as a personal computer so that data communication is possible. For example, image data indicating an image to be recorded is input from an external device to the inkjet recording apparatus 1 via a connection interface. The control unit controls the ink jet recording method according to the input image data.

  The ink tank 60 functions as a supply side storage unit and stores active energy curable ink supplied to the recording head 20. For example, when active energy curable inks of yellow, magenta, cyan, and black are used, the ink tank 60 includes four ink tanks 60Y, 60M, 60C, and 60K that store the active energy curable inks of these colors, respectively. Composed. The ink tank 60Y is an ink tank that stores yellow active energy curable ink. The ink tank 60M is an ink tank that stores magenta active energy curable ink. The ink tank 60C is an ink tank that stores cyan active energy curable ink. The ink tank 60K is an ink tank that stores black active energy curable ink. The ink tanks 60Y, 60M, 60C, and 60K have the same configuration. In the present embodiment, when the ink tanks 60Y, 60M, 60C, and 60K are not distinguished from each other (when the ink colors are not distinguished from each other), or when they are collectively referred to, they are simply referred to as “ink tank 60”. The ink tank 60 may be provided with a stirring unit (not shown) for stirring the active energy curable ink stored in the ink tank 60. According to the agitation unit, the active energy curable ink stored in the ink tank 60 can be agitated, and in this state, the pigment can be prevented from settling. The pigment concentration of the active energy curable ink stored in the ink tank 60 can be kept constant. In addition, according to the stirring unit, other components contained in the active energy curable ink together with the pigment can also be stirred.

  The ink flow path 70 is a flow path for connecting the ink tank 60 and the recording head 20 and connecting the ink tray 78 and the ink tank 60. The active energy curable ink flows through the ink flow path 70. When a plurality of colors of active energy curable ink is used, the ink jet recording apparatus 1 includes an ink flow path 70 for each color. For example, when active energy curable inks of yellow, magenta, cyan, and black are used, the inkjet recording apparatus 1 includes a yellow ink flow path 70Y, a magenta ink flow path 70M, and a cyan ink flow path. 70C and a black ink flow path 70K. The ink flow paths 70Y, 70M, 70C, and 70K have the same configuration. In the present embodiment, the ink flow paths 70Y, 70M, 70C, and 70K are simply referred to as “ink flow paths 70” when they are not distinguished from each other (when ink colors are not distinguished from each other) or collectively. The ink flow path 70 is formed by a predetermined flow path as will be described later with reference to FIG. Each part as will be described later is provided at a predetermined position of the ink flow path 70. In FIG. 1, the ink flow paths 70 (70Y, 70M, 70C, and 70K) are simplified in illustration.

<Inkjet recording method and ink recovery method>
The inkjet recording method controlled by the control unit of the control box 50 and executed by the inkjet recording apparatus 1 includes, for example, an inkjet recording process and an irradiation process. The ink jet recording method includes a supply-side circulation process, an ink supply process, and a supply-side switching process. The supply side circulation step is a step of circulating the active energy curable ink before being supplied to the recording head 20. The ink supply step is a step of supplying active energy curable ink. In the supply-side switching step, the supply-side switching unit 72 (see FIG. 2) is set to a supply-side circulation state in which the active energy curable ink flows into the ink tank 60, or the active energy curable ink is moved to the recording head 20 side. It is the process of making it the supply state which flows.

  The ink recovery method includes a receiving step, an ink recovery step, a recovery side circulation step, and a recovery side switching step. In the receiving process, the active energy curable ink discharged from the nozzles of the recording head 20 by the maintenance unit 40 and not used for image recording is received and received by the collection side storage unit. This is a step of storing the obtained active energy curable ink in the recovery side storage section. Specifically, this is a step of receiving the above-mentioned active energy curable ink by the ink tray 78 and flowing the received active energy curable ink into the relay tank 80 for storage. The ink recovery process is a process of causing the active energy curable ink to flow into the ink tank 60. The collection-side circulation step is a step of circulating the active energy curable ink before being collected in the ink tank 60. In the recovery side switching step, the recovery side switching unit 82 (see FIG. 2) is set in a recovery state in which the active energy curable ink flows into the ink tank 60, or the recovery side in which the active energy curable ink flows into the relay tank 80. This is a step of making a circulating state. Hereinafter, the ink jet recording process and the irradiation process will be mainly described, and other processes and the ink recovery method will be described later.

  In the inkjet recording method, the inkjet recording process is started when an image recording command, image data indicating an image to be recorded, and the like are input from an external device connected to the inkjet recording apparatus 1. In the inkjet recording apparatus 1 to which the recording command is input, first, the transport unit 10 starts operating, and the transport of the industrial material 3 placed on the transport surface 12 is started. Next, in accordance with the input image data, the recording heads 20K, 20C, 20M, and 20Y arranged in the transport direction discharge the active energy curable ink of each color to the transported industrial material 3, respectively. Is done. The discharged active energy curable ink of each color is landed on the recording surface 5. As a result, black dots, cyan dots, magenta dots, and yellow dots are formed on the recording surface 5 by the active energy curable inks of black, cyan, magenta, and yellow, respectively. Thereafter, the industrial material 3 is further transported by the transport unit 10, and the irradiation unit 30 irradiates the recording surface 5 with active energy rays, and the black dots, cyan dots, magenta dots, and yellow dots are cured (irradiation process). The industrial material 3 is transported to the end of the transport unit 10 on the downstream side in the transport direction. As a result, the image recording for one industrial material 3 is completed. The industrial material 3 is sequentially placed on the transport surface 12 at a predetermined timing, the transport of the industrial material 3 is started, and the above-described processing is continuously repeated. That is, in the inkjet recording apparatus 1, the inkjet recording method including the inkjet recording process and the irradiation process is repeatedly performed continuously.

  By the way, when an inkjet recording process and an irradiation process are performed in the inkjet recording method, the recording head 20 moves to the maintenance unit 40 at predetermined time intervals, and the above-described maintenance operation is performed. For example, the maintenance operation is performed at intervals of 4 hours or less. More preferably, it is performed at intervals of 2 hours or less. For example, in an active energy curable ink containing an inorganic pigment, when the maintenance operation interval exceeds 4 hours, the precipitation of the inorganic pigment and other components tends to start to occur, and the recording of suitable images is hindered. May be. If the maintenance operation is frequently performed, productivity in processing production decreases. Therefore, the time interval at which the maintenance operation is performed may be, for example, 1 hour or more. The discharge amount (discharge amount) of the active energy curable ink at the time of the maintenance operation is appropriately set to an amount that can suppress sedimentation of components such as inorganic pigments. A large amount of discharge prolongs the time required for the maintenance operation and becomes a factor of reducing productivity in processing production. Accordingly, the discharge amount may be an amount that is equal to or less than the capacity of the sub tank 22. For example, the discharge amount during one maintenance operation is 5 g or more, preferably 30 g or less, and more preferably 15 g or less. Note that the maintenance operation may be performed as described above, for example, even during standby in which the inkjet recording process is not performed.

<Ink channel>
The ink flow path 70 will be described with reference to FIG. As described above, since the ink flow paths 70Y, 70M, 70C, and 70K have the same configuration, the following description will be made without specifying the ink color (without distinguishing the ink color). The ink flow path 70 includes an ink supply flow path 702 and an ink circulation flow path 704 as supply flow paths, and an ink recovery flow path 706 and an ink circulation flow path 708 as recovery flow paths. Including. The ink flow path 70 (ink supply flow path 702, ink circulation flow path 704, ink recovery flow path 706, ink circulation flow path 708) is configured by a tube or a steel pipe.

  The ink supply channel 702 connects the recording head 20 (specifically, the sub tank 22 integrated with the recording head 20) and the ink tank 60, and the active energy curable ink stored in the ink tank 60 is used. This is a flow path for supplying ink from the ink tank 60 to the recording head 20. The ink supply flow path 702 is provided with (connected to) a supply-side switching unit 72, a supply-side pump 73, and a pressure tank 74. A pressure mechanism 76 is connected to the pressure tank 74. The ink circulation channel 704 is a channel branched from the ink supply channel 702 at a third position in the middle of the ink supply channel 702 as shown in FIG. The ink circulation channel 704 branches from the ink supply channel 702 and is connected to the ink tank 60. The branch of the ink circulation channel 704 from the ink supply channel 702 is performed by the supply side switching unit 72 provided at the third position. The supply side switching unit 72 is configured by, for example, a three-way valve, specifically, a three-way electromagnetic valve. However, the supply side switching unit 72 may have any configuration as long as it can be branched in three directions. The supply side switching unit 72 is in a supply side circulation state in which the active energy curable ink flows through the ink circulation flow path 704 and flows into the ink tank 60, or the active energy curable ink passes through the third position and the ink supply flow. It is switched whether the path 702 is in a supply state that flows toward the recording head 20 (supply side switching step).

  When the supply-side switching unit 72 is in the supply-side circulation state, the active energy curable ink that has reached the third position of the ink supply channel 702 does not flow in the direction of the recording head 20 through the ink supply channel 702, and thus the ink. It flows in the direction of the circulation channel 704. The active energy curable ink flowing through the ink circulation channel 704 flows into the ink tank 60. That is, when the supply side switching unit 72 is in the supply side circulation state, the active energy curable ink stored in the ink tank 60 is brought into the ink supply flow path 702 to the third position and the supply side circulation state. It flows through the supply side switching unit 72 and the ink circulation flow path 704 and is circulated (supply side circulation step). As a result, the active energy curable ink existing in the ink supply channel 702 before being supplied to the recording head 20 can be periodically replaced. When the supply side switching unit 72 is in the supply state, the active energy curable ink does not flow in the direction of the ink circulation flow path 704 but flows through the ink supply flow path 702 as it is, flows into the sub tank 22, and enters the recording head 20. Is supplied (ink supply step). The active energy curable ink supplied to the recording head 20 is ejected from the nozzles in accordance with the image data input to the inkjet recording apparatus 1 in a state controlled by the control unit. For example, when the amount of the active energy curable ink stored in the sub tank 22 is equal to or less than a predetermined lower limit amount, the supply side switching unit 72 is in a supply state. When the amount of the active energy curable ink reaches a predetermined upper limit amount, the supply side switching unit 72 is in a supply side circulation state. Switching of the supply side switching unit 72 is controlled by the control unit in accordance with an output signal from a detection sensor (not shown) that detects the amount of active energy curable ink stored in the sub tank 22.

  The supply-side pump 73 is a drive source for feeding the active energy curable ink stored in the ink tank 60 to the pressurized tank 74 side. The capacity of the supply side pump 73 is appropriately determined in consideration of various conditions such as ink viscosity, flow path length, flow path inner diameter and the like. When the supply side pump 73 is driven, the active energy curable ink flows out from the ink tank 60. The active energy curable ink that has flowed out of the ink tank 60 flows through the ink supply channel 702 and flows into the pressure tank 74 provided at the fourth position of the ink supply channel 702. The fourth position of the ink supply channel 702 is closer to the ink tank 60 than the third position where the supply side switching unit 72 is provided. The pressurization tank 74 is a tank for pressurizing the active energy curable ink flowing through the ink supply channel 702. Pressurization of the active energy curable ink in the pressurization tank 74 is performed by a pressurization mechanism 76 connected to the pressurization tank 74. Specifically, the pressurization mechanism 76 sends the compressed air into the pressurization tank 74, brings the internal pressure of the pressurization tank 74 to a state higher than atmospheric pressure, and is stored in the pressurization tank 74. Pressurize the energy curable ink. The active energy curable ink stored and pressurized in the pressure tank 74 flows out of the pressure tank 74 and flows through the ink supply channel 702 again. That is, the active energy curable ink that has flowed into the pressure tank 74 is pumped from the pressure tank 74 and reaches the third position of the ink supply channel 702. The active energy curable ink that has reached the third position then flows through the ink supply channel 702 or the ink circulation channel 704 as described above.

  The ink tray 78 is provided in the maintenance unit 40 at a position facing the ejection surface of the recording head 20 moved to the maintenance unit 40. Active energy curable ink is ejected from the nozzles of the recording head 20 moved to the maintenance unit 40. The ink tray 78 receives the discharged active energy curable ink (receiving step). An ink recovery channel 706 is connected to a predetermined position at the bottom of the ink tray 78. The ink recovery flow path 706 is provided with (connected to) a relay tank 80, a recovery side switching unit 82, and a recovery side pump 84. The relay tank 80 is connected to the ink tray 78 by an ink recovery channel 706. Accordingly, the active energy curable ink discharged from the nozzles of the recording head 20 moved to the maintenance unit 40 and received in the ink tray 78 flows out of the ink tray 78 and flows through the ink recovery flow path 706, and is connected to the relay tank 80. And is stored in the relay tank 80 (accepting process). The relay tank 80 includes a valve (not shown) that can open the inside of the relay tank 80 to the atmosphere. In the receiving step, the collecting step, and the collecting side circulation step, the relay tank 80 is opened to the atmosphere. The ink tray 78 and the relay tank 80 receive and store the discharged active energy curable ink. That is, the ink tray 78 and the relay tank 80 function as a collection side storage unit.

  The ink recovery flow path 706 connects the ink tray 78 and the relay tank 80 as the recovery side storage unit, and the ink tank 60, and the ink stored in the relay tank 80 (recovery side storage unit) flows into the ink tank 60. It is a channel for making it happen. In the ink recovery channel 706, a filter may be provided between the recovery side switching unit 82 and the ink tank 60 at a position close to the ink tank 60. Foreign substances contained in the active energy curable ink flowing through the ink recovery channel 706 can be removed, and the recovered active energy curable ink can be brought into a clean state. A strainer may be provided in the ink collection flow path 706 on the inflow side of the collection side pump 84 and close to the collection side pump 84. The recovery side pump 84 can be protected. The ink circulation flow path 708 is branched from the ink recovery flow path 706 at a first position in the middle of the ink recovery flow path 706 and connected to the relay tank 80, and the ink that has flowed out of the relay tank 80 is transferred to the relay tank 80. It is a channel for making it flow. The branch of the ink circulation channel 708 from the ink recovery channel 706 is performed by the recovery side switching unit 82 provided at the first position. The collection side switching unit 82 is configured by a three-way valve, specifically, a three-way electromagnetic valve. However, the collection-side switching unit 82 may have any configuration as long as it can be branched in three directions. The recovery side switching unit 82 is in a recovery state where the active energy curable ink flows through the ink recovery flow path 706 and flows into the ink tank 60, or the active energy curable ink flows through the ink circulation flow path 708 and relay tank 80. Switching to the recovery-side circulation state that flows into the tank (recovery-side switching step). The collection side switching unit 82 may be provided at a position close to the ink tank 60, and the distance of the ink collection channel 706 between the collection side switching unit 82 and the ink tank 60 may be shortened. The collection-side switching unit 82 is preferably provided at a position higher than the ink tank 60 so that the active energy curable ink that has flowed toward the ink tank 60 flows under its own weight.

  For example, the recovery side switching unit 82 is set in the recovery state or the recovery side circulation state according to the amount of the active energy curable ink stored in the relay tank 80. Switching of the collection side switching unit 82 is controlled by the control unit in accordance with output signals from detection sensors 90 and 92 that detect the amount of active energy curable ink stored in the relay tank 80. The detection sensors 90 and 92 may be of any type as long as they can detect the amount of the active energy curable ink stored in the relay tank 80 (the upper limit amount and the lower limit amount). For example, the detection sensors 90 and 92 detect the level of the active energy curable ink stored in the relay tank 80 and detect the amount thereof. The detection sensors 90 and 92 are configured by, for example, a float sensor or a photo sensor. The mass of the relay tank 80 may be measured, and the amount of the active energy curable ink (the upper limit amount and the lower limit amount) may be detected based on the measured mass. In this case, the detection sensors 90 and 92 are configured by a single device (sensor) such as a mass meter.

  The detection sensor 90 detects whether the active energy curable ink is stored in the relay tank 80 by the upper limit amount. When the liquid level of the active energy curable ink stored in the relay tank 80 increases and the amount reaches the upper limit, the detection sensor 90 is turned on, the liquid level decreases, and the upper limit is reached. If it is less, it will be off. The detection sensor 92 detects whether the active energy curable ink is stored in the relay tank 80 by the lower limit amount. When the liquid level of the active energy curable ink stored in the relay tank 80 increases and the amount reaches the lower limit, the detection sensor 92 is turned on, the liquid level decreases, and the lower limit is reached. If it is less, it will be off. The upper limit amount is set in consideration of the amount that the active energy curable ink does not leak from the relay tank 80. The lower limit amount is the ink that can exist in all the channels through which the active energy curable ink that has flowed out of the relay tank 80 flows into the relay tank 80 when the recovery side switching unit 82 is in the recovery side circulation state. It is set to an amount larger than the amount of.

  The collection-side pump 84 is provided at a second position in the middle of the ink collection channel 706 that is closer to the relay tank 80 than the first position, in other words, closer to the ink tank 60 than the relay tank 80. The recovery side pump 84 is a drive source for feeding the active energy curable ink stored in the relay tank 80 to the ink tank 60 side. The recovery-side pump 84 is a drive source for feeding and circulating the active energy curable ink stored in the relay tank 80 to the relay tank 80 side via the ink circulation channel 708. The capacity of the recovery side pump 84 is appropriately determined in consideration of various conditions such as ink viscosity, flow path length, flow path inner diameter, and the like. When the collection-side pump 84 is driven, the active energy curable ink flows out from the relay tank 80. That is, the recovery side pump 84 functions as a liquid feeding unit for recovering and circulating the active energy curable ink.

<Control for ink recovery method>
Regarding the control for the ink recovery method, two controls will be described. 3 and 4 referred to in the following description and FIGS. 6 to 8, black portions (excluding triangular portions indicating the detection sensors 90 and 92) indicate active energy curable ink. However, regarding the black-painted active energy curable ink stored in the relay tank 80, the amount thereof is not shown in the state corresponding to the above-described lower limit amount and is simplified.

<First control>
The first control for the ink recovery method will be described with reference to FIGS. The first control is executed during image recording or standby. When the first control is executed, the active energy curable ink has a configuration provided on the collection side (an ink collection channel 706, an ink circulation channel 708, an ink tray 78, a relay tank 80, a collection side switching unit 82). And in the recovery side pump 84). For example, when the amount of the active energy curable ink stored in the relay tank 80 is less than the upper limit and greater than the lower limit as in the first stage shown in the upper part of FIG. 3 (detection sensor 90: off, detection sensor 92 : ON), the control unit controls the recovery-side pump 84 to be driven and the recovery-side switching unit 82 to be in the recovery-side circulation state. Accordingly, in the first stage, the collection side pump 84 is driven, and the collection side switching unit 82 is in the collection side circulation state (see “first stage” in FIG. 5). The active energy curable ink flows out of the relay tank 80, flows through the ink recovery channel 706 in the range from the relay tank 80 to the first position, and passes through the recovery side switching unit 82 in the recovery side circulation state. It flows to the side of 708. The active energy curable ink that has passed through the recovery side switching unit 82 then flows through the ink circulation channel 708 and flows into the relay tank 80 (recovery side circulation step).

  In the first stage in which the active energy curable ink is circulated as described above, for example, it is assumed that it is time to perform a maintenance operation. The recording head 20 moves to the maintenance unit 40. After the movement, the active energy curable ink is ejected from the nozzles of the recording head 20 and received in the ink tray 78 (receiving step). The received active energy curable ink flows into the relay tank 80 (reception process), and the stored active energy curable ink gradually increases. As shown in the second stage shown in the lower part of FIG. Reach the limit. When the amount of the active energy curable ink reaches the upper limit amount, the detection sensor 90 that was off in the first stage is turned on. The control unit controls the recovery side switching unit 82 in the recovery side circulation state to be in the recovery state at the timing when the detection sensor 90 is switched on. The drive of the collection side pump 84 is continued. Accordingly, in the second stage, the collection side pump 84 is driven, and the collection side switching unit 82 is in the collection state (see “second stage” in FIG. 5). The recording head 20 moved to the maintenance unit 40 is returned to the position shown in FIG. 1 at a predetermined timing when the maintenance operation is completed.

  In the second stage, when the recovery side switching unit 82 is switched to the recovery state, the active energy curing type that flows out of the relay tank 80 and flows through the ink recovery flow path 706 in the range from the relay tank 80 to the first position. The ink flows through the ink recovery channel 706 as it is and flows into the ink tank 60 (ink recovery process). As a result, the active energy curable ink is collected in the ink tank 60. The active energy curable ink stored in the relay tank 80 by the upper limit amount gradually decreases as in the third stage shown in the upper part of FIG. With this decrease, the detection sensor 90 is switched off. In the third stage, both the collection-side pump 84 and the collection-side switching unit 82 remain in the second stage (see “third stage” in FIG. 5).

  As described above, when the recovery in the third stage is continued, the active energy curable ink stored in the relay tank 80 becomes the lower limit amount, and at a timing when the amount falls below this, the detection sensor 92 4 switches off as in the fourth stage shown in the lower part of FIG. The control unit controls the recovery side switching unit 82 in the recovery state to be in the recovery side circulation state at the timing when the detection sensor 92 is switched off. The drive of the collection side pump 84 is continued. Accordingly, in the fourth stage, the collection-side pump 84 is driven, and the collection-side switching unit 82 is in the collection-side circulation state (see “fourth stage” in FIG. 5). When the maintenance operation is executed again, the active energy curable ink stored in the relay tank 80 increases and becomes the lower limit amount. Thereafter, the control unit repeatedly executes the control at each stage of the first control described above.

<Second control>
The second control for the ink recovery method will be described with reference to FIGS. The second control is executed when the first ink is introduced into the inkjet recording apparatus 1. The time when the first ink is introduced is, for example, the timing when the ink tank 60 is newly installed in the inkjet recording apparatus 1. In this case, the active energy curable ink does not exist in the configuration provided on the collection side. It is assumed that the timing of the maintenance operation comes when the inkjet recording apparatus 1 starts image recording. The recording head 20 moves to the maintenance unit 40. After the movement, the active energy curable ink is ejected from the nozzles of the recording head 20. The discharged active energy curable ink is received by the ink tray 78 and flows through the ink recovery channel 706 to the relay tank 80 side (reception step) as in the first stage shown in the upper part of FIG. In the first stage, the control unit controls the collection side pump 84 to be stopped. In other words, the control unit does not execute control that drives the collection-side pump 84 that is stopped. When the collection side switching unit 82 is in the collection state, the control unit controls the collection side switching unit 82 to enter the collection side circulation state. Therefore, in the first stage, the collection-side pump 84 is stopped and the collection-side switching unit 82 is in the collection-side circulation state (see “first stage” in FIG. 9).

  The active energy curable ink that flows to the relay tank 80 side through the ink recovery channel 706 flows into the relay tank 80 and is stored in the relay tank 80 as in the second stage shown in the lower part of FIG. ). At the timing when the active energy curable ink flows into the relay tank 80, reaches the lower limit amount, and the detection sensor 92 is turned on, the control unit controls the recovery side pump 84 to be driven. In the second stage, the collection-side pump 84 is driven, and the collection-side switching unit 82 remains in the collection-side circulation state (see “second stage” in FIG. 9). At the time of the initial ink introduction, the collection side circulation step is not executed. When the recovery side switching unit 82 is in the recovery side circulation state, the active energy curable ink that has flowed out of the relay tank 80 passes through the relay tank 80 until it flows into the relay tank 80. Not filled with ink. Accordingly, when the circulation is started in the second stage and the active energy curable ink flows out from the relay tank 80, the active energy curable ink stored in the relay tank 80 is like the third stage shown in the upper part of FIG. And less than the lower limit. However, since the lower limit amount is set to the above-described value, the active energy curable ink does not disappear from the relay tank 80, and the outflow of the active energy curable ink is continued. As the active energy curable ink stored in the relay tank 80 decreases, the detection sensor 92 is switched off. In the third stage, the drive of the recovery side pump 84 and the recovery side circulation state of the recovery side switching unit 82 are both left in the second stage (see “third stage” in FIG. 9).

  Thereafter, the active energy curable ink is ejected from the nozzles of the recording head 20 by the maintenance operation, and when the active energy curable ink exceeds the lower limit amount as in the fourth stage shown in the lower part of FIG. Is switched on. Even after the detection sensor 92 is turned on, the control unit drives the collection-side pump 84 and continues the state where the collection-side switching unit 82 is in the collection-side circulation state until the detection sensor 90 is turned on. In the fourth stage, the drive of the collection side pump 84 and the collection side circulation state of the collection side switching unit 82 are both left in the third stage (see “fourth stage” in FIG. 9). The active energy curable ink flows out of the relay tank 80, flows through the ink recovery channel 706 in the range from the relay tank 80 to the first position, and passes through the recovery side switching unit 82 in the recovery side circulation state. It flows to the side of 708. The active energy curable ink that has passed through the recovery side switching unit 82 flows through the ink circulation flow path 708 and flows into the relay tank 80 (recovery side circulation step).

  As described above, the active energy curable ink is stored in the relay tank 80 as in the fifth stage shown in the upper part of FIG. The active energy curable ink increases and reaches the upper limit. When the amount of the active energy curable ink reaches the upper limit, the detection sensor 90 that is off in the fourth stage is turned on. The control unit controls the recovery side switching unit 82 in the recovery side circulation state to be in the recovery state at the timing when the detection sensor 90 is switched on. The drive of the collection side pump 84 is continued. Accordingly, in the fifth stage, the collection-side pump 84 is driven, and the collection-side switching unit 82 is in the collection state (see “fifth stage” in FIG. 9).

  In the fifth stage, when the recovery side switching unit 82 is switched to the recovery state, the active energy curing type that flows out of the relay tank 80 and flows through the ink recovery flow path 706 in the range from the relay tank 80 to the first position. The ink flows through the ink recovery channel 706 as it is and flows into the ink tank 60 (ink recovery process). As a result, the active energy curable ink is collected in the ink tank 60. The active energy curable ink stored in the relay tank 80 by the upper limit amount gradually decreases. With this decrease, the detection sensor 90 is switched off. Thereafter, when the collection is further continued, the active energy curable ink stored in the relay tank 80 becomes the lower limit amount, and at a timing when the amount falls below this, the detection sensor 92 performs the sixth stage shown in the lower part of FIG. Switch off. The control unit controls the recovery side switching unit 82 in the recovery state to be in the recovery side circulation state at the timing when the detection sensor 92 is switched off. The drive of the collection side pump 84 is continued. Accordingly, in the sixth stage, the collection-side pump 84 is driven, and the collection-side switching unit 82 is in the collection-side circulation state (see “sixth stage” in FIG. 9). When the maintenance operation is executed again, the active energy curable ink stored in the relay tank 80 increases and becomes the lower limit amount. Thereafter, the control unit repeatedly executes the control after the first stage of the first control described with reference to FIGS. 3 and 4.

<Effects of this embodiment>
According to this embodiment described above, the following effects can be obtained.

  (1) A recovery-side switching unit 82 is provided at the first position of the ink recovery flow path 706 so that the recovery state and the recovery-side circulation state can be switched. When the recovery side switching unit 82 is in the recovery side circulation state, the active energy curable ink stored in the relay tank 80 is brought into the ink recovery flow path 706 from the relay tank 80 to the first position and the recovery side circulation state. The recovery side switching unit 82 and the ink circulation flow path 708 are circulated (recovery side circulation step). As a result, it is possible to suppress sedimentation of the contained components in the active energy curable ink before collection, and a suitable active energy curable ink in which sedimentation is suppressed can be caused to flow into the ink tank 60. . For example, even in the case of an active energy curable ink containing an inorganic pigment having a specific gravity of 3.0 to 6.0, sedimentation of the inorganic pigment can be suppressed. As a result, even if the active energy curable ink stored in the relay tank 80 is kept at a constant concentration of components such as inorganic pigments and the collected active energy curable ink is reused, the recorded image is recorded. The print quality can be made suitable. Specifically, for a predetermined same color in the image recorded on the recording surface 5, the color difference ΔE can be set to, for example, “color difference ΔE <2”. By collecting the active energy curable ink, the expensive active energy curable ink can be effectively used without being discarded.

  (2) The lower limit amount detected by the detection sensor 92 is set so that the active energy curable ink that has flowed out of the relay tank 80 flows into the relay tank 80 when the recovery side switching unit 82 is in the recovery side circulation state. The amount of ink was greater than the amount of ink that could be present in all the passages that pass. Therefore, in the third stage of the second control described above, it can be avoided that all the active energy curable ink flows out from the relay tank 80 and the relay tank 80 becomes empty. If the recovery-side pump 84 is driven in a state where the relay tank 80 is empty, the air is caught. In the ink jet recording apparatus 1, it is possible to prevent the occurrence of such air entrainment.

<Modification>
This embodiment can also be performed as follows.

  (1) In the maintenance operation, the collection side storage unit that receives and stores the ink ejected from the nozzles of the recording head 20 is configured by the ink tray 78 and the relay tank 80 connected by the ink recovery channel 706. . The collection-side storage unit may be configured with the ink tray 79 alone, as shown in FIG. For example, such an arrangement may be employed when an ink tray can be fixedly provided in an ink jet recording apparatus. The ink tray 79 includes a function as the relay tank 80. The ink circulation channel 708 is connected to the ink tray 79. According to the ink tray 79, the active energy curable ink discharged from the nozzles of the recording head 20 is received by the ink tray 79, flows out of the ink tray 79, flows through the ink circulation flow path 708, and the like, and is supplied to the ink tray 79. Is flowed into. The detection sensors 90 and 92 detect the amount of active energy curable ink stored in the ink tray 79. Even with an ink jet recording apparatus employing the ink tray 79, the same effects as those of the above-described embodiment can be obtained. When the ink jet recording apparatus includes a moving mechanism that moves the ink tray up and down in the vertical direction, for example, from the viewpoint of liquid level fluctuation and spillage of the active energy curable ink accompanying the up and down movement, A configuration including the ink tray 78 and the relay tank 80 is preferable. The ink tray 78 and the relay tank 80 can achieve a suitable circulation regardless of the presence or absence of a moving mechanism. The relay tank 80 can be retrofitted to an ink jet recording apparatus that does not include the relay tank 80.

  (2) For example, in an inkjet recording apparatus in which a considerable amount of active energy curable ink is ejected by a single maintenance operation, the activated energy curable ink that has been ejected and received in the ink tray 78 is immediately removed. Alternatively, the ink may be collected in the ink tank 60. In this case, since the active energy curable ink is not circulated on the collection side, the ink circulation channel 708 and the collection side switching unit 82 can be omitted.

  (3) A pressure tank 74 and a pressure mechanism 76 are provided in the ink supply flow path 702, and compressed air is sent into the pressure tank 74 so that the pressure inside the pressure tank 74 is higher than atmospheric pressure. In the above description, the active energy curable ink that has flowed into the pressure tank 74 is caused to flow toward the recording head 20 or circulate via the ink circulation channel 704. The pressurizing tank 74 and the pressurizing mechanism 76 may be omitted, and the liquid feeding of the active energy curable ink as described above may be performed by the supply-side pump 73, for example. Further, the supply-side pump 73 may be omitted (see FIG. 10). In this case, the active energy curable ink is supplied from the ink tank 60 to the recording head 20 by, for example, supplying air compressed by a device (not shown in FIG. 10) such as the pressurizing mechanism 76 into the ink tank 60. This is performed by feeding and setting the internal pressure of the ink tank 60 higher than the atmospheric pressure. When the ink recovery process is executed and the active energy curable ink is allowed to flow into the ink tank 60, the ink tank 60 is opened to the atmosphere.

  (4) The active energy curable ink containing an inorganic pigment as the pigment has been described as an example. In addition, the active energy curable ink used for image recording may contain an organic pigment. Organic pigments have a lower specific gravity than inorganic pigments, but they do not settle out, and sedimentation may be a problem as in the case of inorganic pigments. In addition, a different type of ink from the active energy curable ink may be used. Any ink contains colorants and can cause sedimentation problems. Therefore, the same effect as that of the present embodiment can be obtained with an active energy curable ink containing an organic pigment or other types of ink.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device, 3 Industrial material, 5 Recording surface 10 Conveyance part, 12 Conveyance surface 20, 20Y, 20M, 20C, 20K Recording head 30 Irradiation part, 40 Maintenance part, 50 Control box 60, 60Y, 60M, 60C, 60K Ink tank 70, 70Y, 70M, 70C, 70K Ink channel 702 Ink supply channel, 704 Ink circulation channel 706 Ink recovery channel, 708 Ink circulation channel 72 Supply side switching unit, 73 Supply side pump, 74 Pressurization Tank, 76 Pressurization mechanism 78, 79 Ink tray, 80 Relay tank, 82 Collection side switching unit 84 Collection side pump

Claims (9)

An inkjet recording apparatus that ejects ink and records an image on a recording medium,
A recording head on which nozzles for discharging ink are formed;
A supply side reservoir for storing ink to be supplied to the recording head;
An ink supply channel for supplying ink from the supply side reservoir to the recording head;
A collection side storage unit that receives ink discharged from the nozzles of the recording head and stores the received ink;
An ink recovery flow path for connecting the recovery side storage section and the supply side storage section, and causing the ink stored in the recovery side storage section to flow into the supply side storage section;
At the first position in the middle of the ink recovery channel, the ink branches off from the ink recovery channel, is connected to the recovery side storage unit, and flows out of the recovery side storage unit into the recovery side storage unit. An ink circulation flow path,
Provided in the first position, the ink is in a recovery state in which the ink flows through the ink recovery flow path and flows into the supply side storage section, or the ink flows through the ink circulation flow path and flows into the recovery side storage section. A switching unit that switches between circulating state and
Provided at the second position in the middle of the ink recovery flow path, which is closer to the recovery side storage section than the first position, and is stored in the recovery side storage section when the switching section is in the recovery state. Ink is sent to the supply side reservoir, and when the switching unit is in the circulating state, the ink stored in the recovery side reservoir is sent to the recovery side reservoir. An ink jet recording apparatus. A detection unit for detecting the amount of ink stored in the recovery side storage unit;
The switching unit is
When the amount of ink detected by the detection unit reaches the upper limit amount, the recovery state is set,
The ink jet recording apparatus according to claim 1, wherein when the amount of ink detected by the detection unit becomes a lower limit amount, the ink jet recording apparatus is in the circulating state.   The lower limit amount is the amount of ink that can exist in all the flow paths through which the ink that has flowed out of the recovery-side storage portion flows into the recovery-side storage portion when the switching portion is in the circulating state. The inkjet recording apparatus according to claim 2, wherein the amount is larger. The collection side storage unit is
An ink tray for receiving ink ejected from the nozzles of the recording head;
A relay tank for storing the ink received in the ink tray, storing the ink flowing through the ink recovery flow path and flowing into the supply-side storage unit,
The ink recovery flow path connects the ink tray, the relay tank, and the supply side reservoir, and allows ink flowing out from the ink tray to flow into the relay tank and out of the relay tank. To flow into the supply side reservoir,
2. The ink jet recording apparatus according to claim 1, wherein the ink circulation flow path is connected to the relay tank and causes the ink that has flowed out of the relay tank to flow into the relay tank. A detection unit for detecting the amount of ink stored in the relay tank;
The switching unit is
When the amount of ink detected by the detection unit reaches the upper limit amount, the recovery state is set,
The ink jet recording apparatus according to claim 4, wherein when the amount of ink detected by the detection unit reaches a lower limit amount, the ink jet recording apparatus is placed in the circulation state.   The lower limit amount is an amount larger than the amount of ink that can exist in all the flow paths through which the ink that has flowed out of the relay tank flows into the relay tank when the switching unit is in the circulating state. The inkjet recording apparatus according to claim 5, wherein The ink is an active energy curable ink,
The ink jet recording apparatus according to claim 1, wherein the ink is recorded on a recording medium by ejecting active energy curable ink. An inkjet recording apparatus that ejects ink and records an image on a recording medium,
A recording head on which nozzles for discharging ink are formed;
A supply side reservoir for storing ink to be supplied to the recording head;
An ink supply channel for supplying ink from the supply side reservoir to the recording head;
An ink tray for receiving ink ejected from the nozzles of the recording head;
A relay tank in which the ink received in the ink tray flows in and stores the flowed-in ink;
The ink tray, the relay tank, and the supply-side reservoir are connected, ink that flows out from the ink tray flows into the relay tank, and ink that flows out of the relay tank flows into the supply-side reservoir. An ink recovery flow path for
For supplying the ink stored in the relay tank to the supply side storage section side, provided at a position in the middle of the ink recovery flow path, which is closer to the supply side storage section than the relay tank. An ink jet recording apparatus comprising: a liquid feeding unit. From the supply-side reservoir that stores ink, flows through the ink supply flow path, is supplied to the recording head, receives the ink ejected from the nozzles formed in the recording head, and receives the received ink. A receiving process for storing in
Ink flows through the ink recovery flow path for connecting the recovery side storage unit and the supply side storage unit, and causing the ink stored in the recovery side storage unit to flow into the supply side storage unit, and then the supply side In a recovery state that flows into the storage unit, or at a first position in the middle of the ink recovery channel, the ink branches from the ink recovery channel and is connected to the recovery side storage unit, and the recovery side storage unit A switching unit for switching whether to circulate the ink that has flowed out from the ink circulation flow path for flowing into the recovery side storage unit and into the recovery side storage unit is set to the recovery state, or , A switching step for setting the circulation state;
When the switching unit is in the recovery state, the switching unit is provided at a second position in the middle of the ink recovery flow path that is closer to the recovery side storage unit than the first position, and is stored in the recovery side storage unit. An ink recovery step of causing the ink flowing out from the recovery side storage section to flow into the supply side storage section via the ink recovery flow path by a liquid supply section for supplying ink;
An ink circulation step in which, when the switching unit is in the circulation state, the liquid feeding unit causes the ink that has flowed out of the recovery side storage unit to flow into the recovery side storage unit via the ink circulation channel; A method for collecting ink.

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