Liquid dispensing device

Abstract

To provide a liquid discharge device which can accurately perform separation between joint non-connection to a supply path of a main tank and an ink end in a system which cannot include a recording medium holding ink residual amount information in the main tank.SOLUTION: A liquid discharge device comprises: a sub tank which temporarily stores liquid to be supplied to a liquid discharge head for discharging liquid; a main tank which stores the liquid to be supplied to the sub tank; a liquid path which communicates to the main tank and the sub tank; a joint which performs connection or shutdown between the main tank and the liquid path; air catching means which is installed in the liquid path and catches the gas including the liquid; liquid feeding means which is installed on a downstream side in a liquid feeding direction of the air catching means; a reverse-flow path which disables communication between the liquid feeding means and the sub tank and changes a connection destination of the liquid feeding means to the main tank; and switching means which switches communication or non-communication of the path from the liquid feeding means to the sub tank and non-communication or communication from the liquid feeding means to the reverse-flow path.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a liquid ejection device. [Background technology]

[0002] In recent years, liquid ejection devices have been developed that form images by ejecting ink onto various recording media using inkjet technology. Some conventional liquid ejection devices are known to have an ink supply path that connects a subtank that temporarily stores ink to be supplied to an ejection head and a main tank that stores ink to be supplied to a head tank. Some conventional liquid ejection devices are known to have a liquid feed pump in the ink supply path, and a configuration that forward transfers ink from an ink cartridge serving as a main tank to a head tank serving as a subtank, or reverse transfers ink.

[0003] Other well-known types include a cartridge type with a main tank with a capacity of about 10 L, and a drum container type that uses a large-capacity drum container of over 100 L as the main tank. Either type uses a configuration in which information on the type of ink and the remaining amount is stored and managed on a non-volatile recording medium such as an IC chip, and whether or not the main tank can be used is determined.

[0004] The cartridge method is a system in which an IC chip is mounted on the cartridge itself as the main tank, and the IC chip information is read / written when the cartridge is installed in the liquid ejection device. Therefore, when the ink in the cartridge runs out (ink end), it can be determined with certainty that a new cartridge has been installed after replacement.

[0005] On the other hand, with the drum container method, it is difficult to mount an IC chip on the drum container, so an IC card equipped with an IC chip is used separately from the main tank, and the IC chip information is read / written using an IC card reader.

[0006] In either method, an air trap tank is provided in the supply unit that supplies ink from the main tank to the sub-tank in order to capture air that gets mixed in from the main tank. If ink is not filled into the air trap tank within a specified time, an ink end process is used to recognize that the main tank is empty (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0007] When the ink end determination process disclosed in Patent Document 1 is applied to the drum container system, it may result in an erroneous determination. In the drum container system, the work of connecting the joint between the drum container and the supply path and the work of installing the IC card in the reading device are separate tasks. Therefore, even if the state of the joint connection differs from the association with the contents of the information recorded on the IC card, the ink liquid can be sent via the supply path. Therefore, even if the ink is not filled in the air trap tank within the specified time, it is difficult to distinguish whether this is due to "ink end" or "joint not being connected."

[0008] If the IC card is installed and operation is started even if the joint is mistakenly not connected, the control unit of the liquid ejection device will recognize the drum as connected and will continue the supply operation without the joint being connected. In this case, the air trap tank will not be filled with ink, and even if there is sufficient ink remaining in the drum, the incorrect information that the "main tank is empty" will be written to the IC card.

[0009] As described above, if the conventional ink end determination process is applied to the drum container system, the process of determining whether the ink has run out in the main tank will result in an erroneous determination of whether the joint is disconnected or the ink has run out.

[0010] The present invention aims to provide a liquid ejection device that can accurately distinguish between a joint not being connected to the supply path of the main tank and ink out in a system in which the main tank cannot be provided with a recording medium for storing remaining ink amount information. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention relates to a liquid ejection device, comprising: a sub-tank for temporarily storing liquid to be supplied to a liquid ejection head that ejects liquid; a main tank for storing liquid to be supplied to the sub-tank; a liquid path connecting the main tank and the sub-tank; a joint for connecting or disconnecting the main tank and the liquid path; air capturing means disposed in the liquid path for capturing gas contained in the liquid; liquid delivery means disposed downstream in the liquid delivery direction of the air capturing means; a backflow path for disconnecting the liquid delivery means from the sub-tank and changing the connection destination of the liquid delivery means to the main tank; and switching means for switching between communication or disconnection of the path from the liquid delivery means to the sub-tank and communication or disconnection from the liquid delivery means to the backflow path. when it is determined that the amount of the liquid stored in the main tank has fallen to a certain amount or less, if the amount of the liquid stored in the air capturing means does not exceed a certain amount before a predetermined time has elapsed since the liquid sending means started to send the liquid from the main tank to the air capturing means, the switching means closes the path from the liquid sending means to the sub tank and connects the path to the backflow path, thereby transferring the liquid back from the air capturing means to the main tank via the backflow path. It is characterized by: Effect of the Invention

[0012] According to the present invention, in a system in which a recording medium for storing remaining ink amount information cannot be provided in the main tank, it is possible to accurately distinguish between a joint not being connected to the supply path of the main tank and an ink out state. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram illustrating an example of the overall configuration of an embodiment of a liquid ejection device according to the present invention. [Diagram 2] FIG. 2 is a plan view illustrating a discharge unit included in the liquid discharge device. [Diagram 3] FIG. 4 is a side view illustrating a discharge unit included in the liquid discharge device. [Figure 4] FIG. 2 is a configuration diagram of a liquid supply unit included in the liquid ejection apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described, but the present invention is not limited to this embodiment. In addition, in each of the drawings referred to below, the same reference numerals are used for common elements, and the description thereof will be omitted as appropriate.

[0015] [Embodiment of liquid ejection device] 1 is a schematic diagram illustrating the overall configuration of a liquid ejection device 1 according to this embodiment. The liquid ejection device 1 includes an input section 10, a printing section 20, a drying section 30, and a carrying-out section 40. In the liquid ejection device 1, the printing section 20 applies liquid to a sheet material P, which is a sheet-like member, carried in from the input section 10, to perform a required image forming process (printing process), and the drying section 30 dries the liquid attached to the sheet material P, and then the sheet material P is collected in the carrying-out section 40.

[0016] The carry-in section 10 includes an input tray 11 on which a plurality of sheet materials P are stacked, a feeding device 12 that separates and sends out the sheet materials P one by one from the input tray 11, and a pair of registration rollers 13 that sends the sheet materials P to the printing section 20.

[0017] The feeding device 12 may have various configurations, such as a device using rollers or a device using air suction, as long as it is configured to separate the stacked sheet material P and send it downstream. The sheet material P sent out from the carry-in tray 11 by the feeding device 12 is sent to the printing unit 20 by a pair of registration rollers 13. After the leading edge of the sheet material P arrives, the pair of registration rollers 13 is driven at a predetermined timing to transport the sheet material P.

[0018] The printing unit 20 includes a transport drum 21, which is a first rotating member that supports and transports the sheet material P on its outer peripheral surface, and a liquid ejection unit 22 that ejects liquid toward the sheet material P supported by the transport drum 21.

[0019] The printing section 20 also includes a transfer drum 24, which is a second rotating member that receives the fed sheet material P and transfers the sheet material P between the transfer drum 21 and the printing section 20, and a transfer drum 25 that transfers the sheet material P transported by the transport drum 21 to the drying section 30.

[0020] The sheet material P transported from the carry-in section 10 to the printing section 20 has its leading edge gripped by a second gripping means serving as a sheet gripper, described later, provided on the transfer cylinder 24, and is transported as the transfer cylinder 24 rotates. The sheet material P transported by the transfer cylinder 24 is delivered to the transport drum 21 at a position opposite to the transport drum 21.

[0021] A first gripping means as a sheet gripper is also provided on the surface of the transport drum 21, and the leading end of the sheet material P is gripped by the first gripping means. A plurality of suction holes are formed in a dispersed manner on the surface of the transport drum 21. A suction device 26, which is a suction stage, generates a suction airflow that flows inward from the suction port of the transport drum 21. The sheet material P transferred from the transfer drum 24 to the transport drum 21 has its leading end gripped by the first gripping means, is sucked onto the transport drum 21 by the suction airflow of the suction device 26, and is transported as the transport drum 21 rotates.

[0022] The liquid discharge section 22 includes discharge units 23 (23A to 23F) which are liquid discharge means. For example, the discharge unit 23A discharges cyan (C) liquid, the discharge unit 23B discharges magenta (M) liquid, the discharge unit 23C discharges yellow (Y) liquid, and the discharge unit 23D discharges black (K) liquid. The discharge units 23F, 23F are used to discharge any of YMCK, or special liquids such as white and gold (silver). Furthermore, a discharge unit 23 that discharges a treatment liquid such as a surface coating liquid can also be provided.

[0023] The discharge operation of each discharge unit 23 of the liquid discharge section 22 is controlled by a drive signal corresponding to the printing information. When the sheet material P supported on the transport drum 21 passes through an area facing the liquid discharge section 22, liquid of each color is discharged from the discharge unit 23, and an image corresponding to the printing information is printed. Liquid of a required color is supplied to each discharge unit 23 of the liquid discharge section 22 from liquid supply units 81 (81A to 81D) of the liquid supply section 80.

[0024] The drying section 30 includes a drying mechanism section 31 for drying the liquid adhered to the sheet material P in the printing section 20, and a suction transport mechanism section 32 for transporting (suction transporting) the sheet material P transported from the printing section 20 in a suctioned state.

[0025] The sheet material P conveyed from the printing unit 20 is received by the suction conveying mechanism 32, then conveyed to pass through the drying mechanism 31 and delivered to the discharge unit 40. When passing through the drying mechanism 31, the liquid on the sheet material P is dried. This causes the water content in the liquid to evaporate, the colorant contained in the liquid to be fixed on the sheet material P, and curling of the sheet material P is suppressed.

[0026] The discharge section 40 includes a discharge tray 41 on which a plurality of sheet materials P are stacked. The sheet materials P conveyed from the drying section 30 are successively stacked and held on the discharge tray 41.

[0027] In addition, the liquid ejection device 1 can have, for example, a pre-processing unit that performs pre-processing on the sheet material P located upstream of the printing unit 20, or a post-processing unit that performs post-processing on the sheet material P to which liquid has adhered, located between the drying unit 30 and the discharge unit 40.

[0028] An example of the pre-treatment section is a section that performs a pre-coating process in which a treatment liquid that reacts with the liquid to suppress bleeding is applied to the sheet material P. An example of the post-treatment section is a section that performs a sheet reversing and conveying process in which a sheet printed in the printing section 20 is reversed and sent back to the printing section 20 to print on both sides of the sheet material P, and a process for binding multiple sheets.

[0029] [Embodiment of the Discharge Unit] Next, the configuration of the discharge unit 23 included in the liquid discharge device 1 will be described with reference to Figures 2 and 3. Figure 2 is an explanatory plan view of the discharge unit, and Figure 3 is an explanatory side view of the discharge unit.

[0030] The discharge unit 23 has a plurality of liquid discharge heads 100 arranged in a staggered manner on a head base 52. The plurality of liquid discharge heads 100 are connected to a manifold 103 for distributing liquid arranged above through a supply path 104. Note that a flow-through type head (circulation type head) can also be used as the liquid discharge head 100.

[0031] A sub-tank 105 that temporarily stores liquid ink to be supplied to the liquid ejection head 100 is provided upstream of the manifold 103, and a negative pressure is created in the sub-tank 105 to generate meniscus pressure in the nozzles of the liquid ejection head 100. Liquid ink of a required color is supplied to the sub-tank 105 from a liquid supply unit 81 that includes a main tank 201 via a liquid path 200.

[0032] The subtank 105 is provided with a filler 135 which is displaced according to the remaining amount of liquid ink inside, and is provided with a full sensor 107 which detects when the filler 135 is in the full position, and a shortage sensor 108 which detects when the filler 135 is in the shortage position.

[0033] [Embodiment of liquid supply unit] Next, an embodiment of a liquid supply unit according to the present invention will be described with reference to Fig. 4. Fig. 4 is a diagram showing an example of the configuration of one of a plurality of liquid supply units 81 included in a liquid supply section 80 according to this embodiment. Each of the plurality of liquid supply units 81 included in the liquid supply section 80 is provided with a main tank 201 which is liquid storage means for storing liquid 300 as liquid ink to be supplied to the subtank 105. Note that the main tank 201 is detachable from the liquid supply unit 81.

[0034] The main tank 201 has a capacity of, for example, about 100 to 200 liters. One end of a first liquid path 202 is connected to the main tank 201 via a joint 203 as a joint used for connecting to the main tank 201. The other end of the first liquid path 202 is connected to an on-off valve 221. A second liquid path 204 is provided at the other end of the on-off valve 221, and is connected to an air trap tank 205, which is an air capture means, via a three-way connector 232 and a third liquid path 209. Note that the liquid 300 is sent from the main tank 201 to the air trap tank 205 through the first liquid path 202, the second liquid path 204, and the third liquid path 209, and then sent to the sub tank 105 through the subsequent path, which is referred to as a "forward liquid transfer". The on-off valve 221 controls communication between the first liquid path 202 and the second liquid path 204.

[0035] The air trap tank 205 is a sealed container of, for example, about 0.3 to 1 liter, and is made of a resin having permeability and chemical resistance, such as PE, PP, or PET, or a glass bottle. The air trap tank 205 is provided with a plurality of liquid level sensors 206 as liquid level detection means. These liquid level sensors 206 are capable of detecting the amount of liquid 300 (also referred to as the liquid amount or the storage amount) in the air trap tank 205. An infrared reflection type sensor can be used for the liquid level sensor 206. Alternatively, a sensor can be used in which a plurality of electrodes of different lengths are provided and the liquid level is detected by the electrostatic capacitance between the electrodes.

[0036] The liquid level sensors 206 include, for example, at least an upper limit sensor 206a as an upper limit detection means and a lower limit sensor 206c as a lower limit detection means. The upper limit sensor 206a is a sensor for detecting that the liquid 300 in the air trap tank 205 has reached its storage limit. The lower limit sensor 206c is a sensor for detecting that the air trap tank 205 is empty. The air trap tank 205 may also include an appropriate amount sensor 206b as an appropriate amount detection means for detecting that an appropriate amount of liquid 300 is stored in the air trap tank 205.

[0037] An exhaust path 211 constituting an exhaust means is connected to the upper part of the air trap tank 205. The exhaust path 211 is provided with an exhaust valve 212 that opens and closes the exhaust path 211, and an exhaust pump 213 that sucks out air from within the air trap tank 205 through the exhaust path 211. The exhaust pump 213 may be shared by multiple liquid supply units 81.

[0038] When the exhaust valve 212 installed in the exhaust path 211 is opened and the exhaust pump 213 is operated to exhaust the air in the air trap tank 205 to the atmosphere, the air pressure in the air trap tank 205 decreases. This allows the liquid 300 in the main tank 201 to be drawn into the air trap tank 205 via the first liquid path 202, the second liquid path 204, and the third liquid path 209.

[0039] In addition, an atmosphere release valve 241 is provided between the exhaust valve 212 and the air trap tank 205, so that the inside of the air trap tank 205 can be communicated with the atmosphere.

[0040] One end of a fourth liquid path 207 that is connected to the sub tank 105 is connected to the bottom of the air trap tank 205, and the other end is connected to a three-way valve 231 as a switching means. A liquid delivery pump 208 that is a liquid delivery means is installed in the fourth liquid path 207. The fourth liquid path 207 is installed so as to be connected to the liquid supply valve 210 via the three-way valve 231. The fourth liquid path 207 may be connected to the top of the air trap tank 205. In that case, the fourth liquid path 207 may be configured to extend to the bottom of the air trap tank 205. A non-reversible liquid delivery pump such as a diaphragm pump is used as the liquid delivery pump 208.

[0041] The liquid supply unit 81 according to this embodiment configures a liquid path 200 that connects the main tank 201 and the sub tank 105 by a first liquid path 202, a second liquid path 204, a third liquid path 209, and a fourth liquid path 207. An air trap tank 205, which serves as an air capturing means, is provided in this liquid path 200, and a liquid delivery pump 208, which serves as a liquid delivery means, is provided downstream of the air trap tank 205 in the liquid delivery direction.

[0042] The liquid supply unit 81 according to this embodiment includes a reverse flow path 230 as a path for reversely transferring the liquid 300 from the air trap tank 205 to the main tank 201. The reverse flow path 230 is installed between a three-way valve 231 and a three-way connector 232. The three-way valve 231 enables liquid transfer from the air trap tank 205 to the sub tank 105 during forward liquid transfer, and disables liquid transfer from the air trap tank 205 to the sub tank 105 during reverse liquid transfer. The three-way connector 232 also enables liquid transfer from the air trap tank 205 to the sub tank 105 during forward liquid transfer, and disables liquid transfer from the air trap tank 205 to the sub tank 105 during reverse liquid transfer, thereby transferring the liquid to the reverse flow path 230.

[0043] One end of the backflow path 230 is connected to the liquid feed pump 208 via a three-way valve 231 and a fourth liquid path 207, and the other end is connected to the second liquid path 204 upstream of the air trap tank 205 by a three-way connector 232. In normal supply operations, this backflow path 230 is not used. Therefore, the backflow path 230 is also a path that changes the connection destination of the liquid feed pump 208 to the main tank 201 when the liquid feed pump 208 as a liquid feed means and the sub tank 105 are not in communication.

[0044] The liquid supply unit 80 is also provided with a write / read unit 260 for reading information from an IC card 261 serving as a recording medium on which information such as the type, remaining amount, and lot information of the main tank 201 is written and recorded. The write / read unit 260 functions as a write / read means for writing information to the IC card 261 and reading information from the IC card 261.

[0045] The liquid 300 is discharged from the liquid discharge head 100 by forward transfer of the liquid 300 from the main tank 201 to the sub tank 105 via the air trap tank 205. To perform this supply operation, a joint 203 provided at the end of the first liquid path 202 is connected to the main tank 201, and an IC card 261 packed with the main tank 201 is placed in the writing / reading unit 260. This makes it necessary to match the remaining amount information, liquid type information, and the like. Note that forward transfer of the liquid is not performed unless the IC card 261 is placed in the writing / reading unit 260. In this case, the amount of the liquid 300 remaining in the main tank 201 is written in the IC card 261, so the condition is that this is not zero (not ink end). A more detailed explanation will be given below.

[0046] [Operation of liquid supply unit 80] Next, the operation of the liquid supply unit 80 when performing normal image forming processing will be described. By operating the liquid sending pump 208 installed in the flow path provided at the bottom of the air trap tank 205, the liquid 300 in the air trap tank 205 is sent to the sub tank 105. At this time, the opening and closing valve 221 is open, and the exhaust valve 212 is closed. Therefore, the space between the air trap tank 205 and the main tank 201 is sealed. In this state, when the liquid 300 in the air trap tank 205 is sent by the liquid sending pump 208, the inside of the air trap tank 205 becomes negative pressure. As a result, the liquid 300 in the main tank 201 is drawn into the air trap tank 205 through the first liquid path 202, the second liquid path 204, and the third liquid path 209. As a result, an appropriate amount of liquid 300 is maintained in the air trap tank 205.

[0047] Next, the function of the air trap tank 205 will be described. By providing the air trap tank 205 downstream in the liquid sending direction of the main tank 201, it is possible to prevent air from being sent to the liquid sending pump 208, which is further downstream in the liquid sending direction than the air trap tank 205. If the air trap tank 205 were not provided, air may be sent together with the liquid 300 sent from the main tank 201 to the sub tank 105. In that case, air will get mixed in with the liquid 300 supplied from the sub tank 105 to the liquid supply unit 81, preventing normal discharge operation and reducing the quality of image formation.

[0048] Next, the flow of liquid from the liquid supply unit 80 toward the subtank 105 will be described. For example, when liquid is supplied from the main tank 201, the on-off valve 221 is open, the appropriate amount sensor 206b is maintained in a state of detecting the liquid level of the liquid 300, and the exhaust valve 212 is closed. Then, the liquid supply valve 210 is in a state of repeatedly opening and closing depending on the position of the filler 135 of the subtank 105. As a result, when the liquid feed pump 208 is operating, the liquid 300 flows from the main tank 201 to the subtank 105.

[0049] As the image formation process progresses and the liquid 300 is discharged from the liquid ejection head 100 and consumed, the amount of liquid 300 stored in the main tank 201 decreases. When the main tank 201 becomes empty, the liquid level in the air trap tank 205 drops from the appropriate level, and it is detected by the lower limit sensor 206c, for example, that it has fallen below the lower limit.

[0050] Here, the operation will be described with a focus on the air trap tank 205. When it is detected that the liquid level in the air trap tank 205 has dropped from the appropriate level and, for example, fallen below the appropriate level sensor 206b, the control unit of the liquid discharger 1 opens the exhaust valve 212 and operates the exhaust pump 213. This causes the air pressure inside the air trap tank 205 to drop, resulting in a state in which liquid 300 is drawn in via the first liquid path 202, the second liquid path 204, and the third liquid path 209. As a result, an attempt is made to draw in liquid 300 from the main tank 201 to bring the liquid level to the appropriate level.

[0051] At this time, if the liquid level in the air trap tank 205 does not recover after a predetermined time (for example, 1 to 10 seconds) has elapsed, that is, if the appropriate amount sensor 206b does not detect the liquid level, it is determined that the main tank 201 is empty. In other words, it is determined that the amount of liquid 300 stored in the main tank 201 has fallen below a certain amount.

[0052] This state of "main tank 201 is empty" is called "ink end." Then, information indicating "ink end" is recorded on IC card 261 attached to writing / reading unit 260. This process is called "ink end process."

[0053] The liquid supply unit 80 does not execute the above-mentioned supply operation when the IC card 261 on which the ink end is recorded is attached to the writing / reading unit 260. Therefore, when the main tank 201 becomes empty and reaches the "ink end" state, it is necessary to replace the main tank 201 and attach a new IC card 261 that comes with the main tank 201 to the writing / reading unit 260. Unless this operation is performed, the supply operation will not normally be resumed.

[0054] However, in order to connect a new main tank 201 to the first liquid path 202, a connection operation via the joint 203 is required, and a new IC card 261 must be attached to the writing / reading unit 260 separately from this operation. That is, the operation of connecting the joint 203 and the operation of replacing the IC card 261 are separate tasks. Therefore, if a user performing this operation makes a mistake in the procedure, the new IC card 261 will be attached to the writing / reading unit 260 with the joint 203 still in an unconnected state.

[0055] In order to prevent the supply operation from being restarted by mistake when such an irregular operation is performed, the connection state detection operation of the joint 203 may be performed before restarting the supply operation. The connection state detection operation of the joint 203 may be performed, for example, when the liquid ejection device 1 is started up, when the liquid ejection device 1 returns from error processing, when the main tank 201 is replaced after an ink end occurs, etc. Note that the connection state detection operation of the joint 203 is not performed during image formation processing.

[0056] [Connection status detection operation of joint 203] Next, a connection state detection operation will be described which detects whether the joint 203 provided at the end of the first liquid path 202 is "connected" or "not connected (disconnected)" to the main tank 201. This operation is also an operation which determines whether the liquid 300 is being sent from the main tank 201 to the air trap tank 205.

[0057] First, a forward flow confirmation operation is performed. In the forward flow confirmation operation, the on-off valve 221 and the exhaust valve 212 are opened, and the exhaust pump 213 is operated to supply liquid 300 from the main tank 201 to the air trap tank 205. When the liquid volume in the air trap tank 205 is equal to or less than the appropriate amount sensor 206b, it is confirmed that the liquid level reaches the appropriate amount sensor 206b within a specified time by the liquid supply from the main tank 201, thereby confirming that the joint 203 is connected.

[0058] If the liquid level does not reach the appropriate amount sensor 206b within a specified time in the forward flow confirmation operation even though an IC card 261 that has not been subjected to the ink end process is attached, it can be determined that the joint 203 is not connected. In other words, if the amount of liquid 300 stored in the air trap tank 205 does not exceed a predetermined amount within a specified time, it can be determined that the joint 203 is not connected. If the main tank 201 is empty, liquid 300 is not supplied to the air trap tank 205, and the liquid level does not reach the appropriate amount sensor 206b within the specified time. In this case, the connection state of the joint 203 can be confirmed by performing a reverse flow confirmation operation described later.

[0059] Next, the backflow checking operation will be described. As described above, the backflow checking operation is executed following the forward flow checking operation before the start of the supply operation after the ink end is detected.

[0060] In the backflow confirmation operation, first, the on-off valve 221 is opened, the exhaust valve 212 and the atmosphere release valve 241 are also opened, and the three-way valve 231 is operated to connect the fourth liquid path 207 to the backflow path 230 serving as a bypass path. Then, the liquid transfer pump 208 is operated to transfer liquid back from the air trap tank 205 to the main tank 201.

[0061] If the liquid volume in the air trap tank 205 is equal to or greater than the appropriate amount sensor 206b, it can be determined that the joint 203 is connected if it is detected that the liquid volume reaches the appropriate amount sensor 206b before the elapsed time from when the reverse transfer of liquid begins exceeds a specified time.

[0062] In addition, when the liquid volume in the air trap tank is below the appropriate volume sensor 206b, if the liquid volume in the air trap tank 205 reaches the lower limit sensor 206c within a specified time after the start of reverse liquid transfer, it can be determined that the joint 203 is connected.

[0063] If the joint 203 is not connected (disconnected state), the liquid 300 cannot be transferred back to the main tank 201 via the first liquid path 202, and the liquid 300 does not decrease in the air trap tank 205. Therefore, even if the elapsed time from the start of the reverse transfer exceeds a predetermined specified time, it can be determined that the joint 203 is not connected to the main tank 201 unless the amount of the liquid 300 in the air trap tank 205 becomes less than a predetermined amount.

[0064] As described above, the liquid supply unit 80 included in the liquid ejection device 1 according to this embodiment can reliably check the connection state of the joint 203 that maintains the connection between the main tank 201 and the first liquid path 202. This makes it possible to distinguish between an ink-out state and a joint set not being connected. Furthermore, the liquid supply unit 80 according to this embodiment can reliably write ink-out information to the IC card 261 during the ink-out process when the liquid 300 in the main tank 201 becomes empty.

[0065] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist of the present invention. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0066] 1:Liquid discharge device 23: Discharge unit 80:Liquid supply section 81: Liquid supply unit 100: Liquid ejection head 103: Manifold 104: Supply route 105: Subtank 107: Full sensor 108: Missing sensor 135: Fila 200: Liquid path 201: Main tank 202: Liquid path 203: Joint 204: Liquid path 205: Air trap tank 206: Liquid level detection sensor 206a: Upper limit sensor 206b: Appropriate amount sensor 206c: Lower limit sensor 207: Liquid path 208: Liquid delivery pump 209: Liquid supply valve 211: Exhaust route 212: Exhaust valve 213: Exhaust pump 221:Shut-off valve 230: Reflux route 231: Three-way valve 232: Three-way connector 241: Atmospheric release valve 260: Writing section 261: IC card 300:Liquid [Prior art documents] [Patent documents]

[0067] [Patent Document 1] JP 2020-001305 A

Claims

1. a sub-tank for temporarily storing liquid to be supplied to a liquid ejection head that ejects liquid; a main tank for storing liquid to be supplied to the sub-tank; a liquid path connecting the main tank and the sub tank; A joint for connecting or disconnecting the main tank and the liquid path; an air trapping means disposed in the liquid path for trapping gas contained in the liquid; A liquid sending means is provided downstream of the air capturing means in the liquid sending direction; a backflow path that disconnects the liquid supplying means from the sub-tank and changes the connection destination of the liquid supplying means to the main tank; a switching means for switching between communication and disconnection of a path from the liquid supplying means to the sub-tank and between communication and disconnection from the liquid supplying means to the backflow path, when determining that the amount of the liquid stored in the main tank has fallen to a certain amount or less, when the amount of the liquid stored in the air capturing means does not exceed a predetermined amount until a predetermined time has elapsed since the liquid transport means started to transport the liquid from the main tank to the air capturing means, The switching means closes the path from the liquid supply to the subtank and connects the liquid supply to the backflow path, transferring the liquid back from the air capture means to the main tank through the backflow path; A liquid ejection device comprising:

2. an exhaust means for exhausting the air captured by the air capturing means; 2. The liquid ejection device according to claim 1, wherein when the reverse transfer of liquid is performed, the reverse flow path is opened and the exhaust means is driven to reverse the liquid from the air capturing means through the reverse flow path to the main tank.

3. The air capture means has a plurality of liquid level detection means, 3. A liquid ejection device as described in claim 1 or 2, wherein when the appropriate amount detection means included in the liquid level detection means does not detect the liquid level before a predetermined specified time has elapsed since the liquid delivery means started to deliver the liquid from the main tank to the air capturing means, the switching means disconnects the path from the liquid delivery means to the subtank and connects it to the backflow path, thereby transferring the liquid back from the air capturing means to the main tank via the backflow path.

4. When the liquid level detection means includes an appropriate amount detection means or a lower limit detection means that does not detect the liquid level of the liquid in the air capture means before a predetermined time has elapsed since the start of the reverse liquid transfer, it is determined that the connection between the main tank and the liquid path is blocked at the joint, A liquid ejection device as described in claim 3, wherein when an appropriate amount detection means or a lower limit detection means included in the liquid level detection means detects the liquid level in the air capture means before a predetermined specified time has elapsed since the start of the reverse liquid transfer, it is determined that the main tank and the liquid path are connected at the joint.

5. a write / read unit for writing or reading information to or from a recording medium for recording information including the amount of the liquid stored in the main tank, A liquid ejection device according to claim 4, wherein when it is determined that the main tank and the liquid path are connected at the joint as a result of performing the reverse transfer of liquid, a writing / reading means performs an ink end process on the recording medium.

6. A sub-tank for temporarily storing liquid to be supplied to a liquid ejection head that ejects liquid; a main tank for storing liquid to be supplied to the sub-tank; a liquid path connecting the main tank and the sub tank; A joint for connecting or disconnecting the main tank and the liquid path; an air trapping means disposed in the liquid path for trapping gas contained in the liquid; A liquid sending means is provided downstream of the air capturing means in the liquid sending direction; a backflow path that disconnects the liquid supplying means from the sub-tank and changes the connection destination of the liquid supplying means to the main tank; a switching means for switching between communication and disconnection of a path from the liquid supplying means to the sub-tank and between communication and disconnection from the liquid supplying means to the backflow path, The air capture means has a plurality of liquid level detection means, when the liquid level detection means, which is included in the liquid level detection means, does not detect the liquid level before a predetermined time has elapsed since the liquid delivery means started to deliver the liquid from the main tank to the air capture means, the switching means disconnects the path from the liquid delivery means to the subtank and connects the path to the backflow path, thereby transferring the liquid back from the air capture means to the main tank via the backflow path. A liquid ejection device comprising:

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