Liquid supply device, inkjet recording device, and air detection method

Abstract

The present invention provides a liquid supply device that can detect the inflow of air into the second storage section and suppress false detections by the overflow sensor. [Solution] The liquid supply device 40 supplies ink (liquid) from the first storage section 41 to the second storage section 42 through the first flow path 47. The liquid supply device 40 includes an overflow sensor 44 that detects when the amount of ink exceeds the storage capacity of the second storage section 42, and a first pump 45 that is driven by power supply and sends ink from the first storage section 41 to the second storage section 42. The downstream end of the first flow path 47 is located in the ink stored in the second storage section 42, and the first pump 45 is stopped when the current value applied when the first pump 45 is driven at normal speed is less than or equal to a predetermined value and a predetermined time has elapsed since the start of operation of the first pump 45.

Description

Technical Field

[0001] The present invention relates to a liquid supply device, an inkjet recording device, and an air detection method.

Background Art

[0002] An inkjet recording device including an ink cartridge is known (Patent Document 1). The inside of the ink cartridge is divided into a plurality of chambers by partition plates, communication holes with adjacent chambers are provided at the lower parts of the partition plates, and an intermediate wall having a communication hole is provided in the chamber having an ink supply port to the recording head. Thereby, the bubbles generated in the ink cartridge are exposed to the space to be easily ruptured, and the function of the ink remaining amount detection device is suppressed from being hindered.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described inkjet recording device, it is impossible to detect the generation of bubbles in the ink cartridge or to stop the generation of bubbles. Therefore, there is a possibility that bubbles adhere to the ink remaining amount detection device, and there is a risk that the remaining amount of ink cannot be properly detected.

[0005] In consideration of the above circumstances, the present invention provides a liquid supply device, an inkjet recording device, and an air detection method that can detect air flowing into the second storage unit and suppress false detection by an overflow sensor.

Means for Solving the Problems

[0006] The liquid supply device according to the present invention is a liquid supply device that supplies liquid from a first storage unit to a second storage unit through a flow path, and comprises an overflow sensor that detects when the liquid exceeds the storage capacity of the second storage unit, and a pump that is driven by supplying power and sends the liquid from the first storage unit to the second storage unit, wherein the downstream end of the flow path is located in the liquid stored in the second storage unit, and the pump is stopped when the current value applied when the pump is driven at a normal speed is less than or equal to a predetermined value and a predetermined time has elapsed since the start of the pump's operation.

[0007] In this case, the first storage unit is detachably mounted to the housing, and after the pump is stopped and the mounting status of the first storage unit to the housing is confirmed, the pump is driven at a speed lower than the normal speed, and after a second predetermined time has elapsed since the restart of the pump at the low speed, it is driven at the normal speed.

[0008] In this case, the predetermined time and the second predetermined time are preferably set based on the length of the flow path and the flow velocity of the air in the flow path, respectively.

[0009] The inkjet recording apparatus according to the present invention comprises the liquid supply device described above and a recording head that ejects the ink, as a liquid, onto a sheet.

[0010] The present invention relates to a liquid supply device that supplies liquid from a first storage section to a second storage section through a flow path, and an air detection method for detecting air flowing into the second storage section, wherein the liquid supply device comprises an overflow sensor that detects when the liquid exceeds the storage capacity of the second storage section, and a pump that is driven by supplying power and sends the liquid from the first storage section to the second storage section, and includes a pump stop step that stops the pump when the current value applied when the pump is driven at a normal speed is less than or equal to a predetermined value and a predetermined time has elapsed since the start of the pump's operation, with the downstream end of the flow path positioned in the liquid stored in the second storage section.

[0011] In this case, it is preferable to further include a confirmation step in which the user is prompted to confirm the mounting status of the first reservoir, which is detachably attached to the housing, after the pump has been stopped; an air discharge step in which the pump is driven at a speed lower than the normal speed after the mounting status of the first reservoir to the housing has been confirmed; and a normal switching step in which the pump is driven at the normal speed after a second predetermined time has elapsed since the restart of the pump at the low speed.

[0012] In this case, the predetermined time and the second predetermined time are preferably set based on the length of the flow path and the flow velocity of the air in the flow path, respectively. [Effects of the Invention]

[0013] According to the present invention, it is possible to detect the inflow of air into the second storage section and to suppress false detections by the overflow sensor. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic front view of an inkjet recording device according to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing the outline of a liquid supply device according to one embodiment of the present invention. [Figure 3] This is a flowchart showing an air detection method according to one embodiment of the present invention. [Figure 4] This graph illustrates the relationship between the current value of the first pump of a liquid supply device according to one embodiment of the present invention and a predetermined value. [Modes for carrying out the invention]

[0015] The inkjet recording apparatus 1 according to this embodiment will be described below with reference to Figure 1. Figure 1 is a schematic front view of the inkjet recording apparatus 1. The front of the paper in Figure 1 is considered the front of the inkjet recording apparatus 1, and the left-right and up-down directions are set based on this front view. The arrows L, R, U, and Lo in Figure 1 indicate the left, right, top, and bottom of the inkjet recording apparatus 1, respectively. In this specification, terms indicating direction and position are used, but these terms are used for the convenience of explanation and do not limit the technical scope of the present invention.

[0016] The inkjet recording device 1 is an inkjet printer that includes a recording head 21 that ejects ink (an example of a liquid) onto a sheet S and forms an image on the sheet S. The inkjet recording device 1 has a box-shaped housing 10 that houses various components. A paper feed cassette 11 into which the sheets S are set is housed in the lower part of the housing 10, and a manual feed tray 12 into which the sheets S are manually inserted is installed on the right side of the housing 10. An output tray 13 into which recorded sheets S are stacked is installed on the upper left side of the housing 10.

[0017] A first transport path 14 is formed on the right side of the housing 10 for transporting sheets S from the paper feed cassette 11 to the recording head 21 in the center of the housing 10. Upstream of the first transport path 14 is a first paper feeding unit 15 for taking sheets S from the sheet bundle in the paper feed cassette 11, and downstream of the first transport path 14 is a pair of registration rollers 18 for adjusting the timing of feeding the sheets S. Further downstream of the first transport path 14 is a paper feeding path 16 for the manual feed tray 12, and the paper feeding path 16 is equipped with a second paper feeding unit 17 for taking sheets S from the sheet bundle in the manual feed tray 12.

[0018] Downstream of the pair of resist rollers 18, a conveying device 22 and four recording heads 21 are installed. The four recording heads 21 are provided corresponding to inks of four colors (for example, black, cyan, magenta, yellow). The pair of resist rollers 18 corrects the skew of the sheet S and sends out the sheet S to the conveying device 22 in accordance with the ink ejection operation by each recording head 21. In the housing 10, a liquid supply device 40 for supplying ink to each recording head 21 is provided (details will be described later).

[0019] The conveying device 22 is configured by stretching a conveying belt 24 over a plurality of tension rollers 23 installed below each recording head 21. Downstream of the conveying device 22, a drying device 25 for drying the ink on the sheet S is provided. Downstream of the drying device 25, a decal device 26 for correcting the curl generated on the sheet S due to the drying of the ink is provided. Downstream of the decal device 26, a second conveying path 27 for conveying the sheet S toward the paper discharge tray 13 is formed. Downstream of the second conveying path 27, a paper discharge unit 28 for discharging the recorded sheet S to the paper discharge tray 13 is provided.

[0020] Below the drying device 25, a maintenance unit 30 for cleaning the recording head 21 and a cap unit 31 for capping the recording head 21 are provided. The maintenance unit 30 is provided with a squeegee-shaped wiping blade, and the ink remaining on the nozzle surface of the recording head 21 is scraped off by the wiping blade. The cap unit 31 is provided with a head cap, and the head cap is placed on the nozzle surface of the recording head 21. Drying of the ink in the nozzles is suppressed by the head cap. Drying of the ink in the nozzles may be further suppressed by storing a liquid such as a cleaning liquid in the head cap.

[0021] In addition, the inkjet recording apparatus 1 includes a control device 20 that performs overall control. The control device 20 may be constituted by a processor or may be constituted by a logic circuit (hardware) formed in an integrated circuit or the like. When constituted by a processor, various processes are implemented by the processor reading and executing a program stored in a memory. As the processor, for example, a CPU (Central Processing Unit) is used. The memory is constituted by one or a plurality of storage devices such as a ROM (Read Only Memory) and a RAM (Random Access Memory) according to the application.

[0022] At the time of image formation (printing), the sheet S is taken out from the paper feed cassette 11 or the manual feed tray 12 by the first and second paper feed units 15 and 17 and sent to the pair of registration rollers 18. In accordance with the ink ejection timing, the sheet S is sent from the pair of registration rollers 18 to the conveyance belt 24, and each recording head 21 ejects ink to form a color image on the sheet S. The ink on the sheet S is dried by the drying device 25, and the curl of the sheet S is corrected by the decal device 26. The recorded (printed) sheet S is conveyed through the second conveyance path 27 to the paper discharge unit 28 and discharged to the paper discharge tray 13 by the paper discharge unit 28.

[0023] [Liquid supply device] Referring to FIG. 2, the liquid supply device 40 according to the present embodiment will be described. FIG. 2 is a schematic diagram showing an outline of the liquid supply device 40.

[0024] The inkjet recording apparatus 1 is provided with four liquid supply devices 40 corresponding to four colors of ink (four recording heads 21). Since the four liquid supply devices 40 have the same structure, in this specification, description will be made focusing on one liquid supply device 40.

[0025] The liquid supply device 40 includes a first storage section 41, a second storage section 42, a replenishment sensor 43, an overflow sensor 44, a first pump 45, a second pump 46, and a control device 20. The control device 20 is a component included in the inkjet recording device 1, but is also a component included in the liquid supply device 40. Furthermore, the liquid supply device 40 may be equipped with a separate control device (not shown) and controlled by that separate control device.

[0026] <Storage Unit 1> The first storage unit 41 stores ink inside. The first storage unit 41 is an ink cartridge that is detachably (replaceable) attached to the housing 10. For example, a user can remove an empty first storage unit 41 from the housing 10 and attach another first storage unit 41 filled with ink to the housing 10.

[0027] <Second Storage Unit> The second storage unit 42 is connected to the first storage unit 41, which is mounted on the housing 10, via a first flow path 47 (flow path). The second storage unit 42 temporarily stores the ink supplied from the first storage unit 41 through the first flow path 47. The second storage unit 42 is fixed to the internal frame (not shown) of the housing 10, and user replacement of the second storage unit 42 is restricted. The downstream end of the first flow path 47 (in the direction of ink flow) is positioned (immersed) in the ink stored in the second storage unit 42. The second storage unit 42 is also connected to the recording head 21 via a second flow path 48. The liquid supply device 40 supplies ink from the first storage unit 41 to the second storage unit 42 through the first flow path 47, and supplies ink from the second storage unit 42 to the recording head 21 through the second flow path 48.

[0028] <Fueling sensor, overflow sensor> The replenishment sensor 43 and the overflow sensor 44 are level sensors provided on the side of the second storage section 42, respectively, to detect whether there is an excess or deficiency of ink stored in the second storage section 42. The replenishment sensor 43 detects when the ink stored in the second storage section 42 has reached its lower limit, preventing an ink shortage in the second storage section 42. The overflow sensor 44 detects when the ink has exceeded the maximum storage limit (upper limit) of the second storage section 42, preventing an oversupply of ink from the first storage section 41 to the second storage section 42. The replenishment sensor 43 and the overflow sensor 44 are each electrically connected to the control device 20 and transmit detection signals (electrical signals) to the control device 20.

[0029] The lower limit of ink in the second storage section 42 refers to the level at which the downstream end of the first flow path 47 can remain submerged in ink. The upper limit of the amount of ink that can be stored in the second storage section 42 refers to the level beyond which, if the amount of ink increases, there is a risk of the ink overflowing from the second storage section 42. Therefore, it is an abnormal condition for the overflow sensor 44 to detect ink, and it is normal for the overflow sensor 44 not to detect ink.

[0030] <Pump 1, Pump 2> The first pump 45 (pump) is interposed in the first flow path 47, and the second pump 46 is interposed in the second flow path 48. The first pump 45 and the second pump 46 are each non-positive displacement pumps, such as centrifugal pumps, and are equipped with a DC motor (not shown) that rotates an impeller. The first pump 45 and the second pump 46 are each electrically connected to the control device 20 and are driven by supplying power (to the DC motor) while being controlled by the control device 20. The first pump 45 sends ink from the first storage unit 41 to the second storage unit 42, and the second pump 46 sends ink from the second storage unit 42 to the recording head 21. Although the first pump 45 and the second pump 46 are centrifugal pumps, they are not limited to centrifugal pumps and may be positive displacement pumps such as diaphragm pumps.

[0031] [Normal operation of liquid supply device] When the first storage unit 41 is correctly installed in the housing 10, the control device 20 drives the first pump 45 based on detection signals from the replenishment sensor 43 and the overflow sensor 44. For example, if the replenishment sensor 43 detects an ink shortage, the control device 20 drives the first pump 45 for a preset time to supply (replenish) ink from the first storage unit 41 to the second storage unit 42. Conversely, if the replenishment sensor 43 and the overflow sensor 44 do not detect an excess or shortage of ink, the control device 20 does not drive the first pump 45. Furthermore, during image formation (printing), the control device 20 drives the second pump 46 as appropriate to supply ink from the second storage unit 42 to the recording head 21.

[0032] If the overflow sensor 44 detects ink, the control device 20 will emergency stop the inkjet recording device 1 and, for example, display information indicating the abnormality on the touch panel 32 provided on the inkjet recording device 1. When the overflow sensor 44 detects ink, it is difficult for the user to restore operation, so a recovery operation such as cleaning or replacing the overflow sensor 44 by a professional maintenance worker is required. Therefore, the user will contact a maintenance worker according to the display on the touch panel 32 and request the recovery operation. As described above, when the overflow sensor 44 detects ink, the inkjet recording device 1 cannot be used until the recovery operation by the maintenance worker is completed.

[0033] Incidentally, when the first storage unit 41 is replaced, the user may not notice that the first storage unit 41 is not properly installed in the housing 10. In this case, the first storage unit 41 and the upstream end of the first flow path 47 are not properly connected, so when the first pump 45 is driven, air is drawn into the first flow path 47 and flows through the first flow path 47 into the second storage unit 42. In detail, since the downstream end of the first flow path 47 is immersed in the ink in the second storage unit 42, the air discharged from the downstream end of the first flow path 47 generates bubbles in the ink, causing the ink to foam. This foamed ink could then adhere to the overflow sensor 44, potentially causing the overflow sensor 44 to malfunction. Therefore, the liquid supply device 40 according to this embodiment is configured to enable an air detection method for detecting air flowing into the second storage unit 42.

[0034] [Air detection method] The air detection method will be explained with reference to Figures 3 and 4. Figure 3 is a flowchart of the air detection method. Figure 4 is a graph illustrating the relationship between the current value (I) and a predetermined value (P) of the first pump 45.

[0035] As shown in Figure 3, the air detection method comprises a pump stop step S1, a confirmation step S2, an air discharge step S3, and a normal switching step S4.

[0036] <Pump shutdown process> The pump stopping process S1 includes a normal driving process S11, a bubble detection process S12, and a normal stopping process S13.

[0037] In the normal drive process S11, the first pump 45 (DC motor) is driven at a normal speed under the control of the control device 20. The normal speed is the rotational speed of the DC motor when sending ink from the first storage unit 41 to the second storage unit 42 with the first storage unit 41 properly installed in the housing 10.

[0038] Here, because ink has a higher viscosity and greater mass than air, the load on the first pump 45 when it is driven differs depending on whether ink or air is being sent from the first storage unit 41 to the second storage unit 42. Specifically, as shown in Figure 4, when ink is being sent, the load on the first pump 45 increases, so the current value (I) supplied to the first pump 45 increases. In contrast, when air is being sent, the load on the first pump 45 decreases, so the current value (I) supplied to the first pump 45 decreases. Therefore, in the bubble determination step S12 of the pump stop step S1, the current value (I) supplied to the first pump 45 is monitored to determine whether the fluid flowing through the first flow path 47 is ink or air.

[0039] As shown in Figure 3, in the bubble detection step S12 of the pump stop step S1, the control device 20 determines whether the current value (I) applied when the first pump 45 is driven at normal speed is less than or equal to a predetermined value (P) ((I)≦(P)). Also, in order to determine that air has reached the second storage section 42 from the upstream end of the first flow path 47, in the bubble detection step S12, the control device 20 determines whether the elapsed time (T) since the start of driving the first pump 45 has exceeded a predetermined time (T1) ((T)>(T1)). If the current value (I) is less than or equal to the predetermined value (P) and the elapsed time (T) has exceeded the predetermined time (T1) (YES in S12), it can be determined that air has flowed into the second storage section 42, and the control device 20 stops the first pump 45 (normal stop step S13). In contrast, if the current value (I) exceeds a predetermined value (P) and the elapsed time (T) has not elapsed to a predetermined time (T1) (NO in S12), the control device 20 can determine that the ink is flowing normally into the second storage unit 42, and therefore continues to drive the first pump 45.

[0040] The predetermined value of the current (P) is determined experimentally and stored in the memory of the control device 20 beforehand. The predetermined time (T1) is the time it takes for the air to pass through the first flow path 47 and reach the second storage section 42, and is set based on the length (L) of the first flow path 47 and the air velocity (Vh) in the first flow path 47 (when the first pump 45 is driven at normal speed) ((T1) = (L) / (Vh)). The predetermined time (T1) is calculated in advance and stored in the memory of the control device 20.

[0041] <Confirmation process> After the first pump 45 is stopped, the verification process S2 is executed. In the verification process S2, the control device 20 displays a message on the touch panel 32, for example, "The first storage unit 41 is not properly installed," prompting (notifying) the user to check the installation status of the first storage unit 41, which is detachably attached to the housing 10. The user checks the installation status of the first storage unit 41 or reinstalls the first storage unit 41 on the housing 10 according to the display on the touch panel 32. After completing the check of the installation status of the first storage unit 41, the user operates the touch panel 32 to indicate the end of the verification process S2.

[0042] <Air discharge process> The air discharge process S3 includes a low-speed drive process S31 and an air discharge determination process S32.

[0043] In the low-speed drive process S31, after confirming the mounting status of the first storage unit 41 to the housing 10, the first pump 45 is driven again. Since air remains in the first flow path 47, if the first pump 45 is driven at normal speed, the air in the first flow path 47 will flow forcefully into the second storage unit 42, causing bubbles to form in the ink in the second storage unit 42. Therefore, in the low-speed drive process S31 of the air discharge process S3, in order to suppress the formation of bubbles in the second storage unit 42, the first pump 45 is driven at a speed lower than normal, under the control of the control device 20. The control device 20 drives the first pump 45 at a speed lower than normal by, for example, reducing the voltage (or current) applied to the DC motor of the first pump 45. Note that a speed lower than normal is, for example, a rotational speed of half or less of the normal speed.

[0044] In the discharge determination step S32 of the air discharge step S3, it is determined whether the elapsed time (T) since the start of operation of the first pump 45 has exceeded a second predetermined time (T2) ((T)>(T2)). If the elapsed time (T) has exceeded the second predetermined time (T2) (YES in S32), it can be determined that the air in the first flow path 47 has been discharged to the second storage unit 42, and the control device 20 proceeds to the next step (normal switching step S4). On the other hand, if the elapsed time (T) has not exceeded the second predetermined time (T2) (NO in S32), the control device 20 continues to operate the first pump 45. The second predetermined time (T2) is the time it takes for air to pass through the first flow path 47 and reach the second storage section 42, and is set based on the length (L) of the first flow path 47 and the air velocity (Vs) in the first flow path 47 (when the first pump 45 is driven at a low speed) ((T2) = (L) / (Vs)). The second predetermined time (T2) is calculated in advance and stored in the memory of the control device 20.

[0045] <Normal changeover process> The normal switching process S4 includes a drive switching process S41, a second bubble detection process S42, and an inspection stop process S43.

[0046] The drive switching process S41 of the normal switching process S4 is executed when a second predetermined time (T2) has elapsed since the restart of the first pump 45 at low speed. In the drive switching process S41, the control device 20 drives the first pump 45 at normal speed. That is, after it is determined that the air in the first flow path 47 has been discharged, the first pump 45 is switched from low-speed operation to normal speed operation.

[0047] Next, the control device 20 executes a second bubble detection process S42, which is the same as the bubble detection process S12. In the second bubble detection process S42, the control device 20 determines whether the current value (I) is less than or equal to a predetermined value (P) and whether the elapsed time (T) has exceeded a predetermined time (T1). If the current value (I) is less than or equal to a predetermined value (P) and the elapsed time (T) has exceeded a predetermined time (T1) (YES in S42), the control device 20 can determine that the air intake has not been eliminated, and therefore the control device 20 stops the first pump 45 and prompts the user to contact a maintenance worker (inspection stop process S43). The control device 20 displays a message on the touch panel 32, for example, "Please contact a maintenance worker." In this case, damage to the first flow path 47 or a malfunction of the first pump 45 may be the cause, so the user contacts a maintenance worker and requests an inspection according to the display on the touch panel 32.

[0048] In contrast, if the current value (I) exceeds a predetermined value (P) and the elapsed time (T) has not elapsed to a predetermined time (T1) (NO in S42), the control device 20 can determine that the air suction has been eliminated, and therefore continues to drive the first pump 45 (returning to the normal drive process S11).

[0049] According to the air detection method (liquid supply device 40) of this embodiment described above, when the current value (I) applied when the first pump 45 is being driven is less than or equal to a predetermined value (P), it can be determined that the first pump 45 is supplying air to the second storage unit 42. Furthermore, when the elapsed time (T) from the start of driving the first pump 45 has exceeded a predetermined time (T1), it can be determined that the air in the first flow path 47 has flowed into the second storage unit 42, causing bubbles to form in the ink in the second storage unit 42. In this way, the air that has flowed into the second storage unit 42 can be detected. When the current value (I) of the first pump 45 is less than or equal to a predetermined value (P) and the driving time of the first pump 45 has exceeded a predetermined time (T1), the first pump 45 stops, thereby suppressing foaming of the ink in the second storage unit 42. As a result, false detections by the overflow sensor 44 can be suppressed.

[0050] Furthermore, in the air detection method (liquid supply device 40) according to this embodiment, the first pump 45, which is restarted, is driven at a lower speed than normal, and is driven at normal speed after a second predetermined time (T2) has elapsed since the restart. With this configuration, the air remaining in the first flow path 47 can be slowly sent to the second storage section 42 (ink stored in the second storage section 42). This suppresses foaming of the ink stored in the second storage section 42 and effectively suppresses false detection by the overflow sensor 44.

[0051] Furthermore, according to the air detection method (liquid supply device 40) of this embodiment, since the predetermined time (T1) and the second predetermined time (T2) are set based on the length (L) of the first flow path 47 and the air flow velocity (Vh, Vs), it is possible to accurately determine when the air in the first flow path 47 has reached the second storage section 42 (ink).

[0052] In the liquid supply device 40 according to this embodiment, ink was stored in the first storage section 41 and the second storage section 42 as an example of liquid, but the present invention is not limited thereto. For example, as another example of liquid, a cleaning fluid for cleaning the nozzle forming surface of the recording head 21 may be stored in the first storage section 41 and the second storage section 42. In this case, the downstream end of the second flow path 48 may be connected to a maintenance unit 30 or a cap unit 31 (not shown).

[0053] Furthermore, although the air detection method according to this embodiment includes a pump stop step S1, a confirmation step S2, an air discharge step S3, and a normal switching step S4, the present invention is not limited thereto. The air detection method only needs to include the pump stop step S1, and the confirmation step S2, air discharge step S3, and normal switching step S4 may be omitted. For example, if the air detection method includes only the pump stop step S1, the first pump 45 will be stopped when the current value (I) is less than or equal to a predetermined value (P) and the elapsed time (T) has elapsed to a predetermined time (T1) (YES in S12), and the user may contact a maintenance worker.

[0054] Furthermore, although the inkjet recording device 1 in this embodiment was a color printer, it is not limited to this and may be a monochrome printer, copier, facsimile, etc. Also, the sheet S used for printing may be any sheet, such as plain paper, coated paper, tracing paper, or OHP (Over Head Projector) sheet.

[0055] The above description of embodiments illustrates one aspect of the liquid supply device, inkjet recording device, and air detection method according to the present invention, and the technical scope of the present invention is not limited to the above embodiments. The present invention may be modified, substituted, or transformed in various ways without departing from the spirit of the technical idea, and the claims include all embodiments that may fall within the scope of the technical idea. [Explanation of symbols]

[0056] 1. Inkjet recording device 10 cabinets 21 Recording head 40 Liquid supply device 41. First Storage Unit 42 Second Storage Unit 44 Overflow Sensor 45. Pump No. 1 (Pump) 47. First channel (channel) S1 Pump Stop Process S2 confirmation process S3 Air discharge process S4 Normal switching process

Claims

1. A liquid supply device that supplies liquid from a first storage section to a second storage section through a flow path, An overflow sensor that detects when the liquid exceeds the storage capacity of the second storage section, The system includes a pump, which is driven by the supply of electricity and sends the liquid from the first storage unit to the second storage unit, The downstream end of the flow path is placed in the liquid stored in the second storage section. A liquid supply device characterized in that the current value applied when the pump is driven at a normal speed is less than or equal to a predetermined value, and the pump is stopped when a predetermined time has elapsed since the start of operation of the pump.

2. The first storage unit is detachably attached to the housing, The liquid supply device according to claim 1, characterized in that, after the pump is stopped and the mounting state of the first storage unit to the housing is confirmed, the pump is driven at a speed lower than the normal speed, and after a second predetermined time has elapsed since the restart of the pump at the low speed, it is driven at the normal speed.

3. The liquid supply device according to claim 2, characterized in that the predetermined time and the second predetermined time are set based on the length of the flow path and the flow velocity of the air in the flow path, respectively.

4. A liquid supply device according to claim 1 or 2, An inkjet recording apparatus characterized by comprising a recording head that ejects the aforementioned liquid ink onto a sheet.

5. In a liquid supply device that supplies liquid from a first storage section to a second storage section through a flow path, an air detection method for detecting air flowing into the second storage section, The liquid supply device is An overflow sensor that detects when the liquid exceeds the storage capacity of the second storage section, The system includes a pump, which is driven by the supply of electricity and sends the liquid from the first storage unit to the second storage unit, An air detection method characterized by comprising a pump stop step, in which, when the downstream end of the flow path is positioned in the liquid stored in the second storage section, the current value applied when the pump is driven at a normal speed is less than or equal to a predetermined value, and a predetermined time has elapsed since the start of driving the pump, the pump is stopped.

6. After the pump has stopped, a confirmation step is performed to prompt the user to confirm the mounting status of the first storage unit, which is detachably attached to the housing. After confirming the mounting state of the first storage unit to the housing, an air discharge step is performed in which the pump is driven at a speed lower than the normal speed, The air detection method according to claim 5, further comprising a normal switching step of driving the pump at the normal speed after a second predetermined time has elapsed since the restart of the pump at the low speed.

7. The air detection method according to claim 6, characterized in that the predetermined time and the second predetermined time are set based on the length of the flow path and the flow velocity of the air in the flow path, respectively.

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