Droplet discharge device, abnormality detection method of the same, and program

Abstract

To provide a droplet discharge device which can detect an abnormality in a liquid passage with high accuracy, and to provide an abnormality detection method of the droplet discharge device and a program.SOLUTION: An inkjet recording device 1 which is a droplet discharge device includes: an inkjet head 24a which discharges an ink; a pump which pumps a liquid stored in an upstream tank at the upstream side in a liquid sending direction to a downstream tank at the downstream side in the liquid sending direction; a liquid passage 42 allowing the upstream tank and the downstream tank to communicate with each other; a liquid level sensor F functioning as a measurement part which measures a value related to a liquid amount of the downstream tank; and a control unit 50 functioning as a determination part which determines whether or not an abnormality occurs in the liquid passage 42. The determination part determines whether or not an abnormality occurs in the liquid passage 42 based on change of the value related to the liquid amount of the downstream tank when the pump pumps the ink for a predetermined liquid sending time.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a droplet ejection device, a method for detecting an abnormality in a droplet ejection device, and a program. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a droplet ejection device that ejects droplets from a droplet ejection head is known. The droplet ejection device includes a plurality of tanks containing liquid, and delivers the liquid to the droplet ejection head by a pump.

[0003] However, as the droplet ejection device is driven repeatedly, components in the liquid can cause abnormalities such as clogging of the liquid flow path. When an abnormality occurs in the liquid flow path, the flow rate of the liquid decreases relatively, causing the droplet ejection device to stop functioning. Therefore, it is necessary to detect abnormalities in the liquid flow path and perform maintenance.

[0004] Therefore, for example, Patent Document 1 describes a method for detecting abnormalities in a liquid flow path upstream of a tank in the liquid transfer direction by pumping liquid into a tank whose liquid level can be measured and measuring the time it takes for the liquid level to reach a second liquid level from a first liquid level. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-201234 Summary of the Invention [Problem to be solved by the invention]

[0006] However, changing the amount of liquid causes fluctuations in the liquid surface, which may prevent accurate detection of the second liquid level. Furthermore, particularly when the pump flow rate is high, the liquid level may exceed the second liquid level due to the time lag between the detection of the second liquid level and the transmission of a liquid transfer stop signal and the pump actually stopping liquid transfer. Therefore, this method cannot accurately detect abnormalities in the liquid flow path.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a droplet ejection device that can detect an abnormality in a liquid flow path with high accuracy, and a method and program for detecting an abnormality in a droplet ejection device. [Means for solving the problem]

[0008] In order to solve the above problems, the invention described in claim 1 is a droplet ejection device, a plurality of tanks for storing liquid; a droplet ejection head that ejects droplets; a pump that sends a liquid stored in an upstream tank on the upstream side in a liquid sending direction to a downstream tank on the downstream side in the liquid sending direction; a liquid flow path that connects the upstream tank and the downstream tank; a measuring unit for measuring a value related to the liquid volume of the liquid in the downstream tank; a determination unit that determines whether or not there is an abnormality in the liquid flow path, The determination unit determines whether or not there is an abnormality in the liquid flow path based on a change in a value related to the amount of liquid in the downstream tank when the pump is caused to deliver liquid for a predetermined liquid delivery time.

[0009] The invention described in claim 2 is the droplet ejection device described in claim 1, A setting unit is provided that sets the predetermined liquid transfer time based on a flow rate of the pump that is measured in advance.

[0010] The invention described in claim 3 is the droplet ejection device described in claim 1, the measuring unit includes a liquid level sensor capable of measuring the liquid level in the downstream tank, The measurement unit measures the amount of change in the liquid level in the downstream tank measured by the liquid level sensor.

[0011] The invention described in claim 4 is the droplet ejection device described in claim 2, The setting unit sets the predetermined liquid transfer time so that, as a result of causing the pump to transfer the liquid, the liquid level in the downstream tank reaches a predetermined value.

[0012] The invention described in claim 5 is the droplet ejection device described in claim 2, The setting unit sets the predetermined liquid transfer time in accordance with the measurement accuracy of the measurement unit.

[0013] The invention described in claim 6 is the droplet ejection device described in claim 1, The pump includes an adjusting unit that adjusts the liquid level in the downstream tank to a predetermined value before causing the pump to deliver the liquid for the predetermined liquid delivery time.

[0014] The invention described in claim 7 is the droplet ejection device described in any one of claims 1 to 6, The pump is a diaphragm pump.

[0015] The invention described in claim 8 is the droplet ejection device described in any one of claims 1 to 6, The system further includes a calculation unit that calculates the liquid level in the downstream tank based on an average value of the measurement values ​​of the measurement unit over a predetermined period of time.

[0016] The invention described in claim 9 is a plurality of tanks for storing liquid; a droplet ejection head that ejects droplets; a pump that sends a liquid stored in an upstream tank on the upstream side in a liquid sending direction to a downstream tank on the downstream side in the liquid sending direction; a liquid flow path that connects the upstream tank with the downstream tank; a measurement unit that measures a value related to a flow rate of the liquid in the downstream tank, a determination step of determining whether or not there is an abnormality in the liquid flow path, The determining step determines whether or not there is an abnormality in the liquid flow path based on a change in a value relating to the amount of liquid in the downstream tank when the pump is caused to deliver liquid for a predetermined liquid delivery time.

[0017] The invention described in claim 10 is a program, a plurality of tanks for storing liquid; a droplet ejection head that ejects droplets; a pump that sends a liquid stored in an upstream tank on the upstream side in a liquid sending direction to a downstream tank on the downstream side in the liquid sending direction; a liquid flow path that connects the upstream tank and the downstream tank; a measuring unit for measuring a value related to the amount of liquid in the downstream tank; a determination unit that determines whether or not there is an abnormality in the liquid flow path; The determination unit determines whether or not there is an abnormality in the liquid flow path based on a change in a value relating to the amount of liquid in the downstream tank when the pump is caused to deliver liquid for a predetermined liquid delivery time. [Effects of the Invention]

[0018] According to the present invention, abnormalities in the liquid flow path can be detected with high accuracy. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a side cross-sectional view of an inkjet recording apparatus. [Figure 2] FIG. 2 is a schematic diagram of a liquid delivery section. [Figure 3] FIG. 2 is a schematic cross-sectional view of a liquid level sensor and a subtank. [Figure 4] FIG. 1 is a block diagram of an inkjet recording apparatus. [Figure 5] 10 is a flowchart of a process for detecting clogging of a liquid flow path. [Figure 6] 10A and 10B are diagrams illustrating an example of an increase in the liquid level in the second sub-tank during the liquid flow path clogging detection process. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, droplet ejection devices according to embodiments of the present invention will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, components having the same functions and configurations will be given the same reference numerals, and their description will be omitted.

[0021] [Overall configuration of inkjet recording device] 1 is a side cross-sectional view showing the main configuration of an inkjet recording apparatus 1, which is one embodiment of the droplet ejection device of the present invention. The inkjet recording apparatus 1 includes a paper feed unit 10, an image forming unit 20, a paper discharge unit 30, a liquid delivery unit 40 (see FIG. 2), a control unit 50, and a notification unit 60 (both of which are shown in FIG. 4).

[0022] Under the control of the control unit 50, the inkjet recording device 1 transports the recording medium P from the paper feed unit 10 to the image forming unit 20. Then, the control unit 50 forms an image on the recording medium P in the image forming unit 20 using ink supplied from the liquid delivery unit 40. After the image formation, the control unit 50 ejects the recording medium P to the paper ejection unit 30.

[0023] The recording medium P is not limited to paper such as plain paper or coated paper. The recording medium P may be any medium, such as fabric or sheet-like resin, on whose surface the ink can be fixed.

[0024] In the following description, the X direction, Y direction, and Z direction are the directions shown in Fig. 1. In addition, in the following description, the X direction, Y direction, and Z direction are also referred to as the width direction, conveyance direction, and height direction, respectively.

[0025] (Paper feed section) The paper feed unit 10 stores recording media P before image formation. The paper feed unit 10 transports the recording media P to the image forming unit 20 under the control of the control unit 50. The paper feed unit 10 includes a paper feed tray 11, a transport unit 12, and the like.

[0026] {Paper feed tray} The paper feed tray 11 is a plate-like member that stores recording media P. The paper feed tray 11 is provided so that one or more recording media P can be placed on it. The paper feed tray 11 moves up and down depending on the amount of recording media P placed on it. By this up and down movement, the paper feed tray 11 is held at a position where the top recording medium P can be transported by the transport unit 12.

[0027] {Transportation section} The conveying unit 12 conveys the recording medium P from the paper feed tray 11 to the image forming unit 20. The conveying unit 12 includes a conveying mechanism. The conveying mechanism drives a belt 123 to convey the recording medium P on the belt 123. The belt 123 is ring-shaped, and the inside of the ring is supported by a plurality of rollers 121 and 122. The conveying unit 12 delivers the top recording medium P placed on the paper feed tray 11 onto the belt 123, and conveys the recording medium P along the belt 123.

[0028] (Image forming section) The image forming unit 20 cooperates with the liquid supply unit 40 to record an image on the recording medium P under the control of the control unit 50. The image forming unit 20 includes an image forming drum 21, a delivery unit 22, a paper heating unit 23, a head unit 24, an irradiation unit 25, a delivery unit 26, and the like.

[0029] {Image forming drum} The image forming drum 21 carries the recording medium P along its cylindrical outer circumferential surface and transports the recording medium P as it rotates. The transport surface of the image forming drum 21 faces the paper heating unit 23, the head unit 24, and the irradiation unit 25, and performs an image forming process on the transported recording medium P.

[0030] {Delivery unit} The delivery unit 22 is provided at a position interposed between the transport section 12 and the image forming drum 21. The delivery unit 22 includes a claw portion 221, a delivery drum 222, and the like.

[0031] The claw portion 221 is a cylindrical member that holds one end of the recording medium P conveyed by the conveying unit 12. The delivery drum 222 is a member that guides the recording medium P held by the claw portion 221.

[0032] The delivery unit 22 picks up the recording medium P on the conveying section 12 with the claw portion 221 and moves it along the outer circumferential surface of the delivery drum 222. The delivery unit 22 delivers the recording medium P to the image forming drum 21 by this operation.

[0033] {Paper heating section} The paper heating unit 23 includes, for example, an electric heating wire, and generates heat in response to the passage of electricity. The paper heating unit 23 is controlled by the control unit 50, and generates heat so that the recording medium P passing nearby reaches a predetermined temperature. The paper heating unit 23 is located near the outer circumferential surface of the image forming drum 21, and is positioned upstream of the head unit 24 in the transport direction of the recording medium P.

[0034] A temperature sensor (not shown) is provided near the paper heating unit 23. The control unit 50 uses the temperature sensor to detect the temperature near the paper heating unit 23. The control unit 50 controls the heat generation of the paper heating unit 23 based on the detected temperature.

[0035] {Head Unit} The head unit 24 is composed of, for example, a plurality of inkjet heads. The head unit 24 forms an image by ejecting ink droplets from nozzles onto the recording medium P. The head units 24 are provided corresponding to the colors C (cyan), M (magenta), Y (yellow), and K (black). In FIG. 1, the head units 24 corresponding to the colors Y, M, C, and K are provided in this order from upstream in the transport direction of the recording medium P.

[0036] In this embodiment, a plurality of head units 24 are arranged in the width direction with a length (width) that covers the entire recording medium P. In other words, the inkjet recording apparatus 1 is a one-pass line-head type inkjet recording apparatus. The head unit 24 is configured by arranging a plurality of inkjet heads 24a (see FIG. 2), which are droplet ejection heads. The number of head units 24 may be five or more or three or less. Alternatively, the head unit 24 may be configured by a single inkjet head 24a.

[0037] The ink ejected by the head unit 24 is, for example, ultraviolet curable ink (UV ink). The ultraviolet curable ink contains, for example, an ultraviolet curable resin. The ultraviolet curable resin contains a monomer and a polymerization initiator. When the ink containing the ultraviolet curable resin is irradiated with ultraviolet light, the monomer is polymerized by the action of the polymerization initiator, and the ink is cured and fixed to the recording medium P.

[0038] The ink ejected by the head unit 24 may be ink containing a gelling agent. Ink containing a gelling agent changes phase between a gel state and a liquid (sol) state depending on the temperature. Ink containing a gelling agent has a phase change temperature of, for example, about 40 to 100°C, and is uniformly liquefied (solized) when heated to or above the phase change temperature. On the other hand, ink containing a gelling agent gels at normal room temperature, i.e., about 0 to 30°C. Therefore, the ink in the head unit 24 is heated to an appropriate temperature by an ink heater (not shown) or the like to be put into a sol state. After being ejected and landing on the recording medium P, the ink transitions appropriately to a gel state while being transported by the image forming drum 21.

[0039] {Irradiation unit} The irradiation unit 25 includes, for example, a fluorescent tube such as a low-pressure mercury lamp. The irradiation unit 25 emits energy rays such as ultraviolet light by emitting light from the fluorescent tube. The irradiation unit 25 is provided near the outer peripheral surface of the image forming drum 21. The irradiation unit 25 is also provided so as to be located downstream of the head unit 24 in the transport direction of the recording medium P. The irradiation unit 25 irradiates the recording medium P onto which ink has been ejected with energy rays. If the ink on the recording medium P is UV ink, it is cured by the action of the energy rays.

[0040] The fluorescent tube that emits ultraviolet light is not limited to a low-pressure mercury lamp. The fluorescent tube may be a mercury lamp with an operating pressure of, for example, several hundred Pa to 1 MPa. The fluorescent tube may also be a light source that can be used as a germicidal lamp, such as a cold cathode tube, an ultraviolet laser light source, a metal halide lamp, or a light-emitting diode. Among these, it is preferable that the fluorescent tube is a light source that can irradiate ultraviolet light with higher illuminance and is energy-saving. The fluorescent tube is, for example, a light-emitting diode. The energy rays are not limited to ultraviolet light, and may be energy rays that have the property of curing ink depending on the properties of the ink. The light source is also replaced depending on the energy rays.

[0041] Although the above describes an example in which the head unit 24 ejects ultraviolet curable ink or ink containing a gelling agent, the present invention is not limited to this. The ink ejected by the head unit 24 may be water-based ink or ink with other physical properties.

[0042] {Delivery Department} The delivery unit 26 includes a transport mechanism. The transport mechanism drives a ring-shaped belt 263, the inside of which is supported by a plurality of rollers 261 and 262, to transport the recording medium P. The delivery unit 26 includes a cylindrical delivery roller 264. The delivery roller 264 delivers the recording medium P from the image forming drum 21 to the transport mechanism. The delivery unit 26 transports the recording medium P delivered onto the belt 263 by the delivery roller 264, and sends it out to the paper discharge unit 30.

[0043] (Paper ejection section) The paper discharge unit 30 discharges the recording medium P on which an image has been formed in the image forming unit 20. The paper discharge unit 30 includes a plate-shaped paper discharge tray 31. The recording medium P sent out from the image forming unit 20 by the delivery unit 26 is placed on the paper discharge tray 31. The paper discharge unit 30 stores the recording medium P until the user removes it.

[0044] (liquid delivery section) Fig. 2 is a schematic diagram of the liquid delivery unit 40. Note that Fig. 2 shows only one inkjet head 24a, omitting the multiple inkjet heads 24a. The liquid delivery unit 40 includes a tank 41, a liquid flow path 42, and the like (see Fig. 4 for both).

[0045] {tank} The tank 41 stores ink. The tank 41 is made of, for example, metal and has a rigid, sealed structure. The tank 41 includes a main tank 411, a first sub-tank 412, and a second sub-tank 413.

[0046] [Main tank] The main tank 411 contains ink of each color that is supplied to each part of the liquid delivery unit 40. Although omitted in FIG. 2, a main tank 411 is provided for each ink color. The ink is supplied to the inkjet head 24a via a first liquid flow path 421, a first sub-tank 412, a second liquid flow path 422, a second sub-tank 413, and a third liquid flow path 423, which will be described later. The main tank 411 is replaceable as a whole, and is formed to be detachable from the first liquid flow path 421 regardless of the operating state of a supply pump 4211, which will be described later.

[0047] [First sub-tank] The first sub-tank 412 temporarily stores the ink supplied from the main tank 411. The provision of the first sub-tank 412 in the liquid delivery unit 40 reduces pressure changes caused by pulsation when the supply pump 4211 supplies ink from the main tank 411. Furthermore, ink that is not discharged from the inkjet head 24a is collected in the first sub-tank 412 from an outlet.

[0048] [Second sub-tank] The second sub-tank 413 temporarily stores the ink from which foreign matter has been collected by a filter 4223 (described later). The second sub-tank 413 is provided with a back pressure adjustment means (not shown) that applies an appropriate negative pressure to the inkjet head 24a to prevent ink from leaking.

[0049] In the following description, the first sub-tank 412 and the second sub-tank 413 will be simply referred to as "sub-tanks" unless a distinction is made between them.

[0050] <Liquid level sensor> Each subtank is provided with a liquid level sensor F. The liquid level sensor F measures information about the amount of ink in the attached subtank. Specifically, the liquid level sensor F measures the liquid level position in the subtank and transmits the data to the control unit 50. The control unit 50 obtains the liquid level in the subtank based on the data.

[0051] A detailed configuration of the liquid level sensor F in this embodiment is shown in Fig. 3. As shown in Fig. 3, for example, the liquid level sensor F is a float sensor including a float Fa, a magnetic sensor Fb, and a magnetic body Fc.

[0052] A float Fa is provided inside the subtank. A magnet is built into the float Fa. The float Fa rises and falls in response to an increase or decrease in the amount of ink in the subtank, generating a magnetic field. A magnetic sensor Fb is provided on top of the subtank. The magnetic sensor Fb measures the magnetic flux density of the magnetic field, which changes in response to the rise and fall of the float Fa. The magnetic sensor Fb then measures the liquid level in the subtank. A magnetic body Fc is provided near the magnetic sensor Fb. The magnetic body Fc improves the sensitivity of the magnetic sensor Fb by concentrating the magnetic flux on it. In this way, the liquid level sensor F according to this embodiment is a magnetic sensor that uses magnetism to measure information about the amount of ink.

[0053] The magnetic sensor Fb may be provided on the side of the sub-tank, but it is preferable to provide the magnetic sensor Fb on the top of the sub-tank, as this improves its sensitivity.

[0054] Furthermore, the liquid level sensor F that measures the liquid level in the sub-tank is not limited to a float sensor equipped with a float Fa and a magnetic sensor Fb. For example, the liquid level in the sub-tank may be measured by a capacitance sensor that utilizes an electric field.

[0055] 3 shows the first sub-tank 412 as an example, the liquid level sensor F is also attached to the second sub-tank 413. In the following description, for the sake of distinction, the liquid level sensor F provided in the first sub-tank 412 will be referred to as the first liquid level sensor F1, and the liquid level sensor F provided in the second sub-tank 413 will be referred to as the second liquid level sensor F2.

[0056] The subtank is provided with an ink heating unit (not shown) that maintains the ink inside at an appropriate temperature. The ink heating unit is composed of a heater, a heat transfer member that transfers heat from the heater, and the like. The heater that makes up the ink heating unit is, for example, an electric heating wire that generates Joule heat when electricity is applied. The heat transfer member that makes up the ink heating unit is, for example, a material with high thermal conductivity, such as a heat conduction plate made of various metals (alloys).

[0057] Each sub-tank is provided with a pressure sensor capable of measuring the internal pressure and an atmosphere communication passage that communicates with the atmosphere. The atmosphere communication passage is provided with an air pump that can suck air from each sub-tank and reduce the pressure under the control of the control unit 50, thereby controlling the pressure inside each sub-tank.

[0058] In particular, the control unit 50 sends ink from the first subtank 412 to the second subtank 413 by, for example, sending air from the second subtank 413 to the first subtank 412, thereby making the pressure inside the first subtank 412 higher than the pressure inside the second subtank 413. More specifically, when the amount of liquid in the first subtank 412 is greater than a predetermined lower limit and the amount of liquid in the second subtank 413 reaches the predetermined lower limit, the control unit 50 sends ink from the first subtank 412 to the second subtank 413 by this control.

[0059] Furthermore, a flow path that connects the first sub-tank 412 and the second sub-tank 413 may be provided in addition to the second liquid flow path 422. Then, the pressure inside the second sub-tank 413 may be set higher than the pressure inside the first sub-tank 412, and the ink in the second sub-tank 413 may be circulated to the first sub-tank 412 via this flow path.

[0060] {Liquid flow path} The liquid flow path 42 is an ink flow path that connects the main tank 411 to the inkjet head 24a in a manner that allows the ink to be returned. The liquid flow path 42 includes a first liquid flow path 421, a second liquid flow path 422, a third liquid flow path 423, and a fourth liquid flow path 424. The liquid flow path 42 is preferably ink-resistant, and has a hollow, annular tube structure.

[0061] [First liquid flow path] The first liquid flow path 421 communicates between the main tank 411 and the first sub-tank 412. A supply pump 4211 and a supply valve 4212 are provided in the first liquid flow path 421.

[0062] <Supply pump> The supply pump 4211 sends ink from the main tank 411 to the first sub-tank 412. When the control unit 50 detects, as a result of measurement by the first liquid level sensor F1, that the amount of liquid in the first sub-tank 412 is a predetermined lower limit, it drives the supply pump 4211 for a predetermined time to send the ink from the main tank 411 to the first sub-tank 412.

[0063] The supply pump 4211 is preferably a diaphragm pump from the viewpoints of durability, cost, size, and variety.

[0064] <Supply valve> The supply valve 4212 is, for example, a solenoid valve. Under the control of the control unit 50, the supply valve 4212 selectively opens the first liquid flow path 421 when the supply pump 4211 is driven.

[0065] [Second liquid flow path] The second liquid flow path 422 is a flow path that connects the first sub-tank 412 and the second sub-tank 413. In the second liquid flow path 422, a circulation pump 4221, a pressure sensor 4222, a filter 4223, and a first circulation valve 4224 are provided.

[0066] <Circulation pump> The circulation pump 4221 sends ink from the first subtank 412 to the second subtank 413. When the control unit 50 detects, as a result of measurement by the second liquid level sensor F2, that the amount of liquid in the second subtank 413 is at a predetermined lower limit, it drives the circulation pump 4221 for a predetermined time to send the ink from the first subtank 412. For the same reasons as for the supply pump 4211, the circulation pump 4221 is preferably a diaphragm pump.

[0067] <Pressure sensor, filter, first circulation valve> The pressure sensor 4222 detects the pressure value of the second liquid flow path 422 and sends it to the control unit 50. The filter 4223 is formed, for example, from a mesh-like metal or porous resin body, and has a mesh of a predetermined size. The filter 4223 collects foreign matter in the ink flowing through the second liquid flow path 422. The first circulation valve 4224 is an electromagnetic valve, and selectively opens the second liquid flow path 422 when the circulation pump 4221 is driven.

[0068] [Third and fourth liquid flow paths] The third liquid flow path 423 is a flow path that connects the second sub-tank 413 and the inlet of the inkjet head 24a. The fourth liquid flow path 424 is a flow path that connects the outlet of the inkjet head 24a and the first sub-tank 412. A second circulation valve 4241, which is an electromagnetic valve, is provided in the fourth liquid flow path 424. Under the control of the control unit 50, the second circulation valve 4241 selectively opens the fourth liquid flow path 424 when circulating ink from the inkjet head 24a to the first sub-tank 412.

[0069] (Control unit) Fig. 4 is a block diagram showing the configuration of the inkjet recording apparatus 1. A control unit 50 controls each unit constituting the inkjet recording apparatus 1. As shown in Fig. 4, the control unit 50 is connected to each unit constituting the inkjet recording apparatus 1. The control unit 50 includes a CPU (Central Processing Unit) 51, a RAM (Random Access Memory) 52, a ROM (Read Only Memory) 53, etc.

[0070] The CPU 51 reads and executes various programs, data, etc. corresponding to the processing content from a storage device such as the ROM 53. The CPU 51 also controls the operation of each part of the inkjet recording apparatus 1 according to the processing content executed. The RAM 52 temporarily stores various programs, data, etc. processed by the CPU 51. The ROM 53 stores various programs, data, etc. read by the CPU 51, etc.

[0071] (Notification Department) The notification unit 60 notifies various pieces of information under the control of the control unit 50. The notification unit 60 is, for example, a display unit having a screen, or a communication unit capable of communicating with other devices via a network.

[0072] [Pump flow rate measurement processing] A description will be given of the pump flow rate measurement process and the liquid flow path clogging detection process performed by the above-described inkjet recording apparatus 1. The control unit 50 executes the pump flow rate measurement process prior to the liquid flow path clogging detection process.

[0073] The control unit 50 causes the circulation pump 4221 to send liquid for a predetermined liquid sending time S1 [s]. Then, as a result of measurement by the second liquid level sensor F2, it is assumed that the liquid level in the second sub-tank 413 has risen by L1 [mm]. At this time, the control unit 50 calculates the flow rate V1 [mm / s] per unit time of the circulation pump 4221 using the following formula (1). Formula (1)...V1[mm / s]=L1[mm] / S1[s]

[0074] The control unit 50 stores the calculated flow rate V1 of the circulation pump 4221 in the ROM 53, and ends the pump flow rate measurement process.

[0075] It is particularly preferable to perform the pump flow rate measurement process when the inkjet recording apparatus 1 is installed. When the inkjet recording apparatus 1 is installed, the liquid flow path 42 is least clogged and the maximum flow rate can be obtained. This is because it becomes clearer whether or not the liquid flow path 42 has become clogged and the flow rate has decreased in the liquid flow path clogging detection process described below.

[0076] [Liquid flow path clogging detection process] Next, the liquid flow path clogging detection process performed by the inkjet recording apparatus 1 as described above will be described with reference to the flowchart in Fig. 5 and Fig. 6. The control unit 50 executes the liquid flow path clogging detection process at a predetermined timing, such as after a predetermined number of image formation processes or when starting up the inkjet recording apparatus 1. In the following, it is assumed that the process detects whether or not the second liquid flow path 422, particularly the filter 4223, is clogged.

[0077] First, the control unit 50 adjusts the liquid level in the second subtank 413, which is the tank 41 downstream in the liquid sending direction of the second liquid flow path 422, which is the liquid flow path 42 targeted for abnormality detection, to a lower limit value A1 of the liquid level in the second subtank 413 (step S101). If the liquid level in the second subtank 413 is higher than the lower limit value A1, the control unit 50 adjusts the pressure in the second subtank 413 using the back pressure adjustment means. Through this control, the control unit 50 discharges ink from the second subtank 413 to adjust the liquid level in the second subtank 413 so as to lower it. In this way, the control unit 50 functions as an adjustment unit that adjusts the liquid level in the second subtank 413 to a predetermined value before step S105.

[0078] The control unit 50 acquires measurement values ​​from the second liquid level sensor F2 for a predetermined time (e.g., 10 seconds). Then, the control unit 50 calculates the first liquid level A2 of the second subtank 413 from the average value of the measurement values ​​(step S102). By varying the liquid level of the second subtank 413 in step S101, fluctuations occur in the liquid level in the second subtank 413. Therefore, one measurement value from the second liquid level sensor F2 acquired at a predetermined timing has low accuracy as the liquid level of the second subtank 413. However, as described above, by having the control unit 50 function as a calculation unit that calculates the first liquid level A2 based on the average value of the measurement values ​​from the second liquid level sensor F2 over a predetermined time, a highly accurate first liquid level A2 can be acquired.

[0079] The control unit 50 sets (step S103) a liquid sending time S2 of the circulation pump 4221 in the subsequent step S105. The liquid sending time S2 can be calculated from the following formula (2) based on the flow rate V1 [mm / s] of the circulation pump 4221 calculated in the pump flow rate measurement process and the liquid level rise value L2 [mm] of the second sub-tank 413, which is a target value. Formula (2)...S2[s]=L2[mm] / V1[mm / s]

[0080] The target value L2 may be any value so long as A2+L2 is equal to or less than the upper limit B of the liquid level in the second sub-tank 413. However, it is preferable that the target value L2 be a value such that A2+L2=B, in other words, L2=B-A2. If the liquid level in the second sub-tank 413 is set to the lower limit A1 in step S101 and then the target value L2 is set such that L2=B-A2, the liquid transfer time S2 will be the longest. Therefore, in step S110, which will be described later, the difference between L2-(A3-A2) and the predetermined value will be more likely to appear, making it clearer whether or not there is a blockage in the second liquid flow path 422.

[0081] In this way, the control unit 50 functions as a setting unit that sets the liquid sending time S2 in step S104 based on the flow rate V1 of the circulation pump 4221 calculated in advance in the pump flow rate measurement process.

[0082] The control unit 50 opens the first circulation valve 4224 (step S104). Then, the control unit 50 drives the circulation pump 4221 for the liquid delivery time S2 set in step S103, thereby delivering the liquid to the second sub-tank 413 (step S105). After the predetermined time has elapsed (step S106; Yes), the control unit 50 stops the driving of the circulation pump 4221 (step S107) and closes the first circulation valve 4224 (step S108).

[0083] The control unit 50 acquires the measurement value of the second liquid level sensor F2 for a predetermined time (e.g., 10 seconds). Then, the average value of the measurement values ​​is calculated (step S109). As in step S102, the liquid level in the second sub-tank 413 is changed, causing fluctuations in the liquid level in the second sub-tank 413. However, by acquiring the average value of the measurement value of the second liquid level sensor F2 for a predetermined time in this manner, a highly accurate second liquid level A3 can be obtained.

[0084] The control unit 50 determines whether the difference between the target value L2 and the amount of change A3-A2 in the liquid level height is less than a predetermined value (step S110). If the value of L2-(A3-A2) is less than the predetermined value (step S110; Yes), that is, if an amount of ink close to the target value L2 is being delivered, the control unit 50 determines that there is no abnormality in the second liquid flow path 422 and ends the liquid flow path clogging detection process. On the other hand, if the value of L2-(A3-A2) is equal to or greater than the predetermined value (step S110; No), that is, if an amount of ink close to the target value L2 is not being delivered, the control unit 50 determines that there is an abnormality in the second liquid flow path 422. Therefore, the control unit 50 issues a warning to the user via the notification unit 60 (step S111). In this way, the control unit 50 functions as a determination unit that determines whether or not there is an abnormality in the liquid flow path 42.

[0085] [Effects of the embodiment] As described above, the inkjet recording apparatus 1 according to this embodiment includes multiple tanks 41 for storing liquid. The inkjet recording apparatus 1 also includes a droplet ejection head 24a for ejecting droplets. The inkjet recording apparatus 1 also includes a pump for transferring liquid stored in an upstream tank located upstream in the liquid transfer direction to a downstream tank located downstream in the liquid transfer direction. The inkjet recording apparatus 1 also includes a liquid flow path 42 connecting the upstream tank and the downstream tank. The inkjet recording apparatus 1 also includes a liquid level sensor F that functions as a measurement unit for measuring a value related to the liquid volume of the downstream tank. The inkjet recording apparatus 1 also includes a control unit 50 that functions as a determination unit for determining whether or not an abnormality exists in the liquid flow path 42 based on a change in the value related to the liquid volume of the downstream tank when the pump is caused to deliver the liquid for a predetermined liquid delivery time. This configuration differs from a case in which liquid is delivered to achieve a predetermined liquid level height; the liquid delivery time for achieving the predetermined liquid level height is preset. Therefore, the presence or absence of an abnormality in the liquid flow path can be detected with high accuracy.

[0086] [Modifications, etc.] As described above, specific explanations have been made based on the embodiments of the present invention. However, the present invention is not limited to the above-described embodiments. It is of course possible for the present invention to be subject to various modifications including the scope of the invention described in the claims and its equivalent scope.

[0087] For example, in the above, a configuration for detecting the presence or absence of clogging in the second liquid flow path 422 was exemplified, but it is not limited thereto. Any liquid flow path 42 provided with a pump and a tank 41 on the upstream side in the liquid feeding direction and a tank 41 on the downstream side in the liquid feeding direction can be a target for abnormality detection. Therefore, in the present embodiment, the first liquid flow path 421 provided with the main tank 411 and the supply pump 4211 on the upstream side in the liquid feeding direction and the first sub-tank 412 on the downstream side in the liquid feeding direction can also be a target for the liquid flow path clogging detection process.

[0088] Also, in the above, in step S101, the liquid level height in the second sub-tank 413 was adjusted to the lower limit value A1 of the liquid level height in the second sub-tank 413, but it is not limited thereto. In step S101, the liquid level height in the second sub-tank 413 may be set to a determined predetermined value, and the predetermined value is not limited to the lower limit value A1. For example, when the current liquid level height in the second sub-tank 413 is the lower limit value A1 and the predetermined value is equal to or higher than the lower limit value A1, ink may be fed from the first sub-tank 412 to the second sub-tank 413.

[0089] Also, in the above, in step S103, it was preferable to set a target value L2 such that L2 = B - A2, but it is not limited thereto. However, if as a result of the liquid feeding in step S106, the second liquid level height A3 of the second sub-tank 413 exceeds the upper limit value B, there is a risk that ink will overflow from the second sub-tank 413. Therefore, when the measurement accuracy of the second liquid level sensor F2 is low, it is preferable to appropriately set a target value L2 such that L2 < B - A2.

[0090] Furthermore, although the above example illustrates a configuration in which the liquid flow path 42 is a circulation flow path, the present invention is not limited to this. That is, the configuration of the present invention is applicable even if the liquid flow path 42 does not include the fourth liquid flow path 424 that connects the outlet of the inkjet head 24a and the first sub-tank 412.

[0091] Furthermore, although the droplet ejection device is an inkjet recording device 1 in the above example, the present invention is not limited to this. That is, the liquid ejected by the droplet ejection device is not limited to ink, and may be, for example, water or a predetermined pretreatment liquid.

[0092] Although the above describes an example in which a hard disk or a semiconductor nonvolatile memory is used as a computer-readable medium for the program according to the present invention, the present invention is not limited to this example. Other computer-readable media include portable recording media such as CD-ROMs. Furthermore, a carrier wave can also be used as a medium for providing the program data according to the present invention via a communication line. [Explanation of symbols]

[0093] 1. Inkjet recording device (droplet ejection device) 24a Inkjet head (droplet ejection head) 41 Tank 42 Liquid flow path 50 control unit (setting unit, determination unit, adjustment unit, calculation unit) F Liquid level sensor (measurement part)

Claims

1. a plurality of tanks for storing liquid; a droplet ejection head that ejects droplets; a pump that sends a liquid stored in an upstream tank on the upstream side in a liquid sending direction to a downstream tank on the downstream side in the liquid sending direction; a liquid flow path that connects the upstream tank and the downstream tank; a measuring unit for measuring a value related to the liquid volume of the liquid in the downstream tank; a determination unit that determines whether or not there is an abnormality in the liquid flow path, The droplet ejection device, wherein the determining unit determines whether or not there is an abnormality in the liquid flow path based on a change in a value related to the amount of liquid in the downstream tank when the pump is caused to send out liquid for a predetermined liquid sending time.

2. The droplet ejection device according to claim 1 , further comprising a setting unit that sets the predetermined liquid sending time based on a previously measured flow rate of the pump.

3. the measuring unit includes a liquid level sensor capable of measuring the liquid level in the downstream tank, The droplet ejection device according to claim 1 , wherein the measurement unit measures a change in the liquid level in the downstream tank measured by the liquid level sensor.

4. The droplet ejection device according to claim 2 , wherein the setting unit sets the predetermined liquid sending time so that the liquid level in the downstream tank reaches a predetermined value as a result of the pump sending out the liquid.

5. The droplet ejection device according to claim 2 , wherein the setting unit sets the predetermined liquid sending time in accordance with the measurement accuracy of the measurement unit.

6. The droplet ejection device according to claim 1 , further comprising an adjusting unit that adjusts the liquid level in the downstream tank to a predetermined value before causing the pump to deliver the liquid for the predetermined liquid delivery time.

7. The droplet ejection device according to claim 1 , wherein the pump is a diaphragm pump.

8. The droplet ejection device according to claim 1 , further comprising a calculation unit that calculates the liquid level in the downstream tank based on an average value of the measurement values ​​of the measurement unit over a predetermined time period.

9. a plurality of tanks for storing liquid; a droplet ejection head that ejects droplets; a pump that sends a liquid stored in an upstream tank on the upstream side in a liquid sending direction to a downstream tank on the downstream side in the liquid sending direction; a liquid flow path that connects the upstream tank with the downstream tank; a measurement unit that measures a value related to a flow rate of the liquid in the downstream tank, a determination step of determining whether or not there is an abnormality in the liquid flow path, The determination step is an anomaly detection method for determining whether or not there is an abnormality in the liquid flow path based on a change in a value related to the liquid volume in the downstream tank when the pump is caused to deliver liquid for a predetermined liquid delivery time.

10. a plurality of tanks for storing liquid; a droplet ejection head that ejects droplets; a pump that sends a liquid stored in an upstream tank on the upstream side in a liquid sending direction to a downstream tank on the downstream side in the liquid sending direction; a liquid flow path that connects the upstream tank and the downstream tank; a measuring unit for measuring a value related to the amount of liquid in the downstream tank; a determination unit that determines whether or not there is an abnormality in the liquid flow path; The determination unit is a program that determines whether or not there is an abnormality in the liquid flow path based on a change in a value related to the liquid volume in the downstream tank when the pump is caused to deliver liquid over a predetermined liquid delivery time.

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