LIQUID DISCHARGE APPARATUS AND LIQUID DISCHARGE METHOD

Abstract

To efficiently wash a plurality of liquid discharge heads.SOLUTION: A liquid discharge device according to one aspect of the present invention includes: a plurality of liquid discharge heads; a first storage part that stores first liquid; a second storage part that stores second liquid; a first liquid feeding part that feeds the first liquid to each of the plurality of liquid discharge heads; a second liquid feeding part that feeds the second liquid to each of the plurality of liquid discharge heads; a first flow passage including a first manifold, through which the first liquid is fed between each of the plurality of liquid discharge heads and the first storage part; a second flow passage including a second manifold, through which the second liquid is fed between each of the plurality of liquid discharge heads and the second storage part; a switching part that switches liquid that is fed to each of the plurality of liquid discharge heads to either of the first liquid or the second liquid; and a control part that controls switching by the switching part.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a liquid ejection apparatus and a liquid ejection method. [Background technology]

[0002] Conventionally, liquid ejection devices having a plurality of liquid ejection heads are known. When the liquid ejection heads are not ejected for a long period of time, the ink inside the heads thickens, and other such reasons can cause ejection abnormalities. When an ejection abnormality occurs in a liquid ejection head, cleaning is required.

[0003] A liquid ejection device capable of cleaning multiple liquid ejection heads has been disclosed that has an inkjet head having multiple head blocks, and flushes cleaning liquid onto one selected head block among the multiple head blocks (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the device of Patent Document 1, since the cleaning liquid is flowed through one selected head block, there is a concern that multiple liquid ejection heads cannot be cleaned efficiently.

[0005] An object of the present invention is to efficiently clean a plurality of liquid ejection heads. [Means for solving the problem]

[0006] A liquid ejection device according to one aspect of the present invention includes a plurality of liquid ejection heads, a first storage section that stores a first liquid, a second storage section that stores a second liquid, and a first liquid delivery section that delivers the first liquid to each of the plurality of liquid ejection heads; Using gasa second liquid delivery section that delivers the second liquid to each of the plurality of liquid ejection heads; a first flow path including a first manifold, through which the first liquid is delivered between each of the plurality of liquid ejection heads and the first reservoir; a second flow path including a second manifold, through which the second liquid is delivered between each of the plurality of liquid ejection heads and the second reservoir; The first manifold and the corresponding liquid ejection head are provided in a flow path between the first manifold and the corresponding liquid ejection head, The liquid to be sent to each of the plurality of liquid ejection heads is switched to either the first liquid or the second liquid. Multiple A switching unit and the Multiple Switching section Each of A control unit for controlling switching by the an air regulating unit that adjusts an opening / closing amount of a gas flow passage through which the gas flows; and an air pressure measuring unit that measures a pressure of the gas; having The first flow path and the second flow path have different lengths, and the air regulating unit adjusts the opening and closing amount of the gas flow path through which the gas flows based on the measurement result by the air pressure measuring unit. . Effect of the Invention

[0007] According to the present invention, a plurality of liquid ejection heads can be efficiently cleaned. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment. [Diagram 2] 4 is a front view showing an example of the configuration of a liquid supply unit according to the first embodiment. FIG. [Diagram 3] 4 is a side view showing an example of the configuration of a liquid supply unit according to the first embodiment. FIG. [Figure 4] 4A and 4B are diagrams showing a heating portion provided in a pressure-side cleaning liquid manifold, FIG. 4A being a side view and FIG. 4B being a front view. [Diagram 5] FIG. 4 is a diagram illustrating a waste liquid discharge path and a waste liquid tank. [Figure 6] 5A and 5B are diagrams illustrating an air regulation portion in a gas flow path. [Figure 7] FIG. 1 is a diagram illustrating an example of use of an uninterruptible power supply. [Figure 8] FIG. 13 is a diagram showing a configuration example for manually switching a flow path. [Figure 9] 13 is a front view showing an example of the configuration of a liquid supply unit according to the second embodiment. FIG. [Figure 10]13 is a block diagram showing an example of a functional configuration of a control unit according to a second embodiment. FIG. [Figure 11] 10 is a flowchart of an example of the operation of an image forming apparatus according to the second embodiment. [Figure 12] 13A and 13B are diagrams illustrating another example of the means for detecting an ejection abnormality. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and duplicated descriptions will be omitted where appropriate.

[0010] It should be noted that the following embodiments are illustrative of a liquid ejection device for embodying the technical concept of the present invention, and the present invention is not limited to the following embodiments. The dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative, and are not intended to limit the scope of the present invention, unless otherwise specified. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation.

[0011] In the following, an image forming apparatus that forms an image on a long recording medium by a liquid ejection method will be described as an example of a liquid ejection apparatus. The long recording medium is, for example, continuous paper. Note that the terms image formation, recording, printing, copying, and printing in the embodiments are all synonymous.

[0012] [First embodiment] <Configuration Example of Image Forming Apparatus 100> Fig. 1 is a diagram showing an example of the configuration of an image forming apparatus 100. Fig. 1 shows the inside of the image forming apparatus 100 seen through a direction substantially perpendicular to a transport direction 30 of a continuous paper 102.

[0013] 1, image forming apparatus 100 has a liquid supply unit 110 and an inkjet head 103. An unwinding unit 101 is provided upstream of inkjet head 103 in transport direction 30. A heat drum 105, a hot air drying unit 106, a transport roller 107, and a winding unit 108 are provided downstream of inkjet head 103 in transport direction 30. In addition, a platen 104 is provided at a position facing inkjet head 103.

[0014] The image forming apparatus 100 applies ink ejected from an inkjet head 103 to the continuous paper 102 while transporting the continuous paper 102 by an unwinding unit 101 and a winding unit 108, thereby forming an image on the continuous paper 102. Each component will be described in detail below.

[0015] (Unwinding means, winding means) In this embodiment, an unwinding unit 101 is used as the means for unwinding the continuous paper 102, and a winding unit 108 is used as the means for winding the continuous paper 102. The unwinding unit 101 rotates the continuous paper 102, which is stored in a roll, to supply the continuous paper 102 to the transport path of the image forming device 100. The winding unit 108 winds up the continuous paper 102 on which an image has been formed, and stores it in a roll.

[0016] (Transportation means) The platen 104 guides the continuous paper 102 so that it is transported along a transport path. In addition to the transport roller 107, transport rollers not indicated with a reference number are also used as transport means. The transport means, unwinding means, and winding means constitute the transport means for the continuous paper 102.

[0017] Although this also relates to other processes, the image forming speed by the image forming apparatus 100 is preferably 30 [m / min] to 100 [m / min]. This allows it to be suitably used in cases where high-speed image formation is required.

[0018] Continuous paper 102 is a sheet of paper that continues along a transport direction 30. Image forming apparatus 100 transports continuous paper 102 along a transport path between unwinding section 101 and winding section 108. The length of continuous paper 102 along transport direction 30 is at least longer than the transport path between unwinding section 101 and winding section 108. Image forming apparatus 100 can continuously form images on continuous paper 102.

[0019] (ink) The ink is an example of the first liquid ejected by each of the inkjet heads. It is not particularly limited as long as it has a viscosity and surface tension that allows it to be ejected from the inkjet head, but it is preferable that the viscosity of the ink is 30 mPa s or less at room temperature and pressure, or when heated or cooled.

[0020] More specifically, they are solutions, suspensions, emulsions, etc. that contain solvents such as water and organic solvents, functionality-imparting materials such as dyes, pigments, polymerizable compounds, resins, surfactants, etc., biocompatible materials such as DNA, amino acids, proteins, calcium, etc., edible materials such as natural dyes, etc. These can be used, for example, as printing inks, surface treatment liquids, components of electronic elements and light-emitting elements, liquids for forming various devices such as electronic circuit resist patterns, etc.

[0021] (Liquid supply section) The liquid supply unit 110 supplies ink and cleaning liquid to each of the multiple inkjet heads included in the inkjet head 103. The cleaning liquid is a liquid for cleaning the inside of each of the multiple inkjet heads, and is an example of a second liquid.

[0022] (Liquid ejection head) The liquid ejection head ejects ink and applies the ink onto the continuous paper 102. As shown in Fig. 1, the image forming apparatus 100 has an inkjet head 103 as an example of a liquid ejection head.

[0023] The image forming apparatus 100 includes inkjet heads 103A, 103B, 103C, and 103D arranged along the transport direction 30 of the continuous paper 102, and also includes a plurality of inkjet heads in the width direction of the continuous paper 102 that intersects with the transport direction 30. Hereinafter, the multiple inkjet heads included in the inkjet head 103 will be collectively referred to as multiple inkjet heads 103 unless otherwise specified.

[0024] The inkjet head 103 has a plurality of nozzle rows in which a plurality of nozzles are arranged along the width direction of the continuous paper 102. The inkjet head 103 is disposed so that the direction in which ink is ejected from the nozzles faces the continuous paper 102.

[0025] The inkjet head 103 is, for example, a line-type inkjet head. A line-type inkjet head is an inkjet head in which nozzles that eject ink are arranged across the entire width of the continuous paper 102 in the width direction.

[0026] When the image forming apparatus 100 is used for industrial purposes, image formation is performed continuously for a long period of time, so when a line-type head is used, some nozzles will not eject ink for a long period of time depending on the form of the image to be formed. In these nozzles, the ink components in the ink may become non-uniform due to drying of the ink in the nozzles or settling of particle components in the ink, which may cause ejection abnormalities.

[0027] Therefore, in a nozzle that does not eject ink, it is preferable to vibrate the interface of the ink in the nozzle or to constantly circulate the ink in the ejection head. By vibrating the interface of the ink in the nozzle or constantly circulating the ink in the ejection head, the ink in the nozzle and the ink in the ink flow path of the inkjet head, such as a pressure chamber communicating with the nozzle, can be made uniform, and non-uniformity of the ink in the nozzle can be suppressed. This makes it possible to further suppress abnormal images caused by ejection abnormalities. The interface of the ink in the nozzle is the interface of the ink that comes into contact with the atmosphere or gas.

[0028] In the inkjet head 103, a means for applying a stimulus to the ink to eject the ink can be appropriately selected depending on the purpose, and for example, a pressure device, a piezoelectric element, a vibration generator, an ultrasonic oscillator, a light, etc. Specific examples include a piezoelectric actuator such as a piezoelectric element, a shape memory alloy actuator that uses a metal phase change due to a temperature change, and an electrostatic actuator that uses an electrostatic force.

[0029] Among these, it is particularly preferable to use a method of applying a voltage to a piezoelectric element attached to a position called a pressure chamber (also called a liquid chamber, etc.) in an ink flow path in the inkjet head 103. In this inkjet head 103, the application of a voltage causes the piezoelectric element to bend, and the volume of the pressure chamber to shrink, thereby pressurizing the ink in the pressure chamber and ejecting the ink as droplets from the nozzle.

[0030] The inkjet head 103 includes an inkjet ejection unit, which is a collection of functional parts and mechanisms related to ink ejection from the inkjet head 103. The inkjet ejection unit includes at least one of a supply mechanism, a maintenance and recovery mechanism, and a liquid ejection head moving mechanism, which are combined with the inkjet head 103.

[0031] (Drying means) The drying means is a means for drying the ink on the continuous paper 102 after the ink has been ejected. In FIG. 1, the drying means 200 includes the heat drum 105 and the hot air drying section 106.

[0032] The heat drum 105 is a rotatable drum. The heat drum 105 brings the outer circumferential surface into contact with the continuous paper 102 to which ink has been applied and which is being transported, thereby heating or cooling the continuous paper 102.

[0033] Methods of temperature adjustment using the heat drum 105 include a method in which a liquid or gas filled inside the heat drum 105 is used as a heat exchange medium to heat or cool the continuous paper 102, or a method in which a heat source device is provided inside the heat drum 105. The drying means 200 uses the liquid or gas filled inside the heat drum 105 as a heat exchange medium and maintains the heat exchange medium at a predetermined temperature by circulating the liquid or gas between the heat drum 105 and an external device such as a chiller provided outside the heat drum 105. The drying means 200 heats or cools the continuous paper 102 by exchanging heat with this heat exchange medium to adjust it to a predetermined temperature.

[0034] The liquid to be passed inside the heat drum 105 is not particularly limited as long as it has fluidity, such as water or oil, but water is preferable because it is easy to handle. As the gas to be passed inside the heat drum 105, it is preferable to use heated air in terms of cost and safety.

[0035] The drying means 200 draws liquid or gas circulating between an external device such as a chiller into the interior of the heat drum 105 and expels it to the outside via valves provided at both ends of the heat drum 105 (ends in a direction perpendicular to the conveying direction 30).

[0036] The method of providing a heat source device inside the heat drum 105 includes a halogen heater, an infrared heater, a nichrome heater, or the like as the heat source device.

[0037] The hot air drying unit 106 is provided facing the outer peripheral surface of the heat drum 105 and includes a nozzle with an opening extending in the width direction. The hot air drying unit 106 heats the continuous paper 102 by blowing hot air from a nozzle onto the continuous paper 102 wrapped around the heat drum 105, thereby drying the ink on the continuous paper 102. Alternatively, instead of or in addition to the hot air drying unit 106, an infrared heater can be provided and the surface of the continuous paper 102 can be irradiated with infrared rays to dry the ink on the continuous paper 102.

[0038] When the temperature of the heat drum 105, the temperature of the hot air from the hot air drying section 106, and the wind speed of the hot air blown by the hot air drying section 106 are set within an appropriate range depending on the drying properties of the solvent used in the ink and the effect of damage to the coated material being used, the power consumption required for drying is reduced.

[0039] <Configuration Example of Liquid Supply Unit 110> 2 and 3, the configuration of the liquid supply unit 110 of the image forming apparatus 100 will be described. Fig. 2 is a front view showing an example of the configuration of the liquid supply unit 110, and Fig. 3 is a side view.

[0040] 2 and 3, the liquid supply unit 110 includes a pressurization-side ink tank 1a, a depressurization-side ink tank 1b, an ink delivery unit 2a, an ink suction unit 2b, a pressurization-side ink flow path 4a, and a depressurization-side ink flow path 4b. It also includes a pressurization-side cleaning liquid tank 9a, a depressurization-side cleaning liquid tank 9b, a cleaning liquid delivery unit 8a, a cleaning liquid suction unit 8b, a pressurization-side cleaning liquid flow path 7a, a depressurization-side cleaning liquid flow path 7b, an electromagnetic valve 6, and a control unit 10.

[0041] The pressurizing ink tank 1a is an example of a first storage unit that stores ink. The ink delivery unit 2a delivers ink to each of the inkjet heads 103. For example, the ink delivery unit 2a is an air pressure mechanism that delivers ink using pressurized air.

[0042] The pressurization-side ink flow path 4a includes the pressurization-side ink manifold 3a, and is an example of a first flow path through which ink flows between each of the multiple inkjet heads 103 and the pressurization-side ink tank 1a. For example, the pressurization-side ink flow path 4a is configured with an ink tube or the like that includes the pressurization-side ink manifold 3a in its path. Each flow path other than the pressurization-side ink flow path 4a described below can also be configured to mainly include an ink tube in the same manner.

[0043] The pressurization-side ink manifold 3a is a branch flow path for communicating between the pressurization-side ink tank 1a and each of the multiple inkjet heads 103, and is an example of a first manifold. The ink delivery unit 2a can supply ink stored in the pressurization-side ink tank 1a to the multiple inkjet heads 103 through the pressurization-side ink flow path 4a.

[0044] The ink suction unit 2b absorbs ink in the inkjet heads 103 and sends the ink to the ink tank 1b through the ink flow passage 4b. For example, the ink suction unit 2b is an air pressure mechanism that sends ink using reduced pressure air. The ink flow passage 4b ​​includes an ink manifold 3b, and is a flow passage through which ink flows between each of the inkjet heads 103 and the ink tank 1b. The ink manifold 3b is a branch flow passage that connects the ink tank 1b and each of the inkjet heads 103.

[0045] The pressurized ink tank 1a and the reduced pressure ink tank 1b are in communication with each other, so that ink can circulate through the pressurized ink tank 1a, the inkjet head 103, and the reduced pressure ink tank 1b.

[0046] The pressurizing side cleaning liquid tank 9a is an example of a second storage unit that stores the cleaning liquid. The cleaning liquid sending unit 8a sends the cleaning liquid to each of the multiple inkjet heads 103. For example, the cleaning liquid sending unit 8a is an air pressure mechanism that sends ink by using pressurized air.

[0047] The pressurization-side cleaning liquid flow path 7a includes the pressurization-side cleaning liquid manifold 5a, and is an example of a second flow path through which cleaning liquid flows between each of the multiple inkjet heads 103 and the pressurization-side cleaning liquid tank 9a. The pressurization-side cleaning liquid manifold 5a is a branch flow path for connecting the pressurization-side cleaning liquid tank 9a and each of the multiple inkjet heads 103, and is an example of a second manifold. The cleaning liquid delivery unit 8a can supply the cleaning liquid stored in the pressurization-side cleaning liquid tank 9a to the multiple inkjet heads 103 through the pressurization-side cleaning liquid flow path 7a.

[0048] The cleaning liquid suction unit 8b sucks up the cleaning liquid in the inkjet heads 103 and sends it to the reduced-pressure side cleaning liquid tank 9b through the reduced-pressure side cleaning liquid flow path 7b. For example, the cleaning liquid suction unit 8b is an air pressure mechanism that sends ink by using reduced-pressure air.

[0049] The reduced-pressure side cleaning liquid flow path 7b includes a reduced-pressure side cleaning liquid manifold 5b, and is a flow path through which the cleaning liquid flows between each of the multiple inkjet heads 103 and the reduced-pressure side cleaning liquid tank 9b. The reduced-pressure side cleaning liquid manifold 5b is a branched flow path for connecting the reduced-pressure side cleaning liquid tank 9b and each of the multiple inkjet heads 103.

[0050] The pressurized cleaning liquid tank 9a and the reduced pressure side cleaning liquid tank 9b are in communication with each other, so that the cleaning liquid can circulate through the pressurized cleaning liquid tank 9a, the inkjet head 103, and the reduced pressure side cleaning liquid tank 9b.

[0051] The solenoid valve 6 is an example of a switching unit that switches the liquid sent to each of the multiple inkjet heads 103 between ink and cleaning liquid. The solenoid valve 6 has multiple solenoid valves that are paired with the multiple inkjet heads 103, and switches the liquid sent to the paired inkjet head 103 by opening and closing the valve. For example, when sending ink, the valve on the ink side is opened and the valve on the cleaning liquid side is closed. When sending cleaning liquid, the valve on the ink side is closed and the valve on the cleaning liquid side is opened.

[0052] The control unit 10 controls switching by the solenoid valve 6 by outputting a control signal to the solenoid valve 6. The functions of the control unit 10 can be realized by software (CPU: Central Processing Unit). These functions may also be realized by multiple circuits or multiple software programs.

[0053] For example, when an inkjet head 103 having an ejection abnormality occurs among the multiple inkjet heads 103, the control unit 10 operates the solenoid valve 6 to send cleaning liquid to the inkjet head 103 having the ejection abnormality and stop sending ink. By sending cleaning liquid, the inkjet head 103 having the ejection abnormality is cleaned, and recovery from the ejection abnormality is promoted.

[0054] The inkjet head 103 in which the ejection abnormality has occurred is identified, for example, by a user of the image forming apparatus 100 visually checking an image formed on the continuous paper 102 by the image forming apparatus 100. When the user recognizes the abnormality, he or she uses an operation unit provided in the image forming apparatus 100 to specify the inkjet head in which the ejection abnormality has occurred. The control unit 10 operates the solenoid valve 6 based on a specification signal indicating the inkjet head specified by the user, thereby sending cleaning liquid to the inkjet head 103 in which the ejection abnormality has occurred and stopping the sending of ink. This makes it possible to selectively clean the inkjet head 103 in which the ejection abnormality has occurred.

[0055] <Example of the configuration of the heating unit that heats the cleaning liquid> At least one of the pressurized cleaning liquid manifold 5a and the reduced pressure cleaning liquid manifold 5b may be provided with a heating unit that heats the cleaning liquid sent through the pressurized cleaning liquid flow path 7a. Fig. 4 shows a heater 51 provided in the pressurized cleaning liquid manifold 5a, Fig. 4(a) is a side view, and Fig. 4(b) is a front view. The heater 51 is an example of a heating unit that heats the cleaning liquid.

[0056] 4, a heater 51 is provided inside the pressurization-side cleaning liquid manifold 5a. The heater 51 generates heat in response to a control signal from a temperature control device 52, and can heat the cleaning liquid passing around the heater 51 inside the pressurization-side cleaning liquid manifold 5a. The temperature control device 52 controls the heat generation of the heater 51 so that the temperature of the cleaning liquid heated by the heater 51 is kept approximately constant.

[0057] The cleaning power of the cleaning liquid for cleaning the inkjet head 103 increases in proportion to the temperature of the cleaning liquid. For example, in the case of a latex ink containing a resin, setting the temperature of the cleaning liquid to 40° C. improves the cleaning ability after immersion, and most of the solid content disperses in the cleaning liquid.

[0058] Therefore, by heating the cleaning liquid using the heater 51 provided in the pressurization side cleaning liquid manifold 5a and setting the temperature of the cleaning liquid to a predetermined temperature, the cleaning effect of the inkjet head 103 can be improved when an abnormality occurs.

[0059] <Example of cleaning solution discharge path configuration> The liquid supply unit 110 may also be provided with a waste liquid discharge path for discharging the cleaning liquid used to clean the inkjet head 103 as waste liquid, and a waste liquid tank for storing the cleaning liquid discharged through the discharge path as waste liquid.

[0060] 5 is a diagram illustrating the waste liquid discharge path 11 and the waste liquid tank 12. As shown in FIG. 5, the liquid supply unit 110 has a waste liquid discharge path 11, one end of which is connected to the solenoid valve 6, and a waste liquid tank 12, which is connected to the other end of the waste liquid discharge path 11. A liquid feed pump 13 is provided between the pressurized cleaning liquid manifold 5a and the reduced pressure side cleaning liquid manifold 5b, so that the cleaning liquid can be circulated between the pressurized cleaning liquid manifold 5a and the reduced pressure side cleaning liquid manifold 5b. The filter 14 filters out foreign matter in the circulated cleaning liquid.

[0061] When the cleaning liquid is sent into the inkjet head 103, the ink filled in the inkjet head 103 and the sent cleaning liquid are mixed together. The mixed liquid is discharged as waste liquid through the inside of the waste liquid discharge path 11 into the waste liquid tank 12. Since the waste liquid tank 12 is depressurized when the waste liquid is discharged, the waste liquid can be sent in one direction from the inkjet head 103 to the waste liquid tank 12. The waste liquid tank 12 is an example of a waste liquid storage section.

[0062] With this configuration, when cleaning liquid is delivered to the inkjet head 103, the mixed liquid inside the inkjet head 103 can be almost completely replaced with the cleaning liquid, thereby suppressing impurities after cleaning and further improving the cleaning effect.

[0063] <Example of arrangement of air regulation parts in gas flow path> Here, the pressurized ink flow path 4a and the reduced pressure ink flow path 4b, and the pressurized cleaning liquid flow path 7a and the reduced pressure cleaning liquid flow path 7b each have a different flow path length according to the difference in the arrangement position. Due to the difference in flow path length, the pressure of the air pressurized by the ink delivery unit 2a is different from the pressure of the air pressurized by the cleaning liquid delivery unit 8a. Also, the pressure of the air decompressed by the ink suction unit 2b is different from the pressure of the air decompressed by the cleaning liquid suction unit 8b. As a result, if the inkjet head 103 is over-pressurized or over-decompressed, ink may leak from the nozzle holes of the inkjet head 103, contaminating the continuous paper 102, or air may be sucked through the nozzle holes, causing ejection abnormalities such as non-ejection or deflected ejection.

[0064] Therefore, the cleaning liquid delivery unit 8a delivers the cleaning liquid using gas, and the liquid supply unit 110 may have a regulating unit that adjusts the opening / closing amount of the gas flow path through which the gas flows, and an air pressure measuring unit that measures the pressure of the gas. Fig. 6 is a diagram illustrating the regulating unit provided in the gas flow path.

[0065] 6, the liquid supply unit 110 has a pressurization-side gas flow path 15a between the cleaning liquid delivery unit 8a and the pressurization-side cleaning liquid manifold 5a, and has a depressurization-side gas flow path 15b between the cleaning liquid suction unit 8b and the depressurization-side cleaning liquid manifold 5b. A pressurization-side pressure gauge 16a and a pressurization-side regulator 17a are provided in the pressurization-side gas flow path 15a, and a depressurization-side pressure gauge 16b and a depressurization-side regulator 17b are provided in the depressurization-side gas flow path 15b. The pressurization-side pressure gauge 16a is an example of an air pressure measurement unit, and the pressurization-side regulator 17a is an example of an air regulation unit.

[0066] The pressurizing side pressure gauge 16a measures the air pressure before it acts on the pressurizing side cleaning liquid manifold 5a. The pressurizing side regulator 17a adjusts the air pressure of the cleaning liquid delivery section 8a based on the value measured by the pressurizing side pressure gauge 16a.

[0067] The reduced pressure gauge 16b measures the air pressure before it acts on the reduced pressure cleaning liquid manifold 5b. The reduced pressure regulator 17b adjusts the air pressure in the cleaning liquid suction section 8b based on the value measured by the reduced pressure gauge 16b.

[0068] With this configuration, when switching from a state of delivering ink to the inkjet head 103 to a state of delivering cleaning liquid, it is possible to prevent ink or cleaning liquid from leaking from the inkjet head 103 or air from being sucked in due to pressure fluctuations associated with differences in the length of the flow path or differences in fluid resistance between the ink delivery and the cleaning liquid delivery.

[0069] <Examples of using an uninterruptible power supply> In the case of the image forming apparatus 100, if the power supply to the image forming apparatus 100 is stopped at an unexpected time due to lightning or a broken power line, the ink in the inkjet head 103 may thicken, causing the inkjet head 103 to break down.

[0070] Therefore, the image forming apparatus 100 may have an uninterruptible power supply. Fig. 7 is a diagram for explaining an example of the use of an uninterruptible power supply. As shown in Fig. 7, the image forming apparatus 100 has an uninterruptible power supply 300.

[0071] Uninterruptible power supply 300 is a standby power supply that supplies power to image forming apparatus 100 when the power supply to image forming apparatus 100 is stopped due to lightning or a broken power line. When image forming apparatus 100 receives power from uninterruptible power supply 300, image forming apparatus 100 replaces the ink in inkjet head 103 with cleaning liquid. This reduces the risk of failure of inkjet head 103 due to thickening of the ink in inkjet head 103, for example, even if the state in which power is not supplied to image forming apparatus 100 continues for a long period of time.

[0072] <Example of manual flow path switching> The flow path may be manually switchable so that the cleaning liquid can be supplied to the inkjet head 103 when the power supply to the image forming apparatus 100 is stopped due to lightning or a broken power line.

[0073] Fig. 8 is a diagram showing an example of a configuration for manually switching the flow path. As shown in Fig. 8, the liquid supply unit 110 has a pressurized gas manual valve 18a, a reduced pressure side gas manual valve 18b, a pressurized liquid manual valve 19a, and a reduced pressure side liquid manual valve 19b.

[0074] The pressurization-side gas manual valve 18a is provided in the pressurization-side gas flow path 15a connected to the pressurization-side ink manifold 3a, and is an on-off valve that switches between a state in which air pressure is applied to the inkjet head 103 and a state in which it is not applied. The depressurization-side gas manual valve 18b is provided in the depressurization-side gas flow path 15b connected to the depressurization-side ink manifold 3b, and is an on-off valve that switches between a state in which air pressure is applied to the inkjet head 103 and a state in which it is not applied.

[0075] The pressurization-side manual liquid valve 19a is provided between each of the pressurization-side ink manifold 3a and the pressurization-side cleaning liquid manifold 5a and the inkjet head 103. The pressurization-side manual liquid valve 19a is an on-off valve that can manually switch the liquid sent to the inkjet head 103 to either ink or cleaning liquid, and is an example of a manual switching unit. The depressurization-side manual liquid valve 19b is provided between each of the depressurization-side ink manifold 3b and the depressurization-side cleaning liquid manifold 5b and the inkjet head 103. The depressurization-side manual liquid valve 19b is an on-off valve that can manually switch the liquid sent to the inkjet head 103 to either ink or cleaning liquid, and is an example of a manual switching unit.

[0076] The pressurized side cleaning liquid manifold 5a and the reduced pressure side cleaning liquid manifold 5b are preferably disposed at a location with higher potential energy in the direction of gravity than the inkjet head 103. It is also preferable that the pressurized side cleaning liquid manifold 5a and the reduced pressure side cleaning liquid manifold 5b are provided with a window coated with a semi-transparent fluororesin having good water repellency. This allows the user to carry out the following long-term storage process of the inkjet head 103 even if the power supply to the image forming apparatus 100 is stopped.

[0077] (Long-term storage processing) (1) Close the pressurized gas manual valve 18a and the depressurized gas manual valve 18b. This prevents air pressure from being applied to the inkjet head 103. (2) The flow path is switched by the pressurized liquid manual valve 19a and the reduced pressure liquid manual valve 19b so that the cleaning liquid is supplied to the inkjet head 103. (3) Due to the above (1) and (2), the cleaning liquid flows toward the inkjet head 103 due to the difference in water head. (4) At the same time as (3) above, a mixture of the ink and cleaning liquid in the inkjet head 103 is discharged from the nozzle holes of the inkjet head 103. (5) After the user visually confirms through the translucent windows provided in each of the pressurized side cleaning liquid manifold 5a and the reduced pressure side cleaning liquid manifold 5b that a predetermined amount of cleaning liquid has been discharged (e.g., approximately the same as the capacity of the inkjet head 103), the pressurized side liquid manual valve 19a and the reduced pressure side liquid manual valve 19b are closed.

[0078] The above long-term storage process can prevent the inkjet head 103 from breaking down even in the event of a power outage.

[0079] <Functions and Effects of Image Forming Apparatus 100> As described above, in this embodiment, the ink jet head 103 (liquid ejection head), the pressurization side ink tank 1a (first storage section) storing ink (first liquid), and the pressurization side cleaning liquid tank 9a (second storage section) storing cleaning liquid (second liquid) are included. The ink jet head 103 also includes an ink liquid delivery section 2a (first liquid delivery section) that delivers ink to each of the ink jet heads 103, and a cleaning liquid delivery section 8a (second liquid delivery section) that delivers cleaning liquid to each of the ink jet heads 103. The ink jet head 103 also includes a pressurization side ink flow path 4a (first flow path) including a pressurization side ink manifold 3a (first manifold) and through which ink is delivered between each of the ink jet heads and the pressurization side ink tank 1a, and a pressurization side cleaning liquid flow path 7a (second flow path) including a pressurization side cleaning liquid manifold 5a (second manifold) and through which cleaning liquid is delivered between each of the ink jet heads 103 and the pressurization side cleaning liquid tank 9a. The inkjet head further includes a solenoid valve 6 that switches the liquid to be sent to each of the inkjet heads 103 between ink and cleaning liquid, and a control unit 10 that controls the switching performed by the solenoid valve 6 .

[0080] Since it is possible to switch between sending either ink or cleaning liquid for each of the multiple inkjet heads 103, it is possible to selectively clean an inkjet head 103 in which an ejection abnormality has occurred among the multiple inkjet heads 103. Furthermore, even if there are multiple inkjet heads 103 in which an ejection abnormality has occurred, it is possible to clean the multiple inkjet heads 103 in parallel. In this way, it is possible to efficiently clean the multiple inkjet heads 103.

[0081] [Second embodiment] FIG. 9 is a front view showing an example of the configuration of a liquid supply unit 110a included in an image forming apparatus 100a according to the second embodiment.

[0082] 9, the liquid supply unit 110a has a flow meter 20 and a control unit 10a. The flow meter 20 is provided in at least one of the pressurized ink flow path 4a or the depressurized ink flow path 4b so as to be paired with each of the multiple inkjet heads 103. The flow meter 20 measures the flow rate of ink sent to each of the multiple inkjet heads 103. Various types of flow meters can be used for the flow meter 20, such as an electromagnetic type, an ultrasonic type, an impeller type, or a turbine type.

[0083] Fig. 10 is a block diagram showing an example of a functional configuration of the control unit 10a. As shown in Fig. 10, the control unit 10a has an abnormality detection unit 121 and a switching control unit 122. Each of these functions can be realized by software. Furthermore, these functions may be realized by multiple circuits or multiple pieces of software.

[0084] The abnormality detection unit 121 receives the measurement results from the flowmeter 20 and detects an inkjet head having an ejection abnormality among the multiple inkjet heads 103 based on the measurement results. For example, when the flow rate indicated by the measurement results from the flowmeter 20 is equal to or lower than a predetermined flow rate threshold, the abnormality detection unit 121 detects that an ejection abnormality has occurred in the inkjet head 103 paired with the flowmeter 20. Alternatively, the abnormality detection unit 121 can detect that an ejection abnormality has occurred in the inkjet head 103 paired with the flowmeter 20 when a change in flow rate is equal to or higher than a predetermined flow rate change threshold. When an ejection abnormality is detected, the abnormality detection unit 121 outputs information indicating the inkjet head 103 in which the ejection abnormality has occurred to the switching control unit 122.

[0085] Based on the detection result by the abnormality detection unit 121, the switching control unit 122 operates the solenoid valve 6 paired with the inkjet head 103 in which the ejection abnormality has occurred so as to send cleaning liquid to the inkjet head 103 in which the ejection abnormality has occurred.

[0086] Fig. 10 is a flowchart showing an example of the operation of the image forming apparatus 100a. Fig. 11 shows an operation in which the image forming apparatus 100a starts image formation in response to a user's operation to start image formation, and when an ejection abnormality occurs, the inkjet head 103 in which the ejection abnormality occurs is cleaned and image formation is resumed.

[0087] First, in step S111, the abnormality detection unit 121 in the control unit 10a determines whether or not any of the inkjet heads 103 has experienced an ejection abnormality.

[0088] If it is determined in step S111 that there is an inkjet head in which an ejection abnormality has occurred (Yes in step S111), the abnormality detection unit 121 outputs information indicating the inkjet head 103 in which an ejection abnormality has occurred to the switching control unit 122, and then the image forming apparatus 100a proceeds to step S112. On the other hand, if it is determined that there is no inkjet head in which an ejection abnormality has occurred (No in step S111), the image forming apparatus 100a performs the operation of step S111 again.

[0089] Next, in step S112, the image forming apparatus 100a stops controlling the ink ejection from the inkjet head 103 and stops transporting the continuous paper 102, thereby stopping image formation.

[0090] Next, in step S113, the image forming apparatus 100a moves the inkjet head 103 in which the ejection abnormality has occurred to a maintenance position. The maintenance position is, for example, an area on the continuous paper 102 where an image is not formed. The inkjet head 103 may be moved, or the continuous paper 102 may be transported to relatively move the inkjet head 103 to an area on the continuous paper 102 where an image is not formed.

[0091] Next, in step S114, the switching control unit 122 operates the solenoid valve 6 so as to send cleaning liquid to the inkjet head 103 in which the ejection abnormality has occurred.

[0092] Next, in step S115, the liquid supply unit 110a supplies cleaning liquid to the inkjet head 103 in which the ejection abnormality has occurred.

[0093] Next, in step S116, the image forming apparatus 100a causes the inkjet head 103 in which the ejection abnormality has occurred to perform an empty ejection. Here, the empty ejection is an ejection that is not for forming an image, but is an ejection for discharging thickened ink or ink containing air bubbles from within the inkjet head 103.

[0094] Next, in step S117, the image forming apparatus 100a sucks the ink in the inkjet head 103 in which the ejection abnormality has occurred. This sucking can be performed by a suction pump or the like provided in the image forming apparatus 100a.

[0095] Next, in step S118, the switching control unit 122 operates the solenoid valve 6 so that ink is sent to the inkjet head 103 in which the ejection abnormality has occurred.

[0096] Next, in step S119, the liquid supply unit 110a supplies ink to the inkjet head 103 in which the ejection abnormality has occurred.

[0097] Next, in step S120, the image forming apparatus 100a performs wiping on the inkjet head 103 in which the ejection abnormality has occurred. Wiping refers to an operation of wiping off the nozzle plate in which the nozzle holes are provided in the inkjet head 103 with a wiper member or the like.

[0098] Next, in step S121, the image forming apparatus 100a resumes control of ink ejection by the inkjet head 103 and transport of the continuous paper 102, thereby restarting image formation.

[0099] Next, in step S121, image forming apparatus 100a determines whether or not to end image formation.

[0100] If it is determined in step S121 that the operation is to be ended (Yes in step S122), the image forming apparatus 100a ends the operation, and if it is determined that the operation is not to be ended (No in step S122), the image forming apparatus 100a performs the operations from step S111 onwards again.

[0101] In this manner, even if an ejection abnormality occurs, the image forming apparatus 100a can perform image formation after cleaning the inkjet head 103 in which the ejection abnormality occurred.

[0102] Here, in this embodiment, an example has been shown in which a discharge abnormality is detected based on the measurement results by the flow meter 20, but the means for detecting a discharge abnormality is not limited to this. Fig. 12 is a diagram showing another example of the means for detecting a discharge abnormality.

[0103] 12, image forming apparatus 100a has camera 21 downstream of inkjet heads 103 in transport direction 30. Camera 21 captures an image formed on continuous paper 102 by ink ejection from multiple inkjet heads 103, and transmits the captured image to controller 10a. Abnormality detection unit 121 in controller 10a detects an ejection abnormality by processing the captured image, and outputs information indicating the inkjet head 103 in which the ejection abnormality has occurred to switching controller 122.

[0104] There are no particular limitations on the method of detecting ejection abnormalities using image processing, but one that can be used is a method in which a specified image for detecting ejection abnormalities, such as a solid image, is formed and streaks or gaps in the image are detected using image processing.

[0105] <Functions and Effects of Image Forming Apparatus 100a> As described above, this embodiment has an abnormality detection unit 121 that detects an inkjet head 103 having an ejection abnormality among the multiple inkjet heads 103, and the control unit 10a controls the switching operation of the solenoid valve 6 based on the detection result of the ejection abnormality.

[0106] This allows automatic detection of inkjet heads 103 with ejection abnormalities among the multiple inkjet heads 103, and allows selective delivery of cleaning liquid to perform cleaning. Furthermore, when there are multiple inkjet heads 103 with ejection abnormalities, cleaning liquid can be selectively delivered to the multiple inkjet heads 103 with ejection abnormalities and cleaned in parallel. This allows multiple inkjet heads 103 to be cleaned more efficiently.

[0107] By detecting an ejection abnormality based on the flow rate of ink delivered to each of the multiple inkjet heads 103, the abnormality can be detected even when image formation is not being performed, making cleaning and maintenance of the multiple inkjet heads 103 easier.

[0108] On the other hand, an image is formed on continuous paper 102 (recording medium) by ejecting ink, and if an ejection abnormality is detected based on the image formed on the continuous paper 102, the inkjet head 103 in which the ejection abnormality occurred can be cleaned during image formation. This prevents interruption of image formation, ensures high productivity in image formation, and enables multiple inkjet heads 103 to be efficiently cleaned.

[0109] It is also possible to determine whether the inkjet head 103 in which the ejection abnormality has occurred is an inkjet head used for image formation, and to determine whether image formation should be suspended. If the inkjet head 103 in which the ejection abnormality has occurred is not used for image formation, image formation is continued, and if it is used, image formation is stopped. Information indicating the inkjet head 103 in which the ejection abnormality has occurred or related information, and whether image formation should be suspended, may be displayed on a display panel of the image forming apparatus 100a.

[0110] Although the embodiments have been described above, the present invention is not limited to the above specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0111] In addition, all numbers such as ordinal numbers and quantities used in the description of the embodiments are merely examples for specifically explaining the technology of the present invention, and the present invention is not limited to the exemplified numbers. Furthermore, the connection relationships between the components are merely examples for specifically explaining the technology of the present invention, and the connection relationships for realizing the functions of the present invention are not limited to these.

[0112] The embodiment also includes a liquid ejection method. For example, a liquid ejection method is a liquid ejection method using a liquid ejection device having a plurality of liquid ejection heads, a first storage section for storing a first liquid, a second storage section for storing a second liquid, a first liquid delivery section for delivering the first liquid to each of the plurality of liquid ejection heads, a second liquid delivery section for delivering the second liquid to each of the plurality of liquid ejection heads, a first flow path through which the first liquid is delivered between each of the plurality of liquid ejection heads and the first storage section via a first manifold, a second flow path through which the second liquid is delivered between each of the plurality of liquid ejection heads and the second storage section via a second manifold, and a switching section for switching the liquid delivered to each of the plurality of liquid ejection heads to either the first liquid or the second liquid, the method including the steps of: detecting a liquid ejection head among the plurality of liquid ejection heads that is abnormal in ejection; and controlling switching by the switching section based on a detection result of the abnormality. By using such a liquid ejection method, it is possible to obtain the same effects as those of the above-mentioned liquid ejection device.

[0113] Each function of the above-described embodiments can be realized by one or more processing circuits. Here, the term "processing circuit" in this specification includes a processor programmed to execute each function by software, such as a processor implemented by an electronic circuit, and a device such as an ASIC (Application Specific Integrated Circuit), a DSP (digital signal processor), an FPGA (field programmable gate array), or a conventional circuit module designed to execute each function described above. [Explanation of symbols]

[0114] 1. Ink cartridge (an example of a storage unit) 100 Image forming apparatus (an example of a liquid ejection apparatus) 102 Continuous paper (an example of a recording medium) 103 Inkjet head (an example of a liquid ejection head) 110 Liquid supply section 1a Pressurized ink tank (an example of a first storage section) 1b Pressure reducing ink tank 2a Ink delivery unit (an example of a first delivery unit) 2b Ink absorbing part 3a Pressurized ink manifold (example of the first manifold) 3b Pressure reducing side ink manifold 4a Pressurizing side ink flow path (an example of a first flow path) 4b Pressure reducing side ink flow path 5a Pressurized side cleaning fluid manifold (example of second manifold) 5b Pressure side cleaning fluid manifold 51 Heater (an example of a heating unit) 52 Temperature control device 6. Solenoid valve 7a Pressurized cleaning fluid flow path (an example of the second flow path) 7b Pressure reducing side cleaning fluid flow path 8a Cleaning liquid delivery section (an example of a second liquid delivery section) 8b Cleaning fluid suction part 9a Pressurized cleaning fluid tank (an example of the second storage section) 9b Pressure reducing side cleaning solution tank 10, 10a Control section 121 Anomaly detection unit 122 Switching control section 11 Waste liquid discharge route 12 Waste liquid tank (an example of a waste liquid storage section) 13 Liquid delivery pump 14 Filters 15a Pressurized gas flow path (an example of a gas flow path) 15b Pressure reducing gas flow path 16a Pressure gauge on the pressurizing side (an example of an air pressure measuring part) 16b Pressure reducing side pressure gauge 17a Pressure regulator (an example of an air regulation part) 17b Pressure reducing regulator 300 Uninterruptible Power Supply 18a Pressurized gas manual valve (an example of a manual switching part) 18b Pressure reducing gas manual valve 19a Pressurized side liquid manual valve 19b Pressure reducing side liquid manual valve 20 Flow meter 21 Camera 30 Conveying direction [Prior art documents] [Patent documents]

[0115] [Patent Document 1] JP 2018-30047 A

Claims

1. A plurality of liquid ejection heads; a first reservoir configured to retain a first liquid; a second reservoir configured to store a second liquid; a first liquid delivery unit that delivers the first liquid to each of the plurality of liquid ejection heads; a second liquid delivery unit that delivers the second liquid to each of the plurality of liquid ejection heads by using a gas; a first flow path including a first manifold through which the first liquid is transferred between each of the plurality of liquid ejection heads and the first reservoir; a second flow path including a second manifold through which the second liquid is transferred between each of the plurality of liquid ejection heads and the second reservoir; a plurality of switching units provided in flow paths between the first manifold and the corresponding liquid ejection heads, each switching the liquid to be sent to each of the plurality of liquid ejection heads to either the first liquid or the second liquid; A control unit that controls switching by each of the plurality of switching units; an air regulating unit that adjusts the opening and closing amount of a gas flow path through which the gas flows; An air pressure measuring unit that measures the pressure of the gas, The first flow path and the second flow path have different lengths, The air regulation unit adjusts an amount of opening and closing of a gas flow passage through which the gas flows based on a measurement result by the air pressure measurement unit.

2. an abnormality detection unit that detects a liquid ejection head in which an ejection abnormality has occurred among the plurality of liquid ejection heads; The liquid ejection device according to claim 1 , wherein the control unit controls switching by each of the plurality of switching units based on a detection result of the ejection abnormality.

3. The liquid ejection device according to claim 2 , wherein the abnormality detection unit detects the ejection abnormality based on a flow rate of the first liquid delivered to each of the plurality of liquid ejection heads.

4. the liquid ejection device forms an image on a recording medium by ejecting the first liquid; The liquid ejection device according to claim 2 , wherein the abnormality detection unit detects the ejection abnormality based on the image formed on the recording medium.

5. The liquid ejection device according to claim 1 , wherein the second manifold is provided with a heating portion that heats the second liquid being pumped through the second flow path.

6. a discharge path through which the second liquid is discharged from each of the plurality of liquid ejection heads; The liquid ejection device according to claim 1 , further comprising: a waste liquid storage section for storing the second liquid discharged through the discharge path.

7. The liquid ejection device according to claim 1 , further comprising an uninterruptible power supply.

8. the second manifold is disposed at a position higher than each of the liquid ejection heads in a gravity direction, The liquid ejection device according to claim 1 , further comprising a manual switching unit capable of manually switching the liquid to be delivered to the liquid ejection head between the first liquid and the second liquid.

9. A plurality of liquid ejection heads; a first reservoir configured to retain a first liquid; a second reservoir configured to store a second liquid; a first liquid delivery unit that delivers the first liquid to each of the plurality of liquid ejection heads; a second liquid delivery unit that delivers the second liquid to each of the plurality of liquid ejection heads by using a gas; a first flow path including a first manifold through which the first liquid is transferred between each of the plurality of liquid ejection heads and the first reservoir; a second flow path including a second manifold through which the second liquid is transferred between each of the plurality of liquid ejection heads and the second reservoir; a plurality of switching units provided in flow paths between the first manifold and the corresponding liquid ejection heads, each switching the liquid sent to each of the plurality of liquid ejection heads to either the first liquid or the second liquid; an air regulating unit that adjusts the opening and closing amount of a gas flow path through which the gas flows; a pressure measuring unit that measures the pressure of the gas, The first flow path and the second flow path have different lengths, detecting a liquid ejection head in which an ejection abnormality has occurred among the plurality of liquid ejection heads by an abnormality detection unit; a step of controlling switching by each of the plurality of switching units based on a detection result of the ejection abnormality by a control unit; and adjusting, by the air regulating section, an amount of opening or closing of a gas flow passage through which the gas flows, based on a measurement result by the air pressure measuring section.

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