Replenishment liquid cartridge and ink cartridge

Abstract

To suppress ink peeling due to adhesion of alcohol after drying and prevent apparatus malfunctions caused by changes in a component ratio of a mixed solvent even when viscosity adjustment of the ink with the mixed solvent is repeatedly performed in the apparatus.SOLUTION: An ink jet recording apparatus receives ink containing a solvent in which ketone and alcohol having higher volatility than the ketone are mixed, an ink colorant, and a binder, and also receives a replenishment liquid containing the ketone and the alcohol having the higher volatility than the ketone. The ink contains 15 mass% or more of solids including the ink colorant and the binder. The ketone is one or more selected from the group consisting of diethyl ketone, methyl isopropyl ketone, and methyl propyl ketone. The mass percent concentration of the ketone in the replenishment liquid is lower than the mass percent concentration of the ketone in the solvent of the ink.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to, for example, an inkjet recording apparatus that performs printing on a printing object or the like, an ink for an inkjet recording apparatus, a replenishing liquid for an inkjet recording apparatus, and a combination of an ink and a replenishing liquid.

Background Art

[0002] For example, Patent Document 1 discloses a so-called continuous inkjet recording apparatus that circulates ink inside the apparatus even when not printing on a printing object. In this continuous inkjet recording apparatus, ink droplets ejected from a discharge head are charged, the flying direction (traveling direction) of the charged ink is deflected by an electrode, and the deflected ink droplets are ejected to the outside for printing. Ink droplets not used for printing are recovered through a recovery path and reused.

[0003] Further, Patent Document 1 discloses, as an ink composition used in the inkjet recording apparatus, a composition containing a binder, a dye or a pigment, and a solvent. The solvent includes acyclic acetals such as ethylal, methylal, acetal, and dimethylacetal, and organic compounds of low molecular weight alcohols (ketones, etc.).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in a continuous inkjet recording apparatus, air is also sucked into the recovery path together with ink particles that were not used for printing, and the sucked air is discharged to the outside through the exhaust port. As disclosed in Patent Document 1, the ink composition contains a solvent that is volatile at normal temperature. The solvent component is also contained in a large amount in the air sucked into the recovery path, and the air containing a large amount of this solvent component is discharged from the apparatus. For this reason, over time, the solvent component in the tank storing the ink decreases and the viscosity of the ink increases, which can cause printing defects. Therefore, the viscosity of the ink in the tank is measured at any time, and a replenishing liquid having a lower viscosity than the ink in the tank is replenished into the tank so that the viscosity of the ink is maintained within a predetermined range, thereby adjusting the viscosity of the ink in the tank.

[0006] On the other hand, there are requirements for high functionality regarding the adhesion, quick-drying property, conductivity, stability, etc. of the ink in a continuous inkjet recording apparatus. For example, when the printed object is sterilized with alcohol for sterilization after printing on the printed object, even if alcohol adheres to the printed surface, it is desired to suppress ink dissolution, peeling of the print, etc. as much as possible. Furthermore, various ink solvents are selected in view of handling ease, availability, economy, etc. For example, among solvents not subject to regulations such as the Poisonous Organic Solvents Prevention Regulations (solvents not subject to the organic regulations), an ink using a solvent in which methyl isopropyl ketone, methyl propyl ketone, diethyl ketone, etc. are mixed with ethanol, etc. (an ink of a mixed solvent of two or more components) can be considered. Also, not limited to this, selection of an ink solvent according to the characteristics of the solid content of the ink and selection of an ink solvent having a high allowable concentration indicating the exposure limit can also be considered.

[0007] Examples of organic non-compliant solvents include methyl isopropyl ketone, methyl propyl ketone, diethyl ketone, ethanol, etc. Examples of solvents with high allowable concentrations include diethyl ketone, ethanol, etc. Here, since solvents such as methyl isopropyl ketone, methyl propyl ketone, and diethyl ketone are relatively expensive, it is conceivable to use an ink (ink of a mixed solvent of two or more components) diluted with relatively inexpensive ethanol or the like.

[0008] However, in the case of a mixed solvent, if the volatilities of the two are different, the mixing ratio after repeated viscosity adjustment may deviate from the initial mixing ratio. If an ink containing a solvent with a mixing ratio deviated from the initial mixing ratio is used in an apparatus that is assumed to operate normally at the initial mixing ratio, there is a concern that unintended problems may occur.

[0009] The present invention has been made in view of such points, and an object thereof is to avoid the occurrence of problems in an apparatus due to changes in the component ratio of a mixed solvent even when repeatedly adjusting the viscosity of an ink of the mixed solvent in a continuous inkjet recording apparatus using a highly functional ink such as suppressing peeling of the ink due to adhesion of alcohol after drying.

Means for Solving the Problems

[0010] To achieve the above object, in a first aspect of the present disclosure, an inkjet recording apparatus that performs printing on a printing target using ink can be assumed. The inkjet recording apparatus includes an ink receiving portion, and the ink receiving portion receives an ink containing a solvent in which a ketone and an alcohol having a higher volatility than the ketone are mixed, an ink colorant, and a binder. The inkjet recording apparatus also includes an ink flow path that sends the ink received by the ink receiving portion, and separately from the ink receiving portion, a replenishing liquid receiving portion. The replenishing liquid receiving portion receives a replenishing liquid containing a ketone and an alcohol having a higher volatility than the ketone. Further, the inkjet recording apparatus includes a replenishing liquid flow path that sends the replenishing liquid received by the replenishing liquid receiving portion, a mixing container that mixes the ink sent through the ink flow path and the replenishing liquid sent through the replenishing liquid flow path in order to adjust the viscosity of the ejected ink, an adjusted ink flow path that sends the ink whose viscosity has been adjusted in the mixing container, and a discharge head that discharges the ink sent through the adjusted ink flow path. The ink contains 15 mass percent or more of a solid content including the ink colorant and the binder. The ketone can be one selected from the group including diethyl ketone, methyl isopropyl ketone, and methyl propyl ketone, or any two or more thereof. The mass percent concentration of the ketone in the replenishing liquid received by the replenishing liquid receiving portion is set lower than the mass percent concentration of the ketone in the solvent of the ink received by the ink receiving portion.

[0011] According to this configuration, since printing is performed on a printing object using an ink containing 15 mass percent or more of solid content, for example, the film thickness of the ink after drying increases, and the adhesiveness is likely to improve. In this case, since the film thickness is increased to reinforce the adhesiveness, even those that do not satisfy the desired adhesiveness when the film thickness is thin can be adopted as the solid content of the ink. Also, when a material that forms a coating film that is difficult to dissolve in alcohol is adopted as the solid content, the alcohol resistance becomes high, and for example, dissolution of the ink or peeling of the print when germicidal alcohol or the like adheres is suppressed. Thus, by using an ink containing 15 mass percent or more of solid content, a high-performance ink can be designed.

[0012] Also, by using an ink containing a two-component or more mixed solvent in which a ketone and a relatively inexpensive alcohol are miscible, the cost of the ink is reduced. When the viscosity of the ink in the mixing container increases over time due to the volatilization of the solvent, a replenishing liquid is sent to the mixing container and mixed with the ink to adjust the viscosity of the ink. Usually, alcohol is more volatile than ketone, so the ratio of alcohol becomes lower than the initial ratio. In contrast, in this configuration, since the mass percent concentration of ketone in the replenishing liquid to be mixed is set lower than the mass percent concentration of ketone in the solvent of the ink, the ratio of alcohol after adjustment in the mixing container approaches the initial ratio. Therefore, the ratio of ketone and alcohol in the mixing container is less likely to change over time. As a result, it becomes less likely for unintended device malfunctions to occur. Examples of device malfunctions include swelling of rubber used as a sealing material or the like in the device, and nozzle clogging due to precipitation of the ink. These malfunctions can be avoided if the ratio of ketone and alcohol is the initial ratio or close to it.

[0013] The inkjet recording apparatus according to the second aspect of the present disclosure includes a viscometer that measures the viscosity of the ink in the mixing container, and based on the viscosity of the ink measured by the viscometer, the viscosity of the ink in the mixing container is within a predetermined range. Further provided is a control unit that executes a viscosity adjustment process for controlling the flow rates of the ink supplied into the mixing container via the ink receiving portion and the replenishing liquid supplied into the mixing container via the replenishing liquid receiving portion.

[0014] According to this configuration, based on the viscosity of the ink in the mixing container, the amounts of the ink and the replenishing liquid supplied into the mixing container can be made appropriate amounts, so that the viscosity of the ink can be maintained within a predetermined range.

[0015] In the third aspect of the present disclosure, the control unit is configured to be able to execute a startup process of discharging ink from the discharge head to make it printable, and executes the viscosity adjustment process after the startup process.

[0016] According to this configuration, since the viscosity of the ink in the mixing container can be adjusted to be within a predetermined range after the startup process, while maintaining good solubility of the ink colorant and the binder and obtaining high printing quality, the occurrence of device failures can be prevented in advance.

[0017] In the fourth aspect of the present disclosure, the inkjet recording apparatus further includes a recovery flow path for recovering a part of the ink discharged from the discharge head and refluxing it to the mixing container.

[0018] That is, air is sucked into the recovery flow path together with the ink, and the sucked air contains a solvent component volatilized from the ink. At this time, the volatilization amount of alcohol, which is more volatile than ketone, relatively increases, and this causes the ratio of ketone to alcohol to change compared to the initial state. In a configuration where such a ratio change is likely to occur, since a replenishing liquid with a low mass percentage concentration of ketone is mixed in the mixing container, the operational effects of this configuration become even more remarkable.

[0019] In a fifth aspect of the present disclosure, the ink receiving portion is configured to receive an ink cartridge having a first storage medium storing information about the ink and to receive the ink stored in the ink cartridge. Further, the refill liquid receiving portion is configured to receive a refill liquid cartridge having a second storage medium storing information about the refill liquid and to receive the refill liquid stored in the refill liquid cartridge. The inkjet recording apparatus further includes a first access portion that accesses the first storage medium, a second access portion that accesses the second storage medium, and a management portion. The management portion is configured to regulate at least one of the acceptance of the ink via the ink receiving portion and the acceptance of the refill liquid via the refill liquid receiving portion based on the information about the ink obtained from the first storage medium via the first access portion and the information about the refill liquid obtained from the second storage medium via the second access portion.

[0020] According to this configuration, it is possible to configure to accept ink only from an ink cartridge containing ink of a predetermined composition and not to accept ink from an ink cartridge containing ink of another composition. Further, it is possible to configure to accept the refill liquid only from a refill liquid cartridge containing a refill liquid of a predetermined composition and not to accept the refill liquid from a refill liquid cartridge containing a refill liquid of another composition. Therefore, it is possible to prevent the occurrence of device malfunctions while obtaining high print quality.

[0021] In a sixth aspect of the present disclosure, the information about the ink includes information on the concentration of ketone in the ink, and the information about the refill liquid includes information on the concentration of ketone in the refill liquid. The management portion is configured to regulate at least one of the acceptance of the ink via the ink receiving portion and the acceptance of the refill liquid via the refill liquid receiving portion based on the information on the concentration of ketone in the ink or the information on the concentration of ketone in the refill liquid.

[0022] According to this configuration, it is possible to configure to accept only the ink with the ketone concentration being a predetermined concentration and not to accept inks with other concentrations. Further, it is possible to configure to accept only the replenishing liquid with the ketone concentration being a predetermined concentration and not to accept replenishing liquids with other concentrations.

[0023] In a seventh aspect of the present disclosure, the ink contains 70 to 85 mass percent or less of the solvent. The ketone concentration of the replenishing liquid received by the replenishing liquid receiving portion can be 5 to 15 percentage points lower in mass percentage concentration than the ketone concentration of the ink received by the ink receiving portion.

[0024] In an eighth aspect of the present disclosure, ethanol, that is, industrial alcohol can be used as the alcohol. The ketone concentration of the replenishing liquid received by the replenishing liquid receiving portion can be 8 to 12 percentage points lower in mass percentage concentration than the ketone concentration of the ink received by the ink receiving portion.

[0025] In a ninth aspect of the present disclosure, the alcohol is ethanol, and for example, during operation at a predetermined ambient temperature of 0 to 40°C, even if the adjustment of the viscosity of the ink is repeated a plurality of times, the ketone concentration of the solvent component in the mixing container is maintained within ±1 point with respect to the initial concentration. Thus, the ketone concentration of the replenishing liquid received by the replenishing liquid receiving portion is lower in mass percentage concentration than the ketone concentration in the solvent of the ink received by the ink receiving portion.

[0026] That is, in the conventional case, when the viscosity of the ink is adjusted repeatedly, the ketone concentration of the solvent component in the mixing container changes. However, according to this configuration, even if the viscosity adjustment of the ink is repeated multiple times, the ketone concentration of the solvent component in the mixing container is maintained within ±1 point of the initial concentration. Therefore, the occurrence of device malfunctions can be prevented. The predetermined ambient temperature is the temperature at which the inkjet recording apparatus is frequently used, and can be, for example, a temperature range of 0°C or higher and 40°C or lower. That is, the ketone concentration of the replenishing liquid can be set in advance so that the ketone concentration does not deviate significantly from the initial concentration even if the viscosity adjustment of the ink is repeated several times in the temperature range of 0°C or higher and 40°C or lower.

[0027] In the tenth aspect of the present disclosure, the ketone concentration in the solvent of the ink received by the ink receiving portion can be 70 to 80 mass percent concentration, and can also be 72 to 78 mass percent concentration.

[0028] In the eleventh aspect of the present disclosure, the solid content of the ink has an alcohol solubility of 5% or less after being discharged from the discharge head, adhering to the printing object, and drying. Therefore, for example, when sterilizing alcohol or the like adheres, the ink is less likely to peel off.

[0029] The twelfth aspect of the present disclosure is the combination of the ink and the replenishing liquid used in the inkjet recording apparatus.

[0030] The thirteenth aspect of the present disclosure is the ink used in the inkjet recording apparatus, and this ink is an ink for an inkjet recording apparatus.

[0031] The fourteenth aspect of the present disclosure is the replenishing liquid used in the inkjet recording apparatus, and this replenishing liquid is a replenishing liquid for an inkjet recording apparatus.

Advantages of the Invention

[0032] As described above, an ink with high alcohol resistance after drying can be obtained. Further, even if the viscosity adjustment of the ink containing the mixed solvent of ketone and alcohol is repeated in the inkjet recording apparatus, the ratio of ketone and alcohol can be made close to the initial ratio. Therefore, it is possible to avoid the occurrence of problems in the inkjet recording apparatus due to the change in the ratio of ketone and alcohol.

Brief Description of the Drawings

[0033]

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DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0035] That is, in this specification, as an example of an inkjet recording apparatus, an industrial inkjet printer will be described. However, the technology disclosed herein can be applied to general devices using an inkjet that causes particulate ink to fly and land on a workpiece, regardless of the names of the inkjet recording apparatus and the industrial inkjet printer.

[0036] Also, in this specification, printing by an inkjet recording apparatus will be described. However, the “printing” referred to herein includes all processing operations applying an inkjet, such as printing of characters, marking of figures, and the like.

[0037] <OVERALL CONFIGURATION> FIG. 1 is a diagram illustrating the overall configuration of an inkjet recording system S. FIG. 2 is a diagram illustrating the schematic configuration of an inkjet recording apparatus I, and FIG. 3 is a diagram illustrating the schematic configuration of a discharge head 1 in the inkjet recording apparatus I. FIG. 4 is a diagram illustrating the paths of ink and a replenishing liquid (solvent) in the inkjet recording apparatus I. The ink can be individually supplied by an ink cartridge 104a, and the replenishing liquid can be individually supplied by a replenishing liquid cartridge 105a as needed. The replenishing liquid accommodated in the replenishing liquid cartridge 105a is a replenishing liquid for an inkjet recording apparatus. The ink accommodated in the ink cartridge 104a is an ink for an inkjet recording apparatus. Further, a combination of the ink and the replenishing liquid is constituted by the ink accommodated in the ink cartridge 104a and the replenishing liquid accommodated in the replenishing liquid cartridge 105a. Details of the supply of the ink and the replenishing liquid will be described later.

[0038] The automatic printing system S illustrated in FIG. 1 is installed, for example, on a conveyance line L in a factory or the like, and is configured to perform printing on each workpiece (printing target) W flowing through the conveyance line L in order. Note that the application target of the present disclosure is not limited to the automatic printing system S. It can also be applied to a printing system using a method other than automatic. The conveyance line L can be configured by, for example, a belt conveyor or the like, but is not limited to a belt conveyor.

[0039] The automatic printing system S includes an inkjet recording apparatus I that performs printing by landing particulate ink (ink particles) on a workpiece W, an operation terminal 800 and an external device 900 connected to the inkjet recording apparatus I, and a cleaning mounting unit 200 connected to the inkjet recording apparatus I for cleaning the discharge head 1. The cleaning mounting unit 200 is configured such that the discharge head 1 is mounted when cleaning the discharge head 1 using a cleaning liquid. Note that the cleaning mounting unit 200, the operation terminal 800, and the external device 900 are not essential.

[0040] The inkjet recording apparatus I illustrated in FIGS. 1 to 3 includes a discharge head 1 that discharges ink particles from a nozzle 12 and lands the ink particles on a workpiece W, and a controller 100 that supplies a control signal, ink, and a replenishing liquid to the discharge head 1. By the controller 100 supplying a control signal to the discharge head 1, the start and stop of the discharge of ink particles and the trajectory of the discharged ink particles are controlled.

[0041] The inkjet recording apparatus I according to the present embodiment is configured as a so-called continuous ink jet printer (CIJ). That is, in order to prevent clogging (particularly, clogging of the nozzle 12) caused by the evaporation of ink, even when printing is not being executed, if the inkjet recording apparatus I is in an operating state, the ink is constantly circulating inside the inkjet recording apparatus I. By adopting the continuous method, it becomes possible to use quick-drying ink without causing clogging by the ink.

[0042] In order to realize the circulation of ink, the discharge head 1 includes, in addition to the nozzle 12 that discharges ink or a replenishing liquid, a gutter 16 that recovers a part of the ink or the replenishing liquid discharged from the nozzle 12 (see FIG. 3). The ink or replenishing liquid recovered by the gutter 16 is sent back to the controller 100 and reused. In such an ink flow path, a sealing material may be provided at a portion that comes into contact with the ink. As the material of the sealing material, mainly EPDM (ethylene propylene diene rubber) or the like is used.

[0043] The operation terminal 800 has, for example, a central processing unit (CPU) and a storage device, and is connected to the controller 100. This operation terminal 800 functions as a terminal for setting processing conditions in printing and presenting information related to printing to the user.

[0044] The processing conditions set by the operation terminal 800 are output to the controller 100 and stored in its storage unit 102. In addition to, or instead of, the storage unit 102 of the controller 100, the operation terminal 800 may store the processing conditions. The processing conditions include contents such as the character string to be printed.

[0045] Note that the operation terminal 800 can be incorporated into and integrated with the controller 100, for example. In this case, a name such as a control unit will be used instead of the name "operation terminal".

[0046] The external device 900 is connected to the controller 100 as necessary. In the examples shown in FIGS. 1 and 2, as the external device 900, a work detection sensor 901, a conveyance speed sensor 902, a programmable logic controller (PLC) 903, etc. are provided.

[0047] Specifically, the work detection sensor 901 detects the presence or absence of the work W on the conveyance line L and outputs a signal (detection signal) indicating the detection result to the controller 100. The detection signal output from the work detection sensor 901 functions as a trigger (print trigger) for starting printing.

[0048] The conveyance speed sensor 902 is composed of, for example, a rotary encoder and can detect the conveyance speed of the work W. The conveyance speed sensor 902 outputs a signal (detection signal) indicating the detection result to the controller 100. The controller 100 controls the timing of discharging ink particles from the discharge head 1 based on the detection signal input from the conveyance speed sensor 902.

[0049] Also, as illustrated in FIG. 2, the PLC 903 is electrically connected to the controller 100. The PLC 903 is used to control the inkjet recording system S according to a predetermined sequence.

[0050] <Controller 100> The controller 100 is configured to control the ejection head 1 and supply ink and a replenishing liquid to the ejection head 1. Specifically, the controller 100 according to the present embodiment includes, as components related to control, a storage unit 102 that stores processing conditions, a control unit 101 that controls each part of the controller 100 and the ejection head 1, an operation display unit 103 that receives operations by a user and displays information to the user, and a power supply unit 121 that guides power supplied from the outside to the control unit 101.

[0051] As components related to the supply of ink and the like, the controller 100 includes an ink supply unit 104 that supplies ink to the nozzles 12 of the ejection head 1, and a replenishing liquid supply unit 105 that supplies a replenishing liquid to the nozzles 12 and the ink supply unit 104.

[0052] The control unit 101, the ink supply unit 104, and the replenishing liquid supply unit 105 may be configured as separate units. The storage unit 102 may also be configured as a separate unit from the ink supply unit 104 and the replenishing liquid supply unit 105. The operation display unit 103 may also be configured as a separate unit from the ink supply unit 104 and the replenishing liquid supply unit 105. In these cases as well, the components can be combined to form the controller 100.

[0053] (Storage unit 102) The storage unit 102 is configured to store the processing conditions set via the operation display unit 103 described later or the operation terminal 800, and output the stored processing conditions to the control unit 101 based on a control signal from the outside.

[0054] Specifically, the storage unit 102 is configured using a volatile memory, a non-volatile memory, a hard disk drive (HDD), a solid state drive (SSD), etc., and can temporarily or continuously store information indicating processing conditions. When the operation terminal 800 is incorporated into the controller 100, the operation terminal 800 may also serve as the storage unit 102.

[0055] (Control unit 101) Based on the processing conditions stored in the storage unit 102, the control unit 101 controls the ink supply unit 104 and the replenishing liquid supply unit 105 in the controller 100, and the nozzles 12, the charging electrodes 13, and the deflection electrodes 15 in the ejection head 1. By the control unit 101 controlling each part, printing on the workpiece W is performed at a predetermined timing.

[0056] Specifically, the control unit 101 has, for example, a CPU, a memory, an input / output bus, etc., and generates a control signal based on a signal indicating the information input via the operation display unit 103 or the operation terminal 800 and a signal indicating the processing conditions read from the storage unit 102. The control unit 101 outputs the thus generated control signal to each part of the controller 100 and the inkjet recording apparatus I.

[0057] For example, when printing on the workpiece W, the control unit 101 reads the printing content on the workpiece W stored in the storage unit 102 and generates a control signal based on the printing content. Then, the control unit 101 outputs the control signal to the charging electrode 13 to set the flying direction of the ink particles so as to realize the landing position corresponding to the printing content.

[0058] (Operation display unit 103) As shown in FIG. 1, the operation display unit 103 can be provided, for example, on the housing or the like that constitutes the controller 100. This operation display unit 103 includes a display unit 103a that displays various information related to the inkjet recording apparatus I, and an operation unit 103b that includes, for example, a touch operation panel, buttons, switches, and the like. The display unit 103a is composed of, for example, a liquid crystal display panel, an organic EL display panel, or the like, and is controlled by the control unit 101, and is configured to be able to display a user interface and the like as described later.

[0059] When the user operates the operation unit 103b of the operation display unit 103, the operation information is input to the control unit 101, and the control unit 101 can detect what operation has been performed. For example, by operating the operation unit 103b, it is possible to switch the power ON / OFF of the inkjet recording apparatus I, perform various settings, input information, and the like. When the operation terminal 800 is incorporated into the controller 100, the operation terminal 800 may also serve as the operation display unit 103. The display unit 103a of the operation display unit 103 is a notification unit that notifies the user of various information, and the operation unit 103b is an input unit that can input various information.

[0060] This operation display unit 103 can also set the processing conditions in printing, similar to the aforementioned operation terminal 800. The processing conditions set by the operation display unit 103 are output to the controller 100 and stored in its storage unit 102. In the following description, the case where the user operates the operation display unit 103 is assumed, but the operation terminal 800 can also be used instead of the operation display unit 103.

[0061] (Ink supply unit 104) As shown in FIG. 4, the ink supply unit 104 mainly includes an ink cartridge 104a that stores ink, a main tank 104b to which ink is supplied from the ink cartridge 104a, an ink flow path 104c, and an ink receiving unit 104d. The ink cartridge 104a, the main tank 104b, and the ejection head 1 are fluidly connected via the ink flow path 104c.

[0062] Among these, as also shown in FIG. 5A, the ink cartridge 104a is configured to be detachable from the controller 100, and by replacing this, the main tank 104b can be replenished with ink. When attaching the ink cartridge 104a to the controller 100, first, as shown in FIG. 5C, the ink receiving portion 104d is arranged so as to face outward of the controller 100, and then, as shown in FIG. 5D, the ink cartridge 104a is held by the ink receiving portion 104d, and finally, as shown in FIG. 5E, the ink receiving portion 104d is rotated so that the ink cartridge 104a is accommodated in the controller 100.

[0063] The ink contained in the ink cartridge 104a contains, as shown in FIG. 6, an ink colorant, a binder, and a solvent. The solvent is a mixed solvent of two or more components, which is a mixture of a ketone and an alcohol having a higher volatility than the ketone. The ketone is a ketone for ink dissolution, and is one or any two or more selected from the group including diethyl ketone, methyl isopropyl ketone, and methyl propyl ketone. In this embodiment, the alcohol is industrial alcohol (denatured ethanol), and 1-propanol and isopropyl alcohol are added as denaturing agents. Other denaturing agents include, for example, methanol, methyl ethyl ketone, etc., and any denaturing agent may be added. Also, an alcohol other than ethanol may be used as long as it has a higher volatility than the ketone, or ethanol and an alcohol having a higher volatility than the ketone may be mixed. The high-functional ink having high alcohol resistance and strong adhesiveness may contain, for example, a mixed solvent in which diethyl ketone having a relatively high allowable concentration among C5 ketones and denatured ethanol having relatively high availability are mixed.

[0064] The ink in the ink cartridge 104a contains 70 to 85 mass percent of a solvent. The lower limit of the solvent content can be 70 mass percent or more, and can also be 75 mass percent or more. The upper limit of the solvent content can be 85 mass percent or less, and can also be 80 mass percent or less. If the lower limit of the solvent content is less than 70 mass percent, the content of the solid components including the ink colorant and the binder in the ink increases, so that the solid components cannot be completely dissolved in the solvent. When the solubility of the solid components deteriorates, the precipitation of the solid components due to temperature changes increases, and problems such as poor printing stability and easy clogging of the filter F described later may occur. Furthermore, when the solvent volatilizes, the viscosity of the ink tends to increase, and there is also a risk of immediately reaching a viscosity range in which suction by the pump described later becomes difficult. Therefore, the lower limit of the solvent content in the ink in the ink cartridge 104a is set to 70 mass percent or more.

[0065] Also, if the upper limit of the solvent content in the ink in the ink cartridge 104a is higher than 85 mass percent, the ratio of the solid components decreases, making it difficult to design a high-functional ink having a desired adhesiveness. Furthermore, if the upper limit of the solvent content in the ink in the ink cartridge 104a is higher than 85 mass percent, the ratio of the solid components decreases, so that even if the concentration of ketone in the solvent of the ink is constant, the concentration of ketone in the ink increases. For example, the swelling amount of the sealing material (EPDM) used in the inkjet recording apparatus I increases, and the possibility of adversely affecting the life of the sealing material increases. Therefore, the upper limit of the solvent content in the ink in the ink cartridge 104a is set to 85 mass percent or less.

[0066] The higher the vapor pressure, the higher the volatility, and the lower the vapor pressure, the lower the volatility. Therefore, an alcohol with higher volatility than a ketone can also be said to be an alcohol with a higher vapor pressure than the ketone. More specifically, the higher the vapor pressure in the temperature range assumed within the inkjet recording apparatus I, the higher the volatility, and the lower the vapor pressure in this temperature range, the lower the volatility. The temperature range assumed here is, for example, about 0°C to 50°C. Also, in many cases, the lower the boiling point, the higher the volatility, and the higher the boiling point, the lower the volatility. Therefore, an alcohol with higher volatility than a ketone can also be said to be an alcohol with a lower boiling point than the ketone.

[0067] Among the solvents of the ink in the ink cartridge 104a, when a ketone is used as the main solvent (solvent A) and an alcohol is used as the secondary solvent (solvent B), a combination of solvents in which the value of the vapor pressure of solvent A / the vapor pressure of solvent B at 10°C and the value of the vapor pressure of solvent A / the vapor pressure of solvent B at 50°C are different may be used.

[0068] The ink in the ink cartridge 104a contains 15 mass percent or more of a solid content including an ink colorant and a binder. The lower limit of the solid content in the ink can also be 20 mass percent or more. The upper limit of the solid content in the ink can be 30 mass percent or less, or 25 mass percent or less. By containing 15 mass percent or more of the solid content in the ink, even if, for example, germicidal alcohol or the like adheres to the printed surface (the surface where the ink has solidified) after the ink adheres to the work W and dries, dissolution of the ink and peeling of the print are suppressed.

[0069] The alcohol resistance of such a printed surface can be defined by the alcohol solubility of the ink after drying. The solid content of the ink is set so that the alcohol solubility after being discharged from the discharge head 1 and adhering to the work W and drying is 5% or less. The alcohol solubility of the dried ink may be, for example, 4% or less. The alcohol solubility is the amount that diffuses into the solution side when a substance of 100 by weight is immersed in absolute ethanol with a purity of 99.9%. For example, an alcohol solubility of 5% means that when a solid content of 100 by weight is immersed in absolute ethanol with a purity of 99.9%, the weight becomes 95.

[0070] The ink colorant may be a dye-based colorant or a pigment-based colorant. The dye-based ink colorant exists in the ink in a dissolved state in the above solvent. On the other hand, the pigment-based ink colorant exists in the ink in a dispersed state without dissolving in the above solvent.

[0071] The color of the ink colorant can be, for example, black, but is not limited to black, and may be a yellow or white pigment-based colorant or the like. The binder is a so-called adhesive and fixes the ink colorant to the printed surface of the work W. The binder exists in the ink in a dissolved state in the solvent, and after adhering to the printed surface of the work W, the solvent volatilizes to fix the ink to the printed surface. In the present embodiment, those having an alcohol solubility of the binder after drying within the above range can be used.

[0072] As also shown in FIG. 5C, the ink receiving portion 104d is provided in the controller 100 and is configured to be able to receive the ink cartridge 104a. The ink receiving portion 104d is configured to be able to accommodate the ink cartridge 104a from the outside, for example, and is also configured to be able to take out the accommodated ink cartridge 104a. Receiving the ink cartridge 104a from the outside can be referred to as "receiving the ink cartridge 104a".

[0073] The ink receiving part 104d is configured not only to receive the ink cartridge 104a but also to receive the ink contained in the ink cartridge 104a. Specifically, the ink receiving part 104d has a suction pipe or the like that communicates with the inside of the ink cartridge 104a, and is configured to be able to suck the ink contained in the ink cartridge 104a from the suction pipe or the like. Sucking the ink contained in the ink cartridge 104a can be referred to as "receiving ink". The reception of the ink cartridge 104a and the reception of ink are separate. Although details will be described later, even if the ink receiving part 104d receives the ink cartridge 104a, it may not receive ink. Note that if the ink receiving part 104d does not receive the ink cartridge 104a, it is configured so that ink cannot be received.

[0074] As shown in FIG. 4, the ink supply unit 104 further includes an ink mounting detection switch 104f for detecting whether the ink cartridge 104a is mounted or not. The ink mounting detection switch 104f can be provided in the ink receiving part 104d and is composed of, for example, a micro switch or a proximity switch. The ink mounting detection switch 104f is arranged such that it turns ON only when the ink cartridge 104a is received at the normal position of the ink receiving part 104d, and turns OFF in other cases. The ink mounting detection switch 104f is connected to the control unit 101, and the detection result of the ink mounting detection switch 104f is output to the control unit 101.

[0075] As also shown in FIG. 5A, an ink information storage unit (first storage medium) 104e is attached to the ink cartridge 104a. The ink information storage unit 104e is composed of a non-volatile memory or the like that stores information regarding the ink. The information regarding the ink includes information on the type, the date of manufacture, and the concentration of ketone. Information is stored in the ink information storage unit 104e in a form as shown as an example in FIG. 7A, for example. That is, there are a plurality of addresses, and for each address, an information type and data are associated as items. The information type is classified into items such as "ink / refill liquid", "date of manufacture", and "ketone concentration". "Ink / refill liquid" is an item indicating whether the liquid stored in the ink cartridge 104a is ink or a refill liquid. As will be described later, it is information for distinguishing from the refill liquid cartridge 105a. In the case of the ink information storage unit 104e, since it is attached to the ink cartridge 104a, the data is "ink".

[0076] Also, "date of manufacture" is an item for specifying the date on which the ink stored in the ink cartridge 104a was manufactured or the date on which the ink cartridge 104a was manufactured. Since the date on which the ink was manufactured is almost the same as the date on which the ink was filled into the ink cartridge 104a, "date of manufacture" can also be said to be the filling date into the ink cartridge 104a. The reason for storing the date of manufacture in the ink information storage unit 104e is that although the solvent contained in the ink after manufacture (or after filling into the ink cartridge 104a) is in a very small amount, it is inevitable that it volatilizes to the outside of the ink cartridge 104a. Therefore, it is presumed that the earlier the date of manufacture, the more the solvent component of the ink in the ink cartridge 104a has decreased. As will be described in detail later, the date of manufacture is used at the time of ink suction as information for estimating the concentration of the solvent component of the ink in the ink cartridge 104a.

[0077] In addition, the "ketone concentration" stored in the ink information storage unit 104e is an item indicating the ketone concentration in the solvent of the ink contained in the ink cartridge 104a. The ketone concentration is the ketone concentration obtained by analyzing the ink immediately before filling the ink cartridge 104a with a nuclear magnetic resonance apparatus (NMR) or the like, and the numerical value can be stored in the ink information storage unit 104e as data. Although the ink is manufactured so that the ketone concentration is constant, the mixing amounts of alcohol and ketone may vary slightly, and the ketone concentrations are not necessarily the same in all ink cartridges 104a. Therefore, by measuring the ketone concentration in the solvent of the ink in the ink cartridge 104a and storing it in the ink information storage unit 104e, it can be used as information for estimating the concentration of the solvent component of the ink in the ink cartridge 104a during the suction of the ink described later. As shown in FIG. 6, the ketone concentration in the solvent of the ink is the mass percentage concentration of the ketone Kin contained in the solvent SV when focusing on the solvent SV in the ink In, and is not the concentration for the entire ink In.

[0078] The ink supply unit 104 further includes an ink information access unit (first access unit) 104g that accesses the ink information storage unit 104e. The ink information access unit 104g can be configured by a reader or the like that can read the information stored in the ink information storage unit 104e. The ink information access unit 104g is connected to the control unit 101, and the information about the ink read by the ink information access unit 104g is output to the control unit 101.

[0079] As described above, the inkjet recording apparatus I according to the present embodiment is configured as a so-called "cartridge type" inkjet printer, but is not limited to this configuration. For example, a manually openable and closable tank may be provided, and the tank may be configured to be replenished with ink.

[0080] The main tank 104b is a container that stores the ink supplied to the nozzle 12. Specifically, it is a mixing container for adjusting the viscosity of the ink that is mixed with the replenishing liquid and discharged so that the viscosity becomes the desired viscosity. That is, the ink whose viscosity has been adjusted by the replenishing liquid is stored in the main tank 104b.

[0081] Also, the ink flow path 104c is a path that includes an ink discharge path for supplying the ink with adjusted viscosity in the main tank 104b to the discharge head 1 and a recovery path for returning the ink sucked by the gutter 16 to the main tank 104b, and constitutes an adjusted ink flow path. By this ink flow path 104c, the ink can be circulated between the discharge head 1 and the controller 100.

[0082] As will be described later, the ink flow path 104c is provided with a plurality of electromagnetic valves including the first valve V1 and a plurality of pumps including the ink pump P1. Among these, each electromagnetic valve opens and closes in response to a control signal output from the control unit 101 and can control the flow of ink. On the other hand, each pump pumps the ink in response to a control signal output from the control unit 101 and can control the flow of ink in the same way as the electromagnetic valve.

[0083] (Replenishing liquid supply unit 105) The replenishing liquid supply unit 105 mainly includes a replenishing liquid cartridge 105a that stores the replenishing liquid, a conditioning tank 105b, a replenishing liquid flow path 105c, and a replenishing liquid receiving portion 105d. The replenishing liquid cartridge 105a, the conditioning tank 105b, and the discharge head 1 are fluidly connected via the replenishing liquid flow path 105c. The replenishing liquid flow path 105c through which the replenishing liquid flows is composed of a plurality of paths, and a part of them is also used as a path for sending back the ink from the gutter 16.

[0084] As shown in FIG. 5B, the replenishing liquid cartridge 105a is configured to be detachable from the controller 100. By replacing the replenishing liquid cartridge 105a, the controller 100 can be replenished with the replenishing liquid. The method of attaching the replenishing liquid cartridge 105a to the controller 100 is the same as the method of attaching the ink cartridge 104a to the controller 100.

[0085] The replenishing liquid in this embodiment is a solvent. Specifically, as shown in FIG. 6, it is a mixed solvent of two or more components, which is a mixture of a ketone and an alcohol having a higher volatility than the ketone. The ketone is a replenishing ketone, and is the same as the ink-dissolving ketone contained in the ink housed in the ink cartridge 104a, and is composed of one kind or any two or more kinds selected from the group including diethyl ketone, methyl isopropyl ketone, and methyl propyl ketone. Also, the alcohol contained in the replenishing liquid is the same as the alcohol contained in the ink housed in the ink cartridge 104a. As the alcohol contained in the replenishing liquid, an alcohol other than ethanol may be used as long as it has a higher volatility than the ketone, or ethanol and an alcohol having a higher volatility than the ketone may be mixed and used. The replenishing liquid corresponding to the highly functional ink having high alcohol resistance and strong adhesiveness may contain, for example, a mixed solvent in which diethyl ketone having a relatively high allowable concentration among C5 ketones and denatured ethanol having relatively high availability are mixed.

[0086] The mass percentage concentration of ketone in the replenishing liquid is set lower than the mass percentage concentration of ketone in the solvent of the ink contained in the ink cartridge 104a. Specifically, the concentration of ketone in the replenishing liquid is set 5 to 15 percentage points lower in mass percentage concentration than the ketone concentration in the solvent of the ink contained in the ink cartridge 104a. Also, the concentration of ketone in the replenishing liquid may be set 8 to 12 percentage points lower in mass percentage concentration than the ketone concentration in the solvent of the ink contained in the ink cartridge 104a. The reason why the ketone concentration of the replenishing liquid is set lower than the ketone concentration of the ink and the resulting effects will be described later.

[0087] The replenishing liquid cartridge 105a containing the replenishing liquid may be provided in combination with the ink cartridge 104a containing the corresponding ink, or may be provided alone for use with the corresponding ink. For example, the replenishing liquid may be provided in a form specified by the ink type or ketone concentration for use with the ink.

[0088] The ink cartridge 104a containing the ink may be provided in combination with the replenishing liquid cartridge 105a containing the corresponding replenishing liquid, or may be provided alone for use with the corresponding replenishing liquid. For example, the ink may be provided in a form specified by the replenishing liquid type or ketone concentration for use with the replenishing liquid.

[0089] As shown in FIGS. 5A and 5B, the ink cartridge 104a and the refill liquid cartridge 105a may have substantially the same shape. Further, an ink information storage unit (first storage medium) 104e may be attached to the ink cartridge 104a, and a refill liquid information storage unit (second storage medium) 105e may be attached to the refill liquid cartridge 105a and provided. In this case, the ink information storage unit (first storage medium) 104e and the refill liquid information storage unit (second storage medium) 105e each hold information regarding each of the contents in a format readable by the common inkjet recording apparatus I. Examples of the information regarding the contents include the type of the contents such as ink and refill liquid, the remaining amount of the contents, the manufacturing date, the ketone concentration, and the like.

[0090] As shown in FIG. 5C, the ink receiving portion 104d and the refill liquid receiving portion 105d in the inkjet recording apparatus I may have substantially the same shape. In this case, the ink cartridge 104a and the refill liquid cartridge 105a may have substantially the same shape at least at a portion that contacts the ink receiving portion 104d or the refill liquid receiving portion 105d in the inkjet recording apparatus I. For example, the shapes may be made different to prevent misinsertion of the ink cartridge 104a and the refill liquid cartridge 105a, and the remaining shapes at the portions that contact the ink receiving portion 104d or the refill liquid receiving portion 105d may be made common.

[0091] The refill liquid receiving portion 105d is provided in the controller 100 separately from the ink receiving portion 104d and is configured to be able to receive the refill liquid cartridge 105a. The refill liquid receiving portion 105d is configured in the same manner as the ink receiving portion 104d, for example. Receiving the refill liquid cartridge 105a from the outside can be referred to as "receiving the refill liquid cartridge 105a".

[0092] The replenishing liquid receiving portion 105d is configured to not only receive the replenishing liquid cartridge 105a but also receive the replenishing liquid stored in the replenishing liquid cartridge 105a. Specifically, the replenishing liquid receiving portion 105d has a suction tube or the like that communicates with the inside of the replenishing liquid cartridge 105a, and is configured to be able to suck the ink stored in the replenishing liquid cartridge 105a from the suction tube or the like. Sucking the replenishing liquid stored in the replenishing liquid cartridge 105a can be referred to as "receiving the replenishing liquid". The reception of the replenishing liquid cartridge 105a and the reception of the replenishing liquid are separate. Although details will be described later, even if the replenishing liquid receiving portion 105d receives the replenishing liquid cartridge 105a, it may not receive the replenishing liquid. Note that if the replenishing liquid receiving portion 105d does not receive the replenishing liquid cartridge 105a, it is configured so that the replenishing liquid cannot be received.

[0093] The replenishing liquid supply unit 105 further includes a replenishing liquid mounting detection switch 105f for detecting whether or not the replenishing liquid cartridge 105a is mounted. The replenishing liquid mounting detection switch 105f can be provided in the replenishing liquid receiving portion 105d. Similar to the ink mounting detection switch 104f, the replenishing liquid mounting detection switch 105f is turned on only when the replenishing liquid cartridge 105a is received at the normal position of the replenishing liquid receiving portion 105d, and is arranged to be turned off in other cases. The replenishing liquid mounting detection switch 105f is connected to the control unit 101, and the detection result of the replenishing liquid mounting detection switch 105f is output to the control unit 101.

[0094] The replenishing liquid cartridge 105a is attached with a replenishing liquid information storage unit (second storage medium) 105e. The replenishing liquid information storage unit 105e is composed of a non-volatile memory or the like that stores information regarding the replenishing liquid. The information regarding the replenishing liquid includes information on the type, the manufacturing date, and the concentration of ketone, similar to the information regarding the ink. In the replenishing liquid information storage unit 105e, the information is stored in a form shown as an example in FIG. 7B, for example. In the case of the "ink / replenishing liquid" item, since it is attached to the replenishing liquid cartridge 105a, the data is "replenishing liquid".

[0095] Also, the "manufacturing date" is an item that specifies the date when the replenishing liquid stored in the replenishing liquid cartridge 105a was manufactured or the date when the replenishing liquid cartridge 105a was manufactured. Since the date when the replenishing liquid was manufactured is almost the same as the date when the replenishing liquid was filled into the replenishing liquid cartridge 105a, the "manufacturing date" can also be said to be the filling date into the replenishing liquid cartridge 105a. The reason for storing the manufacturing date in the replenishing liquid information storage unit 105e is the same as in the case of the ink, and the manufacturing date is used at the time of sucking the replenishing liquid as information for estimating the concentration of the solvent component of the replenishing liquid in the replenishing liquid cartridge 105a.

[0096] In addition, the "ketone concentration" stored in the replenishing liquid information storage unit 105e is an item indicating the ketone concentration of the replenishing liquid contained in the replenishing liquid cartridge 105a. Similar to the case of ink, the ketone concentration is the ketone concentration obtained by measurement before filling, and the numerical value can be stored in the replenishing liquid information storage unit 105e as data. Although the replenishing liquid is manufactured so that the ketone concentration is constant, the mixing amount of alcohol and ketone may vary slightly, and the ketone concentration may not be the same in all the replenishing liquid cartridges 105a. Therefore, by measuring and storing the ketone concentration of the replenishing liquid in the replenishing liquid cartridge 105a, it can be used as information for estimating the ketone concentration of the replenishing liquid in the replenishing liquid cartridge 105a when sucking the replenishing liquid, which will be described later. As shown in FIG. 6, the ketone concentration in the replenishing liquid is the mass percentage concentration of the ketone Kre contained in the solvent when focusing on the solvent in the replenishing liquid Re. Since the replenishing liquid Re is almost composed of the solvent, it may also be the mass percentage concentration of the ketone Kre with respect to the entire replenishing liquid Re.

[0097] The replenishing liquid supply unit 105 further includes a replenishing liquid information access unit (second access unit) 105g that accesses the replenishing liquid information storage unit 105e. The replenishing liquid information access unit 105g can be composed of a reader or the like that can read the information stored in the replenishing liquid information storage unit 105e. The replenishing liquid information access unit 105g is connected to the control unit 101, and the information on the replenishing liquid read by the replenishing liquid information access unit 105g is output to the control unit 101.

[0098] A replenishing liquid tank may be provided instead of the replenishing liquid cartridge 105a. The replenishing liquid supply unit 105 has a function of detecting whether the replenishing liquid in the replenishing liquid cartridge 105a has become empty or whether the replenishing liquid has become less. The replenishing liquid contained in the replenishing liquid cartridge 105a is used for adjusting the concentration of the ink and also as a cleaning agent for cleaning the path through which the ink flows.

[0099] The conditioning tank 105b is configured to store the replenishing liquid used for cleaning. The replenishing liquid used for cleaning contains ink. As described above, the replenishing liquid discharged from the nozzle 12 is recovered by the gutter 16 in the same manner as the ink.

[0100] Also, the replenishing liquid flow path 105c is a path for supplying the replenishing liquid to the discharge head 1, the main tank 104b, etc., and returning the replenishing liquid sucked by the gutter 16 to the main tank 104b.

[0101] As will be described later, the replenishing liquid flow path 105c is provided with a plurality of electromagnetic valves including the 16th valve V16, and a plurality of pumps including the replenishing liquid pump P2. Among these, each electromagnetic valve opens and closes in response to a control signal output from the control unit 101, and can control the flow of the replenishing liquid. On the other hand, each pump pumps the replenishing liquid in response to a control signal output from the control unit 101, and can control the flow of the replenishing liquid in the same manner as the electromagnetic valve.

[0102] Note that the classification of the replenishing liquid flow path 105c and the aforementioned ink flow path 104c is only a convenient classification made for the sake of simplicity of explanation. Since the replenishing liquid flow path 105c and the ink flow path 104c are connected to each other or one serves as the other, they are substantially inseparable.

[0103] (Power supply unit 121) The power supply unit 121 is interposed between the commercial power supply 700 and the control unit 101, and can relay the power supplied from the commercial power supply 700) and supply this to the control unit 101.

[0104] (Other components) The controller 100 is provided with a connection cable 107 in which electric wiring for transmitting and receiving control signals, a tube for transmitting and receiving ink (specifically, a tube partitioning the ink flow path 104c), and a tube for transmitting and receiving a replenishing liquid (specifically, a tube partitioning the replenishing liquid flow path 105c) are bundled and covered. This connection cable 107 has flexibility and is connected to the upper end of the discharge head 1 (see FIG. 1). The controller 100 and the discharge head 1 are electrically and fluidly connected via this connection cable 107.

[0105] <discharge head 1> The discharge head 1 discharges the viscosity-adjusted ink as particulate ink particles based on the control signal, ink, and replenishing liquid supplied from the controller 100. The discharge head 1 can execute printing on the work W by deflecting the flying direction of the discharged ink particles and landing the deflected ink particles on the surface of the work W.

[0106] Specifically, as shown in FIG. 3, the discharge head 1 according to the present embodiment includes a vibrator 11 that generates ink particles by applying vibration to the ink, a nozzle 12 that discharges the ink vibrated by the vibrator 11, a charging electrode 13 that charges the particulate ink discharged from the nozzle 12, a charge detection sensor 14 that monitors the charged state of the ink, a deflection electrode 15 that deflects the flying direction of the ink charged by the charging electrode 13, and a gutter 16 that recovers the non-deflected ink by the deflection electrode 15 or the replenishing liquid discharged from the nozzle 12.

[0107] The discharge head 1 includes a housing 10 that houses the vibrator 11, the nozzle 12, the charging electrode 13, the charge detection sensor 14, the deflection electrode 15, and the gutter 16 inside and partitions the flying space S1 of the ink particles. An opening A for discharging the ink deflected by the deflection electrode 15 to the outside is formed on the lower surface of the housing 10 of the discharge head 1. The ink is discharged downward from the housing 10 through this opening A.

[0108] As shown in FIG. 1, the ejection head 1 during printing is supported by, for example, a support member 2. The ejection head 1 supported by the support member 2 is arranged such that its ejection holes A face the printing surface of the workpiece W from above.

[0109] Hereinafter, each part constituting the ejection head 1 will be described in order. In the following description, the "vertical direction" refers to the direction along the vertical direction. For example, the upper part of the paper surface in FIG. 3 corresponds to the "upward direction", and the lower part of the paper surface in the same figure corresponds to the "downward direction". In other figures as well, the corresponding direction is referred to as the "vertical direction".

[0110] (Vibrator 11) As illustrated in FIG. 3, the vibrator 11 is provided on the nozzle 12. The vibrator 11 according to the present embodiment incorporates a device (for example, a piezo element) for imparting (vibrating) vertical vibration to the ink. The vibrator 11 is configured such that ink is supplied via a connection cable 107, and the ink thus supplied can be vibrated. The ink vibrated by the vibrator 11 is supplied to the nozzle 12. Although not shown in the figure, the vibrator 11 according to the present embodiment is grounded.

[0111] (Nozzle 12) As illustrated in FIG. 3, the main body portion of the nozzle 12 is connected to the lower end portion of the vibrator 11. The lower end surface of the nozzle 12 is formed such that an ejection port (not shown) through which the ink vibrated by the vibrator 11 ejects opens downward. A suction path 27 (shown in FIG. 4 etc.) that constitutes an ink supply unit 104 is connected to the flow path in the nozzle 12, and a negative pressure can be applied to the flow path in the nozzle 12. The flow path in the nozzle 12 is for sucking the ink in the nozzle 12. The suction path 27 also functions as a return path for discharging the pressure inside the ejection head 1, for example, when standing upright. It is also possible to suck the replenishing liquid from the nozzle 12 through the suction path 27.

[0112] The ink ejected from the nozzle 12 without being vibrated by the vibrator 11 flows as an axial so-called "ink axis". On the other hand, the vibrated ink is atomized immediately after being ejected from the nozzle 12 and becomes so-called "ink particles". The ink ejected from the nozzle 12 is axial immediately after being ejected from the nozzle 12, but becomes particulate as it moves away from the nozzle 12. The position where it becomes particulate is called the break point. The ink (ink particles) ejected from the nozzle 12 passes through the charging electrode 13 described later.

[0113] Note that the replenishing liquid supplied to clean the ejection head 1 passes through the vibrator 11 and the nozzle 12 in sequence and is ejected from the tip of the nozzle 12. The replenishing liquid thus ejected flows axially and passes through the charging electrode 13.

[0114] (Charging electrode 13) As illustrated in FIG. 3, the charging electrode 13 is composed of a pair of conductive metal plates and is disposed below the nozzle 12. The pair of metal plates constituting the charging electrode 13 are fixed to the housing 10 in a posture in which their longitudinal directions are along the vertical direction and in a posture facing each other in the horizontal direction. The ink ejected from the nozzle 12 passes between the pair of metal plates.

[0115] In the charging electrode 13 according to the present embodiment, a potential (positive potential) is applied at least when the printing operation is executed. This makes it possible to generate a potential difference between the vibrator 11 and the charging electrode 13 and charge the ink particles passing through the charging electrode 13. In order to charge each ink particle, the charging electrode 13 according to the present embodiment is disposed near the break point where the ink ejected from the nozzle 12 is atomized.

[0116] A pulse potential controllable by the controller 100 is applied to the charging electrode 13. Here, when a relatively high voltage is applied to the charging electrode 13, the charge amount (magnitude of negative charge) of each ink particle becomes larger than when a lower voltage is applied. When the charge amount of each ink particle is large, it is deflected more greatly by the deflection electrode 15 than when it is small. By adjusting the magnitude of the pulse potential by the controller 100, the amount of deflection of the ink particles can be controlled. The ink particles charged by the charging electrode 13 reach the deflection electrode 15 passing by the side of the charge detection sensor 14. Also, the replenishing liquid ejected from the nozzle 12 reaches the deflection electrode 15 without being charged.

[0117] (Charge detection sensor 14) As illustrated in FIG. 3, the charge detection sensor 14 is disposed below the charging electrode 13. Specifically, the charge detection sensor 14 is disposed below the metal plate constituting the charging electrode 13 (in the example shown in FIG. 3, the metal plate on the right side of the paper surface) so as not to intersect the trajectory when the ink particles fly. By disposing the charge detection sensor 14 in this way, it is possible to avoid the collision between the ink particles and the charge detection sensor 14.

[0118] Also, the charge detection sensor 14 according to the present embodiment is connected to a circuit board provided inside the housing 10. The charge detection sensor 14 can detect the charge state of the ink particles passing by its side. The detection result by the charge detection sensor 14 is output to the control unit 101 as a detection signal. Based on this detection signal, the control unit 101 can determine whether each ink particle is appropriately charged.

[0119] (Deflection electrode 15) As illustrated in FIG. 3, the deflection electrode 15 is composed of a pair of conductive metal plates (so-called "opposing electrodes"), and is disposed below the charging electrode 13 and the charge detection sensor 14. Here, the pair of metal plates are fixed to the housing 10 in a posture where their respective longitudinal directions are substantially along the vertical direction and in a posture where they face each other in the horizontal direction. The ink particles that have passed between the pair of metal plates constituting the charging electrode 13 will pass between the pair of metal plates constituting the deflection electrode 15.

[0120] A voltage controllable by the controller 100 is applied to the deflection electrode 15. As a result, a potential difference will occur between the pair of metal plates constituting the deflection electrode 15. Due to this potential difference, the flying direction of the ink particles can be deflected according to the charge amount of the ink particles. The flying direction of the ink particles can be deflected along the arrangement direction of the pair of metal plates constituting the deflection electrode 15.

[0121] That is, the flying direction of the ink particles can be controlled via the voltages applied to the charging electrode 13 and the deflection electrode 15 respectively. Among the ink particles whose flying direction is thus controlled, there are those deflected by the deflection electrode 15 and those not deflected by the deflection electrode 15 (non-deflected ones). Among these, the ink particles deflected by the deflection electrode 15 are involved in printing on the work W. The ink particles deflected by the deflection electrode 15 are ejected from the opening A provided on the lower surface of the housing 10 and land on the work W.

[0122] On the other hand, the ink particles that are non-deflected by the deflection electrode 15 are not involved in printing on the work W. Such ink particles, or the axial ink that has not been atomized in the first place, reach the gutter 16 as illustrated by the dashed line in FIG. 3. Similarly, the replenishing liquid used for cleaning the nozzles 12 etc. in the ejection head 1 and passing through the deflection electrode 15 also reaches the gutter 16.

[0123] (Gutter 16) As illustrated in FIG. 3, the gutter 16 is constituted by a curved pipe with its open end facing upward, and is disposed below the deflection electrode 15. The gutter 16 according to the present embodiment can collect ink that is not involved in printing the workpiece W and the replenishing liquid that has passed through the nozzle 12 (specifically, the replenishing liquid discharged from the nozzle 12).

[0124] In the present embodiment, the open end (upstream end) of the gutter 16 and the open end of the nozzle 12 are arranged to face each other, and the open end of the nozzle 12 is located directly above the open end of the gutter 16. By arranging in this way, it becomes possible to receive the fluid flowing along the vertical direction from the open end of the nozzle 12 at the open end of the gutter 16. The ink or replenishing liquid recovered by the gutter 16 is refluxed to the main tank 104b of the controller 100 via the recovery flow path.

[0125] Hereinafter, the recovery of the ink or replenishing liquid by the gutter 16 will be described with reference to FIG. 4. In FIG. 4, the components marked with reference symbol F illustrate filters. In the following description, the description of the arrangement, configuration, etc. of the filter F will be omitted.

[0126] <Regarding the paths of ink and replenishing liquid> The ink circulation path 104c, as a path related to the supply of ink to the nozzle 12, includes a first ink path 21 connecting the ink cartridge 104a and the first branch portion 51, a sixth ink path 26 connecting the first branch portion 51 (specifically, an intermediate portion in the second ink path 22) and the second branch portion 52, an eighth ink path 28 connecting the second branch portion 52 and the main tank 104b, and a fourth ink path 24 connecting the main tank 104b and the nozzle 12. Here, the sixth ink path 26 according to the present embodiment is connected to the second branch portion 52 via the fifth ink path 25 described later.

[0127] The ink received by the ink receiving section 104d is sent to the main tank 104b through the first ink path 21, the first branch section 51, the second ink path 22, the sixth ink path 26, the second branch section 52, and the eighth ink path 28. That is, the ink flow path for sending the ink received by the ink receiving section 104d is composed of the first ink path 21, the first branch section 51, the second ink path 22, the sixth ink path 26, the second branch section 52, and the eighth ink path 28.

[0128] Further, the ink supply section 104 has a viscometer 53. The viscosity of the ink changes according to the concentration of the solvent in the ink. That is, the viscosity of the ink changes according to the ratio of the solid content to the solvent, and the higher the ratio of the solid content, the higher the viscosity of the ink. By utilizing this, the concentration of the solvent in the ink can be estimated by measuring the viscosity of the ink. As schematically shown in FIG. 8, the viscometer 53 includes an upper container 53a and a lower container 53b. A predetermined amount of ink is introduced into the upper container 53a. A dropping hole 53c for dropping the internal ink is provided at the bottom of the upper container 53a. The lower container 53b is arranged to receive the ink dropped from the dropping hole 53c. The ink in the lower container 53b is returned to the main tank 104b. The viscosity of the ink can be calculated based on the time during which the ink in the upper container 53a changes from the H level to the L level, and the concentration of the solvent in the ink can be estimated.

[0129] The ink circulation path 104c, as a path related to the viscosity measurement by the viscometer 53, has a second ink path 22 that connects the first branch section 51 and the main tank 104b and in which the viscometer 53 is interposed, and a third ink path 23 that is provided independently of the second ink path 22 and connects the main tank 104b and the first branch section 51.

[0130] In addition, the ink circulation path 104c has a fifth ink path 25 that connects the gutter 16 and the main tank 104b as a path related to the recovery of ink by the gutter 16. When ink particles are recovered by the gutter 16, the fifth ink path 25 constitutes a recovery flow path that guides the recovered ink particles to the ink supply unit 104. When the replenishing liquid is sucked by the gutter 16, the replenishing liquid is recovered by the fifth ink path 25.

[0131] Here, a circulation pump P4, an eleventh valve V11, and a viscometer 53 are sequentially provided in the second ink path 22. The circulation pump P4 is a pump that applies a negative pressure to the suction path 27. Since the suction path 27 is connected to the flow path in the nozzle 12, when the circulation pump P4 is operated, the ink in the nozzle 12 can be sucked through the suction path 27.

[0132] An ink pump P1, a pressure reducing valve, a pressure gauge, and a fourteenth valve V14 are sequentially provided in the fourth ink path 24. A tenth valve V10, a gutter pump P3, and a second branch portion 52 are sequentially provided in the fifth ink path 25. The gutter pump P3 is a suction pump that sucks ink particles when ink particles are recovered by the gutter 16 and sucks the replenishing liquid when the replenishing liquid is recovered by the gutter 16 by applying a negative pressure to the fifth ink path 25.

[0133] On the other hand, the replenishing liquid circulation path 105c has a first replenishing liquid path 31 that connects the replenishing liquid cartridge 105a and the nozzle 12 as a path related to the supply of the replenishing liquid to the nozzle 12.

[0134] In addition, the replenishing liquid circulation path 105c has a second replenishing liquid path 32 that connects a middle portion in the first replenishing liquid path 31 and the first branch portion 51 as a path related to the viscosity adjustment of ink by the replenishing liquid stored in the replenishing liquid cartridge 105a. The second replenishing liquid path 32 is a part that constitutes a replenishing liquid flow path for sending the replenishing liquid received by the replenishing liquid receiving portion 105d.

[0135] Further, the replenishing liquid flow path 105c has a third replenishing liquid path 33 that connects the first branch portion 51 and the conditioning tank 105b. Note that the fifth ink path 25, exemplified as the ink flow path 104c, is related to the recovery of the replenishing liquid by the gutter 16. As described above, the classifications of "ink flow path 104c" and "replenishing liquid flow path 105c" are merely for convenience.

[0136] An optical air detection mechanism 44, a replenishing liquid pump P2, a sixteenth valve V16, and a twelfth valve V12 are sequentially provided in the first replenishing liquid path 31. A cleaning nozzle 19 as a replenishing liquid injection portion is connected to the first replenishing liquid path 31. The cleaning nozzle 19 is a nozzle for cleaning the vibrator 11, the outside of the nozzle 12 (around the discharge port 12a), the charging electrode 13, the deflection electrode 15, etc. in the discharge head 1 by injecting the replenishing liquid, and can eject the replenishing liquid as a cleaning liquid. A fifteenth valve V15 is provided in the middle of the path from the cleaning nozzle 19 to the first replenishing liquid path 31.

[0137] Here, the first branch portion 51 has a fifth valve V5 that opens and closes between the third ink path 23 and the second ink path 22, an eighth valve V8 that opens and closes between the first ink path 21 and the second ink path 22, a ninth valve V9 that opens and closes between the third replenishing liquid path 33 and the second ink path 22, and a thirteenth valve V13 that opens and closes between the second replenishing liquid path 32 and the second ink path.

[0138] Further, the second branch portion 52 has a first valve V1 that opens and closes between the sixth ink path 26 and the eighth ink path 28, a third valve V3 that opens and closes between the sixth ink path 26 and the conditioning tank 105b, and a fourth valve V4 that opens and closes between the sixth ink path 26 and the waste liquid tank (illustrated as "waste liquid" in FIG. 4).

[0139] The control unit 101 can configure a desired flow path within the controller 100 by outputting control signals to the valves provided in each path, such as the 11th valve V11, or by outputting control signals to the valves forming the first branch unit 51 and the second branch unit 52.

[0140] For example, by opening the 8th valve V8 and the 1st valve V1, it becomes possible to replenish ink from the ink cartridge 104a to the main tank 104b. The replenishment of ink to the main tank 104b may be performed, for example, by providing a level sensor for detecting the ink level in the main tank 104b and based on the output signal from this detection sensor. The level sensor is configured to be able to detect the ink level in multiple levels, such as five levels. When the ink level detected by the level sensor becomes equal to or lower than the first predetermined level, a replenishment process for replenishing ink to the main tank 104b is executed, and when it reaches a second predetermined level higher than the first predetermined level, the ink replenishment process is stopped.

[0141] The replenishment of ink to the main tank 104b may be performed, for example, during the startup process or after the startup process is completed and the printer is in a printable state. When replenishing ink during the startup process, the ink level may be detected in the first step of the process start, and the replenishment process may be executed as necessary.

[0142] Also, although it is not the original circulation operation, by opening the 5th valve V5 and the 11th valve V11, it becomes possible to circulate ink among the second ink path 22, the main tank 104b, and the third ink path 23, and measure the viscosity of the ink with the viscometer 53.

[0143] The same applies to the path related to the replenishing liquid. For example, by opening the 13th valve V13 and the 1st valve V1, the replenishing liquid stored in the replenishing liquid cartridge 105a can be supplied to the main tank 104b, so that the viscosity of the ink stored in the main tank 104b can be adjusted. Also, by opening the 9th valve V9 and the 1st valve V1, the ink-containing replenishing liquid stored in the conditioning tank 105b passes through the 3rd replenishing liquid path 33, the 1st branch portion 51, the 6th ink path 26, the 2nd branch portion 52, and the 8th ink path 28 and is supplied to the main tank 104a.

[0144] The controller 100 also has a path related to the air flow. For example, the main tank 104b is connected to a 1st exhaust pipe 41 leading to an exhaust port (not shown). Similarly, the conditioning tank 105b is connected to a 2nd exhaust pipe 42 leading to the exhaust port.

[0145] As another example of the path related to the air flow, the controller 100 has a suction path 27 connecting the nozzle 12 and the 1st branch portion 51. A 6th valve V6 is provided in the suction path 27. By opening the 6th valve V6 and the aforementioned 5th valve V5, the nozzle 12 can be communicated with the atmosphere via the suction path 27, the 1st branch portion 51, the 6th ink path 26, the 2nd branch portion 52, the 8th ink path 28, the main tank 104b, and the 1st exhaust pipe 41. Thereby, the injection pressure of the ink particles ejected from the nozzle 12 can be adjusted.

[0146] Also, when printing is performed, by opening the 14th valve V14, ink is supplied from the main tank 104b via the 4th ink path 24. The 14th valve V14 is provided between the pressure-relief valve V2 and the reservoir portion 12b of the nozzle 12 and is a supply valve for controlling the supply of ink to the nozzle 12.

[0147] A branch path 24a leading to the main tank 104b is provided in the fourth ink path 24 of the ink supply unit 104. A pressure release valve V2 controlled by the control unit 101 is provided in the branch path 24a. When the pressure release valve V2 is closed by the control unit 101, the ink pressure in the fourth ink path 24 is maintained, while when it is opened by the control unit 101, the ink pressure in the fourth ink path 24 is reduced. The ink pressure in the fourth ink path 24 can be adjusted according to the time the pressure release valve V2 is open.

[0148] Also, by opening the fourteenth valve V14, the ink supplied through the fourth ink path 24 becomes particulate ink droplets by the vibration force of the oscillator 11 and is ejected from the nozzle 12. Among the ink (ink droplets) ejected from the nozzle 12, the ink not involved in printing and the replenishing liquid used for cleaning the nozzle 12 and the like are collected by the gutter 16 and refluxed to the controller 100 through the fifth ink path 25. In that case, the ink to be refluxed to the main tank 104b flows from the first branch portion 51 to the main tank 104b through the sixth ink path 26, the first valve V1 in the second branch portion 52, and the eighth ink path 28. On the other hand, the replenishing liquid sent to the conditioning tank 105b is sent from the fifth ink path 25 through the third valve V3 in the second branch portion 52.

[0149] The collection of the ink or the replenishing liquid by the gutter 16 is, for example, carried out in association with the startup process and the shutdown process of the inkjet recording apparatus I. Here, the "startup process" refers to the process executed before starting printing when the power is turned on to the inkjet recording apparatus I. On the other hand, the "shutdown process" refers to the process executed before stopping the operation of the apparatus when the power of the inkjet recording apparatus I is turned off.

[0150] Specifically, even when the power switch of the inkjet recording apparatus I is turned on, printing is not immediately started. The inkjet recording apparatus I executes a predetermined startup process before starting printing. In this startup process, after cleaning the ejection head 1 using the replenishing liquid, ink ejection is started. The ink ejected immediately after the start of the startup process forms the aforementioned ink shaft and is recovered by the gutter 16.

[0151] Similarly, when the power switch of the inkjet recording apparatus I is about to be turned off, its operation is not immediately stopped. The inkjet recording apparatus I executes a predetermined shutdown process including nozzle cleaning before stopping the operation. In this shutdown process, the replenishing liquid can be ejected from the nozzles 12 to clean and recover the ink remaining therein. The ink discharged from the nozzles 12 along with the ejection of the replenishing liquid is recovered by the gutter 16 in the same manner as the ink shaft in the startup process.

[0152] Note that the "power switch" in this embodiment includes switches constituted by touch-type operation panels displayed on the operation display unit 103 etc. in addition to physical push buttons. And the OFF operation of the power switch refers to a shutdown operation commanded through the operation terminal 800, the operation display unit 103 etc. in addition to the operation of physically pressing a push button etc. The same applies to the ON operation of the power switch.

[0153] Hereinafter, the startup process and the shutdown process of the inkjet recording apparatus I will be described in detail.

[0154] <Basic Operation of Inkjet Recording Apparatus I> FIG. 9 is a flowchart illustrating the basic operation of the inkjet recording apparatus I. This flowchart illustrates the basic operation of the inkjet recording apparatus I including the startup process.

[0155] First, in step SA1 of FIG. 9, the power switch of the inkjet recording apparatus I is turned from OFF to ON, and the inkjet recording apparatus I is powered on.

[0156] In step SA2 following step SA1, the control unit 101 executes a startup process. As will be described later, a cleaning operation can be performed in the startup process.

[0157] FIG. 10 is a flowchart illustrating the startup process of the inkjet recording apparatus I. This flowchart illustrates the details of step SA2 in FIG. 9. That is, four steps SB1, SB2, SB3, and SB4 in FIG. 10 constitute step SA2 in FIG. 9.

[0158] Also, FIG. 11 is a diagram for explaining step A in the startup process, FIG. 12 is a diagram for explaining step B in the startup process, and FIG. 13 is a diagram for explaining step C in the startup process.

[0159] In step SB1 of the flowchart shown in FIG. 10, the control unit 101 executes step A and boosts the pressure in the paths of the ink and the replenishing liquid in the inkjet recording apparatus I. In this step A, in order to prepare the replenishing liquid, the control unit 101 keeps the 16th valve V16 open and the 12th valve V12 closed and waits. In that state, when the replenishing liquid pump P2 operates, the replenishing liquid stored in the replenishing liquid cartridge 105a is supplied through the first replenishing liquid path 31 to the vicinity of the 12th valve V12 (see the thick line in FIG. 11).

[0160] Also, in order to prepare the ink, the control unit 101 keeps the 14th valve V14 closed and waits. In that state, when the ink pump P1 that sends ink to the fourth ink path 24 operates, the pressure of the ink in the fourth ink path 24 increases (see the thick line in FIG. 11).

[0161] Also, to prepare the gutter 16, the control unit 101 waits with the 10th valve V10 and the 1st valve V1 open. In this state, when the gutter pump P3 operates, the ink or the replenishing liquid collected by the gutter 16 can be sent back to the main tank 104b via the 5th ink path 25 and the 2nd branch portion 52 (see the thick line in FIG. 11).

[0162] In step A, a detection signal from the pressure gauge is input to the control unit 101. Based on such a detection signal, the control unit 101 waits until the pressure in the 4th ink path 24 becomes equal to or higher than the specified value.

[0163] In step SB2 following step SB1, the control unit 101 executes step B and discharges the replenishing liquid from the nozzles 12. In this step B, by opening the 12th valve V12 by the control unit 101, the replenishing liquid is sucked out and discharged from the nozzles 12. The replenishing liquid thus discharged is collected by the gutter 16. Since this step B is executed for a short period of less than 1 second, a small amount of replenishing liquid is discharged compared to other steps. Therefore, the replenishing liquid discharged in step B is sent back from the 5th ink path 25 to the main tank 104b via the 1st valve V1 (see the thick line in FIG. 12).

[0164] Note that when a large amount of replenishing liquid is ejected in step B, instead of the 1st valve V1, the 3rd valve V3 is opened and the replenishing liquid is sent back from the 5th ink path 25 to the conditioning tank 105b.

[0165] In step SB3 following step SB2, the control unit 101 executes step C and discharges ink from the nozzles 12. In this step C, in order to discharge the ink, the control unit 101 closes the 12th valve V12 and opens the 14th valve V14. Thereby, axial ink (ink axis) is discharged from the nozzles 12. The discharged ink is collected by the gutter 16 and sent back from the 5th ink path 25 to the main tank 104b via the 1st valve V1 (see the thick line in FIG. 13).

[0166] In step SB4 that follows step SB3, the control unit 101 starts to apply vibration to the ink ejected from the nozzle 12 and to apply power to the charging electrode 13 and the deflection electrode 15. As a result, it becomes possible to atomize, charge, and deflect the ink.

[0167] When the process shown in step SB4 ends, the control process returns from the control process shown in FIG. 10 to the control process shown in FIG. 9. Then, the control unit 101 executes step SA3 that follows step SA2. In step SA3, the control unit 101 prints on the workpiece W by landing particulate ink (ink particles) on the workpiece W.

[0168] Further, since the inkjet recording apparatus I according to the present embodiment is a continuous inkjet printer, in the printable state (operating state of the inkjet recording apparatus I) after the startup process, ink continues to be ejected from the nozzle 12 even when printing is not being executed. The ink ejected at this time is not deflected by the deflection electrode 15 (in other words, is “non-deflected”). The non-deflected ink is recovered by the gutter 16 without participating in printing, circulates inside the apparatus, and is reused.

[0169] When printing is completed and the inkjet recording apparatus I is normally shut down, in step SA3, the power switch of the inkjet recording apparatus I is switched from ON to OFF. In this case, the process proceeds to step SA4, and the control unit 101 executes a shutdown process. A cleaning operation can also be executed in this shutdown process.

[0170] FIG. 14 is a flowchart exemplifying the shutdown process of the inkjet recording apparatus I. This flowchart exemplifies the details of step SA4 in FIG. 9. That is, five steps SC1 to SC5 in FIG. 14 constitute step SA4 in FIG. 9.

[0171] Further, FIG. 15 is a diagram for explaining step D in the downward process, FIG. 16 is a diagram for explaining step E in the downward process, and FIG. 17 is a diagram for explaining step F in the downward process.

[0172] In step SC1 of the flowchart shown in FIG. 14, the control unit 101 stops the vibration applied to the ink ejected from the nozzle 12 and the voltage application to the charging electrode 13 and the deflection electrode 15 (atomization, charging, and deflection of the ink: ON → OFF). As a result, the atomization, charging, and deflection of the ink are stopped, and an axial ink shaft is ejected from the nozzle 12.

[0173] In step SC2 following step SC1, the control unit 101 stops the ejection of the ink shaft (stops the ejection of the ink). Specifically, in this step SC2, in order to stop the ejection of the ink, the control unit 101 closes the 14th valve V14. As a result, ink is no longer ejected from the nozzle 12.

[0174] In step SC3 following step SC2, the control unit 101 alternately executes step D illustrated in FIG. 15 and step E illustrated in FIG. 16 in order to intermittently eject the replenishing liquid. By intermittently ejecting the replenishing liquid, the inkjet recording apparatus I, particularly the nozzle 12, can be cleaned. Hereinafter, this operation is referred to as an "intermittent ejection operation".

[0175] Among these, in step D shown in FIG. 15, the control unit 101 opens the 16th valve V16, the 12th valve V12, the 10th valve V10, and the 1st valve V1. In that state, by operating the replenishing liquid pump P2 and the gutter pump P3, the replenishing liquid stored in the replenishing liquid cartridge 105a is ejected from the nozzle 12 through the first replenishing liquid path 31 and recovered by the gutter 16. The replenishing liquid recovered by the gutter 16 is sent back to the main tank 104b through the fifth ink path 25 and the second branch portion 52 (refer to the thick line in FIG. 15).

[0176] Immediately after starting the process shown in FIG. 14, since it is considered that a large amount of ink remains in the fifth ink path 25, the replenishing liquid in step D shown in FIG. 15 is sent back to the main tank 104b instead of the conditioning tank 105b.

[0177] Also, in step E shown in FIG. 16, the control unit 101 closes the twelfth valve V12 and opens the sixth valve V6. Then, due to the negative pressure exerted by the circulation pump P4, the replenishing liquid remaining in the nozzle 12 is sucked into the main tank 104b through the suction path 27, the first branch portion 51, the sixth ink path 26, the first valve V1, and the eighth ink path 28 (see the thick line in FIG. 16).

[0178] Note that in step E shown in FIG. 16, the twelfth valve V12 may be left open without being closed. In that case, while the replenishing liquid is being supplied from the replenishing liquid cartridge 105a to the nozzle 12, the replenishing liquid thus supplied is directly sucked from the suction path 27. By doing so, the flow rate of the replenishing liquid flowing through the sixth valve V6 can be improved, and more thorough cleaning can be achieved.

[0179] The process D shown in FIG. 15 and the process E shown in FIG. 16 are repeated a plurality of times (for example, several sets). Here, the time for performing process D in step SC3 (for example, less than 1 second) is shorter than the time for performing process E (for example, about several seconds).

[0180] Also, after closing the twelfth valve V12 in step E and then opening the twelfth valve V12 in step D, the replenishing liquid is intermittently ejected. When shifting from process D to process E, the twelfth valve V12 may be closed for about several seconds. By doing so, the pressure of the replenishing liquid near the twelfth valve V12 can be increased, and when the twelfth valve V12 is opened, the replenishing liquid can be ejected vigorously.

[0181] In step SC4 that follows step SC3, the control unit 101 executes only process D shown in FIG. 15 and discharges the replenishing liquid from the nozzle 12. The time for performing process D in this step SC4 is, for example, about 30 seconds, which is longer than the time for performing process D in step SC3. By executing this step SC4, mainly, the fifth ink path 25 leading to the gutter 16 can be cleaned.

[0182] In step SC5 that follows step SC4, the control unit 101 executes process F shown in FIG. 17 and recovers the replenishing liquid from the discharge head 1. Specifically, in this process F, the control unit 101 opens the tenth valve V10 and the third valve V3. With the gutter pump P3 operating in that state, the replenishing liquid remaining in the nozzle 12 is sucked into the conditioning tank 105b via the fifth ink path 25 and the second branch portion 52 (see the thick line in FIG. 17). By executing this step SC5, the replenishing liquid used for cleaning can be recovered.

[0183] Before step SC5 is executed, since the replenishing liquid was discharged in step SC4, it is considered that relatively a large amount of replenishing liquid remains in the fifth ink path 25. Therefore, the replenishing liquid in process F is sent back to the conditioning tank 105b instead of the main tank 104b.

[0184] When the process shown in step SC5 ends, it returns, and returns from the control process shown in FIG. 14 to the control process shown in FIG. 9. Then, in step SA5 that follows step SA4, the power supply to the inkjet recording apparatus I is cut off, and the inkjet recording apparatus I stops its operation.

[0185] (Viscosity adjustment process) Since the solvent of the ink in the main tank 104b volatilizes over time, the ratio of the solid content increases, and the viscosity of the ink in the main tank 104b increases. In the present embodiment, a viscosity adjustment process for adjusting the viscosity of the ink in the main tank 104b is configured to be executable. The viscosity adjustment process is continuously executed after the start-up process of step SA2 in the flowchart shown in FIG. 9 is completed until the down process of step SA4 is completed.

[0186] An example of the viscosity adjustment process will be described based on the flowchart shown in FIG. 18. This flowchart may be started after the ink replenishment process to the main tank 104b described above is executed as necessary, or may be started at the timing when a predetermined time has elapsed since the start of operation.

[0187] In step SD1 after starting, the viscosity measurement of the ink in the main tank 104b is started using the viscometer 53 shown in FIG. 8. In step SD2, the control unit 101 opens the fifth valve V5 and the eleventh valve V11 shown in FIG. 4, and circulates the ink among the second ink path 22, the main tank 104b, and the third ink path 23. By this circulation operation, the ink in the main tank 104b is supplied to the H level of the upper container 53a as shown in FIG. 8. The liquid level height of the ink in the upper container 53a can be detected by a sensor or the like (not shown), and when the liquid level of the ink in the upper container 53a reaches the H level by the control unit 101 controlling each valve V5, V11, the supply of the ink to the upper container 53a is stopped (step SD3).

[0188] Next, in step SD4, the time from immediately after the supply of the ink is stopped until the liquid level of the ink in the upper container 53a drops below the L level is measured. Since the relationship between the time until the liquid level of the ink drops below the L level and the viscosity of the ink can be obtained in advance by tests or the like, the viscosity of the ink can be calculated based on the measurement result of the time by using the viscometer 53 (step SD5). The viscosity of the ink calculated by the viscometer 53 is output to the control unit 101. Note that the viscometer 53 is an example, and other sensors or the like may be used to measure the viscosity of the ink.

[0189] In step SD6, the difference between the measured viscosity calculated in step SD5 and the target viscosity is obtained, and it is determined whether or not the difference is greater than or equal to a predetermined value. The target viscosity is a viscosity at which high-quality printing can be performed normally, and this can also be obtained in advance by tests or the like and can be stored in advance in the storage unit 102 or the like. The predetermined value in step SD6 can be set to, for example, 0.1 cP, 0.2 cP, or the like, but is not limited thereto.

[0190] If it is determined as NO in step SD6 and the difference between the measured viscosity and the target viscosity is less than the predetermined value, it means that the ink in the main tank 104b has a viscosity at which high-quality printing can be performed normally. In this case, the process returns to step SD1, and the above steps SD2 to SD6 are executed. On the other hand, if it is determined as YES in step SD6 and the difference between the measured viscosity and the target viscosity is greater than or equal to the predetermined value, it means that the viscosity of the ink in the main tank 104b is too high. In this case, the process proceeds to step SD7.

[0191] In step SD7, the control unit 101 opens the 13th valve V13 and the 1st valve V1. Thereby, the replenishing liquid stored in the replenishing liquid cartridge 105a is supplied to the main tank 104b. The amount of the replenishing liquid supplied to the main tank 104b in one execution of step SD7 may be set so that the viscosity does not fall below the target viscosity. Based on the measured viscosity calculated in step SD5, the supply amount of the replenishing liquid in step SD7 may be set, and the higher the measured viscosity, the larger the supply amount of the replenishing liquid can be increased.

[0192] Thereafter, the process proceeds to step SD8. In step SD8, it waits for a predetermined time until the viscosity of the ink in the main tank 104b stabilizes. That is, immediately after supplying the replenishing liquid, the viscosity may vary depending on the location within the main tank 104b. Therefore, by waiting for the time until the ink in the main tank 104b reaches a uniform viscosity, the subsequent processes of steps SD1 to SD6 can be performed accurately. In this way, after the startup process, the viscosity of the ink in the main tank 104b can be adjusted to be within a predetermined range, so that while maintaining good solubility of the ink colorant and the binder and obtaining high printing quality, the occurrence of defects can be prevented in advance.

[0193] Therefore, the control unit 101 of the present embodiment is a part that executes a viscosity adjustment process of controlling the flow rates of the ink supplied into the main tank 104b via the ink receiving portion 104d and the replenishing liquid supplied into the main tank 104b via the replenishing liquid receiving portion 105d so that the viscosity of the ink in the main tank 104b is within a predetermined range based on the viscosity of the ink in the main tank 104b measured by the viscometer 53. During the viscosity adjustment process, when the execution of the shutdown process is started, the control unit 101 interrupts this flow and executes the shutdown process.

[0194] In the present embodiment, as described above, the solvent of the ink is a mixed solvent containing ketone and alcohol, and since the volatility of alcohol is higher than that of ketone, if ketone and alcohol in the same ratio as the solvent of the ink are used as the replenishing liquid, the ketone concentration in the ink in the main tank 104b after repeating the viscosity adjustment process will increase compared to the initial concentration.

[0195] For example, as shown in FIG. 19, when the ketone concentration in the solvent of the ink is 50 mass percent and the ketone concentration of the replenishing liquid is 50 mass percent, if the above viscosity adjustment process is continuously carried out for a long time, when the temperature around the main tank 104b is 40°C, the ketone concentration in the solvent of the ink in the main tank 104b rises to 65 mass percent, when it is 35°C, it rises to 55 - 57 mass percent, when it is 25°C, it rises to 59 - 62 mass percent, and when it is 0°C, it rises to 54%. Thereafter, the ketone concentration reaches an equilibrium state. The equilibrium state means a state where the ketone concentration in the solvent of the ink in the main tank 104b does not change even if the viscosity adjustment process is continuously carried out further.

[0196] If an ink containing ketone at a concentration higher than the initial concentration is used in the inkjet recording apparatus I, which is assumed to operate normally at the initial concentration, as shown in FIG. 19, there is a concern that unintended problems may occur. Examples of the problems in the inkjet recording apparatus I include, for example, swelling of the rubber used as a sealing material or the like in the inkjet recording apparatus I, and nozzle clogging due to precipitation of the ink.

[0197] Regarding the fact that the ketone concentration of the ink in the main tank 104b gradually increases by repeating the viscosity adjustment process, in this embodiment, instead of using ketone and alcohol in the same ratio as the solvent of the ink in the ink cartridge 104a as the replenishing liquid, the mass percent concentration of ketone in the replenishing liquid is set lower than the mass percent concentration of ketone in the solvent of the ink in the ink cartridge 104a.

[0198] As shown in FIG. 20, for example, the present inventors set the mass percentage concentration of ketone in the solvent of the ink in the ink cartridge 104a to 74% by mass, and the mass percentage concentrations of ketone in the refill liquid to 70% by mass, 66% by mass, and 62% by mass. It was found that in a wide temperature range of 0 to 40° C. for the ambient temperature, the mass percentage concentration of ketone in the solvent of the ink converges within the range of +10 to 12 points of the mass percentage concentration of ketone in the refill liquid. The "concentration difference" in FIG. 20 is obtained by subtracting the ketone concentration of the refill liquid from the saturated ketone concentration of the ink.

[0199] From the results shown in FIG. 20, it is possible to determine the ketone concentration of the refill liquid that can stabilize the concentration of ketone in the solvent of the ink in the ink cartridge 104a within a certain range. In addition, it becomes easier to design a high-performance ink solution, for example, to design the solubility of the ink after drying and to determine the degree of swelling of the rubber sealing material used in the inkjet recording apparatus I.

[0200] In short, by setting the mass percentage concentration of the ketone concentration in the refill liquid to be 8 to 12 points lower than the mass percentage concentration of ketone in the solvent of the ink in the ink cartridge 104a, the concentration of ketone in the solvent of the ink in the ink cartridge 104a can be maintained at the initial concentration and in its vicinity s. In other words, when the inkjet recording apparatus I is operating in a predetermined ambient temperature range (0 to 40° C.), even if the adjustment of the viscosity of the ink in the main tank 104b is repeated a plurality of times, the ketone concentration in the solvent in the main tank 104b is maintained within ±1 point with respect to the initial concentration. The ketone concentration of the refill liquid is lower in mass percentage concentration than the ketone concentration in the solvent of the ink in the ink cartridge 104a.

[0201] In addition, in the present embodiment, the concentration of ketone in the replenishing liquid is set to be 5 to 15 percentage points lower in mass percentage concentration than the ketone concentration in the solvent of the ink stored in the ink cartridge 104a, and the ketone concentration in the solvent of the ink in the ink cartridge 104a can be maintained at the initial concentration and its vicinity. Therefore, even for a high-functional ink with a high ratio of solid content of the ink, the risk of the solid content not being completely dissolved and precipitating is reduced. That is, for example, in the case of a mixed solvent of alcohol such as ethanol, which is relatively easily available compared to ketone, even if the ratio of alcohol such as ethanol, which is relatively easily available, in the replenishing liquid is increased, the risk of the solid content of the high-functional ink not being completely dissolved and precipitating in the main tank 104b of the inkjet recording apparatus I is reduced. As the high-functional ink, for example, an ink using a mixed solvent of diethyl ketone, which is an organic solvent not subject to regulations and has a relatively high allowable concentration, and denatured ethanol, which is easily available, or an alcohol-resistant strong adhesive ink with low alcohol solubility and a thick coating thickness can be applied.

[0202] Also, from another perspective, the concentration of ketone in the replenishing liquid is set to be 5 to 15 percentage points lower in mass percentage concentration than the ketone concentration in the solvent of the ink stored in the ink cartridge 104a, and the ketone concentration in the solvent of the ink in the ink cartridge 104a can be maintained at the initial concentration and its vicinity. Therefore, it is possible to avoid shortening the life of the rubber sealing material and enable stable use of high-functional inks such as alcohol-resistant inks. That is, when it is less than 5 percentage points, the ketone concentration in the solvent of the initial ink increases, so ink designs and rubber sealing material designs compatible with a wide range of ketone concentrations are required, but in many cases, such design requirements cannot be met, resulting in a decrease in the life of the sealing material and the stability of the ink. On the other hand, when it is greater than 15 percentage points, there is a case where the ketone concentration significantly decreases, so there is a risk that the solid content of high-functional inks such as alcohol-resistant inks will not be completely dissolved and will precipitate. When a stable ink is required, it becomes inevitable to prioritize solubility and reduce functions such as the alcohol resistance of the ink.

[0203] (Administrative Department) As shown in FIG. 2, the control unit 101 is provided with a management unit 101a that regulates at least one of ink reception via the ink reception unit 104d and replenisher reception via the replenisher reception unit 105d.

[0204] That is, as described above, in order to keep the ketone concentration of the solvent in the main tank 104b at the initial concentration and in its vicinity, the ketone concentration in the solvent of the ink in the ink cartridge 104a and the ketone concentration in the replenisher in the replenisher cartridge 105a are important. If these ketone concentrations are different from the assumptions, the ketone concentration of the solvent in the main tank 104b will deviate from the initial concentration. The management unit 101a is provided to prevent this.

[0205] When supplying the ink in the ink cartridge 104a, the management unit 101a executes the process shown in the flowchart of FIG. 21. In step SE1 at the start, it is determined whether the ink mounting detection switch 104f is ON. If it is determined to be NO and the ink mounting detection switch 104f is OFF, it means that the ink cartridge 104a is not received by the ink reception unit 104d, and it waits until it becomes ON. If it is determined to be YES and the ink mounting detection switch 104f is ON, it means that the ink cartridge 104a has been received by the ink reception unit 104d, and the process proceeds to step SE2. In step SE2, the ink information access unit 104g accesses the ink information storage unit 104e to read information about the ink.

[0206] Thereafter, proceed to step SE3, and estimate the ketone concentration in the solvent of the ink in the ink cartridge 104a based on the information regarding the ink read in step SE2. For example, due to variations in the mixing of the solvent or volatilization after manufacturing, the ketone concentration in the solvent of the supplied ink may change, and this is corrected in step SE3. Specifically, as shown in FIG. 7A, since the information regarding the ink includes the manufacturing date, compare the manufacturing date with the current date. The older the manufacturing date, the lower the concentration of alcohol, which is more volatile than ketone, decreases and the ketone concentration increases. Therefore, in step SE3, correct it so that the ketone concentration increases as the manufacturing date gets older. The correction amount can be obtained in advance through experiments or the like.

[0207] In addition, the information regarding the ink includes the ketone concentration in the solvent of the ink when the ink cartridge 104a was filled. Based on this ketone concentration and the manufacturing date, the ketone concentration in the solvent of the ink in the current ink cartridge 104a can be corrected and estimated in step SE3.

[0208] In step SE4, determine whether the ketone concentration in the solvent of the ink in the ink cartridge 104a estimated in step SE3 is within a predetermined range or outside the predetermined range. The predetermined range can be, for example, a concentration of 74 to 78 mass percent. If it is outside this range, proceed to step SE6 to perform error processing and regulate so as not to supply the ink, that is, not to accept the ink. On the other hand, if it is determined that the ketone concentration in the solvent of the ink in the ink cartridge 104a estimated in step SE3 is within the predetermined range, proceed to step SE5 and do not regulate the acceptance of the ink. In this case, if necessary, the ink in the ink cartridge 104a can be sucked and supplied to the main tank 104b.

[0209] Also, when supplying the replenishing liquid in the replenishing liquid cartridge 105a, the management unit 101a executes the process shown in the flowchart of FIG. 22. In step SF1 at the start, it is determined whether the replenishing liquid mounting detection switch 105f is ON. If it is determined as NO and the replenishing liquid mounting detection switch 105f is OFF, it means that the replenishing liquid cartridge 105a has not been received by the replenishing liquid receiving portion 105d, and it waits until it becomes ON. If it is determined as YES and the replenishing liquid mounting detection switch 105f is ON, it means that the replenishing liquid cartridge 105a has been received by the replenishing liquid receiving portion 105d, and the process proceeds to step SF2. In step SF2, the replenishing liquid information access portion 105g accesses the replenishing liquid information storage portion 105e and reads the information regarding the replenishing liquid.

[0210] Thereafter, the process proceeds to step SF3, and based on the information regarding the replenishing liquid read in step SF2, the ketone concentration in the replenishing liquid in the replenishing liquid cartridge 105a is estimated. For example, due to variations in the mixing of the solvent, volatilization after production, etc., the ketone concentration in the supplied replenishing liquid may change, and it is corrected. As shown in FIG. 7B, since the information regarding the replenishing liquid includes the manufacturing date, the correction is made such that the ketone concentration increases as the manufacturing date gets older. The correction amount can be obtained in advance by experiments or the like.

[0211] Also, the information regarding the replenishing liquid includes the ketone concentration in the replenishing liquid when the replenishing liquid cartridge 105a was filled. Based on this ketone concentration and the manufacturing date, the ketone concentration in the replenishing liquid in the current replenishing liquid cartridge 105a can be corrected and estimated.

[0212] In step SF4, it is determined whether the ketone concentration in the replenishing liquid in the replenishing liquid cartridge 105a estimated in step SF3 is within a predetermined range or outside the predetermined range. The predetermined range can be, for example, a concentration of 10 to 12 mass percent. If it is outside this range, the process proceeds to step SF6 to perform error processing and regulate so as not to supply the replenishing liquid, that is, not to receive the replenishing liquid. On the other hand, when it is determined that the ketone concentration in the replenishing liquid in the replenishing liquid cartridge 105a estimated in step SF3 is within the predetermined range, the process proceeds to step SF5, and if necessary, the replenishing liquid in the replenishing liquid cartridge 105a is sucked and supplied to the main tank 104b.

[0213] (Swelling suppression of rubber sealing material) As the ketone concentration in the solvent of the ink increases, the swelling amount of the rubber sealing material used in the inkjet recording apparatus I increases, and there is a risk that the life will be shortened. Therefore, as described above, the ketone concentration in the solvent of the ink is maintained at the initial concentration and in the vicinity thereof. On the other hand, when the inventor considered the relationship between the ratio of the solid content (non-solvent component) of the ink and the swelling amount of the rubber sealing material, it was found that increasing the ratio of the solid content reduces the swelling amount of the rubber sealing material.

[0214] As shown in FIG. 23, when the ratio of ketone to alcohol in the solvent of the ink is 70:30 and the solid content is changed to 0%, 10%, and 20%, the weight change rate of the sealing material (corresponding to the swelling amount of the sealing material) decreases. Here, diethyl ketone is selected as the ketone, and EPDM is selected as the sealing material. Based on the results shown in FIG. 23, as shown in FIG. 24, even when the ketone concentration in the solvent of the ink becomes high, by increasing the solid content, the ketone concentration in the entire ink can be suppressed, the swelling amount of the sealing material can be suppressed, and it can be made substantially equal to the swelling amount on the replenishing liquid side. Therefore, shortening of the life of the sealing material can be suppressed.

[0215] (Modification of startup process) During the lifting process, printing, etc., a small amount of ink may adhere to the nozzle 12 and the deflection electrode 15, and as a result, printing irregularities may occur. Also, if the power is turned off and the device is left idle for a long time, the ink that has become highly viscous due to volatilization may accumulate in the flow path, which may cause poor ink suction. To prevent this, as described above, the nozzle 12 and the deflection electrode 15 are cleaned with the replenishing liquid. However, if the replenishing liquid used for cleaning flows into the main tank 104b, even though the fluctuation ratio of the ketone concentration at the equilibrium point during the viscosity adjustment process is within ±1%, the ketone concentration in the solvent of the ink in the main tank 104b may fluctuate by about 5 to 10% due to the inflowing replenishing liquid.

[0216] In response to this, in this embodiment, for example, after the cleaning process is performed, the cleaning liquid is recovered into the conditioning tank 105b to control so that an excessive amount of replenishing liquid does not flow into the main tank 104b. The same control can be performed when the ink shaft is adjusted.

[0217] Hereinafter, the control content will be described based on the flowchart of FIG. 25. In step SG1 after starting, it is determined whether residual liquid recovery is necessary. If, for example, a cleaning process has been performed before entering the process of this flowchart, it is determined that residual liquid recovery is necessary. Also, if, for example, the ink shaft has been adjusted before entering the process of this flowchart, it is determined that residual liquid recovery is necessary. If it is determined as YES and residual liquid recovery is necessary, the process proceeds to step SG2, and the residual liquid is recovered from the fifth path 25 to the conditioning tank 105b via the third valve V3 at the second branch portion 52. Then, the process proceeds to step SG3, and the above-described normal startup process is executed. Even if it is determined as NO in step SG1, the process proceeds to step SG3, and the above-described normal startup process is executed.

[0218] (Prevention of Print Quality Degradation and Nozzle Clogging due to Ink Deposits) When an alcohol-resistant ink contains ethanol like the ink of the present embodiment, the margin of solubility decreases, so that extremely small amounts of precipitates may be generated due to subtle disturbances such as a decrease in ambient temperature or long-term storage. Even if the amount of the precipitate is extremely small, if the precipitate reaches the nozzle 12, the timing of ink breakage changes locally greatly, and there is a risk that the print quality will be significantly reduced. Also, if the degree of precipitation is large, it is conceivable that the nozzle 12 will be clogged.

[0219] Although extremely small amounts of precipitates can be filtered by the filter F shown in FIG. 4 and the like, the liquid on the secondary side of the filter F is discharged at the initial stage after the start-up process is completed. When left for a long time, since the liquid on the secondary side of the filter F has passed through filtration for a long time, the above-described phenomenon can occur.

[0220] As a process for preventing print quality degradation and nozzle clogging due to this ink precipitate, the control unit 101 executes a start-up process according to another modification shown in the flowchart of FIG. 26. In step SH1 after starting, the ink is circulated and filtered by the filter F without discharging the ink from the nozzle 12. The flow rate of the ink during circulation is set to be larger than that during printing, whereby the precipitate can be filtered at high speed. Then, in step SH2, the nozzle 12, the deflection electrode 15, etc. are washed with the replenishing liquid. Then, it proceeds to step SH3, and the above-described normal start-up process is executed.

[0221] Step SH1 may be started, for example, when the ambient temperature becomes equal to or lower than a predetermined temperature, or may be started when the elapsed time from turning off the power is equal to or longer than a predetermined time.

[0222] (Operational effects of the embodiment) As described above, according to this embodiment, since printing is performed on the workpiece W using ink containing 15 mass percent or more of a solid content, for example, the film thickness of the ink after drying increases, and the adhesiveness is likely to improve. In this case, since the film thickness is increased to reinforce the adhesiveness, even those that do not satisfy the desired adhesiveness when the film thickness is thin can be adopted as the solid content of the ink. When a material that forms a film that is difficult to dissolve in alcohol is adopted as the solid content, the alcohol resistance of the ink after drying increases, and for example, peeling of the ink when sterilizing alcohol or the like adheres is suppressed. Further, by containing 15 mass percent or more of a solid content in the ink, a highly functional ink with enhanced adhesiveness can be easily designed.

[0223] Further, by using an ink containing a mixed solvent of two or more components in which a ketone and a relatively inexpensive alcohol are miscible, the cost of the ink is reduced. When the viscosity of the ink in the main tank 104b increases over time due to the volatilization of the solvent, a replenishing liquid is sent to the main tank 104b and mixed with the ink to adjust the viscosity of the ink. At this time, since the mass percent concentration of the ketone in the replenishing liquid to be mixed is lower than the mass percent concentration of the ketone in the solvent of the ink, the ratio of the ketone in the solvent after viscosity adjustment approaches the initial ratio. Therefore, it becomes difficult for the ratio of the ketone in the solvent to change over time. As a result, it becomes difficult for unintended device malfunctions to occur.

[0224] The above-described embodiment is merely exemplary in every respect and should not be construed in a limiting sense. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

Industrial Applicability

[0225] As described above, the present invention can be used, for example, when printing on various printing objects and the like.

Explanation of Signs

[0226] 1 Discharge head 21 First ink path 22 Second ink path 25 Fifth ink path (recovery channel) 32 Second replenishing liquid path 53 Viscometer 101 Control unit 101a Management unit 104b Main tank (mixing container) 104c Ink circulation path 104d Ink receiving section 104e Ink information storage section (first storage medium) 104g Ink information access section (first access section) 105d Replenishing liquid receiving section 105e Replenishing liquid information storage section (second storage medium) 105g Replenishing liquid information access section (second access section) I Inkjet recording apparatus

Claims

1. An inkjet recording apparatus for printing on a printing target using ink, an ink receiving section for receiving ink containing a solvent in which a ketone and an alcohol having a higher volatility than the ketone are mixed, an ink colorant, and a binder; an ink flow path for transmitting the ink received in the ink receiving portion; a replenisher receiving section for receiving a replenisher liquid containing a ketone and an alcohol having a higher volatility than the ketone, separate from the ink receiving section; a replenishment liquid flow path for transmitting the replenishment liquid received in the replenishment liquid receiving portion; a mixing vessel for mixing the ink sent through the ink flow passage and the replenishment liquid sent through the replenishment liquid flow passage in order to adjust the viscosity of the ink to be ejected; an adjusted ink flow path for conveying the ink whose viscosity has been adjusted in the mixing container; an ejection head that ejects the ink sent through the adjustment ink flow path, the ink contains a solid content, including the ink colorant and the binder, of 15 mass percent or more; The ketone is one or any two or more selected from the group consisting of diethyl ketone, methyl isopropyl ketone, and methyl propyl ketone; An inkjet recording apparatus, wherein a mass percentage concentration of the ketone in the replenisher received in the replenisher receiving section is lower than a mass percentage concentration of the ketone in the solvent of the ink received in the ink receiving section.

2. 2. The inkjet recording apparatus according to claim 1, a viscometer for measuring the viscosity of the ink in the mixing vessel; an ink jet recording device further comprising a control unit that executes a viscosity adjustment process that controls the flow rate of ink supplied into the mixing container via the ink receiving unit and replenishment liquid supplied into the mixing container via the replenishment liquid receiving unit, based on the viscosity of the ink measured by the viscometer, so that the viscosity of the ink in the mixing container is within a predetermined range.

3. 3. The ink jet recording apparatus according to claim 2, The control unit is configured to be capable of executing a start-up process for causing the ink to be ejected from the ejection head to be in a printable state, and executes the viscosity adjustment process after the start-up process.

4. 4. The inkjet recording apparatus according to claim 1, The inkjet recording apparatus further comprises a recovery flow path for recovering a portion of the ink discharged from the discharge head and returning the ink to the mixing container.

5. 5. The inkjet recording apparatus according to claim 1, the ink receiving section receives an ink cartridge having a first storage medium attached thereto, the first storage medium storing information about the ink, and receives the ink contained in the ink cartridge; the replenishment liquid receiving section receives a replenishment liquid cartridge having a second storage medium attached thereto, the second storage medium storing information about the replenishment liquid, and receives the replenishment liquid contained in the replenishment liquid cartridge; The inkjet recording apparatus further comprises: a first access unit that accesses the first storage medium; a second access unit that accesses the second storage medium; a management unit that regulates at least one of the reception of the ink through the ink receiving unit and the reception of the replenishment liquid through the replenishment liquid receiving unit based on information about the ink obtained from the first storage medium through the first access unit and information about the replenishment liquid obtained from the second storage medium through the second access unit; An inkjet recording apparatus comprising:

6. 6. The ink jet recording apparatus according to claim 5, the information about the ink includes information about a concentration of ketones in the ink; the information about the replenishment solution includes information about a concentration of ketones in the replenishment solution; An inkjet recording device, wherein the management unit regulates at least one of the reception of the ink via the ink receiving unit and the reception of the replenishment liquid via the replenishment liquid receiving unit based on information on the concentration of ketone in the ink or information on the concentration of ketone in the replenishment liquid.

7. 7. The inkjet recording apparatus according to claim 1, The ink received by the ink receiving section contains the solvent in an amount of 70 to 85 mass percent or less, The inkjet recording apparatus, wherein the ketone concentration of the replenisher received in the replenisher receiving section is lower by 5 to 15 mass percentage points than the ketone concentration in the ink solvent received in the ink receiving section.

8. 7. The inkjet recording apparatus according to claim 1, the alcohol is ethanol; The ketone concentration of the replenisher received in the replenisher receiving section is 8 to 12 points lower in mass percentage concentration than the ketone concentration in the solvent of the ink received in the ink receiving section.

9. 7. The inkjet recording apparatus according to claim 1, the alcohol is ethanol; An inkjet recording device, wherein the ketone concentration of the replenisher received in the replenisher receiving section is lower in mass percentage concentration than the ketone concentration in the ink solvent received in the ink receiving section, so that the ketone concentration of the solvent component in the mixing container is maintained within ±1 point of the initial concentration even when adjustment of the viscosity of the ink in the mixing container is repeated multiple times during operation at a specified ambient temperature.

10. 10. The inkjet recording apparatus according to claim 8, The inkjet recording apparatus, wherein the ketone concentration in the solvent of the ink received in the ink receiving section is 70 to 80 mass percent.

11. 11. The inkjet recording apparatus according to claim 1, an inkjet recording apparatus, wherein the solid content of the ink has an alcohol solubility of 5% or less after being discharged from the discharge head, attached to the printing object, and dried.

12. A combination of ink and replenishment liquid used in an inkjet recording device that receives ink and replenishment liquid separately and ejects ink prepared by mixing the ink and replenishment liquid, the ink contains a solvent in which a ketone and an alcohol having a higher volatility than the ketone are mixed, an ink colorant, and a binder, and the ink contains a solid content including the ink colorant and the binder of 15 mass percent or more; The replenisher contains a ketone and an alcohol having a higher volatility than the ketone, The ketone is one or any two or more selected from the group consisting of diethyl ketone, methyl isopropyl ketone, and methyl propyl ketone; An ink and replenisher combination, wherein a weight percent concentration of a ketone in the replenisher is less than a weight percent concentration of a ketone in the solvent of the ink.

13. An ink for an inkjet recording device that receives ink and a replenisher separately and ejects ink prepared by mixing the ink and the replenisher, a solvent including a mixture of one or more ketones selected from the group consisting of diethyl ketone, methyl isopropyl ketone, and methyl propyl ketone and an alcohol having a higher volatility than the ketone; An ink colorant; and a binder dissolved in the solvent, The ink contains a solid content including the ink colorant and the binder of 15 mass percent or more, An ink for an inkjet recording device, which contains the ketone and an alcohol having a higher volatility than the ketone, and in which, for a replenisher liquid used together with the inkjet recording device, the mass percentage concentration of the ketone in the solvent is higher than the mass percentage concentration of the ketone in the replenisher liquid.

14. A replenisher for an inkjet recording device, which receives ink and a replenisher separately, and ejects ink prepared by mixing the ink and the replenisher, A solvent containing one or more replenisher ketones selected from the group consisting of diethyl ketone, methyl isopropyl ketone, and methyl propyl ketone, and an alcohol having a higher volatility than the replenisher ketone; A replenisher liquid for an inkjet recording device contains a solvent in which one or more ink-dissolving ketones selected from the group including diethyl ketone, methyl isopropyl ketone, and methyl propyl ketone are mixed with an alcohol having higher volatility than the ink-dissolving ketones, an ink colorant, and a binder, and contains a solid content including the ink colorant and the binder of 15 mass percent or more, and the mass percent concentration of the replenisher ketone is lower than the mass percent concentration of the ink-dissolving ketone in the solvent of an ink used together with the inkjet recording device.

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