JP5982891B2 - Liquid characteristic measuring method, liquid characteristic measuring apparatus, liquid ejection apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to a liquid characteristic measurement method for measuring the characteristics of liquid ejected from a head, a liquid characteristic measurement apparatus, a liquid ejection apparatus having this apparatus, and an image forming apparatus that acquires these characteristics using these apparatuses.

  2. Description of the Related Art Conventionally, a technique using a liquid ejecting apparatus that ejects liquid from a fine nozzle port, that is, a so-called ink jet head is known in the field of image forming apparatuses such as an ink jet printer (for example, [Patent Document 1] to [Patent Document 1] Reference 8]).

  In recent years, application development using inkjet heads has been active, and in addition to application to image forming apparatuses, application to processing apparatuses for producing fine wiring patterns and patterning for color filters of liquid crystal displays has become widespread. ing.

  In these various apparatuses, it is an important issue to discharge a finer liquid more accurately and stably. When a volatile solvent is used as the liquid to be discharged like water-based ink, there is a problem that the discharge speed and volume are disturbed due to the increase in the liquid viscosity of the nozzle portion due to the evaporation of the solvent. In addition, when using a liquid ejecting device in industrial applications such as forming wiring patterns and color filters, in addition to stably discharging droplets of a predetermined volume, the components contained in the discharged liquid are stabilized. It is also important to make it.

  Therefore, in various apparatuses, it is necessary not only to detect the ejection / non-ejection of liquid but also to detect the physical property value of ink to be ejected, particularly the ink viscosity and the solute content ratio of ink.

  Many methods have already been proposed for detecting abnormalities in the ink thickening state and the like in the head, and the ejection state associated therewith, and the configuration and problems of the representative ones will be briefly described below.

  Many methods have been proposed in which a viscometer that measures ink viscosity is installed in a tank that holds ink in the head and a cleaning operation is performed based on the result (see, for example, [Patent Document 1]). However, since this method uses a viscosity measuring device that is larger than the shape of the nozzle portion, it is impossible to know the local viscosity in the vicinity of the nozzle portion related to a decrease in actual discharge speed or non-discharge.

  Based on information such as the flushing operation and the discharge operation period, a method for predicting the liquid thickening state of the nozzle portion and performing the optimum flushing operation for each nozzle based on the result has been proposed (for example, [Patent Document 2]). reference). However, it is difficult to accurately know the temperature and humidity change in the vicinity of the nozzle portion, and it is considered that it is not easy to improve the viscosity prediction accuracy. In addition, although it is possible to predict a stable dry state over time, it is considered impossible to cope with a change in physical properties (for example, adhesion of foreign matter) due to a sudden event.

  A method has been proposed in which residual vibration inside the cavity is detected by an actuator provided in the cavity of the liquid ejecting apparatus, and the viscosity of the liquid is detected from the vibration frequency (see, for example, [Patent Document 3]). In this configuration, in the configuration using an actuator such as a piezo as the liquid ejecting means, the actuator used for ejection can also be used for viscosity detection, and the number of parts added to the conventional liquid ejecting apparatus is small and simple. It is considered possible to measure the viscosity with a simple configuration. However, since the signal from the actuator is very weak, processing such as summing signals from a plurality of nozzles or averaging signals in a plurality of discharge states is performed in order to perform measurement with high accuracy. It is considered necessary. For this reason, it is considered that there is a problem that it is not easy to inspect a large number of nozzle states at high speed.

  There has been proposed a liquid ejecting apparatus that determines whether or not flushing is performed based on a result of a liquid column measuring unit that measures the length of a liquid column formed when a liquid is ejected from a nozzle by an optical detection unit (for example, (See Patent Document 4). In this device, since the liquid column length depends on the ink viscosity, it is possible to determine whether the ink viscosity is in a normal state by measuring the liquid column length, and without performing a wasteful flushing operation. It is considered that an efficient nozzle state can be maintained. However, this liquid column measuring means is composed of a plurality of light emitting / receiving elements and can perform highly sensitive measurement, but its configuration is considered to be complicated and expensive.

  By applying an electric field between the ejection surface that ejects the liquid and the detection unit that receives the liquid, a voltage change is generated based on electrostatic induction generated according to the movement of the ejected liquid, and the ink viscosity is calculated from the voltage change. A technique has been proposed (see, for example, [Patent Document 5]). However, the voltage change caused by electrostatic induction is extremely small, and it is considered necessary to apply a high voltage of 100 V or more between the ejection surface and the detection unit in order to acquire a signal with high accuracy. It is considered that there is a problem that the apparatus becomes complicated and an unnecessary discharge phenomenon may occur.

  In an ink jet apparatus, a method has been proposed in which liquid discharge / non-discharge is detected based on the presence or absence of energization (see, for example, [Patent Document 6]). Since the energization current signal used in this method is a signal that is strong against the signal from the actuator and the change signal of the induced voltage caused by charged particles, it can be considered to be able to measure with high sensitivity. However, in this method, only the discharge / non-discharge of the liquid is detected, and a method for measuring a physical property value such as the viscosity of the liquid is not mentioned.

  Because of the above circumstances, this technology is not only used to detect whether or not liquid is discharged from the head, but also to acquire characteristic values such as the viscosity of the liquid with the highest possible sensitivity, low cost, and simple configuration. The proposal was awaited.

  The present invention relates to a liquid characteristic measuring method, a liquid characteristic measuring apparatus, a liquid discharging apparatus having this apparatus, and a liquid discharging apparatus that measure the characteristics of the liquid discharged from the head as much as possible with high sensitivity, low cost, and simple configuration. An object of the present invention is to provide an image forming apparatus that acquires such characteristics by using the image forming apparatus.

In order to achieve the above object, the present invention provides a maximum amount of current measured for a current flowing through the liquid that bridges between a head to which a voltage is applied and a receiver that receives the liquid discharged from the head, The amount of charge, the energization start time from when the drive signal for discharging the liquid is issued until the energization is started, the energization stop time from when the drive signal is issued until the energization is stopped, and the energization start In the liquid property measurement method, the viscosity or the conductivity is acquired as the characteristic value of the liquid based on the energization feature amount that is at least two of the energization duration from the time to the energization stop time.

According to the present invention, a maximum current amount, a charge amount, and the liquid measured for a current flowing through the liquid bridged between a head to which a voltage is applied and a receiver that receives the liquid discharged from the head, An energization start time from when a drive signal to be discharged is issued until energization is started, an energization stop time from when the drive signal is issued until energization is stopped, and from the energization start time to the energization stop time In the liquid property measuring method for obtaining the viscosity or the electrical conductivity as the characteristic value of the liquid based on the energization feature amount that is at least two of the energization continuation time of the liquid, the characteristic of the liquid ejected from the head Thus, it is possible to provide a liquid property measuring method capable of measuring a sensor with high sensitivity, low cost, and simple configuration as much as possible.

1 is a schematic front view according to an embodiment of an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic view schematically showing a state in which a recording liquid is applied from a head to an intermediate transfer member or a receiver in the image forming apparatus shown in FIG. 1. FIG. 2 is a schematic cross-sectional view of a part of a liquid characteristic measurement device provided in the image forming apparatus shown in FIG. 1 and a liquid discharge device having the same. FIG. 2 is a schematic block diagram of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a conceptual diagram illustrating a state in which colorants in recording liquid discharged from a head in the image forming apparatus illustrated in FIG. 1 are aggregated via protons. FIG. 2 is a conceptual diagram illustrating a state of a liquid column by a recording liquid formed between a cathode and an anode in the image forming apparatus illustrated in FIG. 1. It is the schematic which showed typically the state between the state shown to Fig.2 (a), and the state shown to FIG.2 (b) continuously. It is the schematic which showed typically the state between the state shown in FIG.2 (b), and the state shown in FIG.2 (c) continuously. It is the conceptual diagram which showed the example of the waveform of the drive signal for discharging a liquid from a head in order to measure an energization feature-value. It is the schematic which showed the time transition of the electric current value which flows into the liquid discharged from the head by the drive signal shown in FIG. It is the chart which showed the example of adjustment of the characteristic value of the liquid for measuring energization feature-value. It is the graph which showed the tendency of the characteristic value acquired based on the energization feature-value measured using the liquid shown in FIG. It is the graph which showed the tendency of the characteristic value acquired based on the other electricity supply feature-value measured using the liquid shown in FIG. It is the graph which showed the energization feature-value measured about the liquid prepared in order to acquire a characteristic value. It is a conceptual diagram for demonstrating that a characteristic value is acquired with a some drive signal. 2 is a flowchart illustrating an outline of an example of control in the case where a characteristic value is acquired in the image forming apparatus illustrated in FIG. 1 and head maintenance is performed according to the acquired characteristic value. It is a schematic front view concerning the other Example of the image forming apparatus to which this invention is applied. It is a schematic front view concerning the other Example of the image forming apparatus to which this invention is applied.

  FIG. 1 shows an outline of an image forming apparatus to which the present invention is applied. The image forming apparatus 100 is a printer as an inkjet printer, and can perform full-color image formation. The image forming apparatus 100 performs an image forming process based on an image signal corresponding to image information received from the outside.

  The image forming apparatus 100 can form an image on a sheet-like recording medium using not only plain paper generally used for copying, but also OHP sheets, cardboard, cardboard, cardboard, and envelopes. It is. The image forming apparatus 100 is a single-sided image forming apparatus capable of forming an image on one side of a transfer sheet S as a recording medium as a recording sheet as a recording medium. It may be a device.

  The image forming apparatus 100 discharges, in other words, ejects a recording liquid as ink of the color, which is a liquid capable of forming an image as an image corresponding to each color separated into yellow, magenta, cyan, and black. The recording heads 61Y, 61M, 61C, and 61BK are ink heads as liquid ejecting heads.

  The heads 61Y, 61M, 61C, and 61BK are disposed at positions facing the outer peripheral surface of the intermediate transfer body 37 as an intermediate transfer roller that is an intermediate transfer drum disposed at a substantially central portion of the main body 99 of the image forming apparatus 100. Has been. The heads 61Y, 61M, 61C, 61BK are arranged in this order from the upstream side in the A1 direction, which is the moving direction of the intermediate transfer body 37 and is the clockwise direction in FIG. In the drawing, Y, M, C, and BK added after the numerals of the reference numerals indicate members for yellow, magenta, cyan, and black.

  The heads 61Y, 61M, 61C, and 61BK are ink ejection devices 60Y, 60M, and 60M as image forming units for forming yellow (Y), magenta (M), cyan (C), and black (BK) images, respectively. It is provided in 60C and 60BK.

The intermediate transfer member 37 has a width corresponding to the width of the maximum transfer sheet S that can form an image in the image forming apparatus 100 in the main scanning direction, which is a direction perpendicular to the paper surface of FIG.
The intermediate transfer body 37 is rotated in the A1 direction and is recorded in yellow, magenta, cyan, and black from the heads 61Y, 61M, 61C, and 61BK in an area facing the heads 61Y, 61M, 61C, and 61BK. The liquids are ejected and applied in such a manner that they are sequentially superimposed, and an image that is a primary image is formed on the primary image forming surface that is the surface thereof.
As described above, the image forming apparatus 100 has a tandem structure in which the heads 61Y, 61M, 61C, and 61BK are opposed to the intermediate transfer member 37 and are arranged in parallel in the A1 direction.

  The recording liquid is ejected or applied to the intermediate transfer member 37 by the heads 61Y, 61M, 61C, 61BK upstream of the A1 direction so that the image areas of yellow, magenta, cyan, and black are overlapped at the same position on the intermediate transfer member 37. The timing is shifted from the side toward the downstream side.

  As illustrated in FIG. 1, the image forming apparatus 100 includes ink discharge devices 60Y, 60M, 60C, and 60BK that include heads 61Y, 61M, 61C, and 61BK, respectively, and an intermediate transfer member 37 in the A1 direction. The transfer unit 10 as a sheet transfer unit that transfers the transfer sheet S in accordance with the rotation of the transfer sheet S, and a transfer unit 10 that can stack a large number of transfer sheets S and transfers only the uppermost transfer sheet S among the stacked transfer sheets S. A paper feed unit 20 that feeds the paper toward the printer, and a paper discharge tray 25 on which a large number of image-formed transfer papers S that have been transported by the transport unit 10 can be stacked.

  The image forming apparatus 100 is also disposed on the side of the intermediate transfer body 37 so as to face the intermediate transfer body 37, and from the intermediate transfer body 37 after the recording liquid is transferred to the transfer paper S, the intermediate transfer body 37. A head support that integrally supports the cleaning device 40 serving as a cleaning mechanism for removing the recording liquid remaining on the top, that is, the primary image forming surface, and cleaning, and the heads 61Y, 61M, 61C, and 61BK. And a carriage 62 as a body.

  In the image forming apparatus 100, as shown in FIG. 2B, the liquid column of the recording liquid immediately after being ejected from the heads 61Y, 61M, 61C, 61BK is changed to the heads 61Y, 61M, 61C, 61BK, the intermediate transfer body 37, and the like. In such a state that a potential difference is formed between the intermediate transfer body 37 and the heads 61Y, 61M, 61C, 61BK in a state where the space between them is temporarily bridged, an electrode oxidation reaction or the inside of the recording liquid in the liquid column state is performed. An energization means 33 capable of energizing including a current component resulting from the electrode reduction reaction is provided.

  The image forming apparatus 100 is also disposed at a position different from the area occupied by the intermediate transfer body 37 in the main scanning direction, specifically, a position on the front side of the paper surface in FIG. 1 and from the heads 61Y, 61M, 61C, 61BK. A liquid characteristic measuring device 70 as liquid characteristic measuring means shown in FIG. 3 for acquiring the characteristic value of the discharged recording liquid is provided.

  The image forming apparatus 100 also drives the heads 61Y, 61M, 61C, and 61BK in the main scanning direction by driving the carriage 62 in the main scanning direction, and the operations of the carriage driving device 91 shown in FIG. And a control section 98 as a control means including a CPU, a memory and the like (not shown) for controlling the whole.

  In addition to the intermediate transfer member 37, the transport unit 10 is disposed so as to face the intermediate transfer member 37, is driven to rotate by the intermediate transfer member 37, and the transfer sheet S passes through the transfer unit 31 between the conveyance unit 10 and the intermediate transfer member 37. In addition, a transfer roller 38 serving as a pressure roller serving as a transfer unit serving as a transfer recording unit that transfers and records the primary image of the recording liquid carried on the intermediate transfer body 37 onto the transfer sheet S is provided.

  The transport unit 10 also includes a transport roller 32 that transports the transfer paper S fed from the paper feed unit 20 toward the transfer unit 31 and the paper discharge table 25, and a transfer paper fed from the paper feed unit 20. A guide plate 39 that guides S to the transfer unit 31 and guides the transfer paper S that has passed through the transfer unit 31 to the paper discharge table 25, and a motor as drive means (not shown) that rotationally drives the intermediate transfer body 37 in the A1 direction. Etc.

The transport roller 32 temporarily stops the transfer paper S transported from the paper supply unit 20, and the image formed on the intermediate transfer body 37 is transferred along with the rotation of the intermediate transfer body 37 in the A1 direction. It has a function as a registration roller that feeds the transfer sheet S stopped according to the timing to the transfer unit 31.
As described above, the image forming apparatus 100 is an indirect image forming apparatus that indirectly forms an image on the transfer sheet S using the intermediate transfer body 37.

  As shown in FIG. 2, the intermediate transfer member 37 includes a support 37a made of aluminum and a surface layer 37b which is a conductive rubber layer made of conductive silicone rubber formed on the support 37a. Thus, the intermediate transfer member 37 is a conductive roller.

  The material of the support body 37a is not limited to aluminum, but must be highly conductive and have mechanical strength, and is formed of a metal or an alloy. Therefore, SUS or the like can be used as the material of the support 37a.

  The surface layer 37b is not limited to the conductive silicone rubber, but may be formed of a smooth elastic material having high conductivity and water repellency. The conductivity of the surface layer 37b is such that a voltage is applied between the intermediate transfer member 37 and the heads 61Y, 61M, 61C, 61BK to cause electrolysis of water at the bridge of the recording liquid formed therebetween. This is a necessary function. The water repellency of the surface layer 37b is an index of ease of transfer when the recording liquid is transferred from the surface layer 37b of the intermediate transfer body 37 to the transfer paper S. The higher the water repellency, the better the transfer rate. However, on the other hand, if the water repellency is high, there is a trade-off relationship that a recording liquid with insufficient viscosity is difficult to fix at the landing position on the surface layer 37b and causes beading. The elasticity of the surface layer 37b is a function required at the time of transfer. When the surface layer 37b is deformed along the fibers of the transfer paper S, the contact area is improved and a high transfer rate is achieved. In order to transfer at a low pressure, a material that is somewhat soft must be selected as the material of the surface layer 37b.

  Examples of the material satisfying these functions of the surface layer 37b include rubber materials such as fluorosilicone rubber, phenylsilicone rubber, fluorine rubber, chloroprene rubber, nitrile rubber, nitrile butadiene rubber, isoprene rubber, carbon black, carbon nanotube, gold And conductive rubber mixed with metal fine particles such as silver. In order to increase the conductivity, it is conceivable to increase the number of conductive fine particles. However, if the density of the conductive fine particles on the surface is high, it causes a decrease in water repellency. It is sufficient that the conductivity is in the film thickness direction of the support 37a and the surface layer 37b, and the anisotropic conductivity may be insulative in the surface direction. The size of the conductive fine particles needs to be sufficiently smaller than the dots of about 20 to 50 μm constituting the image, and there is no problem if it is 0.1 μm or less. Further, the surface layer 37b may be impregnated with silicon oil in order to increase water repellency, and may have either a single layer structure or a multilayer structure.

  The bulk physical properties and surface physical properties of the surface layer 37b are preferably as follows. The water repellency has a receding contact angle of water of 60 ° or more, preferably 80 ° or more, and the hardness is 60 or less, preferably 40 or less in JIS-A. The thickness of the surface layer is preferably about 0.1 to 1 mm, and preferably 0.2 to 0.6 mm. The electrical resistivity is 1000 Ω · cm or less, preferably 10 Ω · cm or less.

  The receding contact angle of the surface layer 37b is further set to be smaller than the receding contact angle of a nozzle surface 61d described later and larger than the receding contact angle of a cleaning blade described later. There is a concern that the recording liquid which is the ejected liquid may adhere to the nozzle surface 61d due to mist or ejection failure, and there is a concern that the recording liquid fills the space between the surface layer 37b and the nozzle surface 61d. Even if this occurs, since the receding contact angle of the surface layer 37b is smaller than the receding contact angle of the nozzle surface 61d, the recording liquid efficiently moves from the nozzle surface 61d to the surface layer 37b as the intermediate transfer member 37 rotates. As a result, the nozzle surface 61d returns to a clean state. Further, since the receding contact angle of the surface layer 37b is larger than the receding contact angle of the cleaning blade, the recording liquid on the surface layer 37b easily moves to the cleaning blade, and the cleaning efficiency is high. Accordingly, the recording liquid is efficiently moved and removed from the surface layer 37b to the cleaning blade as the intermediate transfer member 37 rotates, and the surface layer 37b returns to a clean state.

  As shown in FIG. 1, the paper feeding unit 20 transports only the uppermost transfer paper S among the paper feed tray 21 on which a large number of transfer papers S can be stacked and the transfer paper S stacked on the paper feed tray 21. A paper feed roller 22 as a feed roller for feeding toward the unit 10, a housing 23 supporting the paper feed tray 21 and the paper feed roller 22, and the paper feed roller 22 are arranged in the heads 61 Y, 61 M, 61 C, 61 BK. It has a motor or the like as a driving means (not shown) that rotates and feeds the transfer paper S so as to match the discharge timing of the recording liquid.

  The cleaning device 40 is a cleaning blade (not shown) (noted as 41 in FIG. 17) as an insulating cleaning member that contacts the intermediate transfer body 37 in order to remove and clean the recording liquid adhering to the intermediate transfer body 37. And a waste liquid tank (same configuration as the member denoted by reference numeral 42 in FIG. 17) as a waste liquid receiver for storing the recording liquid removed from the intermediate transfer member 37 by the cleaning blade. If the cleaning blade has a function of scraping off the recording liquid on the surface of the intermediate transfer body 37, specifically, the recording liquid remaining after the transfer, by contacting a part, that is, the tip of the cleaning blade. Good and wear resistant.

  The carriage driving device 91 reciprocates the carriage 62 in the main scanning direction in a range in which the heads 61Y, 61M, 61C, 61BK face the intermediate transfer body 37 when the heads 61Y, 61M, 61C, 61BK discharge recording liquid. Thus, an image is formed on the intermediate transfer member 37 by the recording liquid ejected from the heads 61Y, 61M, 61C, 61BK. As described above, the image forming apparatus 100 is an ink jet printer that is a liquid ejecting apparatus as a shuttle type liquid ejecting apparatus.

  The configuration of the carriage drive device 91 can be a configuration generally employed in such an ink jet printer. For example, as shown in FIG. 18, a screw shaft 32a screwed to the carriage 62, and a screw shaft The structure which has the motor 32b which drives 32a forward / reversely rotation is mentioned.

  In addition to driving the carriage 62 in a reciprocating manner in the main scanning direction when performing image formation, the carriage driving device 91 drives the carriage 62 in the main scanning direction during maintenance and non-image formation described later. 3, the heads 61 </ b> Y, 61 </ b> M, 61 </ b> C, 61 </ b> BK occupy a maintenance position as a liquid characteristic measurement position that is a position facing the liquid characteristic measurement device 70.

  The carriage 62 can be replaced with a new one when the heads 61Y, 61M, 61C, 61BK are deteriorated, and in order to facilitate maintenance, the heads 61Y, 61M, 61C, 61BK can be replaced. And can be attached to and detached from the main body 99. Each of the heads 61Y, 61M, 61C, 61BK can be independently attached to and detached from the main body 99 so that it can be replaced with a new one when deterioration or the like occurs and for easy maintenance. ing. This facilitates replacement work and maintenance work.

  The ink discharge devices 60Y, 60M, 60C, and 60BK have substantially the same configuration with respect to the other points although the colors of the recording liquid to be used are different.

  The ink ejection devices 60Y, 60M, 60C, and 60BK are ink cartridges 81Y, 81M, and 81C that are recording liquid cartridges as main tanks that store the recording liquids of the corresponding colors supplied to the plurality of heads 61Y, 61M, 61C, and 61BK. , 81BK, a pump (not shown) as a supply pump for pumping and feeding the recording liquid stored in the ink cartridges 81Y, 81M, 81C, 81BK toward the heads 61Y, 61M, 61C, 61BK, and ink It has a pipe (not shown) that forms a recording liquid feeding path between the cartridges 81Y, 81M, 81C, and 81BK and the heads 61Y, 61M, 61C, and 61BK together with a pump.

  The ink cartridges 81Y, 81M, 81C, 81BK are replaced with new ones when the internal recording liquid is consumed and the remaining amount is low or no longer used, and in order to facilitate maintenance. 99 is removable.

  The recording liquid is a colorant that is a colorant corresponding to yellow, magenta, cyan, and black, a solvent for this colorant, an ABA type amphiphilic polymer composed of a hydrophobic A segment and a hydrophilic B segment, It contains at least a carboxylic acid surfactant that dissolves or disperses the ABA type amphiphilic polymer in the aqueous solvent. The solvent is an aqueous solvent containing water from the viewpoint of safety and the conductivity from which electrolysis described later is caused, and the recording liquid is an aqueous ink composition. As the colorant, an anionic colorant and / or anionic resin which is dissolved or dispersed in a solvent and has an ionic property in the solvent is anionic.

  Any of the following can be applied as the hydrophobic A segment of the ABA type amphiphilic polymer, that is, the hydrophobic A block. Examples thereof include dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl and the like, which are linear alkyl groups having 12 or more carbon atoms. Examples of the branched alkyl group include 2-decyl dodecyl, 2-dodecyl dodecyl, 2-decyl hexadecyl, and the like. In addition, the aromatic-containing alkyl group includes phenylalkyl, diphenylalkyl, triphenylalkyl, naphthylalkyl, dinaphthylalkyl, trinaphthylalkyl, anthracenylalkyl, and a phenyl group in which the benzene ring is a branched alkyl group. Examples of dialkylphenylalkyl, trialkylphenylalkyl, and cyclic alkyl group-containing compounds include cyclohexylalkyl, dialkylcyclohexylalkyl, trialkylcyclohexylalkyl, cyclopentylalkyl, dialkylcyclopentylalkyl, and trialkylcyclopentylalkyl. As described above, the hydrophobic A block preferably includes at least one of a linear alkyl group, a branched alkyl group, a cyclic alkyl group, and a phenyl group.

  Further, it may be a block polymer made of a hydrophobic monomer. Examples thereof include styrene polymers, alkyl acrylate polymers, alkyl methacrylate polymers, acrylamide alkyl polymers, and methacrylamide alkyl polymers.

  Any hydrophilic B segment of the ABA-type amphiphilic polymer, that is, hydrophilic B block, can be used as long as it has an affinity for an aqueous solvent. In order to increase the viscosity of the ink composition by physical crosslinking by hydrophobic association in an aqueous solvent, the hydrophilic B block needs to have a sufficiently long chain length (larger) than the hydrophobic A block. Examples thereof include those having 100-mer or more such as ethylene oxide polymer and propylene oxide polymer containing linear polyethylene oxide. The hydrophilic B block may have a 4-Arms structure or a 6-Arms structure containing a multi-branched polyethylene oxide having a branched hydrophilic portion. Arms means the number of branches of the hydrophilic B block, and a plurality of hydrophobic A blocks are bonded to the ends of the branched hydrophilic B block by the number of branches. Thus, it is desirable that the hydrophilic B block contains at least one of linear polyethylene oxide and multi-branched polyethylene oxide.

As described above, the ABA type amphiphilic polymer is desirably an _An B type amphiphilic polymer having three or more hydrophobic A blocks. This is because the hydrophobic association between the hydrophobic A segments, which will be described later, easily occurs, and the viscosity responsiveness to pH change is improved. The “ABA type” in the ABA type amphiphilic polymer means a structure in which a hydrophilic B block and a plurality of hydrophobic A blocks are bonded around a hydrophilic B block.

Other examples of the hydrophilic B block include vinyl alcohol polymers, vinyl ether polymers, vinyl pyrrolidone polymers, acrylamide polymers, methacrylamide polymers, and derivatives thereof. Also, it may be ionic, acrylate polymer, methacrylate polymer, alkyl quaternary ammonium salt polymer, alkyl quaternary ammonium salt polymer, acrylamide alkyl quaternary ammonium salt polymer, Examples thereof include styrene sulfonate polymer. In addition, cellulose derivatives such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, starch derivatives such as methyl starch, ethyl starch, hydroxyethyl starch, carboxymethyl starch, alginic acid derivatives such as propylene glycol alginate, gelatin, casein, albumin, collagen, etc. And derivatives of plant polymers such as guar gum, locust bean gum, quince seed gum and carrageenan, and derivatives of microbial polymers such as xanthan gum, dextran, hyaluronic acid, pullulan and curdlan.
The chemical bond between the hydrophobic A block and the hydrophilic B block may be any as long as it is stable, and examples thereof include an ether bond, a urethane bond, an amide bond, and an ester bond.

  Any carboxylic acid surfactant that dissolves or disperses the ABA-type amphiphilic polymer in an aqueous solvent may be used as long as it is composed of a hydrophobic alkyl moiety and a carboxylate. As such, sodium caproate, potassium caproate, sodium caprylate, potassium caprylate, sodium caprate, potassium caprate, sodium laurate, potassium laurate, sodium myristate, potassium myristate, sodium palmitate, Fatty acid salts such as potassium palmitate, sodium stearate, potassium stearate and the like can be mentioned. In addition to the monocarboxylic acid as described above, it may be a dicarboxylate or a tricarboxylate.

  As will be described later, the viscosity of the aqueous ink composition constituting the recording liquid changes depending on the pH. However, the change in pH of the recording liquid in this embodiment means that protons are supplied to the ink composition. means. PKa is a measure of the pH at which a carboxylate ion, which is a weak acid salt, is protonated. The pKa of the fatty acid salt is preferably about pKa: 7-9 and higher.

  There is no particular limitation on the average weight molecular weight of the ABA type amphiphilic polymer, but it is preferable that the molecular weight is small in view of ink jet discharge property in a completely dissolved or dispersed state with a carboxylic acid surfactant or the like. Considering the strength of the thickened state, it is preferable that the molecular weight of the polymer is large. Therefore, the thing of the range of 10,000 or more and 100,000 or less is preferable. Moreover, 20,000 or more and 50,000 or less are more preferable. The number of repeats of the polymer portion is preferably from 100 to 1000 mer. The concentration of the polymer in the ink composition is preferably in the range of 0.1% by weight to 10% by weight, and more preferably 0.5% by weight to 5% by weight.

  The viscosity of the recording liquid during ejection is 1 to 20 mPa · s, preferably 2 to 8 mPa · s. The recording liquid has a viscosity increase at least 10 times, preferably 100 times, more preferably 1000 times or more of the time of ejection due to thickening due to pH change after landing, which will be described later, and becomes a gel state. In addition, the preferable range of the physical properties of the recording liquid is a surface tension of 10 to 60 mN / m, preferably 20 to 50 mN / m, and an electrical conductivity of 0.01 to 1 S / m, preferably 0.02 to 0.2 S / m. m.

Specific examples of the anionic dye that is a colorant component, that is, an anionic colorant contained in the recording liquid include, for example, dyes classified into acid dyes, direct dyes, and food dyes in the color index.
More specifically, as acid dyes and food dyes, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142 C.I. I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254, 289 C.I. I. Acid Blue 9, 29, 45, 92, 249 C.I. I. Acid Black 1, 2, 7, 24, 26, 94 C.I. I. Food Yellow 3, 4 C.I. I. Food Red 7, 9, 14 C.I. I. Food black 1, 2 etc.

  As a direct dye, C.I. I. Direct Yellow 1, 12, 24, 26, 33, 44, 50, 86, 120, 132, 142, 144 C.I. I. Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227 C.I. I. Direct Orange 26, 29, 62, 102 C.I. I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202 C.I. I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171 and the like.

  As reactive dyes, C.I. I. Reactive. Black 3, 4, 7, 11, 12, 17, C.I. I. Reactive. Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67, C.I. I. Reactive. Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97, C.I. I. Reactive. Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95, etc. When recording with the method according to the present invention, high solubility, good color tone It is preferably used because of its good water resistance.

Examples of the colorant component used in the recording liquid, that is, the pigment that is a colorant include inorganic pigments and organic pigments.
Examples of inorganic pigments include white pigments such as titanium oxide, zinc oxide, and barium sulfate, and black pigments such as iron oxide.
Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines). Pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye chelates, acidic dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like.

Further, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used.
More specifically, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 81, 83 (Disazo Yellow HR) ), 95, 97, 98, 100, 101, 104, 408, 109, 110, 117, 120, 138, 153, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (Permanent Red 2B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48: 3 (Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63 : 1, 63: 2, 64: 1, 81 (Rhodamine 6G rake), 83, 88, 101 (Bengara), 104, 105, 106, 108 (Cadmium red), 112, 114, 122 (Quinacridone magenta), 123 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, C I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue E), 16, 17: 1, 56, 60, 63, C.I. I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

  When using a recording liquid containing a pigment as a colorant component, for example, carbon black having a carboxyl group introduced by an oxidation reaction, a radical generated from a diazonium salt containing a carboxyl group or a sulfonic acid group, and carbon black, phthalocyanine, Self-dispersing pigments made by reacting pigments such as quinacridone, self-dispersing pigments made by reacting radical initiators containing carboxyl groups and sulfonic acid groups with pigments such as carbon black, phthalocyanine, quinacridone, and pigment functionality A self-dispersing pigment obtained by reacting a group and an anhydride of carboxylic acid is preferably used.

  When a recording liquid in which a pigment is dispersed is used, the particle diameter of the pigment is not particularly limited, but it is preferable to use a pigment ink having a particle diameter of 20 to 150 nm in terms of the maximum frequency in terms of the maximum number. When the particle diameter exceeds 150 nm, not only the dispersion stability of the pigment as the recording liquid is deteriorated but also the discharge stability of the recording liquid is deteriorated, and the image quality such as the image density is lowered, which is not preferable. In addition, when the particle size is less than 20 nm, the storage stability of the recording liquid and the jetting characteristics in the printer are stable, and high image quality can be obtained. This is because the classification operation becomes complicated and it is difficult to produce the recording liquid economically.

The recording liquid preferably contains an anionic polymer type such as a polymer dispersant or a low molecular type dispersant such as a surfactant as a dispersant for dispersing the pigment.
Examples of polymer type dispersants having an anionic group include polyacrylic acid and salts thereof, polymethacrylic acid and salts thereof, acrylic acid-acrylonitrile copolymers and salts thereof, and acrylic acid-alkyl acrylate copolymers. And its salt, styrene-acrylic acid copolymer and its salt, styrene-methacrylic acid copolymer and its salt, styrene-acrylic acid-alkyl acrylate copolymer and its salt, styrene-methacrylic acid-alkyl acrylate Ester copolymer and salt thereof, styrene-α methylstyrene-acrylic acid copolymer and salt thereof, styrene-α methylstyrene-acrylic acid copolymer-alkyl acrylate copolymer and salt thereof, styrene-maleic acid Copolymers and salts thereof, vinyl naphthalene-male Inacid copolymer and salt thereof, vinyl acetate-ethylene copolymer and salt thereof, vinyl acetate-crotonic acid copolymer and salt thereof, vinyl acetate-acrylic acid copolymer and salt thereof, β naphthalenesulfonic acid formalin condensate , Etc.

  Since these anionic polymers react with hydrogen ions generated by electrolysis of water and aggregate, they are preferable in terms of aggregation than the self-dispersing pigment alone. Further, since these anionic polymers have a colorant adhesion function, there is an advantage of improving the transfer rate from the intermediate transfer body 37 to the transfer paper S in the transfer process.

  Specific examples of the low molecular weight type dispersant having an anionic group include oleic acid and its salt, lauric acid and its salt, behenic acid and its salt, stearic acid and its salt, and such fatty acid and its salt. Salts, dodecylsulfonic acid and salts thereof, decylsulfonic acid and salts thereof, and alkylsulfuric acid and salts thereof, alkyl sulfate ertels such as lauryl sulfate and oleyl sulfate, dodecylbenzenesulfonic acid and salts thereof, lauryl Benzenesulfonic acid and its salts, and such alkylbenzenesulfonic acid and its salts, dioctylsulfosuccinic acid and its salts, dihexylsulfosuccinic acid and its salts, and such dialkylsulfosuccinic acid and its salts, naphthylsulfonic acid and Its salts, naphthylcarboxylic acid and Salts thereof, such aromatic anionic surfactants, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl ether sulfonates, fluorinated alkyl carboxylic acids and salts thereof, Examples thereof include dispersants using fluorine-based anionic surfactants such as fluorinated alkyl sulfonic acids and salts thereof.

Another example of the colorant component used in the recording liquid is a recording liquid that uses a colored emulsion composed of colored resin fine particles.
The colored resin fine particles are those obtained by coloring styrene-acrylic resin, polyester resin, polyurethane resin or the like with an oily dye, a disperse dye or a pigment. For example, anionic coloring can be achieved by forming the part that hits the fine particle shell with a hydrophilic resin such as polyacrylic acid or polymethacrylic acid, or suspending it with an ionic surfactant such as a reactive surfactant. A recording liquid is obtained in which fine particles are suspended in a liquid medium mainly composed of water.

By adding a hydrophilic polymer compound to the recording liquid, it is possible to enhance the thickening action and aggregation action of the recording liquid by reaction with hydrogen ions.
The hydrophilic polymer compounds that can be added to the recording liquid include, in the natural system, vegetable polymers such as gum arabic, tragan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, quince seed starch, alginates, carrageenan , Seaweed polymers such as agar, animal polymers such as gelatin, casein, albumin and collagen, microbial polymers such as xanthene gum and dextran, shellac, etc., semi-synthetic systems such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropyl Fibrin-based polymers such as cellulose and ruboxymethylcellulose, starch-based polymers such as sodium starch glycolate and sodium starch phosphate, sodium alginate, propylene glycol alginate Seaweed polymers such as tellurium, pure synthetic systems such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methyl ether and other vinyl polymers, non-crosslinked polyacrylamide, polyacrylic acid and alkali metal salts thereof, water-soluble styrene-acrylic resin, etc. Acrylic resin, water-soluble styrene-maleic acid resin, water-soluble vinyl naphthalene-acrylic resin, water-soluble vinyl naphthalene-maleic acid resin, polyvinyl pyrrolidone, polyvinyl alcohol, alkali metal salt of β-naphthalene sulfonic acid formalin condensate, etc. It is done.

A resin emulsion or latex that does not contain a colorant may be added to the recording liquid. Depending on the type of the resin emulsion, the resin emulsion forms a film on the surface of the transfer paper S, and there is an advantage of improving the light resistance, water resistance, and abrasion resistance of the transfer paper S when an image is formed. Examples of the resin component in the suspension phase include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, and styrene resins. The particle diameter of these resin components is not particularly limited as long as an emulsion is formed, but is preferably about 150 nm or less, more preferably about 5 to 100 nm. Examples of commercially available resin emulsions include Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.). Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion, Seiden) Chemical Co., Ltd.).
In the recording liquid, the resin emulsion is preferably added so that the resin component is 0.1 to 40% by weight of the recording liquid, and more preferably in the range of 1 to 10% by weight.

  The polymer type pigment dispersants, colored emulsions, and water-soluble polymer compounds described above, together with the ABA type amphiphilic polymer, improve the transfer rate from the intermediate transfer body 37 to the transfer paper S in the transfer process. It is effective to make it.

  The recording liquid uses water as the main liquid medium. In order to make the recording liquid have the desired physical properties or to prevent clogging of the nozzle 61b described later due to the drying of the recording liquid, the water-soluble organic solvent described below is moisturized. It is preferable to use it as an agent component.

  Specific examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, and 1,4-butanediol. 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 1,2,4-butanetriol, 1, Polyhydric alcohols such as 2,3-butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethyl Polyhydric alcohol alkyl ethers such as ethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, N-methyl-2 -Pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, nitrogen-containing heterocyclic compounds such as ε-caprolactam, formamide, N-methylformamide, N, N-dimethylformamide, etc. Amides, monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine and other amines, dimethyl sulfoxide, sulfolane And sulfur-containing compounds such as thiodiethanol, propylene carbonate, ethylene carbonate, and γ-butyrolactone.

  In addition, as other moisturizing components, sugar alcohols such as sorbitol, polysaccharides such as hyaluronic acid, polymers such as polyethylene glycol, and natural moisturizing components such as urea, lactic acid, citrate, and amino acids can be used. is there. These solvents are used alone or in combination with water. Although there is no restriction | limiting in particular in content of these water-soluble organic solvents, Preferably it is 1-60 weight% of the whole ink, More preferably, it uses in the range of 10-40 weight%.

  In order to electrolyze the water in the recording liquid, it is necessary to add an electrolyte component for increasing the ionic conductivity of the recording liquid. As electrolyte components to be added to the recording solution, sodium chloride, potassium chloride, lithium chloride, rubidium chloride, sodium bromide, sodium iodide, sodium sulfate, sodium sulfite, sodium hydrogen sulfite, sodium thiosulfate, potassium sulfate, sodium nitrate, sulfite Inorganic alkali metal salts such as sodium nitrate, potassium nitrate, sodium phosphate, sodium carbonate, sodium bicarbonate, sodium acetate, potassium acetate, sodium oxalate, sodium citrate, sodium hydrogen citrate, potassium citrate, potassium hydrogen citrate Organic alkali metal salts such as ammonium chloride, ammonium nitrate, ammonium sulfate, tetramethylammonium chloride, tetramethylammonium nitrate, and organic ammonium salts such as choline chloride .

  Since a polyvalent metal salt having a valence of 2 or more impairs the solubility or dispersibility of a colorant, an ABA type amphiphilic polymer, or the like, a monovalent metal salt is preferable. In particular, it is preferable to add a quaternary ammonium salt as an electrolyte component. This is because the quaternary ammonium ions are dispersed in charge by an alkyl group bonded to the central element, and the interaction with the colorant, the ABA type amphiphilic polymer, etc. is small and stable. In addition, quaternary ammonium ions hardly form a cluster with water and rarely deprive water of hydration necessary for dissolution or dispersion of a colorant, an ABA type amphiphilic polymer, or the like. The electrical conductivity per unit molecular weight (molar ionic conductivity) is high for compounds having a small molecular weight, and among the quaternary ammonium salts, tetramethylammonium salts are particularly preferred. Counter ions include chloride ions, nitrate ions, sulfate ions, etc., but chloride ions may cause an electrode reaction at the anode to generate chlorine. Therefore, inactive nitrate ions and sulfate ions are preferable.

As the acidic pH adjuster, boric acid, carbonic acid, hydrochloric acid, nitric acid, sulfuric acid, acetic acid, ammonium chloride and the like can be used. Examples of alkaline pH adjusters include hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, lithium carbonate, carbonic acid It is possible to use alkali metal carbonates such as sodium and potassium carbonate, and amines such as diethanolamine and triethanolamine.
In addition, you may use additives, such as a pH buffer, a viscosity modifier, antiseptic | preservative, antioxidant, and a rust inhibitor, as needed.

  The recording liquid thus adjusted has a characteristic that the viscosity changes depending on the pH, specifically, a characteristic that the viscosity increases by an acid. That is, the recording liquid comprises an aqueous solvent, a colorant dissolved or dispersed in the aqueous solvent, an ABA type amphiphilic polymer comprising a hydrophobic A segment and a hydrophilic B segment, and the ABA type amphiphilic property. Since at least the carboxylic acid surfactant that dissolves or disperses the polymer in the aqueous solvent is included, the protonation of the carboxyl ion of the carboxylic acid surfactant, which is a weak acid salt, proceeds as the pH of the recording liquid decreases. If the surface active function is lost, the ABA type polymer cannot be stably dispersed in the ink composition, and the hydrophobic A segments of a plurality of ABA type polymers cause a hydrophobic association (physical crosslinking) to form a network structure in the liquid. As a result, the viscosity of the recording liquid increases. Thus, the recording liquid is a pH-responsive ink composition that exhibits a change in viscosity in response to a change in pH. Thickening may occur with gelation.

  As shown in FIG. 2, each of the heads 61Y, 61M, 61C, 61BK includes a nozzle plate 61a as a nozzle plate that is a conductive nozzle member disposed on the recording liquid discharge side facing downward in the figure, and a nozzle A nozzle 61b, which is a nozzle hole formed in the plate 61a, and an ink chamber 61c, which is a liquid chamber that is supplied with recording liquid from the ink cartridges 81Y, 81M, 81C, 81BK by a pump and is filled with the recording liquid and holds the recording liquid; And an ink discharge means (not shown) for discharging the recording liquid in the ink chamber 61c from the nozzle 61b. The nozzle plate 61a, the nozzle 61b, the ink chamber 61c, and the ink discharge means are provided as a set, and each head 61Y, 61M, 61C, 61BK is provided in large numbers, but only one of them is shown in FIG. Is illustrated.

  Although detailed illustration is omitted, the nozzle plate 61 a includes a conductive substrate and a water repellent film formed on the surface of the substrate facing the intermediate transfer body 37. The water-repellent film may be formed by applying a fluorine-based water repellent or a silicon-based water repellent, or may be formed by plating a fluorine-based polymer or a fluorine-metal compound eutectoid, Any film having water repellency is not particularly limited. The nozzle plate 61a includes a surface on the ink chamber 61c side as an interface forming portion that forms an interface with the recording liquid in the ink chamber 61c, and functions as a cathode as will be described later.

  The entire nozzle plate 61a may be conductive, or may be a member in which only the surface on the ink chamber 61c side is subjected to conductive treatment, or an intermediate member between the conductive member disposed on the ink chamber 61c side. You may comprise by the insulating member arrange | positioned by the transfer body 37 side.

  Since the conductive portion of the nozzle plate 61a is provided as a cathode as will be described later, it does not need to be made of a material resistant to metal elution, and has a high conductivity such as SUS alloy, metal such as nickel, and carbon. What is necessary is just to be comprised with material.

  The nozzle plate 61a of this embodiment is made of metal, and a commercially available inkjet printer GX5000: manufactured by Ricoh can be used as a head equipped with such a nozzle plate. Data to be described later is obtained using this head.

The nozzle plate 61a is set so that the gap with the intermediate transfer member 37 is 50 to 600 μm during image formation. If the gap is less than 50 μm, it may be difficult to maintain the gap between the intermediate transfer member 37, which is a rotating body, and the nozzle plate 61a. If the gap exceeds 600 μm, the liquid injection described later may be performed. This is because it may be difficult to form a bridge. However, if the gap can be maintained, there is no particular problem even if it is less than 50 μm.
The nozzle plate 61a is a nozzle portion provided with a nozzle 61b, and in particular, a nozzle surface 61d that is a surface facing the intermediate transfer member 37 is a nozzle portion.

  The ink discharge means is an actuator which is a pressure application means for applying a pressure to the recording liquid in the ink chamber 61c as a liquid discharge means for discharging the recording liquid from each nozzle 61b to be discharged and landed on the intermediate transfer body 37. As a piezoelectric element.

  The piezoelectric element is driven by a head driving circuit 92 as head driving means shown in FIG. The head drive circuit 92 functions as drive signal generation means for generating a drive signal for discharging recording liquid from the heads 61Y, 61M, 61C, 61BK. The drive signal is generated under the control of the control unit 98 as a head drive waveform that is a predetermined drive waveform corresponding to an image to be formed, in other words, as a voltage pulse of a signal waveform. As described above, the head drive circuit 92 or the control unit 98 can generate a drive signal for controlling on / off of the discharge of the recording liquid as needed. The generated drive signal is input to the piezoelectric element.

  Therefore, the recording liquid is ejected from the nozzle 61b in accordance with the voltage pulse applied to the piezoelectric element under the control of the control unit 98. In this respect, the control unit 98 functions as an ink ejection control unit.

  The control unit 98 functioning as an ink ejection control unit inputs the voltage pulse to each of the piezoelectric elements. The control unit 98 functioning as an ink ejection control unit drives each piezoelectric element in time series so that an arbitrary pattern, that is, an image is formed by the recording liquid ejected from each nozzle 61b. In this regard, the control unit 98 functions as an image control device. The pressure in the ink chamber 61c is maintained at a negative pressure except when the recording liquid is discharged and discharged from the nozzle 61b.

  The actuator of the ink discharge means may be a movable actuator of another type that is a shape deforming element type, such as a piezo type, or the nozzle 61b by boiling of the recording liquid by a heating means that employs a heater type such as a thermal type. The recording liquid may be discharged from the recording medium, and the recording liquid can be discharged by any method.

  As shown in FIG. 2, the energizing means 33 has a power source 33a connected between the support 37a and the nozzle plate 61a, and a current flowing between the support 37a and the nozzle plate 61a due to voltage application by the power source 33a. An ammeter 33b serving as a current detection unit that detects and inputs to the control unit 98, and a voltage application control unit that is realized as part of the function of the control unit 98 and controls the voltage application timing and application time by the power source 33a. doing. The control unit 98 as voltage application control means also functions as voltage changing means for changing the voltage of the power source 33a.

  The power source 33a has an anode connected to the support 37a and a cathode connected to the nozzle plate 61a by an electric circuit. Therefore, the energizing unit 33 includes the intermediate transfer member 37 as an anode and the nozzle plate 61a as a cathode.

  The power source 33a may be any one that is connected to the heads 61Y, 61M, 61C, and 61BK and that allows a current to flow through the recording liquid. Therefore, the power source 33a may be connected to the electrode arranged so as to contact the recording liquid in the ink chamber 61c, for example, instead of the nozzle plate 61a.

  As will be described later, the energizing unit 33 functions as a voltage applying unit that applies a voltage at which the recording liquid is electrolyzed between the support 37a and the heads 61Y, 61M, 61C, and 61BK during image formation. The energizing unit 33 functions as a voltage applying unit during maintenance described later, and applies a smaller voltage than that during image formation.

  The liquid characteristic measuring device 70 is disposed at a position facing the nozzle plate 61a of the heads 61Y, 61M, 61C, 61BK occupying the maintenance position, and receives the recording liquid discharged from the heads 61Y, 61M, 61C, 61BK. A metal mesh 71, which is a conductive member as a body, and a capping member 72 as a receptor support member for capping the heads 61Y, 61M, 61C, 61BK, which are fixed inside the metal mesh 71 and occupy the maintenance position; have.

  The liquid characteristic measuring device 70 is also connected to the bottom of the capping member 72 to discharge the recording liquid that has passed through the metal mesh 71 to the outside of the capping member 72, and the waste liquid for performing the waste liquid by the waste liquid tube 73. A tubing pump 74 as suction means connected to the tube 73 and a waste liquid tank 75 as a waste liquid receiver for storing the recording liquid discharged from the capping member 72 by the waste liquid tube 73 as waste liquid are provided.

The liquid characteristic measuring device 70 is also controlled by the control unit 98 to move the capping member 72 up and down together with the metal mesh 71. The capping driving device 93 shown in FIG. 4 and the heads 61Y, 61M, 61C, 61BK are capping members. A wiping mechanism 94 that wipes the surface of the nozzle plate 61b while being capped by the nozzle 72 to clean the nozzle surface 61d, and a detection device 95 that detects the current flowing between the nozzle plate 61a and the metal mesh 71. doing.
In addition, the liquid characteristic measuring device 70 includes a head drive circuit 92, a control unit 98 that functions as an ink ejection unit, heads 61Y, 61M, 61C, and 61BK.

  When the heads 61Y, 61M, 61C, 61BK occupy the maintenance position, the capping driving device 93 is in contact with the upper end of the capping member 72 abutting against the position where the nozzle 61b is not formed on the nozzle plate 61a. The capping member 72 is raised to the contact position. In other cases, the capping driving device 93 positions the capping member 72 at a retracted position below the contact position so as not to contact the heads 61Y, 61M, 61C, 61BK.

  When the capping member 72 occupies the contact position, the heads 61Y, 61M, 61C, 61BK are sealed by the capping member 72, and the drying and thickening of the recording liquid are suppressed.

  Further, when the capping member 72 occupies the contact position, the distance between the heads 61Y, 61M, 61C, 61BK and the metal mesh 71, more specifically, the distance between the nozzle plate 61a and the heads 61Y, 61M, 61C, 61BK. Kept constant. In this respect, the capping member 72 functions as a spacer member that keeps the distance constant.

  The recording liquid ejected from the heads 61Y, 61M, 61C, 61BK in the state where the capping member 72 occupies the contact position comes into contact with the metal mesh 71. This contact portion has a mesh structure. .

  Further, when the tubing pump 74 is operated under the control of the control unit 98 in a state where the capping member 72 occupies the contact position, the pressure inside the capping member 72 can be reduced.

As a configuration of the capping drive device 93, a mechanism such as a stepping motor, a pinion & rack, or the like can be used.
The wiping mechanism 94 is configured such that the nozzle surface 61d is wiped by a rubber blade that is generally used for cleaning the nozzle surface 61d of a liquid ejecting apparatus such as the heads 61Y, 61M, 61C, 61BK. It is possible to use a mechanism such as

  As shown in FIG. 3, the detection device 95 is shared with the configuration of the energization means 33. Specifically, the detection device 95 is controlled by the control unit 98 that functions as a voltage application control unit and a voltage change unit, and is controlled by the control unit 98 to apply a voltage between the nozzle plate 61 a and the metal mesh 71. A power source 33a functioning as a voltage application means, and an ammeter as a current detection means for detecting and measuring a current flowing between the nozzle plate 61a and the metal mesh 71 by applying a voltage from the power source 33a and inputting the current to the control unit 98 33b.

  The ammeter 33b has a known resistor 33a1 as a resistance unit connected in series to the power source 33a, and a voltmeter 33a2 for measuring a voltage drop caused by the resistor 33a1, and the voltmeter 33a2 measures the voltage. A value is input to the control unit 98.

  The control unit 98 incorporates a processing circuit that measures the current flowing between the nozzle plate 61a and the metal mesh 71 based on the input value from the voltmeter 33a2. Based on the current, the control unit 98 measures an energization feature amount described later as an energization profile in the processing circuit. In this respect, the control unit 98 functions as a feature amount measuring unit.

  Further, the control unit 98 is a liquid characteristic calculation unit as a characteristic value calculation unit that calculates and acquires the characteristic value of the recording liquid based on the energization feature amount measured by the control unit 98 functioning as the feature amount measurement unit. It functions as a certain characteristic value acquisition means.

  The liquid property measuring apparatus 70 having the above-described configuration is configured so that the capping member 72 is moved to the contact position by the capping driving device 93 during the maintenance of the heads 61Y, 61M, 61C, 61BK. The control unit 98 functioning as a changing unit drives the power source 33 a to apply a voltage between the nozzle plate 61 a and the metal mesh 71.

  In this state, the liquid characteristic measuring device 70 drives the head drive circuit 98 to discharge the recording liquid from the heads 61Y, 61M, 61C, 61BK, and the discharged recording liquid passes between the nozzle 61a and the metal mesh 71. The current flowing through the liquid column of the recording liquid when the bridge is detected is detected by the ammeter 33b.

  Then, the liquid property measuring apparatus 70 acquires the characteristic value of the current by the control unit 98 functioning as the characteristic value acquiring unit based on the energized feature amount measured by the control unit 98 functioning as the characteristic amount measuring unit. Based on the acquired characteristic values, the heads 61Y, 61M, 61C, and 61BK are cleaned as necessary, with the capping member 72 kept in the contact position, as necessary. The voltage application between the nozzle plate 61a and the metal mesh 71 by driving the power source 33a is continued until the acquisition of the characteristic value is completed, but is stopped when the acquisition of the characteristic value is completed.

  This cleaning operation is performed by driving the wiping mechanism 94 to discharge the recording liquid by the heads 61Y, 61M, 61C, 61BK and / or forcibly discharge the recording liquid from the heads 61Y, 61M, 61C, 61BK by driving the tubing pump 74. This is performed by appropriately combining the wipe operation of the nozzle surface 61d.

  The waste liquid of the recording liquid generated by the cleaning operation, the solidified component of the recording liquid mixed therein, and foreign matters such as dust are discharged from the capping member 72 by the waste liquid tube 73 by the driving of the tubing pump 74, and are discharged to the waste liquid tank 75. Stored. At this time, the capping member 72 is in contact with the nozzle plate 61a, the inside of the capping member 72 is sealed, and the pressure is reduced, so that the discharge efficiency of waste liquid and the like from the capping member 72 is increased.

  Thus, the liquid property measuring device 70 functions as a maintenance device as a maintenance unit for the heads 61Y, 61M, 61C, and 61BK, and a cleaning device as a cleaning unit.

  Since the receptor is a metal mesh 71 having a mesh structure, the discharged recording liquid drops and permeates downward when a certain amount is reached, so that the recording liquid is prevented from being accumulated more than necessary. Acquisition can be performed continuously and characteristic values can be acquired accurately.

  The tubing pump 74 also functions as a cleaning unit that removes the recording liquid adhering to the metal mesh 71. By cleaning the metal mesh 71, it is possible to continuously acquire characteristic values. At the same time, the characteristic value is accurately acquired.

The acquisition of the characteristic value and the subsequent cleaning operation of the heads 61Y, 61M, 61C, 61BK carried out as necessary is performed by the carriage driving device 91 displacing the heads 61Y, 61M, 61C, 61BK to the maintenance position, and capping driving. This is performed when any of the following conditions is satisfied in addition to the capping state of the heads 61Y, 61M, 61C, 61BK in which the capping member 72 is displaced to the contact position by the device 93.
-When non-image formation after completion of user-specified image formation and when image formation has been performed a predetermined number of times since the previous acquisition of characteristic values-Instructions for maintenance of the heads 61Y, 61M, 61C, 61BK by the user Is input to the image forming apparatus 100. When the capping state is maintained for a predetermined time.

Even when these conditions are not satisfied, the capping state is continued until, for example, the next image formation instruction and a predetermined time elapse, thereby suppressing the thickening of the recording liquid.
Further, the capping state may be formed when a predetermined time has elapsed after completion of the user-specified image formation, or when any of the above conditions is satisfied.

In forming such a capping state, the liquid property measuring device 70 functions as a capping device for capping the heads 61Y, 61M, 61C, 61BK.
The remainder of the liquid property measuring apparatus 70 will be described later.

  In the image forming apparatus 100 having such a configuration, the intermediate transfer body 37 rotates in the A1 direction while facing the heads 61Y, 61M, 61C, 61BK in response to the input of a predetermined signal indicating the start of image formation. In the process, the yellow, magenta, cyan, and black recording liquids are transferred from the heads 61Y, 61M, 61C, and 61BK so that the image areas of the respective colors of yellow, magenta, cyan, and black overlap with the same position on the intermediate transfer body 37. The images are ejected in such a manner that they are sequentially overlapped from the upstream side toward the downstream side in the A1 direction, and an image is temporarily carried on the intermediate transfer member 37.

At this time, the energization unit 33 is driven by the control unit 98 as the voltage application control unit, and a voltage is applied between the support 37a and the nozzle plate 61a from the power source 33a.
In this state, the recording liquid is applied onto the intermediate transfer member 37 from each of the heads 61Y, 61M, 61C, 61BK. At this time, first, from the heads 61Y, 61M, 61C, and 61BK, as shown in FIG. 2A, the recording liquid forming the meniscus in the nozzle 61b is applied by voltage pulses. As shown in FIG. 5B, the recording liquid moves toward the intermediate transfer body 37, the leading end of the recording liquid lands on the intermediate transfer body 37, and the recording liquid is formed between the nozzle 61b and the intermediate transfer body 37. A bridge of the liquid column is temporarily formed, and then, as shown in FIG. 3C, the bridge of the liquid column made of the recording liquid is divided to be carried on the intermediate transfer body 37 and the intermediate transfer body 37. An image is formed on the recording liquid. The diameter of the liquid column forming the bridge is about 10 μm, and the dot diameter of the recording liquid carried on the intermediate transfer body 37 after the bridge division is about 50 μm.

In the state where the liquid injection bridge made of the recording liquid is formed as shown in FIG. 2B, the colorant component in the recording liquid is subjected to an aggregating action by the energizing means 33. Specifically, the voltage application of the energizing means 33 causes the following electrode reactions to occur in the nozzle plate 61a serving as the cathode and the intermediate transfer member 37 serving as the anode, respectively, and the water contained in the bridge of the liquid column of the recording liquid. Electrolyzed.
^{_{Cathode: 4H 2 O + 4e - →}} 2H 2 + 4OH - ··· reaction formula (1)
_{^{Anode: 2H 2 O → 4H + +}} O 2 + 4e - ··· reaction formula (2)

  As a result, the water contained in the bridge of the liquid column of the recording liquid is oxidized on the surface of the intermediate transfer member 37 functioning as the anode to generate protons (H +), and as shown in FIG. The pigment P dispersed by D aggregates via protons. Thereby, the occurrence of bleeding between adjacent dots is suppressed, and a high-definition image is formed. In addition, there is an advantage that clogging of the nozzle 61b is prevented by such voltage application. The time for forming such a bridge can be controlled by the peak voltage and pulse width of the electromagnetic pulse applied to the piezoelectric element.

Here, the bridge of the liquid column formed between the cathode and the anode will be described with reference to FIG. Inside the bridge B of the liquid column, cations and anions move in the vicinity of the cathode C and the anode A, respectively. As a result, the surface of the cathode C and the anode A, the electric double layer E _C and E _A respectively is formed, the charging speed of the electric double layer E _C and E _A is the conductivity of the bridge B of the liquid column, recording It is almost determined by the concentration of ions contained in the liquid. At this time, when the voltage of the electric double layer E _A reaches several V, Faraday current flows water is electrolyzed. As a result, on the surface of the anode A, water is oxidized to generate protons, and the pigment dispersed by the anionic dispersant is aggregated. On the other hand, the capacity of the electric double layer E _C, since sufficiently larger than the capacitance of the electric double layer E _A, the surface of the cathode C, water is unlikely to reduction. This is because the area of the nozzle plate 61a serving as the cathode C is sufficiently larger than the area of the intermediate transfer member 37 serving as the anode A. The degree of pigment aggregation can be controlled by the amount of protons generated, that is, the time for forming the bridge of the liquid column, the voltage applied by the energizing means 33, and the like. Further, when water is oxidized and protons are generated, oxygen is also generated. However, since it is considered to be dissolved in water in addition to a small amount, it does not inhibit image formation.

  In this way, a non-Faraday current corresponding to the formation of an electric double layer at the electrode interface and a Faraday current resulting from the electrolysis of water are generated. In order to form an image of the recording liquid on the intermediate transfer member 37, the voltage applied by the energizing means 33 is 1.23V, which is the theoretical decomposition voltage of water, or several V to tens, which is a general condition for electrolysis of water. Several volts are insufficient, and preferably several tens to several hundreds V. However, when several tens to several hundreds V, the reaction resistance of water electrolysis is so small as to be negligible, and the solution resistance of the recording liquid dominates. It becomes the target. After the liquid column bridge B is formed, the liquid column is divided in the vicinity of the nozzle 61b and the bridge state is finished. The bridge state is several μs to several tens μs, and the product of this time and the Faraday current is the electric charge amount. The larger the is, the more hydrogen ions and hydroxide ions are generated.

  Since the recording liquid has the property of being thickened by acid, a thickened portion is generated in the recording liquid in which the bridge B is formed. Since hydrogen ions are generated from the electrode interface of the intermediate transfer member 37, there are many thickening portions in the portion of the recording liquid in contact with the surface of the intermediate transfer member 37 and in the vicinity thereof. Due to the presence of the thickened portion, the problem of beading such as a dot becoming large or being displaced due to the surface tension of the intermediate transfer member 37 is suppressed.

  The energizing means 33 changes the viscosity of the recording liquid by applying a voltage between the intermediate transfer member 37 and the nozzle plate 61a in the state where the bridge B is formed to electrolyze water contained in the recording liquid. Therefore, specifically, pH treatment for increasing the viscosity is performed. The energization means 33 and the control unit 98 as voltage application control means for driving the energization means 33 function as pH control means for performing such pH treatment.

  In order to perform such electrolysis, it is essential to form the bridge B. Therefore, each of the heads 61Y, 61M, 61C, 61BK faces the intermediate transfer body 37 at a distance at which the bridge B can be formed with the intermediate transfer body 37 when the recording liquid is applied to the intermediate transfer body 37. Arranged. Specifically, the gap distance between the surface of the nozzle plate 61a and the surface of the intermediate transfer body 37 is set between 50 and 300 μm, preferably 100 to 200 μm, and in this embodiment, 100 μm. If it exceeds 200 μm, depending on the type of the recording liquid and the ejection method, the liquid column is divided in the vicinity of the nozzle 61b due to the surface tension of the recording liquid before bridging, and normal droplet formation occurs. This is because electrolysis of water by the bridging of the recording liquid with the transfer body 37 becomes impossible. In addition, if the gap is small, the landing accuracy of the recording liquid is improved, and the advantages of using the intermediate transfer member 37 such as good paper type compatibility can be obtained. However, if the gap is less than 50 μm, vibration and alignment errors are caused. This is because it is easily affected by the variation in distance and it is difficult to maintain the gap, and further, contact between the nozzle plate 61a and the intermediate transfer member 37 can occur.

  From the state shown in FIG. 2A to the state shown in FIG. 2B, the state shown in FIG. 2B is changed to the state shown in FIG. 2C. In the meantime, the states of FIGS. 7A to 7C and FIGS. 8A to 8C are passed, respectively.

  For example, in the state shown in FIG. 7A, a liquid column is being formed, and a very small induced current is generated between the nozzle plate 61a and the intermediate transfer body 37 as the charged liquid column tip moves. However, this current is very weak and cannot be detected by the ammeter 33b.

  In the state shown in FIG. 5B, the tip of the liquid column has landed on the surface of the intermediate transfer body 37 to form a bridge-shaped liquid column. A large current begins to flow simultaneously with the landing of the liquid column tip onto the surface of the intermediate transfer member 37, and the current value is measured by the ammeter 33b.

FIG. 8B shows a state in which the liquid column is divided in the vicinity of the nozzle surface 61d. As the liquid column becomes thinner, the resistance of the liquid column increases and the amount of energization current decreases. Finally, the energization current stops when the liquid column is divided.
Each of the states shown in FIGS. 2, 7, and 8 similarly occurs when the recording liquid is discharged onto the metal mesh 71.

  In synchronization with the timing at which the leading edge of the image carried on the intermediate transfer body 37 reaches the transfer unit 31, a single sheet of transfer paper S fed from the paper supply unit 20 is supplied to the transfer unit 31, and the transfer roller 38. A transfer step of applying pressure to the transfer sheet S passing through the transfer unit 31 to bring it into close contact with the intermediate transfer body 37 and transferring the image carried on the intermediate transfer body 37 onto the surface of the transfer sheet S. Thus, an image is formed on the transfer paper S. As described above, the transfer roller 38 transfers the recording liquid whose viscosity has been changed by the pH treatment from the intermediate transfer body 37 to the transfer paper S. The transfer sheet S on which an image is formed by the transfer is guided to the paper discharge table 25 and stacked on the paper discharge table 25.

  In this way, when the image is transferred to the transfer paper S, a mixture of the thickened recording liquid and the agglomerated components formed by the reaction of the recording liquid is transferred to the transfer paper S. Therefore, even when the transfer paper S is plain paper, feathering and bleeding are prevented together with beading by forming an image with the colorant aggregated by the aggregation action in the thickened recording liquid. It is possible to form an image with high image density and high image quality at a high speed while being suppressed.

  In order to perform high-speed image formation, since the recording liquid needs to be quick-drying, the recording liquid generally has high absorbability to the transfer paper S. In this case, the recording liquid is deep in the transfer paper S. Penetrating to the surface and causing so-called offset, making it unsuitable for double-sided image formation. However, since the thickening and aggregating actions reduce the absorbability of the recording liquid onto the transfer paper S, such set-off is prevented or suppressed, which is suitable for double-sided image formation. Furthermore, since the transfer process is performed by pushing the thickened recording liquid into the paper fiber hole while reducing the absorbability of the recording liquid to the transfer paper S, deformation of the transfer paper S such as cockling and curling. This also suppresses or prevents the transfer paper S, thereby improving the transportability of the transfer paper S carrying the image, and facilitating handling of the transfer paper S, such as preventing or suppressing jamming.

  In the image forming apparatus 100, since the recording liquid is thickened, it is considered that the recording liquid is less likely to penetrate into the transfer paper S and the quick drying property is reduced as compared with the case where there is no change in viscosity. However, the transfer roller 38 transfers the recording liquid from the intermediate transfer body 37 to the transfer paper S, and at the same time applies a pressure between the intermediate transfer body 37 to the recording liquid and the transfer paper S, thereby transferring the inside of the transfer paper S. Improves the permeability of the recording liquid into In this respect, the transfer roller 38 and the intermediate transfer member 37 function as pressure applying means for applying pressure to the recording liquid and the transfer paper S. The application of pressure in the fixing step improves the fixability of the colorant in the recording liquid that has been thickened to the transfer paper S by pressing and shearing between the intermediate transfer body 37 and the transfer paper S, as well as ensuring quick drying. Is to be done. Since the transfer roller 38 and the intermediate transfer body 37 also serve as a pressure applying unit, the structure of the image forming apparatus 100 is simplified, contributing to downsizing and cost reduction.

  The transfer roller 38 is preferably provided with a water-repellent member having a low surface energy on the surface from the viewpoint of preventing contamination by the recording liquid. Therefore, the transfer roller 38 has a fluororesin such as tetrafluoroethylene resin, tetrafluoroethylene / perfluoroalkoxyethylene copolymer, fluorosilicone rubber, phenylsilicone rubber, fluororubber, chloroprene rubber, nitrile rubber on the surface. , Nitrile butadiene rubber, isoprene rubber, and other rubber materials, resin, metal, and rubber have a surface layer treated with fluorine.

  Regarding the physical properties of the transfer roller 38 as a surface member, the water receding contact angle is 60 ° or more, preferably 80 ° or more, and the hardness is 60 or more, preferably 80 or more, according to JIS-A. The thickness of the surface layer is preferably about 0.1 to 1 mm, and preferably 0.2 to 0.6 mm.

As a pressure at the time of pressurizing, 1-100 kgf / cm < ₂ > is preferable and 5-20 kgf / cm < ₂ > is more preferable. By pressurizing the recording liquid on the transfer paper S, it is possible to improve the smoothness of the dots of the recording liquid in addition to assisting the permeability of the recording liquid, and there is an advantage that the glossiness of the image is improved. is there. Since the transfer paper S has improved recording liquid permeability due to such pressurization, transfer of the recording liquid to the back surface of the other transfer paper S when being stacked on the paper discharge tray 25 is prevented or suppressed. The

  After the above-described image forming operation is completed, when the above-described conditions are satisfied, the characteristic value is acquired, and subsequently, a cleaning operation is performed as necessary.

  In acquiring the characteristic values, the recording liquid is ejected from the heads 61Y, 61M, 61C, 61BK, and the nozzle plate 61a and the metal mesh are used in the same manner as the recording liquid bridge between the nozzle plate 61a and the intermediate transfer body 37 described above. It is necessary to form a recording liquid bridge between the recording liquid 71 and the recording liquid.

  Therefore, the distance between the nozzle plate 61a and the metal mesh 71 in the capping state is set in the same manner as described above for the distance between the nozzle plate 61a and the intermediate transfer member 37.

  Specifically, the distance is set between 50 and 300 μm, preferably 100 to 200 μm, and in this embodiment, 100 μm. If it exceeds 200 μm, depending on the type of the recording liquid and the ejection method, the liquid column is divided in the vicinity of the nozzle 61b by the surface tension of the recording liquid before bridging, resulting in normal droplet formation, and the nozzle plate 61a and the metal This is because electrolysis of water by the bridge of the recording liquid with the mesh 71 becomes impossible. Further, if the thickness is less than 50 μm, it is easy to be affected by distance fluctuation due to vibration or alignment error, and it is difficult to maintain the gap.

  In this respect, the liquid characteristic measuring device 70 has an advantage that the capping member 72 functions as a spacer member, the distance is kept constant with high accuracy, and contact between the nozzle plate 61a and the metal mesh 71 is prevented. There is.

  The portion of the mesh structure of the metal mesh 71 that forms the bridge of the recording liquid is fine enough that the ejected recording liquid contacts sufficiently to form a bridge, so that the droplets do not stay on the mesh structure. It is rough. The optimum mesh interval greatly depends on the volume of the liquid to be ejected, but it has been found by trial and error that it is preferably 5 μm or more and 40 μm or less. In order to quickly drop the droplets, the metal mesh 71 preferably has high wettability with respect to the discharged liquid.

  In this embodiment, the receptor has a mesh structure for allowing the recording liquid to pass therethrough. However, if it is not necessary to allow the recording liquid to pass through, the receiver has any shape such as a plate shape, a roller shape, or a belt shape. Also good. In addition to metals, conductive oxides, conductive polymers, conductive rubber containing carbon, and the like may be used as materials as long as they have high conductivity. An example in which the receptor is a roller-like conductive rubber will be described later with reference to FIG.

  The voltage applied by the power source 33a for obtaining the characteristic value is sufficient to be about several volts to several tens of volts. For example, the conventional technique described above, that is, between the ejection surface for ejecting liquid and the detection unit for receiving liquid, is used. It is possible to detect a signal having a sufficient strength with a voltage lower than the method of applying an electric field, and it is possible to reduce the size and simplification of the apparatus and to suppress discharge.

  Moreover, this voltage is lower than the voltage already described for electrolyzing water as shown in Reaction Formula (1) and Reaction Formula (2). Therefore, the thickening of the recording liquid due to voltage application for obtaining the characteristic value does not occur.

By the way, the resistance value Rlig in the liquid column is theoretically expressed by the following equation 1.
In this equation, σ represents the conductivity of the liquid, here, the recording liquid, and r (x) represents the radius of the liquid column cross section in the direction from the nozzle plate 61a toward the metal mesh 71.

  From this equation, it can be seen that the change in the energization current amount is due to the change in the liquid column resistance Rlig caused by the change in the liquid column shape, and the energization current amount is a value reflecting the liquid column shape. In particular, when a part of the liquid column is thin, the resistance value at the thinnest part is dominant over the resistance value of the entire liquid column.

  FIG. 9 shows the drive waveform of the drive signal generated by the head drive circuit 92 and applied to the piezoelectric element, and FIG. 10 shows the time change of the energization current value detected by the ammeter 33b by the input of this drive signal. . In FIG. 9, symbol PW indicates the pulse width of the drive waveform.

Point A, point B, point C, and point D in FIG. 10 are the recording liquid states shown in FIGS. 7B, 7C, 8A, and 8B, respectively. The energization current value is shown.
The time variation of the energization current amount will be described with reference to FIG.

  The recording liquid ejected by applying the drive waveform reaches the metal mesh 71 at the energization start time T1, and current starts to flow. At this time, since a thick liquid column is formed in the initial state as shown in FIG. 7B, a large current flows rapidly as shown in the vicinity of the point A.

  Next, as shown in the vicinity of point B, when a stable and relatively uniform liquid column is formed as in the state shown in FIG. 7C, a stable current flows. Thereafter, as shown in the vicinity of the point C, the current value decreases as the liquid column gradually narrows in a part of the liquid as in the state shown in FIG. At this time, as described above, since the resistance value of the liquid column is dominant in the thinnest liquid column portion, the change in the flowing current value well reflects the process of thinning the liquid column.

Finally, as shown in the vicinity of the point D, the energization is terminated at the energization end time T2 because the recording liquid is cut off from the nozzle 61b as in the state shown in FIG. 8B.
Note that the processing circuit provided in the control unit 98 functioning as the feature amount measuring unit directly processes a voltage signal corresponding to the voltage drop amount, and provides, for example, a threshold value. It is possible to take a configuration that measures time.

  In this way, the amount of current flowing through the bridge of the liquid column is very large compared to the amount of dielectric current measured by the conventional method and the pressure detection signal of the piezoelectric element, etc., so the characteristic value is highly accurate. There is an advantage that it can be obtained.

  As is apparent from the above description, the energization profile is deeply related to the discharge speed of the recording liquid and the shape of the liquid column formation process, and the energization profile is deeply related to the characteristic value of the discharge liquid. For example, the energization time Tw reflecting the time during which the bridge of the liquid column is formed tends to increase as the viscosity increases, and decrease as the surface tension increases. Alternatively, the amount of current at point C decreases more rapidly as the surface tension is higher.

  Therefore, the control unit 98 functioning as a feature amount measuring unit captures the characteristics of such an energization profile, the maximum current amount Imax during energization, the energization charge amount CL, which is the charge amount during energization, that is, the total charge amount, Until the energization is started after the drive signal generated by the head drive circuit 92 is issued, in other words, the energization start time T1 until the energization is measured, after the drive signal generated by the head drive circuit 92 is issued. In other words, the energization end time T2 from when the energization is stopped until the energization is stopped until the energization is completed, from the energization end time T2 that is the time from when the energization is started until the liquid is divided and the energization is stopped. The energization time Tw as the energization duration equal to the difference between the energization start times T1 is used as the energization feature amount.

  The relationship between the energization characteristic amount and the liquid property, for example, the viscosity, as shown in the measurement results described below, calculates the tendency for a plurality of recording liquids with known physical properties, and functions as a characteristic value acquisition unit 98. The control unit 98 functioning as the characteristic value acquisition unit uses this relationship to calculate a characteristic value such as viscosity based on the measurement result of the energization feature amount actually measured by the control unit 98 functioning as the characteristic amount measurement unit. Obtained by calculation.

An example of the result of obtaining the relationship between the energization feature amount and the liquid viscosity will be described.
As a condition, in the configuration shown in FIG. 3, a SUS plate, which is a receiving plate, is used as a receiving body, the gap between the nozzle surface 61d and the receiving plate is kept at 100 μm, and an energization current profile is measured at the same time as ejection. The energization feature amount was calculated from

  FIG. 11 shows physical property values of the three types of recording liquids used in the evaluation. These recording liquids are mixed liquids of water, a carbon black pigment, a wetting agent, and a surfactant, as in the recording liquid described above, and the viscosity is adjusted by changing only the amount of the wetting agent.

FIGS. 12 and 13 show the relationship between the energization feature amount and the viscosity of the recording liquid shown in FIG.
From FIG. 12, it can be seen that the viscosity can be approximated by a linear function for the energization start time T1, the energization end time T2, and the energization time Tw. Therefore, based on this relationship, at the time of measurement, at least one of the energization start time T1, the energization end time T2, or the energization time Tw is measured as the energization feature amount, thereby controlling the control unit 98 functioning as a characteristic value acquisition unit. The viscosity can be calculated as a characteristic value.

  In FIG. 13, an average current amount Iavg obtained by dividing the energized charge amount CL by the energization time Tw is used as the energization feature amount. From the figure, it can be seen that there is a quadratic function correlation between the average current amount Iavg and the viscosity. Therefore, by obtaining the relationship between the average current amount Iavg and the viscosity by a quadratic function based on this result, the control unit 98 functioning as a characteristic value acquisition unit from the average current amount Iavg at the time of measurement as a characteristic value. The viscosity can be calculated.

  As described above, a parameter that becomes one new energization feature amount from a plurality of energization feature amounts may be calculated by the control unit 98 functioning as a feature amount measuring unit, and the characteristic value of the ejected liquid may be calculated from the parameter. . As the energization feature amount different from the average current amount Iavg, for example, one obtained by further dividing the average current amount Iavg by the maximum current amount Imax can be cited.

In summary, it is possible to acquire a physical property value such as a viscosity, which is a characteristic value of the recording liquid, based on at least one of the energization feature amounts.
Among the characteristic values, the viscosity greatly affects the discharge state of the recording liquid. Therefore, it is important that this is acquired among the various characteristic values.

  The method for calculating the viscosity, which is the characteristic value described above, is to measure the degree of thickening when the ink near the nozzle is thickened due to water evaporation in an image forming apparatus using an on-demand ink jet method, for example. It is effective when used to do. Moisture evaporation at the nozzle occurs even on a very short time scale of 1 second or less, and it is very local, so it was not easy to measure with the conventional method. However, according to the characteristic value acquisition method using the energization feature amount described here, the presence or absence and the degree of thickening due to solvent evaporation are measured with a simple device for the local ink in the nozzle portion. Based on the result, it is possible to optimize the ink discharge operation by ink flushing, pressurization / suction, and the like, and wasteful ink and power consumption can be avoided.

  Depending on the properties of the recording liquid, it is possible to change the type of energizing feature amount for acquiring the characteristic value, the method of acquiring the characteristic value, the type of characteristic value, and the like as follows.

  Using the measurement environment described above, a liquid in which 2% by weight of tetramethylammonium nitrate is dissolved in water is used as the liquid. The result of measuring the quantity is shown in FIG.

  From the figure, it can be seen that the tetramethylammonium nitrate mass ratio in the nozzle portion increases as the water is dried, and the electrical conductivity is improved, and the amount of electrified charge is improved as a whole. From this result, it can be seen that it is possible to adopt a method of measuring and acquiring the conductivity of the discharged liquid as a characteristic value from the ratio with the initial energized charge amount.

  The example shown in FIG. 14 is measured for a case where a simple electrolyte aqueous solution is used as the liquid to be discharged. The measurement method obtained from this example discharges a small amount of polymer and fine particles in exactly equal amounts. It is also possible to apply to the purpose.

  For example, when the amount of the dissolved or dispersed material in the solvent is small, the concentration greatly changes due to drying, but the viscosity often hardly changes. In this case, the viscosity is used as a characteristic value. It is not preferable. However, if the above-described measurement method is used, it is possible to measure a change in the concentration of a solute, that is, a dissolved substance, using an index called conductivity, and the conductivity can be measured and acquired as a characteristic value.

  This is not possible with the conventional method already described. Further, when using this measurement method for such a purpose, it is also effective to previously contain a trace amount of electrolyte in the liquid to be measured.

  It is also possible to calculate and acquire a plurality of characteristic values from a plurality of energization feature amounts. For example, it is possible to calculate and acquire the viscosity and the surface tension as the characteristic values using feature amounts such as the average current amount, the maximum current amount, and the energization time.

  However, since the relationship between the energization feature quantity and the liquid characteristics strongly depends on the ejection liquid and the ejection conditions, the energization feature quantity in advance is considered for changes that may occur in the ejection liquid, such as thickening due to drying and changes in density due to drying. It is necessary to measure the change and store it in the control unit 98 functioning as a characteristic value acquisition unit.

  It is also possible to acquire the characteristic value based on the energization feature amount measured for the drive signals generated with a plurality of types of drive waveforms. In the examples shown in FIGS. 12 and 13, there is a good one-to-one relationship between the energization feature amount and the viscosity range shown in the figure. However, such a relationship does not necessarily hold for a wide range of viscosities.

  Therefore, it is more preferable to probe using a plurality of drive waveforms as a method that can correspond to a wider range of liquid characteristics and calculate and acquire the characteristic values. As described above, the head drive circuit 92 can generate a drive signal for controlling on / off of the discharge of the recording liquid as required, and can generate a plurality of drive waveforms.

  For example, the head drive circuit 92 can generate a plurality of drive waveforms by changing the pulse width PW of the drive waveform. FIG. 15 shows an example in which the energization feature amount T1-PW using the difference between the energization start time T1 and the pulse width PW is measured for the drive waveforms having a plurality of pulse widths PW. In the example shown in the figure, the viscosity is acquired as the characteristic value.

  From the figure, for each of the viscosity μ1, μ2, and μ3 (μ1 <μ2 <μ3), a value that minimizes T1−PW is adopted as the energization feature value, and this is used as the viscosity that is the characteristic value. It can be seen that the viscosity can be calculated more accurately over a wide viscosity range.

  The characteristic value can be acquired by various methods as described above. Then, maintenance of the head and the nozzle can be performed using the acquired characteristic value. An example in which the maintenance using the characteristic value is performed in the image forming apparatus 100 will be described with reference to FIG.

  This figure simply shows the nozzle maintenance process flow immediately before using the apparatus. This maintenance process is assumed to be performed immediately before use, for example, with respect to the heads 61Y, 61M, 61C, and 61BK that have been left in a capped state without using the image forming apparatus 100 for a while.

  In this nozzle maintenance process, an initialization operation is first performed (S1). This operation initializes the positions of the heads 61Y, 61M, 61C, and 61BK and the positions of the capping members, and causes the heads 61Y, 61M, 61C, and 61BK to perform a predetermined ejection operation, and to some extent from the heads 61Y, 61M, 61C, and 61BK. An operation of discharging the recording liquid is performed.

  Next, as a liquid characteristic measurement in which a predetermined voltage is applied by the power source 33a and the recording liquid is ejected from the heads 61Y, 61M, 61C, 61BK, the energization feature amount is measured, and the viscosity is obtained as the characteristic value of the recording liquid. The liquid physical properties are measured (S2).

  Since the heads 61Y, 61M, 61C, 61BK have a plurality of nozzles 61b, all the nozzles 61b are sequentially ejected to measure liquid characteristics. However, the discharge from the plurality of nozzles 61b may be performed synchronously. The measurement result is held in the memory of the control unit 98. In this respect, the control unit 98 functions as a characteristic value storage unit. After measuring the liquid characteristics, the power source 33a is turned off.

  For the maintenance process shown in the figure, two-stage maintenance conditions using two threshold values relating to characteristic values are prepared. First, a value relating to a characteristic value as a liquid characteristic measurement result is less than or equal to a first threshold value. It is determined whether or not there is (S3), and if it exceeds the first threshold value, the first maintenance operation (S4) is performed, and step S2 is performed again.

  As the first maintenance operation, the inside of the capping member 72 is depressurized by the tubing pump 74 and the recording liquid is sucked from the heads 61Y, 61M, 61C, 61BK. If necessary, a wiping operation for wiping the recording liquid adhering to the nozzle surface 61 d by driving the wiping mechanism 94 may be performed.

  When it is determined in step S3 that the value related to the characteristic value is less than or equal to the first threshold value, it is determined whether or not the value related to the characteristic value is less than or equal to the second threshold value (S5), and the second threshold value is set. If it exceeds, the second maintenance operation is performed, and step S2 is performed again.

  If it is determined in step S5 that the value related to the characteristic value is equal to or smaller than the second threshold value, the process ends without performing the maintenance operation.

  The first threshold value and the second threshold value are set as conditions such as whether or not there are a predetermined number or more of nozzles that discharge a liquid having a predetermined viscosity or higher from the liquid characteristic measurement result, for example.

  As the second maintenance operation, a predetermined number of ejection operations are performed from the heads 61Y, 61M, 61C, 61BK, and an operation of discharging the thickened recording liquid is performed. Also in this case, if necessary, a wiping operation for wiping the recording liquid adhering to the nozzle surface 61d by driving the wiping mechanism 94 may be performed.

  In the first maintenance operation and the second maintenance operation, the former has a higher nozzle recovery function although the amount of recording liquid discharged is larger. Therefore, a large value is used for the first threshold value for the first threshold value and the second threshold value.

  These maintenance operations may be continued a plurality of times until the result of the liquid property measurement in step S2 finally satisfies the conditions for the first threshold value and the second threshold value. At this time, the number of maintenance operations is counted, and an error is displayed when the liquid property measurement result does not improve to meet the above conditions in spite of many maintenance operations.

  With the above maintenance process, maintenance is performed while constantly measuring the state of the recording liquid and the liquid characteristics of the nozzle portion, so that the unnecessary recording liquid is prevented from being discharged and efficient maintenance is performed. Further, since it is possible to prevent problems such as non-ejection of the recording liquid, a high-quality image forming apparatus having high stability with respect to image formation can be obtained.

  The maintenance processing operation is not limited to the method described here, and it is possible to prepare a multi-stage maintenance operation, and it is also possible to periodically measure the liquid characteristics during the maintenance operation.

  The acquired characteristic values are used not only for determining whether maintenance is necessary, but also for determining the deterioration of the recording liquid, and in addition to this, in order to prompt the replacement of the recording liquid when it is determined that the recording liquid is deteriorated May be used.

  In the image forming apparatus 100 described above, the metal mesh 71 is used as a receiver. However, as shown in FIG. 17, the receiver may be an intermediate transfer member 37 that is a conductive roller. In this case, the liquid property measuring apparatus 70 shown in FIG. 3 can be omitted, and the structure of the apparatus can be simplified, downsized, and inexpensive. Further, the energization means 33 can be used for obtaining characteristic values, and this also makes it possible to simplify the structure of the apparatus, reduce the size, and reduce the cost.

  Further, since it becomes unnecessary to move the heads 61Y, 61M, 61C, 61BK to a position facing the metal mesh 71, the carriage driving device 91 can be omitted, and the structure of the device can be simplified and reduced in size. Cost reduction is possible. When the carriage driving device 91 is omitted, the image forming apparatus 100 may be a full line type.

  In order to discharge the recording liquid for measuring the energization feature amount to the intermediate transfer body 37, it is necessary to clean the intermediate transfer body 37. For this, the cleaning device 40 can be used. Therefore, even if the intermediate transfer member 37 is used as a receiver, it is possible to avoid the complexity, size and cost of the apparatus structure. By cleaning the intermediate transfer member 37, it is possible to continuously acquire characteristic values.

  Further, since the receding contact angle of the surface of the intermediate transfer member 37 is set to be smaller than the receding contact angle of the nozzle surface 61d and larger than the receding contact angle of the cleaning blade 41, it adheres to the nozzle surface 61d. As the recording liquid moves to the surface of the intermediate transfer body 37, the recording liquid discharged to the intermediate transfer body 37 to acquire the characteristic value also moves from the surface of the intermediate transfer body 37 to the cleaning blade 41, and the nozzle surface 61d is cleaned. And the surface of the intermediate transfer member 37 is clean. Therefore, the characteristic value is accurately acquired.

  FIG. 18 shows another configuration example of the image forming apparatus 100. In this image forming apparatus 100, the same components as those provided in the image forming apparatus 100 shown in FIG. 1 are denoted by the same reference numerals and description thereof will be omitted as appropriate, and the image forming apparatus 100 shown in FIG. Differences will be mainly described.

  The image forming apparatus 100 shown in FIG. 18 does not include the intermediate transfer body 37 and the transfer roller 38 included in the image forming apparatus 100 shown in FIG. 1, and is a full-line type head 61Y, 61M, 61C, This is a direct image forming apparatus that directly forms an image on the transfer sheet S at the recording liquid ejection portion 53 in which 61BK and the guide plate 39 face each other.

  In the image forming apparatus 100 shown in FIG. 18, the liquid characteristic measuring device 70 is located on the downstream side of the discharge unit 53 in the conveyance direction of the recording paper S. Accordingly, the maintenance position where the heads 61Y, 61M, 61C, 61BK are opposed to the liquid characteristic measuring device 70 is also downstream of the ejection unit 53 in the conveyance direction of the recording paper S.

  The carriage driving device 91 has a screw shaft 32a that extends along the conveying direction and is screwed to the carriage 62, and a motor 32b that drives the screw shaft 32a to rotate forward and backward. By displacing to the position shown, the heads 61Y, 61M, 61C, 61BK are displaced to the maintenance position.

  In the capping drive device 93, when the heads 61Y, 61M, 61C, 61BK occupy the maintenance position, the upper end portion of the capping member 72 provided in the liquid property measuring device 70 is formed by the nozzle 61b of the nozzle plate 61a. The capping member 72 is raised to the contact position where it comes into contact with the position where it has not been touched. In other cases, the capping driving device 93 is located at a position higher than the abutting position so that the capping member 72 does not abut on the transfer sheet S conveyed toward the paper discharge table 25 via the discharge unit 53. Position it in the lower, retracted position.

  The heads 61 </ b> Y, 61 </ b> M, 61 </ b> C, 61 </ b> BK form images on the transfer paper S by ejecting recording liquids of the respective colors while moving relative to the transfer paper S, which is a medium transported through the ejection unit 53. The heads 61Y, 61M, 61C, and 61BK may be of a shuttle type. In this case, the recording liquid of each color is ejected while moving on the transfer paper S that is a medium to form an image on the transfer paper S.

In the image forming apparatus 100 having such a configuration, one transfer sheet S fed from the sheet feeding unit 20 is fed toward the discharge unit 53 in response to the input of a predetermined signal to start image formation. The The transfer sheet S is supplied to the discharge unit 53 via the conveyance roller 32, and in the process of passing through the discharge unit 53, each head 61Y, so that the image areas of each color of yellow, magenta, cyan, and black overlap each other. From 61M, 61C, and 61BK, yellow, magenta, cyan, and black recording liquids are ejected in such a manner that the recording liquid is sequentially overlapped from the upstream side to the downstream side in the transport direction to form an image.
The transfer paper S that has passed through the pressure application unit 70 is guided to the paper discharge tray 25 and stacked on the paper discharge tray 25.

  The control unit 98 stores, in the memory, the above-described heads 61Y, 61M, 61C, 61BK to which voltage is applied and the metal mesh 71 or the intermediate transfer member 37 that receives the recording liquid discharged from the heads 61Y, 61M, 61C, 61BK. The maximum current amount, the charge amount, and the energization start time from when the drive signal for ejecting the recording liquid is issued until the energization is started are measured. Recording based on an energization feature amount that is at least one of an energization stop time from when the drive signal is issued until the energization stops and an energization continuation time from the energization start time to the energization stop time. A liquid characteristic measurement program for executing a liquid characteristic measurement method for acquiring a liquid characteristic value is stored. In this respect, the control unit 98 or the memory functions as a liquid characteristic measurement program storage unit. Such a liquid property measurement program includes not only a memory provided in the control unit 98 but also a semiconductor medium (eg, RAM, nonvolatile memory, etc.), an optical medium (eg, DVD, MO, MD, CD-R, etc.), magnetic It can be stored in a medium (for example, a hard disk, a magnetic tape, a flexible disk, etc.) or other storage medium. When such a liquid characteristic measurement program is stored in such a memory or other storage medium, the liquid characteristic measurement program is stored. The computer-readable recording medium is configured.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

For example, the liquid characteristic measuring method, the liquid characteristic measuring apparatus, and the liquid ejecting apparatus according to the present invention are not only applied to an image forming apparatus, but also a patterning device for manufacturing a fine wiring pattern and a color filter for a liquid crystal display. The present invention may be applied to a processing apparatus or the like, or may be applied to an independent liquid property measuring apparatus or liquid ejection apparatus.
The liquid ejected from the head is not limited to the recording liquid used for image formation, but may be any liquid such as that used in such a processing apparatus.

The intermediate transfer member may not be a roller but may be an endless belt.
The image forming apparatus to which the present invention is applied is not limited to the above-mentioned type of image forming apparatus, but other types of image forming apparatuses, that is, a copying machine, a single facsimile, or a complex machine thereof, or a monochrome machine related thereto. In addition, an image forming apparatus used for forming an electric circuit or an image forming apparatus used for forming a predetermined image in the biotechnology field may be used.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

33a Voltage application means 37 Intermediate transfer body, receptor 38 Transfer means 40 Cleaning means 41 Cleaning blade 61Y, 61M, 61C, 61BK Head 61a Nozzle plate 70 Liquid characteristic measuring device 71 Receptor, mesh structure 92 Drive signal generation means 98 Feature quantity Measuring means, characteristic value acquisition means 100 Image forming apparatus, liquid ejection apparatus

JP 2004-174773 A JP 2005-125593 A Japanese Patent No. 4273895 JP 2011-46091 A Japanese Patent No. 4407701 Japanese Patent No. 3697209 JP 2010-214664 A JP 2010-188665 A

Claims (11)

A maximum current amount, a charge amount, and a drive signal for discharging the liquid, measured for a current flowing through the liquid that bridges between a head to which a voltage is applied and a receiver that receives the liquid discharged from the head. Energization start time from when the energization is started until energization is started, energization stop time from when the drive signal is issued until energization stops, and energization continuation time from the energization start time to the energization stop time And a liquid property measurement method for obtaining a viscosity or conductivity as a property value of the liquid based on an energization feature amount that is at least two of the above. The liquid property measuring method according to claim 1,
When the characteristic value is the viscosity,
The liquid property measuring method, wherein the viscosity is acquired using at least one of the energization start time, the energization stop time, and the energization duration as the energization feature amount. A head for discharging liquid;
A receiver for receiving the liquid discharged from the head;
Voltage applying means for applying a voltage between the head and the receiver;
Drive signal generating means for generating a drive signal for discharging liquid from the head;
The maximum current amount, the charge amount, and the drive signal measured for the current flowing in the liquid ejected from the head, bridged between the head to which the voltage is applied by the voltage applying means and the receptor. The energization start time from when the drive signal for discharging the liquid is generated by the generating means until the start of energization, the energization stop time from when the drive signal is issued until the energization is stopped, and the energization start A feature amount measuring means for measuring an energization feature amount that is at least two of the energization duration time from the time to the energization stop time; and
A liquid characteristic measuring device comprising: characteristic value acquisition means for acquiring viscosity or conductivity as a characteristic value of the liquid based on the energization characteristic quantity measured by the characteristic quantity measurement means. In the liquid property measuring apparatus according to claim 3,
The drive signal generation means can generate the drive signal with a plurality of types of drive waveforms,
The characteristic value acquisition means acquires viscosity or conductivity as the characteristic value based on the energization characteristic quantity for the plurality of types of drive waveforms measured by the characteristic quantity measurement means. apparatus. In the liquid characteristic measuring apparatus according to claim 3 or 4,
The liquid property measuring apparatus according to claim 1, wherein a portion of the receiver that receives the liquid discharged from the head has a mesh structure. In the liquid characteristic measuring device according to any one of claims 3 to 5,
An apparatus for measuring liquid characteristics, comprising: cleaning means for removing liquid ejected from the head attached to the receptor. In the liquid characteristic measuring apparatus according to claim 6,
The receding contact angle of the receiver is smaller than the receding contact angle of the nozzle plate provided in the head, and the cleaning means is provided in the cleaning means and abuts against the acceptor to remove the liquid adhering to the acceptor. A liquid property measuring apparatus characterized by being larger than a receding contact angle of a member.   A liquid ejecting apparatus comprising the liquid property measuring apparatus according to claim 3. Using the liquid property measuring method according to claim 1 or 2, the liquid property measuring device according to any one of claims 3 to 7, or the liquid ejection device according to claim 8, as the property value. An image forming apparatus that acquires viscosity or conductivity . The image forming apparatus according to claim 9 .
An image forming apparatus characterized in that maintenance of the head is performed in accordance with viscosity or conductivity as the characteristic value. The image forming apparatus according to claim 9 or 1 0 Symbol mounting,
An intermediate transfer member to which the liquid discharged from the head is applied;
Transfer means for transferring the liquid applied to the intermediate transfer body to the recording medium,
An image forming apparatus, wherein the intermediate transfer member is the receiver.

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