JP6931488B2 - Liquid discharge device and liquid exchange method - Google Patents

Description

The present invention relates to a device for discharging a liquid and a method for exchanging the liquid.

Conventionally, there are known devices that supply liquid from a common supply flow path to a plurality of liquid discharge units through a plurality of individual supply flow paths and discharge the liquid from each liquid discharge unit.

For example, in Patent Document 1, ink (liquid) is supplied from an ink supply path (common supply flow path) to a plurality of head units (liquid ejection units) through a plurality of individual flow paths (individual supply flow paths), and each head An image forming apparatus for ejecting ink from a unit is disclosed.

In a conventional liquid discharging device, the filled liquid may be replaced with another liquid. Specifically, by discharging the liquid before replacement and supplying the new liquid after replacement from the common supply flow path, all the liquids in the common supply flow path, the individual flow paths, and the liquid discharge unit can be replaced. Replace the previous liquid with the replaced liquid. However, when the specific densities of the liquid before replacement and the liquid after replacement are different, the amount of liquid after replacement is large before the liquid before replacement is replaced with the liquid after replacement, and the liquid after replacement is large. There was a problem of wasting.

In order to solve the above-mentioned problems, the present invention is a device for supplying a liquid from a common supply flow path to a plurality of liquid discharge units through a plurality of individual supply flow paths and discharging the liquid from each liquid discharge unit. When exchanging a large specific gravity liquid having a large specific gravity in the common supply flow path, the individual supply flow path, and the liquid discharge unit with a small specific gravity liquid having a small specific gravity, the individual supply is connected to a relatively high connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion is larger than the amount of liquid discharged from the liquid discharge unit corresponding to the flow path. , It is characterized by performing a liquid exchange operation.

According to the present invention, even if the liquid before replacement and the liquid after replacement have different specific densities, the liquid after replacement is wasted before the liquid before replacement is replaced with the liquid after replacement. Can be suppressed.

Explanatory drawing which shows the whole structure of the image forming apparatus of embodiment. Explanatory drawing which shows an example of the preprocessing part in the image forming apparatus. The explanatory view which shows an example of the drying part for pretreatment in the image forming apparatus. (A) is a schematic plan view showing an example of four recording head units constituting the image forming unit in the image forming apparatus. (B) is a schematic plan view illustrating one of four head units constituting a black (K) recording head unit. (A) is a schematic cross-sectional view when a part of the head unit is cut along the longitudinal direction of the liquid chamber. (B) is a schematic cross section when a part of the head unit is cut along the cross section shown in SC1 of FIG. 5A, that is, the direction orthogonal to the longitudinal direction of the liquid chamber (nozzle arrangement direction). figure. (A) is a front view showing an example in which a post-treatment liquid is applied to a recording medium on which an image is formed. (B) is a cross-sectional view in the thickness direction of the recording medium showing an example in which the post-treatment liquid is applied to the recording medium on which the image is formed. The block diagram which shows an example of the whole structure of the control part which controls the operation of the image forming apparatus in embodiment. The block diagram which shows an example of the higher-order device which comprises the control part. The block diagram which shows an example of the printer apparatus which comprises the control part. The block diagram which shows an example of the data management part in the printer apparatus. The block diagram which shows an example of the image output part in the printer apparatus. FIG. 5 is a cross-sectional view of the entire head unit according to the embodiment when the entire head unit is cut along a nozzle row. FIG. 5 is a cross-sectional view when the entire head unit is cut along the cross section indicated by reference numeral AA in FIG. The explanatory view which shows the ink supply system of the black (K) recording head part which mounted four head units. Illustrations depicting the way of a conventional ink replacement operation when towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is greater (ρ _{0 <ρ 1).} Explanatory drawing which shows an example of the common supply flow path of embodiment. If direction of gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is greater flowchart showing a flow of ink replacement operation of an embodiment in (ρ _{0 <ρ 1).} Flowchart showing a flow of ink replacement operation of an embodiment in the case towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _0> ρ _1). The explanatory view which shows an example of the common supply flow path of the modification 1. FIG. The explanatory view which shows an example of the common supply flow path of the modification 2. If direction of gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is greater flowchart showing a flow of ink replacement operation of the second modification of the (ρ _{0 <ρ 1).}

Hereinafter, the image forming apparatus 100, which is an embodiment of the apparatus for discharging the liquid according to the present invention, will be described with reference to the drawings.
In the present embodiment, an image including a recording head unit that ejects four colors of ink, black (K), cyan (C), magenta (M), and yellow (Y), and forming an image made of ink on a recording medium. Take the forming device as an example. However, the image forming apparatus to which the present invention can be applied is not limited to this. For example, those further provided with a recording head unit corresponding to inks of green (G), red (R), light cyan (LC) and / or other colors, or only a recording head unit corresponding to black (K) ink. For example, those equipped with. In the following description, the symbols with the subscripts K, C, M, and Y correspond to black, cyan, magenta, and yellow, respectively.

In the present embodiment, continuous paper rolled into a roll (hereinafter referred to as "roll paper Md") is used as the recording medium, but the recording medium on which the image forming apparatus according to the present invention can form an image is a recording medium. Not limited to roll paper. That is, the recording medium on which the image forming apparatus according to the present invention can form an image may be cut paper. The recording medium on which an image can be formed by using the image forming apparatus according to the present invention includes plain paper, high-quality paper, thin paper, thick paper, recording paper and roll paper, as well as transparencies, synthetic resin films, and metals. Includes thin films and other surfaces that can form images with ink or the like. Here, the roll paper is a continuous paper (continuous paper, continuous form) in which cutable perforations are formed at predetermined intervals. Further, the page (page) on the roll paper is, for example, an area sandwiched between perforations at predetermined intervals.

As shown in FIG. 1, the image forming apparatus 100 of the present embodiment includes a carry-in unit 10 for carrying in roll paper Md, a pretreatment unit 20 for pretreating the carried-in roll paper Md, and a pretreated roll paper. It has a drying portion 30 for drying Md. Further, the image forming apparatus 100 comprises an image forming unit 40 that forms an image on the surface of the roll paper Md, a post-processing unit 50 that post-processes the roll paper Md on which the image is formed, and a post-processed roll paper Md. It has a carry-out unit 60 for carrying out. Further, the image forming apparatus 100 has a control unit 70 (see FIG. 7) described later that controls the operation of the image forming apparatus 100.

The image forming apparatus 100 according to the present embodiment carries in the roll paper Md by the carry-in unit 10, and pretreats and dries the surface of the roll paper Md by the pretreatment unit 20 and the drying unit 30. Further, the image forming apparatus 100 forms an image on the surface of the roll paper Md after pretreatment and drying by the image forming unit 40. Further, in the present embodiment, the image forming apparatus 100 post-processes the roll paper Md on which the image is formed by the post-processing unit 50. After that, the image forming apparatus 100 winds up the roll paper Md by the carry-out unit 60.

Hereinafter, each configuration of the image forming apparatus 100 according to the embodiment of the present invention will be specifically described.
The image forming apparatus capable of using the present invention may be configured not to include any one or more of the preprocessing unit 20 and the like, which will be described later, depending on the type of recording medium on which the image is formed. ..

The carry-in unit 10 conveys the recording medium to the pre-processing unit 20 and the like. In this embodiment, the carry-in unit 10 is composed of a paper feed unit 11 and a plurality of transfer rollers 12 and the like. The carry-in unit 10 uses a transport roller 12 or the like to carry in the roll paper Md wound around the paper feed roll of the paper feed unit 11 and held, and conveys the roll paper Md to the pretreatment unit 20 or the like, which will be described later, using a platen or the like.

The preprocessing unit 20 processes the recording medium before the image is formed. In the present embodiment, the pretreatment unit 20 pretreats the surface of the roll paper Md carried in by the carry-in unit 10 with the pretreatment liquid. The pretreatment of the present embodiment is a treatment of uniformly applying a pretreatment liquid described later, which has a function of aggregating ink, onto the surface of a roll paper Md (recording medium). As a result, when the image forming apparatus 100 forms an image on an inkjet type special paper or a recording medium other than the special paper, the preprocessing unit 20 is used to aggregate the ink before forming the image on the recording medium. A pretreatment liquid having a function can be attached to the surface of the recording medium. As a result, the image forming apparatus 100 can reduce the occurrence of quality problems such as blurring, density, color tone and show-through of the formed image, and problems related to water resistance, weather resistance and other image fastness. can. Therefore, the quality of the image formed thereafter can be improved.

FIG. 2 is an explanatory diagram showing an example of the preprocessing unit 20.
As shown in FIG. 2, the pretreatment unit 20 applies the stored pretreatment liquid 20L to the surface of the roll paper Md carried into the pretreatment unit 20 by the carry-in unit 10 by using the roll coating method. .. Specifically, the pretreatment unit 20 first transfers the pretreatment liquid 20L to the surface of the coating roller 23 in the form of a thin film by the stirring roller 21 and the thinning roller 22. The coating roller 23 rotates while being pressed against the rotating platen roller 24, and conveys the roll paper Md to the gap between the coating roller 23 and the platen roller 24 to apply the pretreatment liquid 20L to the surface of the roll paper Md. ..

The pretreatment unit 20 uses the pressure adjusting device 25 to control the nip pressure (the pressure acting at the position where the coating roller 23 and the platen roller 24 come into contact) when the pretreatment liquid 20L is applied. Further, the pretreatment unit 20 may control the rotation speeds of the coating roller 23 and the platen roller 24. As a result, the pretreatment unit 20 can change the rotation speed of the coating roller 23 and the like, and in addition to changing the nip pressure using the pressure adjusting device 25, the coating amount (thickness, liquid) of the pretreatment liquid 20L The amount, adhesion amount, dry adhesion amount, etc.) can be controlled with higher accuracy. Therefore, it is possible to apply 20 L of the pretreatment liquid to the surface of the roll paper Md (recording medium) with a coating amount suitable for the subsequent image formation and post-treatment.

The drying unit 30 dries the recording medium by heating or the like. As shown in FIG. 1, the drying section 30 of the present embodiment includes a pretreatment drying section 31 for drying the roll paper Md pretreated by the pretreatment section 20, and a roll paper post-treated by the post-treatment section 50. It is composed of a post-treatment drying unit 32 for drying Md. The pretreatment drying section 31 and the post-treatment drying section 32 of the present embodiment are both dried using the heat rollers 31h and 32h.

The pretreatment drying unit 31 heats the heat roller 31h to, for example, 40 to 100 ° C., and conveys the surface of the roll paper Md coated with the pretreatment liquid while bringing it into contact with the heat roller 31h. As a result, the pretreatment drying unit 31 can evaporate the moisture of the pretreatment liquid adhering to the surface of the roll paper Md and dry the roll paper Md (pretreatment liquid).

FIG. 3 is an explanatory view showing an example of the pretreatment drying unit 31.
In the pretreatment drying unit 31 of the present embodiment, in order to enhance the drying effect, it is preferable to provide a plurality of heat rollers 31 to 316 in multiple stages as shown in FIG. If the drying strength is to be weakened in this configuration, the heat roller temperature may be lowered. For example, the temperature is about 40 to 80 ° C. Further, some heat rollers (for example, only the heat roller 311 and the heat roller 312) may be heated, and the other heat rollers may not be heated. On the contrary, in order to increase the drying strength, the number of heat rollers used may be increased or the temperature of the heat rollers may be increased. In this way, it is possible to control the drying strength by changing the temperature and / or the number of heat rollers used.

The pretreatment drying unit 31 is not limited to the method of drying with a heat roller. For example, the pretreatment drying unit 31 can use infrared drying, microwave drying, warm air drying, and other drying methods. Further, the pretreatment drying unit 31 may use a drying method that combines a plurality of drying methods. Further, the pretreatment drying unit 31 may heat the roll paper Md (recording medium) before the pretreatment unit 20 applies the pretreatment liquid (preheating step).

Since the configuration of the post-treatment drying unit 32 is the same as the configuration of the pretreatment drying unit 31, the description thereof will be omitted.

The image forming unit 40 forms an image on a recording medium. In the present embodiment, the image forming unit 40 employs an inkjet recording method for forming an image on the surface of the roll paper Md by ejecting ink onto the roll paper Md dried by the pretreatment drying unit 31. There is.

FIG. 4A is a schematic plan view showing an example of four recording head units 40K, 40C, 40M, and 40Y constituting the image forming unit 40 in the present embodiment.
FIG. 4B is a schematic plan view illustrating one of the four head units 40K-1, 40K-2, 40K-3, and 40K-4 constituting the black (K) recording head unit 40K. be.
As shown in FIG. 4A, a full-line type recording head unit can be used as the image forming unit 40. In the image forming unit 40 of the present embodiment, four recording head units 40K and 40C corresponding to black (K), cyan (C), magenta (M) and yellow (Y) from the upstream side in the transport direction Xm of the recording medium. , 40M, 40Y are arranged.

The black (K) recording head unit 40K has four head units 40K-1, 40K-2, 40K-3, and 40K-4 arranged in a staggered manner in a direction orthogonal to the transport direction Xm of the roll paper Md. .. As a result, the image forming unit 40 can form an image in the entire width direction (direction orthogonal to the conveying direction) of the image forming area (printing area) of the roll paper Md (recording medium).

As shown in FIG. 4B, the head unit 40K-1 includes nozzles 40n, which are a plurality of ejection ports, on the nozzle surface (the outer surface of the nozzle plate 43 shown in FIG. 5A described later). Here, the plurality of nozzles 40n are arranged in a row along the longitudinal direction of the head unit 40K-1 to form a nozzle row. The head unit 40K-1 may include a plurality of nozzle rows.

FIG. 5A is a schematic cross-sectional view when a part of the head unit 40K-1 is cut along the longitudinal direction of the liquid chamber 40f.
FIG. 5B shows a part of the head unit 40K-1 cut along a cross section shown in SC1 of FIG. 5A, that is, a direction orthogonal to the longitudinal direction of the liquid chamber 40f (nozzle arrangement direction). It is a schematic cross-sectional view at the time of.
As shown in FIG. 5A, the head unit 40K-1 is joined to the flow path plate 41 forming the flow path of the ink to be ejected and the lower surface of the flow path plate 41 in the drawing (inward direction of the head unit). The diaphragm 42 is provided with a nozzle plate 43 joined to the upper surface of the flow path plate 41 in the drawing (outward direction of the head unit), and a frame member 44 for holding the peripheral edge of the diaphragm 42. Further, the head unit 40K-1 has a pressure generating portion 45 for deforming the diaphragm 42.

In the head unit 40K-1 of the present embodiment, the flow path plate 41, the diaphragm 42, and the nozzle plate 43 are laminated so that the nozzle communication passage 40r and the liquid chamber 40f, which are flow paths communicating with the nozzle 40n, are formed. It is formed. Further, the head unit 40K-1 has an ink inflow port 40s for supplying ink to the liquid chamber 40f by further laminating the frame member 44, a common liquid chamber 40c for supplying ink to the liquid chamber 40f, and a pressure. An accommodating portion for accommodating the generating portion 45 and an ink supply port 40i for supplying ink from the outside of the head unit to the common liquid chamber 40c are formed.

Further, the head unit 40K-1 can deform (deflect) the diaphragm 42 by using the pressure generating unit 45. As a result, the head unit 40K-1 can change the volume of the liquid chamber 40f and change the pressure acting on the ink in the liquid chamber 40f. As a result, the head unit 40K-1 can eject ink from the nozzle 40n.

An electromechanical conversion element can be used as the pressure generating unit 45. In the present embodiment, the pressure generating portion 45 includes a piezoelectric element 45p which is an electromechanical conversion element, a base substrate 45b for joining and fixing the piezoelectric element 45p, and a strut portion arranged in a gap between adjacent piezoelectric elements 45p. ing. Further, the pressure generating unit 45 includes an FPC cable 45c or the like for connecting the piezoelectric element 45p to the drive circuit (drive IC).

As the piezoelectric element 45p, as shown in FIG. 5B, a laminated piezoelectric element (PZT) in which the piezoelectric material 45pp and the internal electrode 45pe are alternately laminated can be used. The internal electrode 45pe is composed of a plurality of individual electrodes 45pei and a plurality of common electrodes 45pec. In the present embodiment, the internal electrodes 45pe are alternately connected to the end faces of the piezoelectric material 45pp with individual electrodes 45pei or common electrodes 45pec.

Further, in the embodiment, the piezoelectric element 45p uses the d33 direction as the piezoelectric direction of the piezoelectric material 45pp. As a result, the pressure generating unit 45 can pressurize or depressurize the ink in the liquid chamber 40f by using the piezoelectric effect (displacement in the d33 direction) of the piezoelectric element 45p. The pressure generating unit 45 may pressurize or depressurize the ink in the liquid chamber 40f by using the displacement of the piezoelectric element 45p in the d31 direction. Further, the pressure generating unit 45 may arrange a row of piezoelectric elements for one nozzle 40n. The strut portion may be formed at the same time as the piezoelectric element 45p by dividing the piezoelectric element member (piezoelectric element 45p). That is, in the head unit 40K-1, the piezoelectric element member can be used as the support column portion by not applying a voltage to the piezoelectric element.

The operation of ejecting ink from the nozzle 40n (pull-pushing operation) will be specifically described below.
First, the head unit 40K-1 lowers the voltage applied to the piezoelectric element 45p (pressure generating portion 45) from the reference potential, reduces the piezoelectric element 45p in the stacking direction, and bends and deforms the diaphragm 42. As a result, the volume of the liquid chamber 40f is expanded (expanded), and ink flows from the common liquid chamber 40c into the liquid chamber 40f. Next, the head unit 40K-1 raises the voltage applied to the piezoelectric element 45p to extend the piezoelectric element 45p in the stacking direction. As a result, the diaphragm 42 is deformed in the nozzle 40n direction, and the volume of the liquid chamber 40f is reduced (contracted). As a result, pressure is applied to the ink in the liquid chamber 40f, and the ink is ejected (jetted) from the nozzle 40n. After that, the voltage applied to the piezoelectric element 45p is returned to the reference potential, and the diaphragm 42 is returned (restored) to the initial position. Due to the expansion of the liquid chamber 40f at this time, the inside of the liquid chamber 40f is depressurized, and ink is filled (replenished) from the common liquid chamber 40c into the liquid chamber 40f. Next, after the vibration of the meniscus surface of the nozzle 40n is attenuated (stable), the operation proceeds to the next operation for ejecting ink, and the above operation is repeated.

The driving method of the head unit 40K-1 is not limited to the above-mentioned example (pull-pushing). That is, the recording head unit can be driven by pulling or pushing by controlling the voltage (driving waveform) applied to the piezoelectric element 45p.
Further, the pressure generating unit 45 is not limited to the above example (piezoelectric element 45p). That is, the pressure generating unit 45 uses a method (so-called thermal type) in which the ink in the liquid chamber 40f is heated using a heat generating resistor to generate bubbles (see, for example, Japanese Patent Application Laid-Open No. 61-59911). You may. Further, the pressure generating unit 45 is a method in which the diaphragm and the electrode are arranged to face each other on the wall surface of the liquid chamber 40f, and the diaphragm is deformed by the electrostatic force generated between the diaphragm and the electrode (so-called electrostatic type). (For example, see JP-A-6-71882).

Since the configurations and operations of the other head units 40K-2, 40K-3, and 40K-4 are the same as those of the above-mentioned head unit 40K-1, the description thereof will be omitted.
Further, since the configurations and operations of the other recording head units 40C, 40M, and 40Y are the same as the configurations of the black (K) recording head unit 40K, the description thereof will be omitted.

As described above, the image forming apparatus 100 of the present embodiment uses the image forming unit 40 (four recording head units 40K, 40C, 40M, 40Y) to carry the recording medium (roll paper Md) once. A black-and-white or full-color image can be formed over the entire image forming region.

Further, in the image forming apparatus 100 of the present embodiment, a test pattern is created in order to determine whether or not maintenance is necessary at a time different from that at the time of printing, for example, before printing. As test patterns, a test pattern for detecting the ejection clogging of each color of the image forming unit 40 and a test pattern for detecting the ejection clogging of the post-processing unit 50 are created. In order to detect ejection clogging of the post-processing unit 50, for example, the image forming unit 40 preferably forms a solid image of any one color.

The post-processing unit 50 processes the recording medium after the image is formed. In the present embodiment, the post-treatment unit 50 post-treats the surface of the roll paper Md on which the image is formed by the image forming unit 40 with the post-treatment liquid. The post-treatment of the present embodiment is a process of applying (discharging) the post-treatment liquid onto the roll paper Md (recording medium). The post-treatment liquid is formed in a shape such as a spot shape or a striped shape. As a result, the recording medium on which the image is formed can improve scratch resistance, glossiness, storage stability (water resistance, light resistance, gas resistance, etc.) and the like.

FIG. 6A is a front view showing an example in which 50 L of the post-treatment liquid is applied to the recording medium on which the image is formed.
FIG. 6B is a cross-sectional view in the thickness direction of the recording medium showing an example in which 50 L of the post-treatment liquid is applied to the recording medium on which the image is formed.
At the start of the post-treatment of the post-treatment unit 50, 20 L of the pre-treatment liquid is applied to the roll paper Md, and the ink 40 Ink forming an image is attached to the roll paper Md. As a post-treatment, the post-treatment unit 50 performs a process of ejecting and adhering 50 L of the post-treatment liquid onto the roll paper Md on which the image is formed. As shown in FIG. 6B, the post-treatment liquid 50L adheres to the recording medium in an area smaller than that of the pretreatment liquid 20L. Further, the post-treatment liquid 50L adheres in an area smaller than the area of the ink 40Ink forming the image.

The post-treatment liquid 50L may be adhered in an area smaller than the area of the portion where the image of the recording medium is formed (the portion where the ink 40 Ink is adhered), and the portion where the image is not formed may be adhered to the post-treatment liquid 50L. , It may or may not be attached.
Further, as a post-treatment method, it is preferable to attach (deposit) 50 L of the post-treatment liquid to the portion where the image of the roll paper Md is formed. The post-treatment unit 50 of the post-treatment liquid is based on the type of recording medium, permeability, glossiness and / or resolution, and / or the amount of adhesion (liquid amount) of the pre-treatment liquid applied by the pre-treatment unit 20. It is more preferable to change the discharge amount (adhesion amount) and the discharge method.

Further, the post-processing unit 50 of the present embodiment uses the same recording head unit as the image forming unit 40 to deliver a desired discharge amount (desired spot shape or desired striped shape) to a target location. The post-treatment liquid can be discharged. Specifically, the post-processing unit 50 discharges the roll paper Md to (1) the entire range in which the image can be formed; (2) discharges to the region where the image is formed; ( 3) Discharge only to the area of the image forming portion (dot ejection portion); etc. can be selected. Further, the post-processing unit 50 selects (4) ejection to a region wider than the image forming portion of the roll paper Md (recording medium) (+1 dot or 2 dots or more with respect to the outer edge of the image forming portion). be able to. Further, the post-treatment unit 50 can discharge the post-treatment liquid to an n% region (spotted shape or striped shape) with respect to the region for discharging the selected post-treatment liquid. Here, n% can be 5 to 50%. Further, n% can be a value predetermined by an experiment, numerical calculation, or the like.

Further, the post-treatment unit 50 according to the present embodiment, as a method of discharging the post-treatment liquid 50L, (1) discharges based on the print duty, and (2) discharges based on the amount of droplets of the post-treatment liquid 50L to be discharged. You can select to discharge, etc. At this time, the post-processing unit 50 calculates the amount of droplets of the print Duty and the post-treatment liquid 50 L from the input information (printed image data, etc.), and determines a method of discharging based on the calculated print Duty and the like. May be good. As a result, according to the image forming apparatus 100 of the present embodiment, as compared with the case where the post-processing liquid is applied (discharged) to the entire surface of the recording medium, the post-processing unit 50 is used to cover the region where the image is formed. The post-treatment liquid can be deposited (discharged) only in a specific part. As a result, the time required for the post-treatment, particularly the time required for drying the post-treatment liquid can be shortened. Further, the amount of the post-treatment liquid required for the post-treatment can be reduced, and the cost required for the post-treatment can be reduced.

The post-treatment method of the post-treatment unit 50 is not particularly limited and may be appropriately selected depending on the type of the post-treatment liquid. As the post-treatment method of the post-treatment unit 50, it is more preferable to use the same method as the method of ejecting the ink of the image forming unit 40 from the viewpoint of miniaturization of the apparatus and storage stability of the post-treatment liquid. Therefore, as for the configuration of the post-processing unit 50, it is preferable to use a liquid discharge head having a plurality of nozzles 40n on the nozzle surface, similarly to the recording head unit of the image forming unit 40.

When the post-treatment liquid is discharged, it is preferable to contain an appropriate amount of the water-soluble organic solvent (wetting agent) used in the method of discharging the ink of the image forming unit 40. Further, the post-processing unit 50 is preferably dried adhesion amount of post-treatment liquid 50L is to ^{0.5g / m 2 ~10g / m 2} . Further, as the post-treatment liquid 50L, a treatment liquid containing a component capable of forming a transparent protective layer on the roll paper Md (recording medium) can be used. The treatment liquid containing a component capable of forming a transparent protective layer includes, for example, a water-dispersible resin (resin), a water-soluble organic solvent (wetting agent), a penetrant, a surfactant, water and / or if necessary. It is a treatment liquid containing other components. Further, the post-treatment liquid may be a resin composition and / or a thermoplastic resin containing a component that is polymerized by irradiation with ultraviolet rays. Further, the post-treatment liquid is preferably a thermoplastic resin emulsion in order to improve glossiness and fixability. As a result, the post-processing unit 50 increases the glossiness of the surface of the roll paper Md on which the image is formed, or protects the surface of the roll paper Md with a resin layer, depending on the method of discharging (imparting) the image. be able to.

By using the post-processing unit 50 as in the present embodiment, the surface of the roll paper Md on which the image is formed is rubbed against another object (for example, roll paper), so that the image (ink) on the recording medium is peeled off (stripping). ), That is, the scratch resistance (scratch resistance) can be improved. Further, it is possible to reduce the occurrence of quality problems such as blurring, density, color tone, gloss and show-through of the formed image, and problems related to water resistance, weather resistance and other image fastness.

The carry-out unit 60 carries out (discharges) the recording medium on which the image is formed. As shown in FIG. 1, the unloading unit 60 is composed of a storage unit 61, a plurality of transport rollers 62, and the like. The carry-out unit 60 uses a transport roller 62 or the like to wind the roll paper Md on which the image is formed around the storage roll of the storage unit 61 and store the roll paper Md. When the roll paper Md is wound around the storage roll of the storage unit 61, if the pressure acting on the roll paper Md becomes large, the roll paper Md is wound in order to prevent other images from being transferred to the back surface of the roll paper Md. A drying portion for further drying the roll paper Md may be provided immediately before the removal.

Further, the image forming apparatus 100 of the present embodiment is provided with a maintenance / recovery unit for maintaining / recovering the image forming unit 40 and the post-processing unit 50. If the image forming unit 40 and the post-processing unit 50 using the liquid ejection head as described above are used for a long time, the nozzle may be clogged with ink or the post-processing liquid. Therefore, it is desirable to perform a maintenance / recovery operation (cleaning / maintenance) at times other than printing, for example, before printing.

As shown in FIG. 1, the image forming unit 40 and the post-processing unit 50 are arranged so as to face the surface of the roll paper Md along the conveying direction of the roll paper Md. A maintenance / recovery unit (maintenance unit) is provided on the upstream side and the downstream side of the roll paper Md in the transport direction with respect to the image forming unit 40 and the post-processing unit 50.

In the present embodiment, a test pattern is formed before maintenance and recovery, and a user, an administrator, or a service person visually confirms the test pattern printed on the recording medium. Only when it is determined by visual confirmation that maintenance (cleaning, etc.) is necessary, the maintenance / recovery unit performs the maintenance / recovery operation. Further, maintenance is performed only on the necessary head portion according to the visual result of the test pattern.

Further, the image forming apparatus 100 of the present embodiment is provided with a control unit that controls the operation of the image forming apparatus 100.
The control unit of the present embodiment instructs each unit of the image forming apparatus 100 to operate and controls the operation. The image forming apparatus 100 according to the present embodiment may use production printing as the printing system. Here, production printing means that a large amount of printed matter (image forming medium, printed matter) can be printed (image forming, printing) in a short time by efficiently performing job management, print data management, and the like. It is a manufacturing system. Specifically, the image forming apparatus 100 according to the present embodiment separates the RIP process for controlling the printing operation of the bitmap data and the like and the printing process based on the bitmap data controlled by the RIP process ( Department). Further, the image forming apparatus 100 (control unit) according to the present embodiment constructs a workflow system that manages from the creation of print data to the distribution of printed matter. That is, the image forming apparatus 100 (control unit) according to the present embodiment can speed up printing by separating the apparatus for performing RIP (Raster Image Processor) processing and the apparatus for performing printing processing, which require processing time. And.

FIG. 7 is a block diagram showing an example of the overall configuration of the control unit 70 that controls the operation of the image forming apparatus 100.
As shown in FIG. 7, the control unit 70 of the image forming apparatus 100 according to the present embodiment includes a host device (DFE: Digital Front End) 71 that performs RIP processing and the like, and a printer device 72 that performs printing processing and the like. Will be done. Here, the host device 71 and the printer device 72 are connected by a plurality of data lines 70LD and control lines 70LC. Hereinafter, the higher-level device 71 and the printer device 72 of the control unit 70 according to the present embodiment will be specifically described.

FIG. 8 is a block diagram showing an example of the host device 71 constituting the control unit 70.
The host device 71 of the present embodiment is a device that performs RIP processing based on print job data (job data, print data) output from the host device. That is, the higher-level device 71 of the present embodiment creates bitmap data (hereinafter referred to as “print image data”) corresponding to each color based on the print job data. Here, the printed image data further includes data related to the discharge of the post-processing liquid discharged by the post-processing unit 50 (hereinafter, referred to as “image data related to post-processing”) in the present embodiment.

Further, the higher-level device 71 of the present embodiment creates data for controlling the printing operation (hereinafter referred to as "control information data") based on the print job data, the information of the host device, and the like. Here, the control information data includes printing conditions (printing form, printing type, paper supply / output information, printing surface order, printing paper size, print image data data size, resolution, paper type information, gradation, color information, and the like. Includes data about (such as information on the number of pages to print). Further, in the present embodiment, the control information data further includes data relating to the discharge of the post-treatment liquid discharged by the post-processing unit 50 (hereinafter referred to as “control data relating to post-processing”). In addition, a user, an administrator, a serviceman, or the like inputs information visually detected during maintenance and recovery to the host device 71.

As shown in FIG. 8, the host device 71 includes a CPU (Central Processing Unit) 71a, a ROM (Read Only Memory) 71b, a RAM (Random Access Memory) 71c, and an HDD (Hard Disc Drive) 71d. Further, the host device 71 includes an external I / F71e, an I / F71f for control information, and an I / F71g for image data. Further, the host device 71 includes a bus 71h for connecting the CPU 71a and the like. That is, the host device 71 is configured to be able to transmit and receive the CPU 71a and the like to and from each other via the bus 71h.

The CPU 71a controls the operation of the entire host device 71. The CPU 71a controls the operation of the host device 71 by using a control program or the like stored (stored) in the ROM 71b and / or the HDD 71d.
The ROM 71b, the RAM 71c and the HDD 71d store data and the like, the ROM 71b and / or the HDD 71d stores a control program for controlling the CPU 71a in advance, and the RAM 71c is used as a work memory of the CPU 71a.
The external I / F71e controls communication (transmission / reception) with the outside of the image forming apparatus 100 (host device or the like). The control information I / F 71f controls the communication of control information data. The image data I / F 71g controls the communication of the print image data. In the present embodiment, the image data I / F 71g has a plurality of channels (described later) corresponding to each color of the printed image data.

The host device 71 of the present embodiment receives the print job data transmitted from the host device by the external I / F 71e and stores the print job data in the HDD 71d using the CPU 71a. Further, the host device 71 uses the CPU 71a to read the print job data from the HDD 71d. Further, the host device 71 uses the CPU 71a to generate bitmap data of each color (yellow (Y), cyan (C), magenta (M), and black (K)) based on the read print job data. The generated bitmap data of each color is stored in the RAM 71c. Here, the host device 71 (CPU71a) can render, for example, a PDL (Page Description Language) to generate bitmap data of each color as RIP processing, and write it to the RAM 71c.

Next, the host device 71 compresses and encodes the bitmap data of each color written in the RAM 71c, and temporarily stores the bitmap data in the HDD 71d. After that, when the printer device 72 starts the printing operation, the host device 71 (CPU 71a) reads the encoded bitmap data of each color from the HDD 71d, decodes it, and writes the bitmap data of each color into the RAM 71c, respectively. .. Next, the host device 71 reads the bitmap data of each color from the RAM 71c and outputs it as print image data of each color to the printer device 72 (printer engine 72E described later) via each channel of the image data I / F 71g. .. Here, the host device 71 uses the data line 70LD shown in FIG. 7 (data line 70LD-Y, 70LD-C, 70LD-M, 70LD-K shown in FIG. 9) as each channel of the image data I / F 71g. The print image data can be output to the printer device 72 via the printer device 72.

Further, the higher-level device 71 according to the present embodiment uses the CPU 71a to connect the I / F 71f (control line 70LC) for control information with the printer controller 72C of the printer device 72 according to the progress of the printing operation or the like. Control information data is transmitted and received via this. Further, the higher-level device 71 according to the present embodiment reads out the image data related to the post-processing encoded from the HDD 71d by using the CPU 71a when the post-processing unit 50 starts the post-processing, and the above-mentioned bitmap data. Similarly, the data is output to the printer engine 72E via the data line 70LD-P shown in FIG.

FIG. 9 is a block diagram showing an example of the printer device 72.
The printer device 72 of the present embodiment is a device that controls an operation of forming an image on a recording medium based on print image data and control information data input from the host device 71. In this embodiment, the printer device 72 has a printer controller 72C and a printer engine 72E.

The printer controller 72C controls the operation of the printer engine 72E, which will be described later. The printer controller 72C transmits and receives control information data and the like to and from the host device 71 via the control line 70LC. Further, the printer controller 72C transmits and receives control information data and the like to and from the printer engine 72E via the control line 72LC. As a result, the printer controller 72C can write the print information such as various print conditions included in the control information data and the data related to the test pattern for ejection to the register of the print control unit 72Cc or the like and store the print conditions. Further, the printer controller 72C can control the printer engine 72E based on the control information data and execute printing according to the print job data (control information data).

As shown in FIG. 9, the printer controller 72C has a CPU 72Cp and a print control unit 72Cc. Further, the printer controller 72C connects the CPU 72Cp and the print control unit 72Cc by a bus 72Cb so as to be able to transmit and receive to each other. Here, the bus 72Cb is connected to the control line 70LC via the communication I / F. The CPU 72Cp controls the operation of the entire printer device 72 by using the control program stored in the ROM. The print control unit 72Cc transmits / receives commands and status information to / from the printer engine 72E based on the control information data transmitted from the host device 71. As a result, the print control unit 72Cc can control the operation of the printer engine 72E.

The printer engine 72E is a device that controls an operation of forming an image on a recording medium based on print image data input from the host device 71 and control information data input from the printer controller 72C. Further, the printer engine 72E performs post-processing based on the print image data (image data related to post-processing) input from the host device 71 and the control information data (control data related to post-processing) input from the printer controller 72C. It is a device that controls.

As shown in FIG. 9, the printer engine 72E is connected to a plurality of data lines 70LD (70LD-Y, 70LD-C, 70LD-M, 70LD-K, 70LD-P). The printer engine 72E receives print image data from the host device 71 via a plurality of data lines 70LD-C and the like. As a result, the printer engine 72E can perform the printing operation of each color and the post-processing of the post-processing liquid based on the received print image data.

In this embodiment, the printer engine 72E has a plurality of data management units 72EC, 72EM, 72EY, 72EK, and 72EP. Further, the printer engine 72E has an image output unit 72Ei for inputting print image data and the like from a data management unit 72EC and the like, and a transfer control unit 72Ec for controlling the transfer of roll paper Md (recording medium). Further, in the present embodiment, the printer engine 72E has a post-processing liquid output unit 72Ep in which image data related to post-processing is input from the data management unit 72EP, and a drying control unit 72Epb that controls the operation of the drying unit 30 (FIG. 1). And have. Further, in the present embodiment, the printer engine 72E also has a maintenance / recovery control unit that controls the operation of the maintenance / recovery mechanism. In the present embodiment, a test pattern used in the maintenance / recovery operation is included as image data in addition to the normal printing.

FIG. 10 is a block diagram showing an example of the data management unit 72EC.
Since the configurations of the data management units 72EM, 72EY, 72EK, and 72EP other than the data management unit 72EC are the same as the configurations of the data management unit 72EC, the description thereof will be omitted.
As shown in FIG. 10, the data management unit 72EC includes a logic circuit 72ECl and a memory unit 72ECm. The data management unit 72EC (logic circuit 72ECl) is connected to the host device 71 via the data line 70LD-C. Further, the data management unit 72EC (logic circuit 72ECl) is connected to the printer controller 72C (print control unit 72Cc) via the control line 72LC.

In the present embodiment, the logic circuit 72ECl stores the print image data output from the host device 71 in the memory unit 72ECm based on the control signal output from the printer controller 72C (print control unit 72Cc). Further, the logic circuit 72ECl reads out the print image data Ic (FIG. 9) corresponding to cyan (C) from the memory unit 72ECm based on the control signal output from the printer controller 72C (print control unit 72Cc), and outputs the image. Output to unit 72Ei.

Regarding post-processing, in the case of the logic circuit 72ECp (data management unit 72EP), the image data Ip (FIG. 11) related to post-processing and the data for controlling the discharge position of the test pattern for discharge inspection are used as the post-processing liquid. Output to the output unit 72Ep.

The memory unit 72ECm can have a capacity capable of storing at least three pages of print image data. The print image data for three pages is, for example, the print image data corresponding to the page being transferred (received) from the host device 71, the print image data corresponding to the page being output to the image output unit 72Ei, and the next page. It is the print image data corresponding to.

The data management unit 72EC may use a hardware logic circuit composed of a combination of logic circuits and the like. As a result, the data management unit 72EC can realize higher-speed processing. Further, the data management unit 72EC may use the logic circuit 72ECl to perform a logic determination on a control signal based on, for example, a bit string, and determine a process to be executed.

FIG. 11 is a block diagram showing an example of the image output unit 72Ei.
Since the configuration of the post-treatment liquid output unit 72Ep is basically the same as the configuration of the image output unit 72Ei, the description thereof will be omitted.
As shown in FIG. 11, the image output unit 72Ei includes an output control unit 72Eic. The output control unit 72Eic outputs the print image data corresponding to each color to the recording head units 40C, 40M, 40Y, and 40K corresponding to each color. As a result, the output control unit 72Eic can control the operation of the recording head unit 40C and the like based on the printed image data.

Specifically, the output control unit 72Eic individually controls a plurality of recording head units 40C, 40M, 40Y, and 40K. Further, the output control unit 72Eic may simultaneously control a plurality of recording head units 40C, 40M, 40Y, and 40K by using the input print image data. Further, the output control unit 72Eic may control the recording head units 40C, 40M, 40Y, 40K based on the input control signal. The output control unit 72Eic may control the recording head units 40C, 40M, 40Y, and 40K based on, for example, a user's operation input.

As described above, the printer device 72 of the present embodiment uses the data management unit 72EC and the like and the output control unit 72Eic to record the print image data output from the host device 71 into a plurality of recording head units 40C, 40M, 40Y, 40K. Enter in. At this time, the printer device 72 can control the print image data of each color independently of each other.

Further, the printer device 72 can easily change the configuration of the printer engine 72E according to the number of colors of the print image data (C, M, Y and K, or only K color, etc.) or the number of recording head units. Is possible. That is, by mounting only the necessary data management unit 72EC and the like and the recording head units 40C, 40M, 40Y, 40K, there is an advantageous effect on the miniaturization and cost reduction of the apparatus. In the printer device 72 according to the present embodiment, for example, when full-color printing is performed in four colors of K, C, M, and Y, the printer engine 72E can be provided with all the data management units 72EC and the like. As a result, the printer device 72 can connect each output of the data management unit 72EC or the like to the recording head units 40C, 40M, 40Y, 40K by using the output control unit 72Eic.

Further, in the case of printing with one color of K, for example, the printer device 72 can be provided with only one data management unit 72EK and a recording head unit 40K as device cost priority. As a result, the printer device 72 can connect the output of the data management unit 72EK to the recording head unit 40K by using the output control unit 72Eic.

Alternatively, for example, when printing with one color of K, one data management unit 72EK and four recording head units 40C, 40M, 40Y, 40K may be provided as printing speed priority. As a result, the image forming apparatus 100 can connect the output of the data management unit 72EK to each of the four recording head units 40C, 40M, 40Y, and 40K by using the output control unit 72Eic. In this case, the image forming apparatus 100 can print the same color (K) a plurality of times by superimposing (overlapping) the same color (K). Double high-speed printing (image formation) can be realized.

Hereinafter, the configuration and operation related to ink replacement (replacement), which is a feature of the present invention, will be described.
FIG. 12 is a cross-sectional view of the entire head unit 40K-1 according to the present embodiment when the entire head unit 40K-1 is cut along a nozzle row.
FIG. 13 is a cross-sectional view of the entire head unit 40K-1 according to the present embodiment when the entire head unit 40K-1 is cut along the cross section indicated by reference numeral AA in FIG.

As described above, the configurations and operations of the other head units 40K-2, 40K-3, and 40K-4 are the same as those of the head unit 40K-1 described above, and thus the description thereof will be omitted. Further, since the configurations and operations of the other recording head units 40C, 40M, and 40Y are the same as the configurations of the black (K) recording head unit 40K, the description thereof will be omitted. Further, in the following description, a case where the ink before replacement and the ink after replacement do not cause problems such as nozzle clogging due to agglutination and solidification of ink and discoloration of ink will be described even if they are mixed with each other.

In the present embodiment, the recording head unit 40K is equipped with four liquid discharge units, head units 40K-1, 40K-2, 40K-3, and 40K-4. Then, the head units 40K-1, 40K-2, 40K-3, and 40K-4 are connected to the head units 40K-1, 40K from the common supply flow path connected to the main tank, which will be described later, through each individual supply flow path. Ink is supplied to -2, 40K-3 and 40K-4.

As shown in FIGS. 12 and 13, the head unit 40K-1 includes a recording head 1 which is a liquid discharging head for discharging liquid, and a head tank 2 for accommodating ink supplied to the recording head 1.

As described above, the recording head 1 includes a plurality of nozzles 40n for ejecting droplets, a liquid chamber 40f in which each nozzle 40n communicates, a common liquid chamber 40c for supplying ink to each liquid chamber 40f, and a common liquid chamber. It is provided with an ink supply port 40i for supplying ink to 40c and an ink discharge port 40o for discharging ink from the common liquid chamber 40c.

The head tank 2 is arranged in the tank case 3 and has an ink accommodating portion 2a for accommodating ink to be supplied to the recording head 1 and a supply port 2b for supplying ink from the ink accommodating portion 2a to the ink supply port 40i of the recording head 1. And have. The tank case 3 is a partially opened member, and a film member 3a (shaded portion in FIG. 12) as a flexible elastically deformable member is attached to the opening to vibrate the ink. The damper effect can be obtained by absorbing the pressure caused by the above.

The ink contained in the head tank 2 is supplied from the supply port 2b to one end of the common liquid chamber 40c through the ink supply port 40i at one end of the recording head 1 and is connected to the other end of the common liquid chamber 40c. It flows from the ink discharge port 40o to the discharge flow path 4. Then, as the ink is consumed as the ink is ejected from the recording head 1, the ink is supplied from the head tank 2 to the recording head 1, and the ink is naturally supplied from the main tank 5 described later to the head tank 2. Will be done.

FIG. 14 is an explanatory diagram showing an ink supply system of a black (K) recording head unit 40K equipped with four head units 40K-1, 40K-2, 40K-3, and 40K-4.
Since the same applies to the ink supply systems of the other recording head units 40C, 40M, and 40Y, the description thereof will be omitted.

In the present embodiment, each individual supply flow path 7K-1 is passed from the common supply flow path (many hold) 6K connected to the main tank 5K through the connection portions 8K-1, 8K-2, 8K-3, 8K-4. , 7K-2, 7K-3, 7K-4, and ink is supplied to each of the head units 40K-1, 40K-2, 40K-3, 40K-4. The individual supply channels 7K-1, 7K-2, 7K-3, 7K-4 of the present embodiment are composed of a flexible tube made of a flexible fluororesin or a Teflon (registered trademark) resin.

Next, an ink exchange operation as a liquid exchange operation for exchanging (replacement) the ink before replacement filled in the recording head portion 40K with another type of ink after replacement will be described.
First, the main tank 5K'before replacement, which is connected to the recording head portion 40K, is replaced with the main tank 5K containing the ink after replacement. Next, individual suction caps are brought into close contact with the nozzle surfaces of the head units 40K-1, 40K-2, 40K-3, and 40K-4 for capping.

Ink is sucked into the suction cap from the nozzles of the head units 40K-1, 40K-2, 40K-3, 40K-4 by discharging the air in the suction cap by the suction pump to make the inside of the suction cap negative pressure. be able to. At this time, in the present embodiment, ink can be sucked out independently for each suction cap, that is, for each head unit 40K-1, 40K-2, 40K-3, 40K-4.

As the ink is sucked out, the head unit 40K-1, 40K-2, 40K-3, 40K-4, the individual supply flow paths 7K-1, 7K-2, 7K-3, 7K-4, and the common supply flow. The pre-replacement ink filled in the road 6K is discharged. Along with this, the replaced ink is discharged from the replaced main tank 5K in the common supply flow path 6K, in the individual supply flow paths 7K-1, 7K-2, 7K-3, 7K-4, and in the head unit 40K-. It is drawn into 1,40K-2, 40K-3, and 40K-4 in sequence. As a result, after replacement, all of the individual supply channels 7K-1, 7K-2, 7K-3, 7K-4 and the head unit 40K-1, 40K-2, 40K-3, 40K-4 were replaced. Replaces with ink.

After the ink replacement (replacement) is completed in this way, the suction cap is decapped from the nozzle surface of each head unit 40K-1, 40K-2, 40K-3, 40K-4. Then, the nozzle surface is wiped with a wiper member made of an elastic body such as silicon rubber to wipe off the ink dripping on the nozzle surface to form a meniscus of the nozzle 40n, and the ink exchange operation is completed.

Here, when the specific densities of the ink before replacement and the ink after replacement are different, conventionally, the amount of ink after replacement is often sucked out to the suction cap by the time the ink replacement (replacement) is completed. There was a problem that there was a lot of waste of ink after replacement.

Figure 15 is an explanatory view showing the middle of state of the conventional ink replacement operation when towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is greater (ρ _{0 <ρ 1)} Is.
As in the present embodiment, there are a plurality of individual supply channels 7K-1, 7K-2, 7K-3, 7K from the connection portions 8K-1, 8K-2, 8K-3, 8K-4 of the common supply channel 6K. In a configuration in which ink is supplied to a plurality of head units 40K-1, 40K-2, 40K-3, 40K-4 via -4, it is proportional to the number of head units connected to the common supply flow path 6K. Therefore, it is necessary to increase the amount of ink flowing in the common supply flow path 6K. Therefore, it is necessary to reduce the flow path resistance of the common supply flow path 6K, and for that purpose, it is necessary to increase the cross-sectional area of the common supply flow path (the area of the cross section orthogonal to the ink flow direction of the common supply flow path). There is. As a result, the flow velocity of the ink flowing in the common supply flow path is in each individual supply flow path 7K-1, 7K-2, 7K-3, 7K-4 or in each head unit 40K-1, 40K-2, 40K-. It will be slower than the flow velocity of the ink flowing in 3,40K-4.

Since the flow velocity of the ink flowing in the common supply flow path 6K is slow in this way, the specific density ρ ₁ of the ink L ₁ after replacement is larger than the specific gravity ρ _{0 of the ink L 0 before replacement (ρ 0} <ρ ₁ ). In the middle stage of the ink replacement operation, inside the common supply flow path 6K, the pre-replacement ink and the post-replacement ink are roughly separated into two upper and lower layers, as shown in FIG. In such a state, the connection portions 8K-1, 8K-2, 8K-3, 8K-4 of each individual supply flow path 7K-1, 7K-2, 7K-3, 7K-4 become a common supply flow path. when present in the lower (bottom or side wall below the common supply channel 6K) of 6K, large exchange after the ink _{L 1} specific gravity [rho ₁ is preferentially separate supply channel 7K-1,7K-2,7K-3, It is drawn to 7K-4. _{As a result, the amount of pre-replacement ink L 0} discharged in the common supply flow path 6K is reduced, and a large amount of post-replacement ink L ₁ is discharged by the time the ink replacement (replacement) is completed. In addition, the time required for the ink replacement operation also increases.

Conversely, if the direction of gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _0> ρ ₁₎ But relatively many After replacing the ink L ₁ is discharged This will lead to a situation where the ink is replaced, and the time required for the ink replacement operation will increase. That is, in this case, the pre-replacement ink L _{0 having a large specific gravity ρ 0} is preferentially drawn into the individual supply flow paths 7K-1, 7K-2, 7K-3, 7K-4. However, at the time of this pull-in, the connection portion 8K-1, 8K-2, 8K of the common supply flow path 6K in which the connection ports of the individual supply flow paths 7K-1, 7K-2, 7K-3, 7K-4 are open. The small replacement ink L _{1 having a specific density ρ 1} existing in the vicinity of −3, 8K-4 is also drawn in together. As a result, by the replacement of the ink (exchange) is finished, to replace after the ink L ₁ equivalent amount is discharged, it becomes much time required for the ink replacement operation correspondingly.

FIG. 16 is an explanatory diagram showing an example of the common supply flow path 6K of the present embodiment.
In the present embodiment, as shown in FIG. 16, at least during the ink exchange operation, the common supply flow path 6K is inclined in the flow path direction (the flow direction of the ink flowing in the common supply flow path 6K). It is provided in. As a result, the connection portions 8K-1, 8K-2, 8K-3, 8K- in which a plurality of individual supply flow paths 7K-1, 7K-2, 7K-3, 7K-4 are connected to the common supply flow path 6K. A height difference is provided in 4.

Figure 17 is a flowchart showing the flow of the ink replacement operation of the present embodiment in the case towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is greater (ρ _{0 <ρ 1)} be.
First, the main tank 5K'before replacement, which is connected to the recording head portion 40K, is replaced with the main tank 5K containing the ink after replacement (S1). Next, the individual suction caps 46K-1, 46K-2, 46K-3, 46K-4 are brought into close contact with the nozzle surfaces of the head units 40K-1, 40K-2, 40K-3, 40K-4, respectively. Capping (S2). After that, the inside of the total suction caps 46K-1, 46K-2, 46K-3, 46K-4 is made negative pressure by the suction pump, and from the nozzles of all the head units 40K-1, 40K-2, 40K-3, 40K-4. The ink is sucked out (S3).

As the ink is sucked out, the head unit 40K-1, 40K-2, 40K-3, 40K-4, the individual supply flow paths 7K-1, 7K-2, 7K-3, 7K-4, and the common supply flow. The pre-replacement ink L ₀ filled in the road 6K is discharged. Accordingly, the exchange after the ink L ₁ from the main tank 5K after replacement, coming drawn from the flow path upstream side of the common supply passage 6K.

At this time, in the present embodiment, as shown in FIG. 16, the common supply flow path 6K is inclined from the upper side to the lower side toward the downstream side in the flow path direction. Therefore, inside the common supply flow path 6K, as shown in FIG. 16, after replacement ink L _{1 having a large specific density ρ 1} supplied from the main tank 5K is moved to the downstream side in the flow path direction of the common supply flow path 6K. The small pre-replacement ink L ₀ having a specific gravity ρ ₀ is moved to the upstream side in the flow path direction of the common supply flow path 6K. As a result, as the ink is sucked out, the inside of the common supply flow path 6K is sequentially filled with the replaced ink L _{1 having a large specific gravity ρ 1 from the downstream end in the flow path direction.}

In the present embodiment, when the first specified time elapses from the start of ink suction (Yes in S4), the first head unit 40K-1 connected to the most downstream side in the flow path direction of the common supply flow path 6K. Ink suction is stopped (S5). The first specified time, large exchange after the ink L ₁ specific gravity [rho ₁ to the connection unit 8K-1 of the common supply channel 6K of the first head unit 40K-1 is connected is filled, and the first one-off the ink supply channels 7K-1 and the first head unit 40K-1 is set to the replaced time to all exchange after the ink L _1. By stopping the ink suction of the first head unit 40K-1 when the first specified time elapses, the first is that the ink replacement of the first head unit 40K-1 is completed. situation in which the head unit replacement after the ink L ₁ from 40K-1 from being wastefully discharged can be suppressed.

Subsequently, in the present embodiment, when the second specified time elapses from the start of ink suction (Yes in S6), the second head connected second from the downstream side in the flow path direction of the common supply flow path 6K. The ink suction of the unit 40K-2 is stopped (S7). The second specified time, large exchange after the ink L ₁ specific gravity [rho ₁ to the connection unit 8K-2 of the common supply passage 6K to the second head unit 40K-2 is connected is filled, and the second one-off the ink supply channels 7K-2 and the second head unit 40K-2 is set to replaced time to all exchange after the ink L _1. By stopping the ink suction of the second head unit 40K-2 when such a second specified time elapses, the second head unit 40K-2 is replaced with ink even though the ink replacement is completed. situation in which the head unit replacement after the ink L ₁ from 40K-2 from being wastefully discharged can be suppressed.

Subsequently, in the present embodiment, when the third specified time elapses from the start of ink suction (Yes in S8), the third head connected third from the downstream side in the flow path direction of the common supply flow path 6K. The ink suction of the unit 40K-3 is stopped (S9). The third specified time, large exchange after the ink L ₁ specific gravity [rho ₁ to the connection unit 8K-3 of the common supply channel 6K the third head unit 40K-3 is connected is filled, and the third one-off the ink supply channels 7K-3 and the third head unit 40K-3 is set to replaced time to all exchange after the ink L _1. By stopping the ink suction of the third head unit 40K-3 when the third specified time elapses, the third head unit 40K-3 has been replaced with ink. situation in which the head unit replacement after the ink L ₁ from 40K-3 from being wastefully discharged can be suppressed.

Subsequently, in the present embodiment, when the fourth specified time elapses from the start of ink suction (Yes in S10), the fourth head unit 40K- connected to the uppermost stream in the flow path direction of the common supply flow path 6K. The ink suction of No. 4 is stopped (S11). The fourth specified time, after replacement ink L ₁ throughout in the common supply channel 6K is filled, and the ink of the four separate supply channel 7K-4 and the fourth head unit 40K-4 is replaced every is set to a time switched to the rear ink L _1. By stopping the ink suction of the fourth head unit 40K-4 when the fourth specified time elapses, the ink replacement (replacement) can be completed.

The main tanks 5K and if the flow path length between the connecting part 8K-4 of the fourth head unit 40K-4 is long, specific gravity smaller before replacement ink [rho ₀ L ₀ is the main tank 5K than the connecting section 8K-4 It may collect on the side (upstream side of the common supply flow path 6K in the flow path direction from the connection portion 8K-4). In such a case, in the middle of the ink replacement operation (around late) and allowed to stir the ink in the common supply channel 6K and the like vibrates the common supply passage 6K, waste further replacement after ink L ₁ The amount of ink discharged can be suppressed, and the time required for the ink replacement operation can be further reduced.

After the ink replacement (replacement) is completed in this way, the suction cap is decapped from the nozzle surface of each head unit 40K-1, 40K-2, 40K-3, 40K-4 (S12). Then, the surface of the nozzle is wiped by the wiper member to wipe off the ink dripping on the nozzle surface (S13) to form the meniscus of the nozzle 40n, and the ink exchange operation is completed.

If direction of gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is large in the ink replacement operation of the embodiment in (ρ _{0 <ρ 1),} the common supply passage 6K relative The amount of ink discharged from the head unit corresponding to the individual supply flow path connected to the relatively low connection portion (the head unit on the downstream side in the flow path direction of the common supply flow path 6K in FIG. 16) is relatively high. The amount of ink discharged from the head unit corresponding to the individual supply flow path connected to the connection portion (the head unit on the upstream side in the flow path direction of the common supply flow path 6K in FIG. 16) is larger. By performing such an ink replacement operation, _{the discharge amount of the pre-replacement ink L 0} that is moved to a high position in the common supply flow path 6K is moved to a low position in the common supply flow path 6K, and the amount of the post-replacement ink L _{1 is moved to a low position.} Can be more than the amount of emissions. _{As a result, the amount of the post-replacement ink L 1} discharged by the time all the _{pre-replacement ink L 0} in the common supply flow path 6K is discharged can be suppressed to a small amount.

In particular, in this embodiment in the case towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is greater (ρ _{0 <ρ 1),} as shown in FIG. 16, the common feed The common supply flow path 6K is inclined from the upper side to the lower side toward the downstream side in the flow path direction in the road 6K. As a result, the replaced ink L _{1 having a large specific density ρ 1} can be efficiently transferred to the downstream side in the flow path direction of the common supply flow path 6K, and the ink replacement in the common supply flow path 6K can be promoted.

Further, in the ink replacement operation of the present embodiment in the case towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is greater (ρ _{0 <ρ 1),} a relatively low connecting portion It is connected to a relatively high connection part without discharging ink from the head unit corresponding to the individual supply flow path connected to (the head unit on the downstream side in the flow path direction of the common supply flow path 6K in FIG. 16). It includes an operation of ejecting ink from a head unit corresponding to an individual supply flow path (a head unit on the upstream side in the flow path direction of the common supply flow path 6K in FIG. 16). Therefore, it is possible to suppress the already situation the exchange after the ink L ₁ from the head unit replacement is finished ink is wastefully discharged.

Figure 18 is a flowchart showing the flow of the ink replacement operation of the present embodiment in the case towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _0> ρ ₁₎ be.
First, the main tank 5K'before replacement, which is connected to the recording head portion 40K, is replaced with the main tank 5K containing the ink after replacement (S21). Next, the individual suction caps 46K-1, 46K-2, 46K-3, 46K-4 are brought into close contact with the nozzle surfaces of the head units 40K-1, 40K-2, 40K-3, 40K-4, respectively. Capping (S22). After that, the inside of the total suction caps 46K-1, 46K-2, 46K-3, 46K-4 is made negative pressure by the suction pump, and from the nozzles of all the head units 40K-1, 40K-2, 40K-3, 40K-4. The ink is sucked out (S23).

In the present embodiment, as shown in FIG. 16, the common supply flow path 6K is inclined from the upper side to the lower side toward the downstream side in the flow path direction. Therefore, inside the common supply flow path 6K, contrary to the state shown in FIG. 16, the small replacement ink L _{1 having a specific gravity ρ 1} supplied from the main tank 5K is upstream in the flow path direction of the common supply flow path 6K. The pre-replacement ink L _{0, which} is moved to the side and has _{a large specific gravity ρ 0} , is moved to the downstream side in the flow path direction of the common supply flow path 6K.

In the present embodiment, when the fifth specified time elapses from the start of ink suction (Yes in S24), the fourth head unit 40K-4 connected to the most upstream side in the flow path direction of the common supply flow path 6K. Ink suction is stopped (S25). The fifth specified time, a small exchange after the ink L ₁ specific gravity [rho ₁ to the connection portion 8K-4 of the common supply passage 6K to fourth head unit 40K-4 is connected is filled, and the fourth one-off the ink supply channels 7K-4 and the fourth head unit 40K-4 is set to replaced time to all exchange after the ink L _1. By stopping the ink suction of the fourth head unit 40K-4 when the fifth specified time elapses, the fourth head unit 40K-4 is replaced with the ink even though the ink replacement is completed. situation in which the head unit replacement after the ink L ₁ from 40K-4 from being wastefully discharged can be suppressed.

Subsequently, in the present embodiment, when the sixth specified time elapses from the start of ink suction (Yes in S26), the third head connected second from the upstream side in the flow path direction of the common supply flow path 6K. The ink suction of the unit 40K-3 is stopped (S27). The sixth specified time, a small exchange after the ink L ₁ specific gravity [rho ₁ to the connection unit 8K-3 of the common supply channel 6K the third head unit 40K-3 is connected is filled, and the third one-off the ink supply channels 7K-3 and the third head unit 40K-3 is set to replaced time to all exchange after the ink L _1. By stopping the ink suction of the third head unit 40K-3 when the sixth specified time elapses, the third head unit 40K-3 has been replaced with ink. situation in which the head unit replacement after the ink L ₁ from 40K-3 from being wastefully discharged can be suppressed.

Subsequently, in the present embodiment, when the seventh specified time elapses from the start of ink suction (Yes in S28), the second head connected third from the upstream side in the flow path direction of the common supply flow path 6K. The ink suction of the unit 40K-2 is stopped (S29). The seventh specified time, a small exchange after the ink L ₁ specific gravity [rho ₁ to the connection unit 8K-2 of the common supply passage 6K to the second head unit 40K-2 is connected is filled, and the second one-off the ink supply channels 7K-2 and the second head unit 40K-2 is set to replaced time to all exchange after the ink L _1. By stopping the ink suction of the second head unit 40K-2 when the seventh specified time elapses, the second head unit 40K-2 has been replaced with ink. situation in which the head unit replacement after the ink L ₁ from 40K-2 from being wastefully discharged can be suppressed.

Subsequently, in the present embodiment, when the eighth specified time elapses from the start of ink suction (Yes in S30), the first head unit 40K- connected to the most downstream in the flow path direction of the common supply flow path 6K. The ink suction of 1 is stopped (S31). The eighth specified time, after replacement ink L ₁ throughout in the common supply channel 6K is filled, and the ink of the first one-off supply channel 7K-1 and the first head unit 40K-1 to be replaced every is set to a time switched to the rear ink L _1. By stopping the ink suction of the first head unit 40K-1 when the eighth specified time elapses, the ink replacement (replacement) can be completed.

After the ink replacement (replacement) is completed in this way, the suction cap is decapped from the nozzle surface of each head unit 40K-1, 40K-2, 40K-3, 40K-4 (S32). Then, the nozzle surface is wiped by the wiper member to wipe off the ink dripping on the nozzle surface (S33) to form the meniscus of the nozzle 40n, and the ink exchange operation is completed.

In the ink replacement operation of the present embodiment in the case towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _0> ρ _1), the common supply passage 6K relative The amount of ink discharged from the head unit corresponding to the individual supply flow path connected to the relatively high connection portion (the head unit on the upstream side in the flow path direction of the common supply flow path 6K in FIG. 16) is relatively low. The amount of ink discharged from the head unit corresponding to the individual supply flow path connected to the connection portion (the head unit on the downstream side in the flow path direction of the common supply flow path 6K in FIG. 16) is larger. By performing such ink replacement operation, when towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _0> ρ _1), the common supply channel 6K _{The discharge amount of the pre-replacement ink L 0} that is brought to a lower position can be larger than the discharge amount of the _{post-replacement ink L 1} that is brought to a higher position in the common supply flow path 6K. _{As a result, the amount of the post-replacement ink L 1} discharged by the time all the _{pre-replacement ink L 0} in the common supply flow path 6K is discharged can be suppressed to a small amount.

Further, in the ink replacement operation of the present embodiment in the case towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _{0 <ρ 1),} relatively high connecting portion It is connected to a relatively low connection part without discharging ink from the head unit corresponding to the individual supply flow path connected to (the head unit on the upstream side in the flow path direction of the common supply flow path 6K in FIG. 16). It includes an operation of ejecting ink from a head unit corresponding to an individual supply flow path (a head unit on the downstream side in the flow path direction of the common supply flow path 6K in FIG. 16). Therefore, it is possible to suppress the already situation the exchange after the ink L ₁ from the head unit replacement is finished ink is wastefully discharged.

[Modification 1]
Next, a modification of the ink exchange operation and its configuration in the above-described embodiment (hereinafter, this modification will be referred to as “modification example 1”) will be described.
FIG. 19 is an explanatory diagram showing an example of the common supply flow path 6K of the present modification 1.
In the first modification, as shown in FIG. 19, the common supply flow path 6K is inclined from the lower side to the upper side toward the downstream side in the flow path direction. Therefore, inside the common supply flow path 6K, as shown in FIG. 19, the small replacement ink L _{1 having a specific gravity ρ 1} supplied from the main tank 5K is moved to the downstream side in the flow path direction of the common supply flow path 6K. Therefore, the pre-replacement ink L ₀ having a large specific density ρ ₀ is moved to the upstream side in the flow path direction of the common supply flow path 6K. As a result, as the ink is sucked out, the inside of the common supply flow path 6K is sequentially filled with the replaced ink L _{0 having a large specific gravity ρ 0 from the upstream end in the flow path direction.}

Exchange basic flow before when the specific gravity [rho towards specific gravity [rho ₁ of the exchange after the ink L ₁ is less than ₀ the ink _{L 0 (ρ 0> ρ 1} ) ink replacement operation of the first modification of the FIG. 17 It is the same as the flowchart shown in.
That is, first, the main tank 5K'before replacement, which is connected to the recording head portion 40K, is replaced with the main tank 5K containing the ink after replacement (S1). Next, the individual suction caps 46K-1, 46K-2, 46K-3, 46K-4 are brought into close contact with the nozzle surfaces of the head units 40K-1, 40K-2, 40K-3, 40K-4, respectively. Capping (S2). After that, the inside of the total suction caps 46K-1, 46K-2, 46K-3, 46K-4 is made negative pressure by the suction pump, and from the nozzles of all the head units 40K-1, 40K-2, 40K-3, 40K-4. The ink is sucked out (S3).

Then, when the first specified time elapses from the start of ink suction (Yes in S4), the ink suction of the first head unit 40K-1 connected to the most downstream side in the flow path direction of the common supply flow path 6K is performed. Stop (S5). The first specified time, a small exchange after the ink L ₁ specific gravity [rho ₁ to the connection unit 8K-1 of the common supply channel 6K of the first head unit 40K-1 is connected is filled, and the first one-off the ink supply channels 7K-1 and the first head unit 40K-1 is set to the replaced time to all exchange after the ink L _1. By stopping the ink suction of the first head unit 40K-1 when the first specified time elapses, the first is that the ink replacement of the first head unit 40K-1 is completed. situation in which the head unit replacement after the ink L ₁ from 40K-1 from being wastefully discharged can be suppressed.

Subsequently, when the second specified time elapses from the start of ink suction (Yes in S6), the second head unit 40K-2 connected second from the downstream side in the flow path direction of the common supply flow path 6K. Ink suction is stopped (S7). The second specified time is a small exchange after the ink L ₁ specific gravity [rho ₁ to the connection unit 8K-2 of the common supply passage 6K to the second head unit 40K-2 is connected is filled, and the second one-off the ink supply channels 7K-2 and the second head unit 40K-2 is set to replaced time to all exchange after the ink L _1. By stopping the ink suction of the second head unit 40K-2 when such a second specified time elapses, the second head unit 40K-2 is replaced with ink even though the ink replacement is completed. situation in which the head unit replacement after the ink L ₁ from 40K-2 from being wastefully discharged can be suppressed.

Subsequently, when the third specified time elapses from the start of ink suction (Yes in S8), the third head unit 40K-3 connected third from the downstream side in the flow path direction of the common supply flow path 6K. Ink suction is stopped (S9). The third specified time, a small exchange after the ink L ₁ specific gravity [rho ₁ to the connection unit 8K-3 of the common supply channel 6K the third head unit 40K-3 is connected is filled, and the third one-off the ink supply channels 7K-3 and the third head unit 40K-3 is set to replaced time to all exchange after the ink L _1. By stopping the ink suction of the third head unit 40K-3 when the third specified time elapses, the third head unit 40K-3 has been replaced with ink. situation in which the head unit replacement after the ink L ₁ from 40K-3 from being wastefully discharged can be suppressed.

Subsequently, when the fourth specified time elapses from the start of ink suction (Yes in S10), the ink suction of the fourth head unit 40K-4 connected to the uppermost stream in the flow path direction of the common supply flow path 6K is performed. Stop (S11). The fourth specified time, after replacement ink L ₁ throughout in the common supply channel 6K is filled, and the ink of the four separate supply channel 7K-4 and the fourth head unit 40K-4 is replaced every is set to a time switched to the rear ink L _1. By stopping the ink suction of the fourth head unit 40K-4 when the fourth specified time elapses, the ink replacement (replacement) can be completed.

The main tanks 5K and if the flow path length between the connecting part 8K-4 of the fourth head unit 40K-4 is long, specific gravity large exchange before ink [rho ₀ L ₀ is the main tank 5K than the connecting section 8K-4 It may collect on the side (upstream side of the common supply flow path 6K in the flow path direction from the connection portion 8K-4). In such a case, in the middle of the ink replacement operation (around late) and allowed to stir the ink in the common supply channel 6K and the like vibrates the common supply passage 6K, waste further replacement after ink L ₁ The amount of ink discharged can be suppressed, and the time required for the ink replacement operation can be further reduced.

After the ink replacement (replacement) is completed in this way, the suction cap is decapped from the nozzle surface of each head unit 40K-1, 40K-2, 40K-3, 40K-4 (S12). Then, the surface of the nozzle is wiped by the wiper member to wipe off the ink dripping on the nozzle surface (S13) to form the meniscus of the nozzle 40n, and the ink exchange operation is completed.

In the ink exchange operation of the modified embodiment 1 in the case towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _0> ρ _1), the common supply passage 6K Relative to the amount of ink discharged from the head unit corresponding to the individual supply flow path connected to the relatively high connection portion (head unit on the downstream side in the flow path direction of the common supply flow path 6K in FIG. 19). The amount of ink discharged from the head unit corresponding to the individual supply flow path connected to the low connection portion (the head unit on the upstream side in the flow path direction of the common supply flow path 6K in FIG. 19) is larger. By performing such ink replacement operation, when towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _0> ρ _1), the common supply channel 6K _{The discharge amount of the pre-replacement ink L 0} that is brought to a lower position can be larger than the discharge amount of the _{post-replacement ink L 1} that is brought to a higher position in the common supply flow path 6K. _{As a result, the amount of the post-replacement ink L 1} discharged by the time all the _{pre-replacement ink L 0} in the common supply flow path 6K is discharged can be suppressed to a small amount.

In particular, in the present modification 1, when the ink L _{0 before replacement having a large specific density ρ 0} is replaced with the ink L ₁ after replacement having a small specific density ρ ₁ , as shown in FIG. 19, the flow path in the common supply flow path 6K. The common supply flow path 6K is inclined from the lower side to the upper side toward the downstream side in the direction. As a result, the replaced ink L _{1 having a small specific density ρ 1} can be efficiently transferred to the downstream side in the flow path direction of the common supply flow path 6K, and the ink replacement in the common supply flow path 6K can be promoted.

Further, in the ink replacement operation of the first modification in the case towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _0> ρ _1), a relatively high connection It is connected to a relatively low connection part without discharging ink from the head unit corresponding to the individual supply flow path connected to the unit (the head unit on the downstream side in the flow path direction of the common supply flow path 6K in FIG. 19). This includes the operation of ejecting ink from the head unit corresponding to the individual supply flow path (the head unit on the upstream side in the flow path direction of the common supply flow path 6K in FIG. 19). Therefore, it is possible to suppress the already situation the exchange after the ink L ₁ from the head unit replacement is finished ink is wastefully discharged.

[Modification 2]
Next, another modification of the ink exchange operation and its configuration in the above-described embodiment (hereinafter, this modification will be referred to as “modification example 2”) will be described.
FIG. 20 is an explanatory diagram showing an example of the common supply flow path 6K of the present modification 2.
As shown in FIG. 20, the common supply flow path 6K of the present modification 2 is low near the center of the common supply flow path 6K in the flow path direction, and is upward from below toward both ends of the common supply flow path 6K in the flow path direction. Inclined to. Therefore, inside the common supply flow path 6K, as shown in FIG. 20, the large replacement ink L _{1 having a specific gravity ρ 1} supplied from the main tank 5K is moved toward the center side of the common supply flow path 6K in the flow path direction. The small pre-replacement ink L ₀ having a specific gravity ρ ₀ is moved to both ends of the common supply flow path 6K in the flow path direction.

Flowchart 21, showing the flow of the ink replacement operation of the second modification when the specific gravity [rho towards specific gravity [rho ₁ of the exchange after the ink L ₁ is larger than the ₀ (ρ _{0 <ρ 1)} before replacement ink L ₀ Is.
First, the main tank 5K'before replacement, which is connected to the recording head portion 40K, is replaced with the main tank 5K containing the ink after replacement (S41). Next, the individual suction caps 46K-1, 46K-2, 46K-3, 46K-4 are brought into close contact with the nozzle surfaces of the head units 40K-1, 40K-2, 40K-3, 40K-4, respectively. Capping (S42). After that, the inside of the total suction caps 46K-1, 46K-2, 46K-3, 46K-4 is made negative pressure by the suction pump, and from the nozzles of all the head units 40K-1, 40K-2, 40K-3, 40K-4. The ink is sucked out (S43).

In the second modification, as shown in FIG. 20, the common supply flow path 6K is inclined from both ends toward the center from the upper side to the lower side. Therefore, inside the common supply flow path 6K, as shown in FIG. 20, the large replacement ink L _{1 having a specific gravity ρ 1} supplied from the main tank 5K is moved toward the center side of the common supply flow path 6K in the flow path direction. The small pre-replacement ink L ₀ having a specific gravity ρ ₀ is moved to both ends of the common supply flow path 6K in the flow path direction. As a result, as the ink is sucked out, the inside of the common supply flow path 6K is sequentially filled with the replaced ink L _{1 having a large specific gravity ρ 1 from the center in the flow path direction.}

In the second modification, when the ninth specified time elapses from the start of ink suction (Yes in S44), the second head unit 40K-2 and the second head unit 40K-2 connected to the central portion of the common supply flow path 6K in the flow path direction The ink suction of the third head unit 40K-3 is stopped (S45). During this ninth specified time, the ink L _{1 after replacement having a large specific gravity ρ 1} up to the connection portion 8K-2, 8K-3 of the common supply flow path 6K to which these two head units 40K-2, 40K-3 are connected. There is filled, and is set to the corresponding two separate supply channel 7K-2,7K-3 and head unit 40K-2,40K-3 times the ink are exchanged all the exchange after the ink _{L 1} in. By stopping the ink suction of these two head units 40K-2 and 40K-3 when the ninth specified time elapses, the inks of these two head units 40K-2 and 40K-3 can be replaced. situation where despite completed after replacement ink L ₁ from these head units 40K-2,40K-3 would be wastefully discharged can be suppressed.

Subsequently, in the present modification 2, when the tenth specified time elapses from the start of ink suction (Yes in S46), the first head unit 40K connected to both ends of the common supply flow path 6K in the flow path direction Ink suction of -1 and the fourth head unit 40K-4 is stopped (S47). The tenth specified time, the common supply channel exchange after ink _{L 1} within the overall 6K is filled, and the corresponding individual supply passages 7K-1,7K-4 and the head unit 40K-1,40K-4 ink of the inner is set to replaced time to all exchange after the ink L _1. By stopping the ink suction of these two head units 40K-2 and 40K-3 when the tenth specified time has elapsed, the ink replacement (replacement) can be completed.

After the ink replacement (replacement) is completed in this way, the suction cap is decapped from the nozzle surface of each head unit 40K-1, 40K-2, 40K-3, 40K-4 (S48). Then, the nozzle surface is wiped by the wiper member to wipe off the ink dripping on the nozzle surface (S49) to form the meniscus of the nozzle 40n, and the ink exchange operation is completed.

In the present modified example 2, the ink replacement operation when towards the specific gravity [rho ₁ before replacement ink L specific gravity [rho ₀ after replacement ink L ₁ than ₀ is small (ρ _0> ρ _1), the common supply flow Ink suction of the first head unit 40K-1 and the fourth head unit 40K-1 connected to both ends of the path 6K in the flow path direction is stopped first, and the common supply flow path 6K is connected to the central portion in the flow path direction. The ink suction of the second head unit 40K-2 and the third head unit 40K-3 may be stopped later.

Further, in the above-described embodiments and modifications 1 and 2, the height difference of the connection portion with the common supply flow path 6K among the plurality of individual supply flow paths 7K-1, 7K-2, 7K-3, 7K-4 is determined. An adjusting means for adjusting may be provided. For example, an adjusting means for changing the inclination angle of the common supply flow path 6K (the angle formed by the ink flow direction and the horizontal direction of the common supply flow path 6K) is provided. The individual supply channels 7K-1, 7K-2, 7K-3, and 7K-4 of the present embodiment are made of a flexible tube made of a flexible fluororesin or Teflon resin. Therefore, when the inclination angle of the common supply flow path 6K is changed by such an adjusting means, the individual supply flow paths 7K-1, 7K-2, 7K-3, 7K-4 connected to the common supply flow path 6K Does not get in the way.

By providing such an adjusting means, for example, in the example of FIG. 16 in which the common supply flow path 6K is inclined from the upper side to the lower side toward the downstream side in the flow path direction, the specific gravity ρ _{0 of the ink L 0 before replacement is provided.} Alternatively, the inclination of the common supply flow path 6K can be relaxed or steepened according to the specific gravity ρ _{1 of the ink L 1 after replacement.} This further possible to suppress wasteful discharge of exchange after the ink L _1, it is possible to further reduce the time required for the ink replacement operation.

Further, by providing such an adjusting means, for example, in the ink exchange operation, the common supply flow path 6K is inclined from the upper side to the lower side toward the downstream side in the flow path direction, and the configuration of FIG. The configuration of FIG. 19 in which the common supply flow path 6K is inclined from the lower side to the upper side toward the downstream side in the flow path direction can be appropriately switched. As a result, for example, when the pre-replacement ink L _{0 having a small specific density ρ 0} is replaced with the post-replacement ink L ₁ having a large specific density ρ ₁ (ρ ₀ <ρ ₁ ), the common supply is as shown in FIG. When the inclination angle of the flow path 6K is adjusted and, conversely, the ink L _{0 before replacement having a large specific density ρ 0} is replaced with the ink L ₁ after replacement having a small specific density ρ _{1 (ρ 0} > ρ ₁ ), FIG. It can be said that the inclination angle of the common supply flow path 6K is adjusted so as to have the above configuration. According to this, in any case of replacement, can be transported efficiently exchange after the ink L ₁ to the flow direction downstream side of the common supply passage 6K, promotes ink replacement of the common supply channel 6K be able to.

Further, by providing such an adjusting means, for example, after the ink replacement operation is completed, during the normal ink supply operation (ink supply operation from the main tank to each head unit), the common supply flow path 6K It can be said that the inclination angle is set to zero (the common supply flow path 6K is made horizontal). If the ink after replacement is a liquid in which solids easily settle (for example, a liquid having a magnetic material), if the common supply flow path 6K is left in an inclined state, the replacement ink will be placed at a lower position of the common supply flow path 6K. It may be preferable to make the common supply flow path 6K horizontal because the solid content of the ink will settle.

Further, when the specific densities ρ ₀ and ρ _{1 of the inks L 0} and L ₁ before and after the replacement are almost the same (ρ ₀ = ρ ₁ ), the ink separation occurs inside the common supply flow path 6K during the ink replacement operation. Hateful. However, an adjusting means is provided, and the inclination angle of the common supply flow path 6K is changed so as to move the common supply flow path 6K up and down (vibration) during the ink exchange operation, and the ink in the common supply flow path 6K is agitated. in, it is possible to suppress wasteful discharge of exchange after the ink L _1, it is possible to reduce the time required for the ink replacement operation.

Further, in the above-described embodiments and modifications 1 and 2, the exchange of inks having different specific densities has been described as an example, but one or both of them are liquids other than ink (for image formation of an image forming apparatus). It may be an unused liquid). For example, cleaning liquids having different specific densities may be replaced with ink, inks having different specific densities may be replaced with cleaning liquids, cleaning liquids having different specific densities may be replaced with different cleaning liquids, and the like.

Further, in the present embodiment, as the device for discharging the liquid, the above-mentioned inkjet recording type image forming device has been described as an example, but the device for discharging the liquid to which the present invention is applicable is not limited to this. That is, the "device that discharges the liquid" is a device that includes a liquid discharge head or a liquid discharge unit and drives the liquid discharge head to discharge the liquid. The device for discharging the liquid includes not only a device capable of discharging the liquid to a device to which the liquid can adhere, but also a device for discharging the liquid toward the air or the liquid.

The "device for discharging the liquid" can also include a part related to feeding, transporting, and discharging paper to which the liquid can adhere, a pretreatment device, a posttreatment device, and the like. For example, as a "device that ejects a liquid", an image forming apparatus that ejects ink to form an image on paper, and a three-dimensional object (three-dimensional object) are formed in layers in order to form a three-dimensional object. There is a three-dimensional modeling device (three-dimensional modeling device) that discharges the modeling liquid into the powder layer. Further, the "device for discharging a liquid" is not limited to a device in which a significant image such as characters and figures is visualized by the discharged liquid. For example, those that form patterns that have no meaning in themselves and those that form a three-dimensional image are also included.

The "liquid-attachable" means a liquid to which the liquid can adhere at least temporarily, such as one that adheres and adheres, and one that adheres and permeates. Specific examples include paper, recording paper, recording paper, film, recording media such as cloth, electronic substrates, electronic components such as piezoelectric elements, powder layers (powder layers), organ models, and media such as inspection cells. Yes, including anything to which the liquid adheres, unless otherwise specified. The material of the "material to which the liquid can be attached" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, or the like as long as the liquid can be attached even temporarily.

The "liquid" may have a viscosity and surface tension that can be discharged from the liquid discharge head, and is not particularly limited, but the viscosity becomes 30 mPa · s or less at room temperature, under normal pressure, or by heating or cooling. It is preferable that it is a thing. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functionalizing materials such as surfactants, biocompatible materials such as DNA, amino acids and proteins, and calcium. , Solvents, suspensions, emulsions, etc. containing edible materials such as natural pigments, etc., for example, inks for inkjets, surface treatment liquids, components of electronic elements and light emitting elements, and formation of electronic circuit resist patterns. It can be used for applications such as a liquid for use and a material liquid for three-dimensional modeling.

Further, the "device for discharging the liquid" includes, but is not limited to, a device in which the liquid discharge head and the device to which the liquid can adhere move relatively. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

In addition, as a "device for ejecting liquid", a treatment liquid coating device for ejecting a treatment liquid to the paper in order to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, raw materials. There is an injection granulation device that granulates fine particles of raw materials by injecting a composition liquid in which the above-mentioned material is dispersed in a solution through a nozzle.

The "liquid discharge unit" is a collection of parts related to liquid discharge, which is a combination of a liquid discharge head, which is a functional part that discharges and ejects liquid from a nozzle, and a functional part and a mechanism. be. For example, the "liquid discharge unit" includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, and a main scanning movement mechanism with a liquid discharge head.

Here, "integration" means, for example, a liquid discharge head and a functional component, a mechanism in which the mechanism is fixed to each other by fastening, adhesion, engagement, etc., or one in which one is movably held with respect to the other. include. Further, the liquid discharge head, the functional parts, and the mechanism may be detachably attached to each other.

As the liquid discharge unit, there is a unit in which the liquid discharge head and the head tank are integrated as in the present embodiment, but there is also a liquid discharge unit in which the liquid discharge head and the carriage are integrated. Further, as a liquid discharge unit, the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably by a guide member forming a part of the scanning movement mechanism. In some cases, the liquid discharge head, the carriage, and the main scanning movement mechanism are integrated.

Further, as a liquid discharge unit, there is a carriage to which a liquid discharge head is attached, in which a cap member which is a part of the maintenance / recovery mechanism is fixed, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. .. Further, as a liquid discharge unit, there is a liquid discharge unit in which a tube is connected to a head tank or a liquid discharge head to which a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. Through this tube, the liquid of the liquid storage source is supplied to the liquid discharge head. The main scanning movement mechanism shall also include a single guide member. Further, the supply mechanism includes a single tube and a single loading unit.

Further, the above-described embodiment can also be applied to a head (so-called circulation type head) that circulates the liquid in the liquid discharge head and collects the liquid that has not been used for discharge. In that case, the individual recovery flow path is connected to each liquid discharge head, and the common recovery flow path is connected to each individual recovery flow path. When exchanging the liquid, if the liquid before the exchange flows into the recovery flow path, it may be mixed with the liquid after the exchange. Therefore, it is desirable to prevent the liquid from flowing into the recovery flow path as much as possible by stopping the circulation device.

In addition, image formation, recording, printing, printing, printing, modeling, etc. in the terms of the present specification are all synonymous.

The above description is an example, and the effect peculiar to each of the following aspects is exhibited.
[First aspect]
In the first aspect, liquid (for example, ink) is supplied from the common supply flow path 6K to a plurality of liquid discharge units (for example, head units 40-1 to 40-4) through a plurality of individual supply flow paths, and each liquid discharge unit supplies the liquid (for example, ink). A device that discharges a liquid (for example, an image forming apparatus 100) and has a large specific gravity liquid (for example, ink L before replacement) having a large _{specific gravity ρ 0 in the common supply flow path, the individual supply flow path, and the liquid discharge unit. When} exchanging 0) for a small specific gravity liquid with a specific gravity of ρ ₁ (for example, ink L ₁ before replacement) (ρ ₀ > ρ ₁ ), an individual supply connected to a relatively high connection portion 8-1 to 8-4. Individual supply channels 7-1 to 7 connected to connecting portions 8-1 to 8-4, which are relatively lower than the amount of liquid discharged from the liquid discharge unit corresponding to the channels 7-1 to 7-4. It is characterized in that a liquid exchange operation (for example, an ink exchange operation) is performed so that the amount of liquid discharged from the liquid discharge unit corresponding to -4 is larger.
When replacing a large-density liquid with a large specific density with a small-density liquid with a small specific gravity (ρ ₀ > ρ ₁ ), the large-density liquid before replacement is discharged from the liquid discharge unit, and the small-density liquid after replacement is gradually discharged. By being supplied, the liquid in the common supply flow path is gradually replaced from the large specific density liquid before replacement to the low specific density liquid after replacement. At this time, even in a situation where the large specific density liquid before replacement and the small specific density liquid after replacement are mixed in the common supply flow path, the small specific density liquid after replacement is not wasted and is not discharged before replacement. It is important to preferentially discharge the liquid with a large specific density.
Under the above-mentioned situation, in the common supply flow path, the small specific density liquid after replacement is moved upward (high position) and the large specific density liquid before replacement is downward (high position) due to the difference in specific density between the liquids before and after replacement. It will be in a state of being moved to a lower position). Therefore, when there is a height difference in the connection portion where each individual supply flow path is connected to the common supply flow path (the connection portion between the common supply flow path and the plurality of individual supply flow paths has a height in the direction of gravity). (When different connections are included), the small specific density liquid after replacement is supplied to the individual supply flow path where the connection part is relatively high from the middle stage of liquid replacement before and after replacement, and the small specific density liquid after replacement. Will be wasted.
According to this aspect, when there is a height difference in the connection portion of each individual supply flow path during the liquid exchange operation, the liquid is discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion is larger than the amount of liquid. As a result, the amount of the large specific density liquid before replacement that is moved downward (low position) in the common supply flow path is moved to the upper side (high position) in the common supply flow path, and the small specific density liquid after replacement is discharged. More than quantity. As a result, it is possible to reduce the amount of the small specific density liquid after the exchange to be discharged before all the large specific density liquid before the exchange is discharged in the common supply flow path. Therefore, even if the specific densities of the liquid before replacement and the liquid after replacement are different, it is possible to prevent the liquid after replacement from being wasted before the liquid before replacement is replaced with the liquid after replacement.

[Second aspect]
In the second aspect, in the first aspect, the liquid exchange operation is relatively low in a state where the liquid is not discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection portion. It is characterized by including an operation of discharging a liquid from a liquid discharge unit corresponding to an individual supply flow path connected to a connection portion.
According to this, it is possible to suppress a situation in which the replaced liquid is wastefully discharged from the liquid discharge unit for which the replacement of the liquid has already been completed, and it is possible to further suppress the wasteful consumption of the replaced liquid.

[Third aspect]
The third aspect is when, in the first or second aspect, a _{small specific density liquid having a specific gravity ρ 0} (for example, pre-replacement ink L ₀ ) is replaced with a large specific density liquid having a specific density ρ ₁ (for example, pre-replacement ink L ₁ ). (Ρ ₀ <ρ ₁ ), to a connection portion that is relatively higher than the amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion of the common supply flow path. It is characterized in that a liquid exchange operation is performed so that the amount of liquid discharged from the liquid discharge unit corresponding to the connected individual supply flow path is larger.
When exchanging a small specific density liquid with a small specific density for a large specific density liquid with a large specific gravity (ρ ₀ <ρ ₁ ), the large specific density liquid after exchange is changed due to the difference in specific density between the liquids before and after the exchange in the common supply flow path. It is moved downward (low position), and the small specific density liquid before replacement is moved upward (high position). Therefore, when there is a height difference in the connection portion where each individual supply flow path is connected to the common supply flow path (the connection portion between the common supply flow path and the plurality of individual supply flow paths has a height in the direction of gravity). (When different connections are included), the large specific density liquid after replacement is supplied to the individual supply flow path where the connection part is relatively low from the middle stage of liquid replacement before and after replacement, and the large specific density liquid after replacement. Will be wasted.
According to this aspect, when there is a height difference in the connection portion of each individual supply flow path during the liquid exchange operation, the liquid is discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection portion is larger than the amount of liquid. As a result, the amount of the small specific density liquid before replacement that is moved upward (high position) in the common supply flow path is moved to the lower side (low position) in the common supply flow path, and the large specific density liquid after replacement is discharged. More than quantity. As a result, it is possible to reduce the amount of the large specific density liquid after the exchange to be discharged before all the small specific density liquid before the exchange is discharged in the common supply flow path. Therefore, even if the specific densities of the liquid before replacement and the liquid after replacement are different, it is possible to prevent the liquid after replacement from being wasted before the liquid before replacement is replaced with the liquid after replacement.

[Fourth aspect]
A fourth aspect is a device that supplies liquid from a common supply flow path to a plurality of liquid discharge units through a plurality of individual supply flow paths and discharges the liquid from each liquid discharge unit. A liquid discharge unit corresponding to an individual supply flow path connected to a relatively low connection portion when exchanging a small specific gravity liquid having a small specific gravity in an individual supply flow path or the liquid discharge unit with a large specific gravity liquid having a large specific gravity. Perform the liquid exchange operation so that the amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection portion is larger than the amount of liquid discharged from the liquid. It is a feature.
When exchanging a small specific gravity liquid with a small specific density for a large specific gravity liquid with a large specific gravity (ρ ₀ <ρ ₁ ), the small specific gravity liquid before the exchange is discharged from the liquid discharge unit, and the large specific gravity liquid after the exchange is gradually discharged. By being supplied, the liquid in the common supply flow path is gradually replaced from the small specific density liquid before replacement to the large specific density liquid after replacement. At this time, even in a situation where the small specific density liquid before replacement and the large specific density liquid after replacement are mixed in the common supply flow path, the large specific density liquid after replacement is not wasted and is not discharged before replacement. It is important to preferentially discharge the small specific density liquid.
Under the above-mentioned situation, in the common supply flow path, the large specific density liquid after replacement is moved downward (low position) and the small specific density liquid before replacement is upward (in the common supply flow path) due to the difference in specific density between the liquids before and after replacement. It will be in a state of being moved to a higher position). Therefore, when there is a height difference in the connection portion where each individual supply flow path is connected to the common supply flow path (the connection portion between the common supply flow path and the plurality of individual supply flow paths has a height in the direction of gravity). (When different connections are included), the large specific density liquid after replacement is supplied to the individual supply flow path where the connection part is relatively low from the middle stage of liquid replacement before and after replacement, and the large specific density liquid after replacement. Will be wasted.
According to this aspect, when there is a height difference in the connection portion of each individual supply flow path during the liquid exchange operation, the liquid is discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection portion is larger than the amount of liquid. As a result, the amount of the small specific density liquid before replacement that is moved upward (high position) in the common supply flow path is moved to the lower side (low position) in the common supply flow path, and the large specific density liquid after replacement is discharged. More than quantity. As a result, it is possible to reduce the amount of the large specific density liquid after the exchange to be discharged before all the small specific density liquid before the exchange is discharged in the common supply flow path. Therefore, even if the specific densities of the liquid before replacement and the liquid after replacement are different, it is possible to prevent the liquid after replacement from being wasted before the liquid before replacement is replaced with the liquid after replacement.

[Fifth aspect]
In a fifth aspect, in the third or fourth aspect, the liquid exchange operation is such that the liquid is not discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion. It is characterized by including an operation of discharging a liquid from a liquid discharge unit corresponding to an individual supply flow path connected to a particularly high connection portion.
According to this, it is possible to suppress a situation in which the replaced liquid is wastefully discharged from the liquid discharge unit for which the replacement of the liquid has already been completed, and it is possible to further suppress the wasteful consumption of the replaced liquid.

[Sixth aspect]
A sixth aspect has, in any one of the first to fifth aspects, an adjusting means for adjusting the height difference of the connecting portion.
By providing such an adjusting means, it is possible to further suppress unnecessary discharge of the liquid after the replacement, and it is possible to further reduce the time required for the liquid replacement operation.

[7th aspect]
A seventh aspect is a liquid exchange method for a device that supplies liquid from a common supply flow path to a plurality of liquid discharge units through a plurality of individual supply flow paths and discharges the liquid from each liquid discharge unit. Corresponds to the individual supply flow path connected to the relatively high connection part when exchanging a large specific gravity liquid with a large specific gravity in the path, the individual supply flow path, and the liquid discharge unit with a small specific gravity liquid having a small specific gravity. It is characterized in that the amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion is larger than the amount of liquid discharged from the liquid discharge unit. Is.
When replacing a large-density liquid with a large specific density with a small-density liquid with a small specific gravity (ρ ₀ > ρ ₁ ), the large-density liquid before replacement is discharged from the liquid discharge unit, and the small-density liquid after replacement is gradually discharged. By being supplied, the liquid in the common supply flow path is gradually replaced from the large specific density liquid before replacement to the low specific density liquid after replacement. At this time, even in a situation where the large specific density liquid before replacement and the small specific density liquid after replacement are mixed in the common supply flow path, the small specific density liquid after replacement is not wasted and is not discharged before replacement. It is important to preferentially discharge the liquid with a large specific density.
Under the above-mentioned situation, in the common supply flow path, the small specific density liquid after replacement is moved upward (high position) and the large specific density liquid before replacement is downward (high position) due to the difference in specific density between the liquids before and after replacement. It will be in a state of being moved to a lower position). Therefore, when there is a height difference in the connection portion where each individual supply flow path is connected to the common supply flow path (the connection portion between the common supply flow path and the plurality of individual supply flow paths has a height in the direction of gravity). (When different connections are included), the small specific density liquid after replacement is supplied to the individual supply flow path where the connection part is relatively high from the middle stage of liquid replacement before and after replacement, and the small specific density liquid after replacement. Will be wasted.
According to this aspect, when there is a height difference in the connection portion of each individual supply flow path during the liquid exchange operation, the liquid is discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion is larger than the amount of liquid. As a result, the amount of the large specific density liquid before replacement that is moved downward (low position) in the common supply flow path is moved to the upper side (high position) in the common supply flow path, and the small specific density liquid after replacement is discharged. More than quantity. As a result, it is possible to reduce the amount of the small specific density liquid after the exchange to be discharged before all the large specific density liquid before the exchange is discharged in the common supply flow path. Therefore, even if the specific densities of the liquid before replacement and the liquid after replacement are different, it is possible to prevent the liquid after replacement from being wasted before the liquid before replacement is replaced with the liquid after replacement.

[8th aspect]
In the eighth aspect, in the seventh aspect, when the high-density liquid is exchanged for the low-density liquid, the common supply flow path is moved from the bottom to the top toward the downstream side in the liquid flow direction in the common supply flow path. It is characterized by being tilted.
According to this, the exchanged liquid (small specific density liquid) having a small specific density can be efficiently transferred to the downstream side in the flow path direction of the common supply flow path, and the replacement of the liquid in the common supply flow path is promoted. Can be done.

[9th aspect]
A ninth aspect is a liquid exchange method in which a liquid is supplied from a common supply flow path to a plurality of liquid discharge units through a plurality of individual supply flow paths, and the liquid of the device that discharges the liquid from each liquid discharge unit is exchanged. When exchanging a small specific gravity liquid having a small specific gravity in the common supply flow path, the individual supply flow path, and the liquid discharge unit with a large specific gravity liquid having a large specific gravity, the individual supply is connected to a relatively low connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection part should be larger than the amount of liquid discharged from the liquid discharge unit corresponding to the flow path. It is a feature.
When exchanging a small specific gravity liquid with a small specific density for a large specific gravity liquid with a large specific gravity (ρ ₀ <ρ ₁ ), the small specific gravity liquid before the exchange is discharged from the liquid discharge unit, and the large specific gravity liquid after the exchange is gradually discharged. By being supplied, the liquid in the common supply flow path is gradually replaced from the small specific density liquid before replacement to the large specific density liquid after replacement. At this time, even in a situation where the small specific density liquid before replacement and the large specific density liquid after replacement are mixed in the common supply flow path, the large specific density liquid after replacement is not wasted and is not discharged before replacement. It is important to preferentially discharge the small specific density liquid.
Under the above-mentioned situation, in the common supply flow path, the large specific density liquid after replacement is moved downward (low position) and the small specific density liquid before replacement is upward (in the common supply flow path) due to the difference in specific density between the liquids before and after replacement. It will be in a state of being moved to a higher position). Therefore, when there is a height difference in the connection portion where each individual supply flow path is connected to the common supply flow path (the connection portion between the common supply flow path and the plurality of individual supply flow paths has a height in the direction of gravity). (When different connections are included), the large specific density liquid after replacement is supplied to the individual supply flow path where the connection part is relatively low from the middle stage of liquid replacement before and after replacement, and the large specific density liquid after replacement. Will be wasted.
According to this aspect, when there is a height difference in the connection portion of each individual supply flow path during the liquid exchange operation, the liquid is discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection portion is larger than the amount of liquid. As a result, the amount of the small specific density liquid before replacement that is moved upward (high position) in the common supply flow path is moved to the lower side (low position) in the common supply flow path, and the large specific density liquid after replacement is discharged. More than quantity. As a result, it is possible to reduce the amount of the large specific density liquid after the exchange to be discharged before all the small specific density liquid before the exchange is discharged in the common supply flow path. Therefore, even if the specific densities of the liquid before replacement and the liquid after replacement are different, it is possible to prevent the liquid after replacement from being wasted before the liquid before replacement is replaced with the liquid after replacement.

[10th aspect]
In the tenth aspect, when the small specific density liquid is exchanged for the large specific density liquid in the ninth aspect, the common supply flow path is moved from the upper side to the lower side toward the downstream side in the liquid flow direction in the common supply flow path. It is characterized by being tilted.
According to this, the exchanged liquid having a large specific density (large specific density liquid) can be efficiently transferred to the downstream side in the flow path direction of the common supply flow path, and the replacement of the liquid in the common supply flow path is promoted. Can be done.

1: Recording head 2: Head tank 2a: Ink accommodating portion 2b: Supply port 3: Tank case 3a: Film member 4: Discharge flow path 5: Main tank 6: Common supply flow path 7-1 to 7-4: Individual supply Flow path 8-1 to 8-4: Connection part 10: Carry-in part 20: Pretreatment part 30: Drying part 40: Image forming part (recording head part)
40-1 to 40-4: Head unit 40c: Common liquid chamber 40f: Liquid chamber 40i: Ink supply port 40n: Nozzle 40o: Ink discharge port 40r: Nozzle communication passage 40s: Ink inlet 41: Flow plate 42: Vibration Plate 43: Nozzle plate 44: Frame member 45: Pressure generating unit 46-1 to 46-4: Suction cap 50: Post-processing unit 60: Carrying out unit 70: Control unit 71: Upper device 72: Printer device 100: Image forming device Md: Roll paper

Japanese Unexamined Patent Publication No. 2009-12452

Claims (10)

A device that supplies liquid from a common supply flow path to a plurality of liquid discharge units through a plurality of individual supply flow paths, and discharges the liquid from each liquid discharge unit.
When exchanging a large specific gravity liquid having a large specific gravity in the common supply flow path, the individual supply flow path, and the liquid discharge unit with a small specific gravity liquid having a small specific gravity, the individual supply is connected to a relatively high connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion is larger than the amount of liquid discharged from the liquid discharge unit corresponding to the flow path. , A device that discharges a liquid, which is characterized by performing a liquid exchange operation. In the device for discharging the liquid according to claim 1,
The liquid exchange operation is an individual supply flow path connected to the relatively low connection portion without discharging liquid from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection portion. A device for discharging a liquid, which comprises the operation of discharging the liquid from the liquid discharge unit corresponding to the above. In the device for discharging the liquid according to claim 1 or 2.
When exchanging a small specific gravity liquid with a small specific gravity for a large specific gravity liquid with a large specific gravity, the amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion of the common supply flow path. The liquid is discharged so that the amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection portion is larger than that of the liquid exchange operation. Equipment to do. A device that supplies liquid from a common supply flow path to a plurality of liquid discharge units through a plurality of individual supply flow paths, and discharges the liquid from each liquid discharge unit.
When exchanging a small specific gravity liquid having a small specific gravity in the common supply flow path, the individual supply flow path, and the liquid discharge unit with a large specific gravity liquid having a large specific gravity, the individual supply is connected to a relatively low connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection part is larger than the amount of liquid discharged from the liquid discharge unit corresponding to the flow path. , A device that discharges a liquid, which is characterized by performing a liquid exchange operation. In the device for discharging the liquid according to claim 3 or 4.
The liquid exchange operation is an individual supply flow path connected to the relatively high connection portion without discharging liquid from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection portion. A device for discharging a liquid, which comprises the operation of discharging the liquid from the liquid discharge unit corresponding to the above. In the device for discharging the liquid according to any one of claims 1 to 5.
A device for discharging a liquid having an adjusting means for adjusting the height difference of the connection portion. A liquid exchange method for a device that supplies liquid from a common supply flow path to a plurality of liquid discharge units through a plurality of individual supply flow paths and discharges the liquid from each liquid discharge unit.
When exchanging a large specific gravity liquid having a large specific gravity in the common supply flow path, the individual supply flow path, and the liquid discharge unit with a small specific gravity liquid having a small specific gravity, the individual supply is connected to a relatively high connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively low connection part should be larger than the amount of liquid discharged from the liquid discharge unit corresponding to the flow path. A characteristic liquid exchange method. In the liquid exchange method according to claim 7,
When exchanging the high-density liquid with the low-density liquid, the liquid exchange method is characterized in that the common supply flow path is inclined from the lower side to the upper side toward the downstream side in the liquid flow direction in the common supply flow path. .. It is a liquid exchange method in which liquid is supplied from a common supply flow path to a plurality of liquid discharge units through a plurality of individual supply flow paths, and the liquid of the device that discharges the liquid from each liquid discharge unit is exchanged.
When exchanging a small specific gravity liquid having a small specific gravity in the common supply flow path, the individual supply flow path, and the liquid discharge unit with a large specific gravity liquid having a large specific gravity, the individual supply is connected to a relatively low connection portion. The amount of liquid discharged from the liquid discharge unit corresponding to the individual supply flow path connected to the relatively high connection part should be larger than the amount of liquid discharged from the liquid discharge unit corresponding to the flow path. A characteristic liquid exchange method. In the liquid exchange method according to claim 9,
When exchanging the small specific density liquid with the large specific density liquid, the liquid exchange method is characterized in that the common supply flow path is inclined from the upper side to the lower side toward the downstream side in the liquid flow direction in the common supply flow path. ..

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