LIQUID EJECTING APPARATUS

There is provided a liquid ejecting apparatus including: a head having a nozzle surface in which a nozzle is opened; a wiper configured to move relative to the head in a state that the wiper is in contact with the nozzle surface; and a controller. The controller is configured to move the wiper relative to the head based on a moving velocity determined based on parameters including first parameter according to a receding contact angle of a liquid to be discharged from the nozzle and second parameter according to a viscosity of the liquid.

REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No. 2023-057191 filed on Mar. 31, 2023. The entire content of the priority application is incorporated herein by reference.

BACKGROUND ART

For example, in some ink-jet recording apparatuses, a wiping velocity is changed according to the viscosity of an ink so as to appropriately remove the ink from a surface, of a head, in which an ejection port is formed. Further, in some liquid jetting apparatuses, a moving velocity of a wiper is set in proportion to the surface tension of an ink intending to recover the meniscus in an ensured manner.

SUMMARY

However, even in a case that the moving velocity of the wiper with respect to the head is set in consideration of the viscosity and/or the surface tension of the liquid, there is such a fear that the liquid on a nozzle surface might not be satisfactorily wiped by the wiper. As an example, there is such a fear that the liquid on the nozzle surface might not be satisfactorily wiped by the wiper in a case that a condition different from the viscosity and/or the surface tension of the liquid affects the wiping by the wiper.

The present disclosure has been made in view of the above-described point; an object of the present disclosure is to provide a means for removing a liquid adhered to a nozzle surface of a head satisfactorily with a wiper.

(1) According to a first aspect of the present disclosure, there is provided a liquid ejecting apparatus including:a head having a nozzle surface in which a nozzle is opened;a wiper configured to move relative to the head in a state that the wiper is in contact with the nozzle surface; anda controller,wherein the controller is configured to move the wiper relative to the head based on a moving velocity determined based on parameters including first parameter according to a receding contact angle of a liquid to be discharged from the nozzle and second parameter according to a viscosity of the liquid.

According to the above-described configuration, a moving velocity of the wiper is determined based on the receding contact angle of the liquid and the viscosity of the liquid, and thus occurrence of unwiped liquid by the wiper is reduced.

(2) The liquid ejecting apparatus of the first aspect may further include a memory. In the first aspect, the memory may store the first parameter and the second parameter, and the controller may be configured to determine the moving velocity based on the parameters including the first parameter and the second parameter.

(3) In the first aspect, the first parameter may be indicated by γ tan θD, provided that “γ” is a surface tension of the liquid and “OD” is the receding contact angle of the liquid.

(4) In the first aspect, the controller may be configured to move the wiper relative to the head based on the moving velocity determined based on the parameters including third parameter according to an equilibrium contact angle of the liquid, the first parameter, and the second parameter.

According to the above-described configuration, the moving velocity of the wiper is determined further based on the equilibrium contact angle of the liquid, and thus occurrence of unwiped liquid by the wiper is further reduced.

(5) The liquid ejecting apparatus of the first aspect may further include a memory. In the first aspect, the memory may store the first parameter, the second parameter and the third parameter; and the controller may be configured to determine the moving velocity based on the parameters including the first parameter, the second parameter and the third parameter.

(6) In the first aspect, the third parameter may be indicated by (cos θD−cos θE), provided that “θD” is the receding contact angle of the liquid and “θE” is the equilibrium contact angle of the liquid.

(7) In the first aspect, the memory may store a table in which the receding contact angle of the liquid corresponding to a kind of the liquid is set as the first parameter; and the controller may be configured to obtain kind information indicating the kind of the liquid and to determine the receding contact angle of the liquid according to the obtained kind information and based on the table.

(8) In the first aspect, in the table, the receding contact angle of the liquid corresponding to an elapsed time elapsed since the wiper has been moved relative to the head may be set; and the controller may be configured to obtain the elapsed time elapsed since the wiper has been moved relative to the head and to determine the receding contact angle of the liquid in the first parameter, according to the obtained elapsed time.

The water content of the liquid is evaporated due to the elapse of time, and consequently the receding contact angle is changed. According to the above-described configuration, the receding contact angle is determined according to the elapsed time, and thus occurrence of unwiped liquid by the wiper is reduced.

(9) The liquid ejecting apparatus of the first aspect may further include a memory. In the first aspect, the memory may store a table in which the moving velocity corresponding to a kind of the liquid is set; and the controller may be configured to obtain kind information indicating the kind of the liquid and to determine the moving velocity according to the obtained kind information and based on the table.

(10) In the first aspect, the moving velocity corresponding to an elapsed time elapsed since the wiper has been moved relative to the head may be set in the table; and the controller may be configured to obtain the elapsed time elapsed since the wiper has been moved relative to the head and to determine the moving velocity according to the obtained elapsed time and based on the table.

(11) In the first aspect, a maximum value of the moving velocity may satisfy following expressions:

V⁢max=γtanθD(cos⁢θD-cos⁢θE)/3⁢ηLL=ln⁢(d/a)provided that, “Vmax” is the maximum value of the moving velocity of the wiper, “γ” is a surface tension of the liquid, “θD” is the receding contact angle of the liquid, “θE” is an equilibrium contact angle of the liquid, “η” is the viscosity of the liquid; “d” is a diameter of a droplet of the liquid, and “a” is a size of one molecule of the liquid.

(12) According to a second aspect of the present disclosure, there is provided a liquid ejecting apparatus including:a head having a nozzle surface in which a nozzle is opened;a wiper configured to move relative to the head in a state that the wiper is in contact with the nozzle surface; anda controller,wherein the controller is configured to move the wiper relative to the head based on a moving velocity determined based on parameters including first parameter according to a receding contact angle of a liquid to be discharged from the nozzle and second parameter according to a viscosity of the liquid; anda maximum value of the moving velocity satisfies the following expressions:

V⁢max=γtanθD(cos⁢θD-cos⁢θE)/3⁢ηLL=ln⁢(d/a)provided that, “Vmax” is the maximum value of the moving velocity of the wiper, “γ” is a surface tension of the liquid, “θD” is the receding contact angle of the liquid, “θE” is an equilibrium contact angle of the liquid, “η” is the viscosity of the liquid, “d” is a diameter of a droplet of the liquid, and “a” is a size of one molecule of the liquid.

(13) The liquid ejecting apparatus of the second aspect may further include a memory. In the second aspect, the memory may store the first parameter and the second parameter; and the controller may be configured to determine the moving velocity based on the parameters including the first parameter and the second parameter.

(14) According to a third aspect of the present disclosure, there is provided a control method for a liquid ejecting apparatus, the liquid ejecting apparatus including:a head having a nozzle surface in which a nozzle is opened;a wiper configured to move relative to the head in a state that the wiper is in contact with the nozzle surface; anda controller,the method including moving the wiper relative to the head, by the controller, based on a moving velocity determined based on parameters including first parameter according to a receding contact angle of a liquid to be discharged from the nozzle and second parameter according to a viscosity of the liquid.

According to the present disclosure, a liquid adhered to a nozzle surface of a head is removed satisfactorily with a wiper.

DESCRIPTION

In the following, a printer10(an example of “liquid ejecting apparatus”) according to an embodiment of the present disclosure will be explained. Note that the embodiment described below is merely an example of the present disclosure; it is needless to say that the embodiment can be appropriately changed within a range in which the gist of the present disclosure is not changed.

In the embodiment, an up-down direction1is defined using a state in which the printer10is installed usably (a state ofFIG.1) as the reference; a front-rear direction2is defined assuming that a side to which a paper feed tray23is drawn out is a front side; and a left-right direction3is defined seeing the printer10from the front side.

<Outer Configuration of Printer10>

As depicted inFIG.1, the printer10is provided with a casing20; and an operating part21, a cover22, a paper feed tray23, a paper discharge tray24, a controller130and a memory140which are held by the casing20. The printer10is configured to record an image on a sheet6(seeFIG.2).

The sheet6may be a recording medium which is cut to a predetermined size, a recording medium drawn from a roll wound in a tube shape, or a recording medium of a fan-fold type.

The operating part21is provided with a display and a plurality of operating switches. The operating part21receives an operation from a user. The operating part21may be a touch panel.

As depicted inFIG.1, the paper feed tray23is positioned at a lower part of the casing20. The paper discharge tray24is positioned at the lower part of the casing20, at a location above the paper feed tray23. The cover22is positioned in a right part of a front surface of the casing20. The cover22is rotatable with respect to the casing20, at a lower end of the cover22. In a case that the cover22is opened, a cartridge70configured to store an ink can be accessed.

In the present embodiment, the cartridge70is not limited to a cartridge which stores one color ink such as a black ink, and may be, for example, four cartridges70configured to store, respectively, four color inks which are black, yellow, cyan and magenta inks. An IC substrate (not depicted in the drawings) is mounted on the cartridge70; kind information specifying the kind of the ink stored in the cartridge70is stored in the IC substrate.

The casing20has a print engine50held in the casing20. As depicted inFIG.2, the print engine50is mainly provided with a feeding roller25, a conveying roller26, a discharging roller27, a platen28and a printing head (an example of a “head”)34. The feeding roller25is held by a non-depicted frame provided in the casing20so that the feeding roller25is capable of making contact with the sheet6placed on the paper feed tray23. The feeding roller25is rotated by a feeding motor102(seeFIG.4). The feeding roller25which is being rotated feeds the sheet6to a conveying path37. The conveying path37is a space defined by a non-depicted guide member. In the depicted example, the conveying path37extends, while curving, from a rear end of the paper feed tray23up to a position above the paper feed tray23, and then extends frontward.

The conveying roller26is located downstream of the paper feed tray23, in a conveying direction (indicated by an arrow inFIG.2) of the sheet6. The conveying roller26constructs a roller pair together with a driven roller35. The conveying roller26is rotated by a conveying motor101(seeFIG.4). The conveying roller26and the driven roller35which are being rotated convey the sheet6fed to the conveying path37by the feeding roller25, while pinching the sheet6therebetween. The discharging roller27is located downstream of the conveying roller26in the conveying direction of the sheet6. The discharging roller27constructs a roller pair together with a driven roller36. The discharging roller27is rotated by the conveying motor101(seeFIG.4), like the conveying roller26. The discharging roller27and the driven roller36which are being rotated convey the sheet6, while pinching the sheet6therebetween, and discharge the sheet6to the paper discharge tray24. The platen28is positioned between the conveying roller26and the discharging roller27in the front-rear direction2, and downstream of the conveying roller26and upstream of the discharging roller27, in the conveying direction of the sheet6.

A rotary encoder75(seeFIG.4) configured to detect a rotation amount of the conveying roller26is provided on the conveying roller26. The rotary encoder75is constructed of an encoder disc (not depicted in the drawings) which rotates together with the conveying roller26and an optical sensor (not depicted in the drawings). A pattern wherein a light transmittable part through which a light is transmittable and a non-light transmittable part through which the light is not transmittable are alternately arranged at an equal pitch therebetween in the circumferential direction is formed in the encoder disc. In a case that the encoder disc rotates, a pulse signal is generated every time the light transmittable part and the non-light transmittable part are detected by the optical sensor. The generated pulse signal is outputted to the controller130(seeFIG.4). The controller130calculates the rotation amount of the conveying roller26based on the pulse signal.

An upper surface of the platen28is a supporting surface for the sheet6. Although not depicted in the respective drawings, an opening in which a suction pressure is generated is formed in the upper surface of the platen28. By the suction pressure generated in the upper surface of the platen28, the sheet6is capable of making a tight contact with the upper surface of the platen28.

The printing head34is positioned between the conveying roller26and the discharging roller27. The printing head34is positioned at a location above and facing the platen28, with the conveying path37being intervened therebetween. The printing head34is a so-called serial head. The printing head34is supported by a carriage40; the carriage40is supported to be movable by a guiderail (not depicted in the drawings) extending along the left-right direction3. The carriage40is moved by a carriage driving motor103(seeFIG.4). Namely, the printing head34is movable along the left-right direction3.

An encoder38(seeFIG.4) is arranged in the guide rail. The encoder38is provided with an encoder strip extending along the guide rail and an optical sensor provided on the carriage40at a location facing the encoder strip. A pattern wherein a light transmittable part through which a light is transmittable and a non-light transmittable part through which the light is not transmittable are alternately arranged at an equal pitch therebetween in the left-right direction3is formed in the encoder strip. The optical sensor detects the light transmittable part and the non-light transmittable part, thereby generating a pulse signal. The pulse signal is a signal according to the position in the left-right direction3of the carriage40. The pulse signal is outputted to the controller130.

The printing head34has, in the inside thereof, a channel in which the ink flows. The channel is communicated with the cartridge70via a tube31. Namely, the ink stored in the cartridge70is supplied to the printing head34through the tube31. The printing head34has a plurality of nozzles33which are opened toward the platen28. The ink supplied to the printing head34via the channel is ejected, as ink droplets, selectively from the plurality of nozzles33, by driving of a piezoelectric element45(seeFIG.4) while the printing head34is being moved. Note that the printing head34may be a line head, rather than the serial head. In a case that the printing head34is the line head, a wiper72(seeFIG.3, to be described later on) may move relative to the line head, thereby wiping a nozzle surface33A.

As depicted inFIG.3, a cap71is constructed of an elastic member such as rubber, etc. The cap71is positioned below the printing head34in a maintenance position. The cap71has a shape of a cup which is opened upward. The cap71is movable in the up-down direction1by a cap driving motor104. As depicted by broken lines inFIG.3, the cap71makes tight contact with the nozzle surface33A of the printing head34in the maintenance position so as to cover the openings of all the plurality of nozzles33.

A waste ink tube71A is connected to the cap71. Specifically, a drain port is formed in a bottom part of the cap71. An end of the waste ink tube71A is connected to the drain port. A fluid is capable of flowing in the waste liquid tube71A. The other end of the waste ink tube71A is connected to a waste ink tank (not depicted in the drawings).

By a flushing processing and a purge processing, the ink inside the printing head34is forcibly discharged. The ink discharged from the printing head34by the pump77is received by the cap71, passes through the waste ink tube71A and is guided to the waste ink tank.

The wiper72is positioned in right of the cap71, and is movable in the up-down direction1as depicted in broken lines inFIG.3. The wiper72holds a forward end part72A of a wiper blade73which is made of an elastic material such as rubber, etc., in a manner that the forward end part72A faces upward. In a case that the printing head34moves in the left-right direction3in a state that the wiper72is located at an upper side, the forward end part72A of the wiper blade73makes contact with the nozzle surface33A and wipes the nozzle surface33A. With this, an ink droplet(s) adhered to the nozzle surface33A of the printing head34is wiped off by the wiper72.

In the printing head34, a maintenance processing which are the purge processing, a wiping processing and the flushing processing is performed. The flushing processing is a processing of discharging the ink toward a flushing foam (not depicted in the drawings). The purge processing is a processing of sucking the ink from the nozzles33by a pump77in a state that the nozzles33are covered by the cap71. In the purge processing, in a case that the pump77is driven in a state that the waste ink tube71A is in a non-communication state (that is, in a state that the waste ink tube71A is closed at a position between the pump77and the waste ink tank), a negative pressure is generated in the inside of the cap71, whereby any foreign matter is sucked out of the nozzles33together with the ink. The wiping processing is a processing of wiping the nozzle surface33A of the printing head34by the wiper72. In a case that the printing head34is positioned at the maintenance position, the printing head34is covered by the cap71(seeFIG.3) which is movable in the up-down direction1, and the purge processing is performed. Further, in a case that the printing head34moves rightward from the maintenance position, whereby the printing head34makes contact with the wiper72and the wiping processing is performed. The flushing processing is performed in a case that the printing head34is located at a position above the flushing foam which is positioned in left of the maintenance position, the conveying path37being interposed between the flushing foam and the maintenance position.

<Maximum Moving Velocity Vmax of Wiper72>

In the following, an explanation will be given about a maximum moving velocity Vmax, of the wiper72, which is a maximum value of a moving velocity V in a case that the nozzle surface33A is wiped by the wiper72. Wiping by the wiper72is performed for a purpose of wiping off the ink adhered to the nozzle surface33A in a case that the flushing processing and/or the purge processing have (has) been performed. In this situation, by driving the wiper72at a velocity which is not more than the maximum moving velocity Vmax, the ink adhered to the nozzle surface33A is wiped off in a satisfactorily manner. Here, provided that: a surface tension of the ink is γ [N/m]; an angle defined by the nozzle surface33A and a liquid surface (a virtual plane P1formed in a boundary between a liquid phase and a gas phase) which is formed in the right side of an ink droplet in a case that the wiper72wipes the ink on the nozzle surface33A (that is, in a case that the wiper72moves leftward with respect to the nozzle surface33A, as indicated by an arrow) is a receding contact angle θD[rad], as depicted inFIG.5A; an angle defined by the nozzle surface33A and a liquid surface (a virtual plane P2formed in a boundary between the liquid phase and the gas phase) in a case that the ink droplet stands still on the nozzle surface33A is an equilibrium contact angle (an example of “third parameter”) θE[rad], as depicted inFIG.5B; the viscosity of the ink (an example of “second parameter”) is n [mPa·s]; the diameter of the ink droplet to be discharged from the nozzle33is d [m], and a size of one molecule of the ink is “a” [m], the maximum moving velocity Vmax [m/s] satisfies the following expressions (1) and (2);

In the above-described expression (1), the maximum moving velocity Vmax is proportional to γ tan θD(an example of “first parameter”) that is the tangent at the receding contact angle θDof the surface tension γ of the ink. Further, the maximum moving velocity Vmax is proportional to a difference cos θD−cos θE(an example of the “third parameter”) that is the difference between the cosine of the receding contact angle θDof the ink and the cosign of the equilibrium contact angle θEof the ink. That is, greater the difference between the receding contact angle θDdepicted inFIG.5Aand the equilibrium contact angle θEdepicted inFIG.5Bis, greater the maximum moving velocity Vmax is. In a case that the maximum moving velocity Vmax, of the wiper72, with respect to the nozzle surface33A is determined, the receding contact angle θDand the equilibrium contact angle θEare considered in the calculation, unlike in the conventional technique. Thus, a value with which occurrence of unwiped ink is reduced is determined more correctly. In the printer10, the wiper72is moved relative to the nozzle surface33A at the moving velocity V which is not more than the determined maximum moving velocity Vmax. For example, in the printer10, the wiper72is caused to wipe the nozzle surface33A at the moving velocity V which is 90% of the maximum moving velocity Vmax. Note that the moving velocity V of the wiper72with respect to the nozzle surface33A is made 90% of the maximum moving velocity Vmax in view of safety.

FIGS.6A and6Bdepict an example of a testing device wherein an ink droplet is wiped off by the wiper72in a state that the ink droplet adheres to the nozzle surface33A.FIGS.6A and6Bdepict behavior of the ink droplet in a case that the wiper72is moved relative to the nozzle surface33A leftward as indicate by an arrow. The moving velocity V of the wiper72relative to the nozzle surface33A inFIG.6Ais slower than the moving velocity V of the wiper72relative to the nozzle surface33A inFIG.6B. The ink used inFIG.6Aand the ink used inFIG.6Bare same as each other, and the receding contact angle θD inFIG.6Aand the receding contact angle θDinFIG.6Bare same as each other. Further, as depicted inFIGS.6A and6B, an advancing contact angle θAwhich is an angle defined by the nozzle surface33A and a liquid surface (a virtual plane P3formed in the boundary between the liquid phase and the gas phase) which is formed in the left side of the ink droplet in the case that the wiper72wipes the ink on the nozzle surface33A is also same as each other betweenFIGS.6A and6B. A volume of an ink droplet L1inFIG.6Aand a volume of an ink droplet L2inFIG.6Bare same as each other.

Since the ink droplet L2ofFIG.6Bis wiped off by the wiper72at a velocity which is faster than a velocity at which the ink droplet L1ofFIG.6Ais wiped off by the wiper72, the ink droplet L2spreads to be long in the left-right direction3. In this situation, greater the difference between the equilibrium contact angle θEand the receding contact angle θDis, greater a force to return to the equilibrium contact angle θEis at a right side portion of the ink droplet L2. Thus, the right side portion of the ink droplet L2is pulled rightward, and in a case that moving velocity V exceeds the maximum moving velocity Vmax, the right side portion of the ink droplet L2is unable to follow the wiper72. The unwiped ink is occurred in such a manner, and thus, as the moving velocity V becomes faster, the liquid is more likely to be left unwiped.

In the following, the details of the ink will be explained. The ink contains resin fine particles, a colorant, an organic solvent, a surfactant and water. The ink is a water-based ink.

Although the ink has a wettability with respect to a hydrophobic recording medium such as coated paper, plastic, film, an OHP sheet, etc., the present disclosure is not limited to this. For example, the ink may be an ink suitable for recording of an image on a recording medium, which is different from the hydrophobic recording medium, such as, for example, plain paper, glossy paper, mat paper, etc. The term “coated paper” means, for example, a paper obtained by applying a coating agent on a plain paper having a pulp as a major component, such as high quality printing paper, medium quality printing paper, etc., for a purpose of improving the smoothness, whiteness, glossiness, etc. Examples of the coated patern are high quality coated paper, medium quality coated paper, etc.

As the resin fine particles, it is acceptable to use, for example, resin fine particles including methacrylic acid and/or acrylic acid as a monomer, and to use, for example, a commercially available product. It is acceptable that the resin fine particles further include, as the monomer, styrene, vinyl chloride, etc. The resin fine particles may be, for example, resin fine particles included in an emulsion. The emulsion is composed, for example, of resin fine particles and a dispersion medium (for example, water, etc.). The resin fine particles are not dissolved in the dispersion medium. The resin fine particles are dispersed in the dispersion medium with a particle diameter of a specific range. Examples of the material of the resin fine particles include, a resin based on acrylic acid, a resin based on maleate ester, a resin based on vinyl acetate, a resin based on carbonate, a resin based on polycarbonate, a resin based on styrene, a resin based on ethylene, a resin based on polyethylene, a resin based on propylene, a resin based on polypropylene, a resin based on urethane, a resin based on polyurethane, a resin based on polyester, and a resin of copolymer of the above-described resins, etc. The resin fine particles may be fine particles of an acrylic resin.

As the resin fine particles, for example, a resin having a glass-transition temperature (Tg) in a range of not less than 0° C. to not more than 200° C. is used. The glass transition temperature (Tg) may be in a range of not less than 20° C. to not more than 180° C., and may be not less than 30° C. to not more than 150° C.

As the emulsion, it is acceptable to use, for example, a commercially available product. The commercially available product is exemplified by “SUPERFLEX 870” (Tg: 71° C.), “SUPERFLEX 150” (Tg: 40° C.) manufactured by DKS CO., LTD (“SUPERFLEX” is a registered trade mark in Japan of DKS CO., LTD (DAI-ICHI KOGYO SEIYAKU CO., LTD); “Mowinyl 6760” (Tg:−28° C.) and “Mowinyl DM774” (Tg: 33° C.) manufactured by Japan Coating Resin Corporation. (“MOWINYL” is a registered trade mark in Japan of Japan Coating Resin Corporation.); “Polysol AP-3270N” (Tg: 27° C.) manufactured by Resonac Holding Corporation (“POLYSOL” is a registered trademark in Japan of Resonac Holdings Corporation); “HILOS-X KE-1062” (Tg: 112° C.), and “HILOS-X QE-1042” (Tg: 69° C.) manufactured by SEIKO PMC CORPORATION; etc.

The average particle diameter of the resin fine particles is, for example, in a range of not less than 30 nm to not more than 200 nm. The average particle diameter can be measured by, for example, using a dynamic light scattering particle diameter distribution measuring apparatus “LB-550” manufactured by HORIBA, Ltd., as an arithmetic average diameter.

A content amount (R) of the resin fine particles in the entire amount of the ink may be, for example, in a range of not less than 0.1 wt % to not more than 30 wt %, may be in a range of not less than 0.5 wt % to not more than 20 wt %, and may be in a range of not less than 1.0 wt % to not more than 15.0 wt %. It is acceptable to use one kind of the resin fine particles singly, or to use not less than two kinds of the resin fine particles in combination.

The colorant is, for example, a pigment which is dispersible in water by, for example, a resin for dispersing pigment (resin dispersant). The colorant is exemplified by carbon black, an inorganic pigment, an organic pigment, etc. The carbon black is exemplified by furnace black, lamp black, acetylene black, channel black, etc. The inorganic pigment is exemplified by titanium oxide, inorganic pigments based on iron oxide, inorganic pigments based on carbon black, etc. The organic pigment is exemplified by azo-pigments such as azo lake, insoluble azo-pigment, condensed azo-pigment, chelate azo-pigment, etc.; polycyclic pigments such as phthalocyanine pigment, perylene and perinone pigments, anthraquinone pigment, quinacridone pigment, dioxadine pigment, thioindigo pigment, isoindolinone pigment, quinophthalone pigment etc.; dye lake pigments such as basic dye type lake pigment, acid dye type lake pigment etc.; nitro pigment; nitroso pigment; aniline black daylight fluorescent pigment; and the like.

A solid content amount of the colorant (colorant solid component amount) in the entire amount of the ink is not particularly limited, and may be appropriately determined according to, for example, a desired optical density or chromaticness, etc. The colorant solid component amount is, for example, in a range of not less than 0.1 wt % to not more than 20.0 wt %, and may be in a range of not less than 1.0 wt % to not more than 15.0 wt %. The colorant solid component amount is the weight only of the pigment, and does not include the weight of the resin fine particles. One kind of the colorant may be used singly, or two or more kinds of the colorant may be used in combination.

Regarding a content amount of the organic solvent in the entire amount of the ink, an organic solvent which exists in isolated liquid state (that is, as a single substance and as a liquid) at 25° C. may be not more than 50 wt %, and may be not more than 40 wt % with respect to the entire amount of the ink.

The water is preferably ion-exchange water or purified water. A content amount of the water with respect to the entire amount of the ink may be, for example, within a range of not less than 15 wt % to not more than 95 wt %, and may be within a range of not less than 25 wt % to not more than 85 wt %. The content amount of the water may be, for example, a remainder of the total from which other components are removed.

The ink may further include a conventionally known additive, as necessary. The additive is exemplified by surfactants, pH-adjusting agents, viscosity-adjusting agents, surface tension-adjusting agents, antiseptics, fungicides, levelling agents, antifoaming agents, light stabilizing agents, antioxidants, drying preventive agents for nozzle, polymer components such as emulsion, dye, etc. The surfactants may further include cationic surfactants, anionic surfactants or nonionic surfactants. The surfactants may be commercially available products. The commercially available products are exemplified by “OLFINE E1010”, “OLFINE E1006”, and “OLFINE E1004” (“OLFINE” is a registered trade mark of Nissin Chemical Industry Co., Ltd.), “SILFACE SAG503A”, “SILFACE SAG002” etc. (“SILFACE” is a registered trademark of Nissin Chemical Industry Co., Ltd.) manufactured by Nissin Chemical Industry Co., Ltd. The content amount of the surfactant in the entire amount of the ink is, for example, not more than 5 wt %, not more than 3 wt %, and in a range of 0.1 wt % to 2 wt %. The viscosity-adjusting agents are exemplified by polyvinyl alcohol, cellulose, water-soluble resin, etc.

The ink can be prepared, for example, by uniformly mixing the resin fine particles, the colorant, the organic solvent, the water, and an optionally other additive(s) as necessary, by a conventionally known method, and then removing any non-dissolved matter, with a filter, etc.

In the following, the controller130and the memory140will be explained, with reference toFIG.4. The controller130is configured to control the entire operation of the printer10. The controller130is provided with a CPU131and an ASIC135. The memory140is provided with a ROM132, a RAM133and an EEPROM134. The CPU131, the ASIC135, the ROM132, the RAM133and the EEPROM134are connected with one another by an internal bus137.

The ROM132stores a program(s), etc., with which the CPU131controls a variety of kinds of operations. The RAM133is used as a memory area configured to temporarily store data, signal, etc., to be used by the CPU131for executing the program, or is used as a work space for data processing. The EEPROM134stores a setting, a flag, etc., which is to be held even after the power source is switched off. As depicted inFIG.7, the EEPROM134stores a table80storing respective values of the size “a” of one molecule of the ink; the diameter d of the ink droplet; the viscosity η of the ink, the equilibrium contact angle θE, the receding contact angle θDand the surface tension γ of the ink, the values corresponding to a plurality of pieces of the kind information. The table80storing respective values of the size “a” of one molecule of the ink; the diameter d of the ink droplet; the viscosity η of the ink, the equilibrium contact angle θE, the receding contact angle θDand the surface tension γ of the ink corresponding to the kind information may be stored in the ROM132.

In the kind information, for example, three kinds of inks which are an ink A, an ink B and an ink C are stored; in the ink A, the size “a” of one molecule of the ink is 1×10−10[m], the diameter d of the ink droplet is 0.00248 [m], the viscosity η is 4.05 [mPa·s], the equilibrium contact angle θEis 1.29 [rad], the receding contact angle θDis 0.87 [rad] and the surface tension γ is 0.0300 [N/m].

In the ink B, the size “a” of one molecule of the ink is 1×10−10[m], the diameter d of the ink droplet is 0.00248 [m], the viscosity η is 5.20 [mPa·s], the equilibrium contact angle θEis 1.05 [rad], the receding contact angle θDis 0.79 [rad] and the surface tension γ is 0.0240 [N/m].

In the ink C, the size “a” of one of molecule of the ink is 1×10−10[m], the diameter d of the ink droplet is 0.00248 [m], the viscosity η is 3.20 [mPa·s], the equilibrium contact angle θEis 1.36 [rad], the receding contact angle θDis 1.23 [rad] and the surface tension γ is 0.0300 [N/m].

The conveying motor101, the feeding motor102, the carriage driving motor103, the cap driving motor104and the wiper driving motor105are connected to the ASIC135. Driving circuits each of which is configured to control one of the motors101to105are incorporated in the ASIC135. The CPU131outputs driving signals each of which is for rotating one of the respective motors101to105to one of the driving circuits corresponding, respectively, to the motors101to105. Each of the driving circuits is configured to output a driving current, corresponding to one of the driving signals obtained from the CPU131, to one of the motors101to105corresponding thereto. With this, each of the motors101to105corresponding to one of the driving circuits is rotated. Namely, the controller130controls the feeding motor102so as to convey the sheet6to the conveying path37. Further, the controller130controls the conveying motor101so as to drive the conveying roller26and the discharging roller27to thereby convey the sheet6. Further, the controller130controls the carriage driving motor103so as to move the carriage40. Furthermore, the controller130controls the cap driving motor104so as to move the cap71in the up-down direction1.

Further, the optical sensor of the rotary encoder75is connected to the ASIC135. The controller130calculates the rotation amount of the conveying motor101based on an electric signal received from the optical sensor of the rotary encoder75. Furthermore, the encoder38is connected to the ASIC135. The controller130recognizes the position of the carriage40and/or as to whether or not the carriage40is moved, based on the pulse signal received from the encoder38.

Moreover, the piezoelectric element45is connected to the ASIC135. The piezoelectric element45is operated by the electric power supplied by the controller130via a non-depicted drive circuit. The controller130controls the supply of the electric power to the piezoelectric element45so as to eject the ink droplets selectively from plurality of nozzles33.

Further, the operating part21is connected to the ASIC135. The ASIC135receives, from the operating part21, a signal indicating that a button is pressed. The ASIC135outputs, with respect to the operating part21, display data indicating a content which is to be displayed on the display. Other than those described above, the pump77is connected to the ASIC135.

In a case that the controller130records an image on the sheet6, the controller130alternately performs a conveying processing and a printing processing. The conveying processing is a processing of conveying the sheet6by a predetermined line feed amount by driving the conveying roller26and the discharging roller27. The controller130executes the conveying processing by controlling the conveying motor101. The printing processing is a processing of controlling the supply of the electric power to the piezoelectric element45so as to cause the printing head34to eject the ink droplets from the nozzles33, while moving the carriage40along the left-right direction3.

The controller130stops the sheet6for a predetermined period of time between the conveying processing performed this time and the conveying processing to be performed the next time. Further, while the sheet6is stopped, the controller130executes the printing processing. Namely, in the printing processing, the controller130executes one pass of causing the nozzles33to discharge the ink droplets, while moving the carriage40rightward or leftwards. With this, recording of an image corresponding to one pass is executed with respect to the sheet6. By executing the conveying processing and the printing processing alternately and repeatedly, the controller130is capable of recording an image on an entire area, of the sheet6, in which the image is recordable. Namely, the controller130records the image on one piece of the sheet6by performing a plurality of times of pass.

Note that the controller130is not limited to the above-described configuration; the controller130may be configured such that only the CPU131performs the various kinds of processing or that only the ASIC135performs the various kinds of processing, or that the CPU131and the ASIC135perform the various kinds of processing in a cooperative manner. The controller130may be configured such that one CPU131singly performs the processing, or that a plurality of pieces of the CPU131performs the processing in a sharing manner. The controller130may be configured such that one ASIC135singly performs the processing, or that a plurality of pieces of the ASIC135performs the processing in a sharing manner.

In the printer10, the wiping processing is performed so as to remove the ink droplet(s) adhered to the nozzle surface33A. The wiping processing is performed as one of operations in the maintenance processing; the maintenance processing is performed in a case that the power source of the printer10is turned on, and is further performed also in a case that a time previously set has elapsed in a state that the power source of the printer10is turned on. In the following, the maintenance processing will be explained with reference toFIGS.8A,8B and8C. Before the power sources of the printer10is turned on, the cap71is located at the upper side and covers the nozzle surface33A. The moving velocity V of the printing head34with respect to the wiper72is explained regarding a case that the maintenance processing is performed at a low velocity mode. Note that the maintenance processing may be performed at a timing different from the above-described timing; for example, the maintenance processing may be performed in a case that the cartridge is replaced, or in a case that the image recording has been performed on the sheet(s)6of the number of sheets previously set. Further, the maintenance processing may be performed based on an input by the user from the operating part21.

As depicted inFIG.8A, the controller130firstly determines as to whether or not the cartridge70is installed in the printer10in a case that the power source of the printer10is turned on (step S10). Next, in a case that the controller130determines that the cartridge70is installed in the printer10(step S10: YES), the controller130obtains the kind information of the ink A from the IC substrate (step S11). In a case that the controller130determines that the cartridge70is not installed in the printer10(step S10: NO), the controller130continues the determination until the cartridge70is installed in the printer10(step S10).

Among the plurality of pieces of the kind information stored in the table80(seeFIG.7), the controller130obtains the value of the size “a” of one molecule, the diameter d of the ink droplet, the viscosity η of the ink, the equilibrium contact angle θE, the receding contact angle θDand the surface tension γ of the ink, of the ink A (step S12). The controller130determines a maximum moving velocity Vmax1based on the obtained values (step S13). The controller130determines a moving velocity V1of the printing head34with respect to the wiper72based on the maximum moving velocity Vmax1(step S14). Specifically, the controller130determines the moving velocity V1to be a velocity which is 90% of the maximum moving velocity Vmax1.

The controller130drives the pump77(step S15) and executes the purge processing. After the purge processing, the controller130drives the cap driving motor104(step S16) so as to move the cap71downward and separate the cap71away from the nozzle surface33A.

The controller130drives the wiper driving motor105(step S17) so as to move the wiper72upward. The controller130drives the carriage driving motor103(step S18) so as to move the printing head34, located at the maintenance position, rightward at the moving velocity V1. With this, the wiping processing is performed. In the wiping processing, the wiper72makes contact with the nozzle surface33A while the printing head34is moved rightward, thereby wiping off the ink adhered to the nozzle surface33A. The moving velocity V1in this situation is a relative velocity in the left-right direction3of the wiper72relative to the nozzle surface33A. After the controller130drives the carriage driving motor103so as to move the printing head34rightward, the controller130drives the wiper driving motor105(step S19) so as to move the wiper72positioned at the upper side downward. The controller130drives the carriage driving motor103(step S20) so as to move the printing head34leftward and up to the maintenance position.

As depicted inFIG.8B, immediately after the nozzle surface33A has been wiped by the wiper72at the moving velocity V1, the controller130starts counting (step S21). The controller130drives the carriage driving motor103(step S22) so as to move the printing head34from the maintenance position to the position above the flushing foam (also referred to as “FF” inFIG.8B). The controller130drives the piezoelectric element45(step S23) and executes the flushing processing. In a case that the flushing processing is executed, the ink inside the nozzles33is discharged and the meniscus is formed without the inks of the respective colors are not mixed with the inks of other color inside the nozzles33. The controller130drives the carriage driving motor103(step S24) so as to return the printing head34to the maintenance position.

After the maintenance processing has been performed as described above, in a case that a time previously set has elapsed while the power source of the printer10is kept in ON-state, the maintenance processing is performed again.

After driving the carriage driving motor103in the step S24, the controller130determines as to whether or not an input of turning the power source off is inputted from the operating part21(step S25). In a case that the controller130determines that the input of turning the power source off is inputted from the operating part21(step S25: YES), the controller130ends the counting started in the step S21(step S26). The controller130drives the cap driving motor104(step S27) so as to move the cap71upward and causes the cap71to cover the nozzle surface33A. The controller130turns the power source off (step S28) and ends the series of operations as described above.

In a case that the controller130determines in step S25that the input of turning the power source off is not inputted from the operating part21(step S25: NO), the controller130determines as to whether or not the time previously set has elapsed since the starting of the counting in the step S21(step S29). In a case that the controller130determines that a predetermined time has elapsed since the starting of the counting in the step S21(step S29: YES), the controller obtains a count value T (step S30). In a case that the controller130determines that the predetermined time has not elapsed since the starting of the counting in the step S21(step S29: NO), the controller keeps on determining as to whether or not the predetermined time has elapsed.

The controller130obtains the values of the size “a” of one molecule of the ink, the diameter d of the ink droplet, the viscosity η of the ink, the equilibrium contact angle θE, the receding contact angle θDand the surface tension γ of the ink which have been previously stored in a table (not depicted in the drawings) based on the count value T (step S31). The kind information in this situation is same as the kind information obtained in the step S11(that is, ink A). The controller130determines a maximum moving velocity Vmax2based on the obtained values (step S32). The controller130determines a moving velocity V2of the printing head34with respect to the wiper72based on the maximum moving velocity Vmax2(step S33). Specifically, the controller130determines the moving velocity V2to be a velocity which is 90% of the maximum moving velocity Vmax2.

The controller130drives the cap driving motor104(step S34) so as to move the cap71upward and to cause the cap71to cover the nozzle surface33A. The controller130drives the pump77(step S35) and executes the purge processing. After the purge processing, the controller130drives the cap driving motor104(step S36) so as to move the cap71downward and to separate the cap71away from the nozzle surface33A.

The controller130drives the wiper driving motor105(step S37) so as to move the wiper72upward. The controller130drives the carriage driving motor103(step S38) so as to move the printing head34, located at the maintenance position, rightward at the moving velocity V2. With this, the wiping processing is performed. After the controller130drives the carriage driving motor103so as to move the printing head34rightward, the controller130drives the wiper driving motor105(step S39) so as to move the wiper72positioned at the upper side downward. The controller130drives the carriage driving motor103(step S40) so as to move the printing head34leftward and up to the maintenance position.

Immediately after the nozzle surface33A has been wiped by the wiper72at the moving velocity V2, the controller130starts counting (step S21). The controller130repeatedly performs the maintenance processing in the state that the power source is not turned off. For example, the controller130drives the carriage driving motor103(step S22) so as to move the printing head34from the maintenance position so that the printing head34is positioned above the flushing foam, and then executes the flushing processing (step S23).

Effects of the Embodiment

According to the above-described configuration, since the moving velocity V of the wiper72is determined based on the receding contact angle θDof the ink and the surface tension γ of the ink, the moving velocity V for wiping the nozzle surface33A by the wiper72with reduced unwiped ink is set precisely and the leaving of unwiped ink by the wiper72is reduced.

According to the above-described configuration, since the moving velocity V of the wiper72is determined further based on the equilibrium contact angle θEas well, the moving velocity V for wiping the nozzle surface33A by the wiper72with reduced unwiped ink is set more precisely and the leaving of unwiped ink by the wiper72is further reduced.

First Modification

In the above-described embodiment, the controller130starts the counting immediately after the nozzle surface33A has been wiped by the wiper72at the moving velocity V1, and the controller130obtains the count value T in the case that the time previously set has elapsed. The obtained count value T, however, is not limited to such a constant value. For example, it is acceptable that the maintenance processing is performed corresponding to a consumption amount of the ink or corresponding to an input by the user. It is acceptable that a count value U which is obtained may be a value which is determined according to the consumption of the ink or a timing of the user input. In this case, it is acceptable that the controller130obtains respective values stored in a table81, based on the count value U. Example of the respective values stored in the table81are as indicated inFIG.9.

After the nozzle surface33A has been wiped by the wiper72, water content evaporates, as the time passes, from the ink, in the nozzle33, forming the meniscus. Thus, even after the nozzle surface33A has been wiped and that the ink adhered thereto has been wiped off, the ink from which the water content has evaporated adheres to the nozzle surface33A by the ejection of the ink from the nozzles33. In view of such a situation, it is possible to perform the wiping processing in a satisfactory manner and in a short period of time, by obtaining the respective values based on the count value T and by wiping the nozzle surface33A at the determined maximum moving velocity Vmax.

In the first modification, respective values corresponding to six kinds of the count value U which are 0, 10, 20, 30, 40 and 50 hours are stored in the table81; the maximum moving velocity Vmax is determined with respect to the count value U, based on the respective values (seeFIG.10).

As depicted inFIG.9, the table81storing the respective values of the size “a” of one molecule of the ink, the diameter d of the ink droplet, the viscosity η of the ink, the equilibrium contact angle θE, the receding contact angle θDand the surface tension γ of the ink corresponding to the count values U is stored in the EEPROM134with, for example, the following content. In a case that the count value U is 0 (zero) hours, then the size “a” of one molecule of the ink is 1×10−10[m], the diameter d of the ink droplet is 0.00248 [m], the viscosity η of the ink is 4.05 [mPa·s], the equilibrium contact angle θEis 1.29 [rad], the receding contact angle θDis 0.87 [rad] and the surface tension γ of the ink is 0.0300 [N/m].

In a case that the count value U is 10 hours, then the size “a” of one molecule of the ink is 1×10−10[m], the diameter d of the ink droplet is 0.00226 [m], the viscosity η of the ink is 6.44 [mPa·s], the equilibrium contact angle θEis 1.27 [rad], the receding contact angle θDis 0.79 [rad] and the surface tension γ of the ink is 0.0295 [N/m].

In a case that the count value U is 20 hours, then the size “a” of one molecule of the ink is 1×10−10[m], the diameter d of the ink droplet is 0.00217 [m], the viscosity η of the ink is 12.59 [mPa·s], the equilibrium contact angle θEis 1.26 [rad], the receding contact angle θDis 0.70 [rad] and the surface tension γ of the ink is 0.0290 [N/m].

In a case that the count value U is 30 hours, then the size “a” of one molecule of the ink is 1×10−10[m], the diameter d of the ink droplet is 0.00203 [m], the viscosity η of the ink is 22.92 [mPa·s], the equilibrium contact angle θEis 1.24 [rad], the receding contact angle θDis 0.61 [rad] and the surface tension γ of the ink is 0.0285 [N/m].

In a case that the count value U is 40 hours, then the size “a” of one molecule of the ink is 1×10−10[m], the diameter d of the ink droplet is 0.00192 [m], the viscosity η of the ink is 193.49 [mPa·s], the equilibrium contact angle θEis 1.22 [rad], the receding contact angle θDis 0.52 [rad] and the surface tension γ of the ink is 0.0280 [N/m].

In a case that the count value U is 50 hours, then the size “a” of one molecule of the ink is 1×10−10[m], the diameter d of the ink droplet is 0.00183 [m], the viscosity η of the ink is 598.54 [mPa·s], the equilibrium contact angle θEis 1.20 [rad], the receding contact angle θDis 0.44 [rad] and the surface tension γ is 0.0275 [N/m]. As the count value U becomes greater, the water content contained in the ink droplet evaporates and the diameter d of the ink droplet and the surface tension γ of the ink become smaller. Further, if the value of the surface tension γ of the ink becomes smaller, the value of each of the receding contact angle θDand the equilibrium contact angle θEbecomes smaller as well. On the other hand, the viscosity η of the ink tends to become greater due to the evaporation of the water content contained in the ink droplet.

FIG.10depicts the relationship between the count value U and the maximum moving velocity Vmax2of the wiper72. InFIG.10, a comparison is made between a case that the receding contact angle θDis changed based on the count value U as indicated by square marks and a case that the retreat angle θDis constant as indicated by circular marks. Specifically, in the case that the receding contact angle θDis changed, the value of the receding contact angle θDofFIG.10corresponding to the count value U is used for the calculation. Meanwhile, in the case that the receding contact angle θDis constant, the value of the receding contact angle θDused in the calculation is 0.44 (that is, the value corresponding to the count value U of 50) regardless of the value of the count value U. In the case that the receding contact angle θDis changed, the maximum moving velocity Vmax2is greater than the maximum moving velocity Vmax2in the case that the receding contact angle is constant. Namely, by considering the change in the receding contact angle θD, it is possible to determine, more precisely, the maximum moving velocity Vvax2with which unwiped ink is reduced. Further, smaller the count value U is, greater the difference between the maximum moving velocity Vmax2and the conventional moving velocity is. Thus, as the elapsed time becomes shorter, it is possible to fasten the moving velocity V of the wiper72compared to the conventional technique, more remarkably. Owing to this, it is possible to perform the wiping processing with reduced unwiped ink in a satisfactory manner, while shortening a waiting time of the user.

According to the above-described configuration, since the receding contact angle θDis determined based on the count value U which varies, it is possible to obtain the respective values of the ink according to the elapsed time. Owing to this, it is possible for the controller130to determine, more precisely, the moving velocity V for causing the wiper72to wipe the nozzle surface33A with reduced unwiped ink. Thus, occurrence of ink left unwiped is further reduced.

Other Modifications

In the above-described embodiments and modifications, the explanation has been given about the case wherein values of each of the size “a” of one molecule of the ink, the diameter d of the ink droplet, the viscosity η of the ink, the equilibrium contact angle θE, the receding contact angle θDand the surface tension γ of the ink are previously stored in the table80, the present disclosure is not limited to this. For example, it is acceptable that the printer10is further provided with a temperature sensor configured to measure the environmental temperature at the inside of the printer10, and that the controller130is configured to set the maximum moving velocity Vmax based on temperature information obtained from the temperature sensor. In this situation, the maximum moving velocity Vmax is set based on respective values which are previously stored in a table and correspond to the obtained temperature information.

In the above-described embodiment, the explanation has been given about the example in which the printing head34moves in the left-right direction3, in the state that the wiper72is moved to the upper side in the up-down direction1, so that the wiper72wipes the nozzle surface33A. However, the present disclosure is not limited to this. It is acceptable, for example, that the wiper72is fixed to a position, in the up-down direction1, at which the wiper72makes contact with the nozzle surface33A.

In the above-described embodiment, the explanation has been given about the example in which the controller130selects, based on the information stored in the IC substrate, the kind information of the ink A stored in the table80. However, the present disclosure is not limited to this. It is acceptable that the controller130obtains kind information of the ink B or kind information of the ink C stored in the IC substrate, and obtains the respective values in the table80.

In the above-described embodiment, the explanation has been given about the example in which the controller130obtains the kind information from the IC substrate mounted on the cartridge70. However, the present disclosure is not limited to this. It is acceptable that the controller130obtains the kind information from the internet or a server, via a terminal connected to the printer10. Further, in a case that the ink is supplied to the printer10from a tank, rather than from the cartridge70, the kind information may be stored previously (in advance) in the table80. In a case that different kinds of inks are assumed to be stored in the tank, it is acceptable that the user inputs the kind information via the operating part21. In the above-described embodiment, the explanation has been given about the example in which the nozzle surface33A is capped by the cap71in a case that the power source of the printer10is turned on, and that the count value Tis reset every time the nozzle surface33A is capped by the cap71. However, the present disclosure is not limited to this configuration. Further, a timing at which the resetting of the count value T is performed may also be a timing at which the nozzle surface33A is capped by the cap71. In a case that the purge processing is not performed even when the capping of the nozzle surface33A is performed, it is acceptable that the resetting of the count value T is not performed.

In the above-described embodiment, the explanation has been given, about the example in which the count value U is the six kinds of elapsed time. However, the present disclosure is not limited to this. The number of the count value U is not more than five kinds, or may be not less than seven kinds. Further, the count value U may be continuous values.

In the above-described embodiment, the explanation has been given, about the example in which the moving velocity V of the wiper72relative to the nozzle surface33A is made 90% of the maximum moving velocity Vmax. However, the present disclosure is not limited to this. The moving velocity V of the wiper72relative to the nozzle surface33A may be the maximum moving velocity Vmax all the time. Further, in a case that the controller130is configured to drive the carriage driving motor103in a state that the moving velocity V of the wiper72with respect to the nozzle surface33A is not set, the moving velocity V becomes slow, depending on the size or the weight of the printing head34. Even in such a case, by making the moving velocity V the maximum moving velocity Vmax, it is possible to perform the wiping processing in a short period of time.

In the above described embodiment, the maximum moving velocity Vmax is determined based on respective values stored in the table80or the table81. However, the present disclosure is not limited to this. The controller130may be configured to move the wiper72relative to the printing head34based on a moving velocity determined based on the receding contact angle θDand the viscosity n. For example, the table80and/or the table81may store the maximum moving velocity Vmax and/or the moving velocity V calculated in advance. In this case, the controller130may determine the moving velocity V based on the maximum moving velocity Vmax and/or the moving velocity V read out from the table80and/or table81.

In the present disclosure, the moving velocity of the wiper means the velocity of the relative movement between the wiper and the head. The relative movement between the wiper and the head includes an aspect in which the wiper is moved and the head is stopped, an aspect in which the wiper is stopped and the head is moved, and an aspect in which both of the wiper and the head are moved.