Patent Publication Number: US-8985836-B2

Title: Liquid stirring device

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid stirring device. 
     2. Related Art 
     There are known ink supply systems which supply ink to an ejection head capable of ejecting ink from an ink tank storing ink via an ink supply tube. When such ink supply systems are used, when ink supply is not performed for a long period of time after the supply of ink to the ejection head, components which are contained in the ink which remains in the flow passage of the ink supply tube precipitate in some cases. When the components contained in the ink precipitate, it is not possible to stably supply ink to the ejection head when ink is again supplied to the ejection head, or an ejection error may be caused. 
     Particularly, when inorganic pigments (for example, titanium oxide), metal pigments (for example, aluminum) or the like are contained as components in the ink, there is a problem in that these pigments easily precipitate in view of differences in the specific gravity between the pigments and the solvent. 
     Regarding this problem, for example, in JP-A-2006-272648, there is a description of an ink supply system which is provided with a sub-tank to always hold a certain amount of ink in an ink flow passage. In addition, in JP-A-2006-272648, there is a description of a stirring ball which is provided in the sub-tank in order to stir the ink in the sub-tank. Due to the provision of the sub-tank, it is possible to reduce the amount of precipitated components, such as a pigment, which is contained in ink. 
     However, in the related art in JP-A-2006-272648, the stirring ball is difficult to move in the sub-tank, or liquid stirring efficiency is reduced in some cases. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a liquid stirring device which has excellent liquid stirring efficiency by solving the problems, and a liquid ejection device which uses the liquid stirring device to make ejection errors less apt to occur. 
     The invention is contrived to solve at least some of the above-described problems and can be realized as the following aspects or applications. 
     Application 1 
     According to an aspect of the invention, a liquid stirring device includes: a liquid storage portion in which a liquid containing a component which may precipitate is stored; a container to which the liquid flows from the liquid storage portion; a stirrer which is housed in the container and stirs the liquid; and a bottom surface portion which constitutes the interior of the container and in which the stirrer moves. The relationship between a height Ht in the vertical direction of a central portion in the container and a height Hb in the vertical direction of the stirrer satisfies the following Expression 1: 0.40×Ht≦Hb≦0.90×Ht. 
     According to Application 1 of the invention, since Ht and Hb satisfy the above relational expression, the stirrer can be easily moved in the container and a liquid stirring device having excellent liquid stirring efficiency can be obtained. 
     Application 2 
     It is preferable that the component is contained at a predetermined concentration in the liquid stored in the liquid storage portion, and it is preferable that the relationships between a height Hi in the vertical direction of precipitates of the component which is contained in the liquid in the container, Ht, and Hb satisfy the following Expressions 2-1 and 2-2: Hi÷Ht≦0.26 and 2.50×Hi≦Hb≦0.90×(Ht−Hi). 
     According to Application 2 of the invention, since Ht, Hb, and Hi satisfy the above relational expressions, superior stirring can be performed, and even when the precipitates are solidified, a liquid stirring device having excellent liquid stirring efficiency can be obtained. 
     Application 3 
     It is preferable that the bottom surface portion has a shape which is curved downward in the vertical direction when viewed from the cross-section in a direction which is perpendicular to the direction in which the stirrer is moved and is perpendicular to the vertical direction. 
     According to Application 3 of the invention, the precipitated component easily accumulates in the curved portion and the stirrer is moved around the curved portion. Therefore, the stirring efficiency of the precipitated component increases. 
     Application 4 
     It is preferable that the container has a side surface portion which is provided in the direction in which the stirrer is moved, and it is preferable that a connecting portion between the side surface portion and the bottom surface portion has a shape which is curved toward the outside of the container. 
     According to Application 4 of the invention, the clearance gap in the vicinity of the connecting portion is reduced, and thus the stirrer easily comes into contact with the precipitated component and the precipitated component is also efficiently stirred, whereby the stirring efficiency increases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a side view schematically showing a liquid stirring device according to an embodiment. 
         FIGS. 2A to 2C  are perspective views of a container of the liquid stirring device according to the embodiment. 
         FIGS. 3A to 3C  are diagrams illustrating a central portion of the container according to the embodiment. 
         FIG. 4  is a perspective view when an ejection head according to the embodiment is a line-type ejection head. 
         FIGS. 5A to 5C  are diagrams showing modified examples of the liquid stirring device according to the embodiment. 
         FIG. 6  is a diagram showing a modified example of the liquid stirring device according to the embodiment. 
         FIGS. 7A and 7B  are diagrams showing the relationship between the container according to the embodiment, a stirrer and precipitates. 
         FIG. 8  is a diagram showing a liquid ejection device according to the embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, embodiments of the invention will be described. However, the invention is not limited to these embodiments. 
     1. Liquid Stirring Device 
     A liquid stirring device according to this embodiment has a container, a stirrer which is disposed in the container, and a carriage. A liquid stirring device  100  according to this embodiment shown in  FIG. 1  has a liquid storage portion  10 , a container  20 , a liquid supply tube  30 , and an ejection head  33 . The container  20  and the ejection head  33  are mounted on a carriage  50 A. The container  20  includes a stirrer  15  therein. The carriage  50 A can reciprocate in a predetermined direction MSD (hereinafter, referred to as the “longitudinal direction”). 
     1.1. Liquid Storage Portion 
     The liquid stirring device  100  according to this embodiment may have the liquid storage portion  10 . The liquid storage portion  10  stores liquid which contains a component at a predetermined concentration. In this specification, the “predetermined concentration” is a concentration when a component which may precipitate is sufficiently stirred in the liquid storage portion  10 . The liquid storage portion  10  shown in  FIG. 1  is connected to the container  20  via the liquid supply tube  30   a . Accordingly, it is possible to allow the liquid to flow to the container  20 . 
     In this specification, the liquid may contain a component which may precipitate, and examples of the component include a dispersion such as an emulsion and a suspension. Examples of the liquid which is stored in the liquid storage portion  10  include an ink composition, material for organic EL display, a material for a color filter for liquid crystal display, a material for field emission display (FED), a material for a color filter or an electrode for electrophoretic display, a bioorganic material used in bio-chip manufacturing, and the like. 
     In addition, “precipitation” means that when a liquid is left for a certain period of time, the component contained therein settles and accumulates in the lower layer of the liquid. A component having high specific gravity with respect to the solvent is exemplified. An ink composition may contain, for example, one type selected from among an inorganic pigment, a metal pigment and hollow resin particles, or may contain a component which combines or adsorbs these. 
     Examples of the inorganic pigment include titanium dioxide, silicon oxide, aluminum oxide, zinc oxide, iron oxide, carbon black, and the like. Examples of the metal pigment include a single substance such as aluminum, gold, silver, copper, titanium, and alloys thereof. Examples of the hollow resin particles include hollow resin particles, of which the description is provided in the specifications such as U.S. Pat. No. 4,880,465 and Japanese Patent No. 3562754. The hollow resin particles have hollows in the interiors thereof, and the outer shells thereof are formed of a liquid-permeable resin. The hollow resin particles can be used as a white pigment. 
     Hereinafter, the white ink composition, which is typically used as a liquid stored in the liquid storage portion  10 , will be described. The white ink composition may include a resin to fix the pigment. Examples of the resin include a polyvinyl alcohol, polyethylene glycol, a polyacrylic acid, polyurethane, polyacrylamide, a cellulose derivative, and the like. In terms of the product name, acrylic resins (for example, Almatex, manufactured by Mitsui Chemicals, Inc.), urethane resins (for example, WBR-022U, manufactured by Taisei Fine Chemical Co., Ltd.) and the like can be used. 
     The white ink composition preferably contains one which is selected from between alkane diol and glycol ether. Alkane diol and glycol ether increase wettability to a recording surface such as a medium to be ejected, and thus increase permeability of ink. 
     Examples of alkane diol preferably include 1,2-alkane diol with the number of carbons of 4 to 8 such as 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and 1,2-octanediol. Among these, 1,2-hexanediol, 1,2-heptanediol, and 1,2-octanediol with the number of carbons of 6 to 8 are more preferably used due to particularly high permeability to a medium to be ejected. 
     Examples of glycol ether include a lower alkyl ether of a polyhydric alcohol such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, and tripropylene glycol monomethyl ether. Among these, when using triethylene glycol monobutyl ether, excellent recording quality can be obtained. 
     In addition, the white ink composition preferably contains an acetylene glycol surfactant or a polysiloxane surfactant. An acetylene glycol surfactant or a polysiloxane surfactant increases wettability to a recording surface such as a medium to be ejected, and thus increase permeability of ink. 
     Examples of acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-1-hexyne-3-ol, 2,4-dimethyl-5-hexyne-3-ol, and the like. In addition, as the acetylene glycol surfactant, commercially available products can be used. For example, Orfin (registered trade name) E1010, Orfin STG, Orfin Y (manufactured by Nissin Chemical Industry Co., Ltd.), and Surfynol (registered trade name) 104, 82, 465, 485, and TG (manufactured by Air Products and Chemicals Inc.) can be used. 
     As the polysiloxane surfactant, commercially available products can be used. For example, BYK-347, BYK-348 (manufactured by BYK-Chemie Japan KK) and the like can be used. 
     Further, the white ink composition may also contain other surfactants such as an anion surfactant, a non-ionic surfactant, and an ampholytic surfactant. 
     The white ink composition preferably contains a polyhydric alcohol. The polyhydric alcohol can suppress drying of ink and prevent ink clogging in the ejection head when the white ink composition is applied to an ink jet recording device. 
     Examples of the polyhydric alcohol include ethylene glycol, diethylene glycole, triethylene glycole, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, trimethylolethane, trimethylolpropane, and the like. 
     The white ink composition may contain water as a solvent. As the water, pure water or ultrapure water such as ion-exchanged water, ultrafiltrated water, reverse osmosis water, or distilled water is preferably used. Particularly, the sterilized water, which is obtained by irradiating ultraviolet rays on or adding hydrogen peroxide to the aforementioned waters, is preferably used since it is possible to prevent mold and bacteria from being generated over a long period of time. 
     Further, the white ink composition may contain additives as needed. Examples of the additives include a fixing agent such as a water-soluble rosin, an antifungal agent and an antiseptic agent such as sodium benzoate, an antioxidizing agent and an ultraviolet absorber such as allophanates, a chelating agent, a pH adjuster such as triethanolamine, an oxygen absorber, and the like. These additives can be used alone or in combination of two or more of them. 
     As an example of the white ink composition, the water-based ink composition has been described, but an ultraviolet curable ink or the like may be used. When using an ultraviolet curable ink, for example, a photopolymerization initiator can be exemplified as a component which may precipitate. 
     1.2. Liquid Supply Tube 
     The liquid stirring device  100  according to this embodiment may have the liquid supply tube  30 . The liquid supply tube  30  includes liquid supply tubes  30   a  and  30   b . In  FIG. 1 , The liquid supply tube  30   a  connects the liquid storage portion  10  to the container  20  and can allow the liquid which is stored in the liquid storage portion  10  to flow to the container  20 . The liquid supply tube  30   b  connects the container  20  and the ejection head  33  and can allow the liquid to flow to the ejection head  33 . 
     1.3. Container and Stirrer 
     The liquid stirring device  100  according to this embodiment is mounted on the carriage  50 A. When the liquid stirring device  100  including the container  20  is mounted on the carriage  50 A, there is no need to separately provide a mechanism for moving only the container  20  and the container  20  can be moved using the movement mechanism of the carriage  50 A. 
     In addition, as shown in  FIG. 1 , the liquid stirring device  100  according to this embodiment has the stirrer  15  which is movably disposed in the container  20 . 
     The stirrer  15  may have a shape so as to be movable within the container  20 . For example, the stirrer may have a spherical body, an ellipsoidal body (for example, like a rugby ball), a circular cylindrical body, an elliptical column body, a polygonal column body, a rectangular parallelepiped body, a cubic body, a polyhedral body, or the like. Among these, when the stirrer  15  has a spherical body or an ellipsoidal body, the stirrer  15  easily moves in the container  20  and stirring of the liquid can be efficiently performed. 
     Examples of the material for the stirrer  15  include glass having silicate as a main component, aluminum oxide, zirconium oxide, metal (for example, aluminum, titanium, chromium, nickel, iron, and alloys containing any of these) and the like. 
     The direction, angle, and the like of the installation of the container  20  are not particularly limited if the stirrer  15  moves in the container  20  on the basis of the reciprocation of the carriage  50 A. 
     The shape of the container  20  of the liquid stirring device  100  according to this embodiment is not limited to a rectangular parallelepiped shape, a cylinder shape, an elliptic cylinder shape and the like, and may have a cubic body, a circular cylindrical body or the like. In this specification, the shape of the container  20  is the shape of the interior of the container  20  with the stirrer  15  disposed therein. 
     As shown in  FIG. 2A , the container  20  has a shape which is surrounded by a bottom surface portion  22 , an upper surface portion  24  opposed to the bottom surface portion  22 , and side surface portions  26   a ,  26   b ,  26   c  and  26   d  connected to the bottom surface portion  22  and the upper surface portion  24 . The container  20  has the first side surface portion  26   a  and the second side surface portion  26   b  opposed to each other in the longitudinal direction MSD shown in the drawing. The liquid supply tube  30   a  is connected to the first side surface portion  26   a  and the liquid supply tube  30   b  is connected to the second side surface portion  26   b . Further, the container  20  has the third side surface portion  26   c  and the fourth side surface portion  26   d  opposed to each other in the direction MSD in which the stirrer  15  is moved and in a direction perpendicular to the vertical direction VD. The connection positions between the liquid supply tube  30   a  and the first side surface portion  26   a  and between the liquid supply tube  30   b  and the second side surface portion  26   b  are not particularly limited, and these may be connected to each other in any of the bottom surface portion  22 , the upper surface portion  24 , the third side surface portion  26   c  and the fourth side surface portion  26   d . In addition, both of the liquid supply tubes  30   a  and  30   b  may be connected to the same surface of the container  20 . 
     In addition, for example, as shown in  FIG. 2B , when the upper surface portion, the bottom surface portion, the third side surface portion and the fourth side surface portion are formed integrally with each other, that is, form a so-called cylinder portion  122 , the cylinder portion  122  include the upper surface portion, the bottom surface portion, the third side surface portion and the fourth side surface portion. 
     A central portion  18  which is a main region in which the stirrer  15  moves will be described. In the invention, the central portion is a region which is surrounded by the bottom surface portion, the upper surface portion, and the straight lines connecting the bottom surface portion and the upper surface portion when viewed from the cross-section in the longitudinal direction of the container. A specific description will be given using the drawings. 
     In  FIG. 3A , the container has the shape of a rectangular parallelepiped body. Neither of the first and second side surface portions  26   a  and  26   b  have a curve. In this case, the region (oblique line region in  FIG. 3A ) which is surrounded by the bottom surface portion  22 , the upper surface portion  24 , the straight line connecting A 1  of the bottom surface portion  22  and A 2  of the upper surface portion  24 , and the straight line connecting B 1  of the bottom surface portion  22  and B 2  of the upper surface portion  24  corresponds to the central portion  18 . That is, in the case of the shape shown in  FIG. 3A , the entire interior of the container  20  becomes the central portion  18 . 
     In addition, in  FIG. 3B , differently from  FIG. 3A , both of the first and second side surface portions  26   a  and  26   b  are curved to the outside. In this case, the region (oblique line region in  FIG. 3B ) which is surrounded by the bottom surface portion  22 , the upper surface portion  24 , the straight line connecting A 1  of the bottom surface portion  22  and A 2  of the upper surface portion  24 , and the straight line connecting B 1  of the bottom surface portion  22  and B 2  of the upper surface portion  24  corresponds to the central portion  18 . That is, the central portion  18  does not include the first and second side surface portions  26   a  and  26   b.    
     Further, in  FIG. 3C , the bottom surface portion  22  and the upper surface portion  24  have different sizes. Also in this case, the region (oblique line region in  FIG. 3C ) which is surrounded by the bottom surface portion  22 , the upper surface portion  24 , the straight line connecting A 1  of the bottom surface portion  22  and A 2  of the upper surface portion  24 , and the straight line connecting B 1  of the bottom surface portion  22  and B 2  of the upper surface portion  24  corresponds to the central portion  18 . 
     Regarding a preferred shape of the container  20 , the bottom surface portion  22  preferably has a shape which is curved downward in the vertical direction when viewed from the cross-section in a direction which is perpendicular to the direction in which the stirrer  15  is moved and is perpendicular to the vertical direction. Through having such a shape, precipitates are easily collected in the curved portion and thus stirring efficiency is improved. In addition, the shape of the stirrer  15  preferably partially has the same shape as that of the bottom surface portion  22 . For example, when the bottom surface portion  22  has a shape which is curved downward in the vertical direction, the stirrer  15  may have a spherical or ellipsoidal shape. Accordingly, the contacting surface between the stirrer  15  and the bottom surface portion  22  increases and thus the stirring efficiency of precipitated precipitates is improved. 
     The shape of a connecting portion between the side surface portion  26  and the bottom surface portion  22  preferably has partially the same shape as that of the stirrer  15 . For example, when the shape of the connecting portion has a curve, the shape of the stirrer  15  may have a spherical or ellipsoidal shape. Accordingly, the stirrer  15  easily comes into contact with the connecting portion, and stirring efficiency of the precipitates precipitating in the vicinity of the connecting portion increases. 
     In addition, the shape of the connecting portion between the side surface portion  26  and the bottom surface portion  22  may be preferably curved toward the outside of the container. Accordingly, the clearance gap in the connecting portion is reduced and the amount of precipitates accumulating in the clearance gap can thus be reduced, whereby the stirring efficiency increases. 
     In greater detail, as shown in  FIG. 2A , when the stirrer  15  has a spherical shape and the bottom surface portion  22  of the container  20  has a shape which is curved downward in the vertical direction when viewed from the cross-section in a direction which is perpendicular to the direction in which the stirrer  15  is moved and is perpendicular to the vertical direction, precipitates are easily collected in the curved portion of the bottom surface portion  22 , and the contacting surface between the stirrer  15  and the bottom surface portion  22  increases. Therefore, the stirring efficiency of the precipitated precipitates is improved. 
     Further, in a container  220  of  FIG. 2C , first and second side surface portions  226   a  and  226   b  have a shape which is curved toward the outside of the container  220 , the stirrer  15  has a spherical shape, and the upper surface portion, the bottom portion, the third side surface portion and the fourth side surface portion are formed integrally with each other to constitute a cylinder portion  222 . Since the container  220  includes the cylinder portion  222 , precipitates are easily collected in the curved portion and the contacting surface between the stirrer  15  and the cylinder portion  222  increases, whereby the stirring efficiency of the precipitates is improved. In addition, in contacting portions  227  between the cylinder portion  222  and the first and second side surface portions  226   a  and  226   b , the contacting surface between the contacting portion  227  and the stirrer  15  increases, and thus the amount of precipitates accumulating in the clearance gap is also reduced. Therefore, the stirring efficiency increases. 
     In  FIG. 2C , both of the first and second side surface portions  226   a  and  226   b  have a shape which is curved toward the outside of the container  220 . However, both of them do not necessarily have a shape which is curved toward the outside, and similar effects to the above-described effects are obtainable even when only one has a shape which is curved toward the outside. 
     1.4. Stirring Means 
     In this embodiment, stirring is performed by using the stirrer  15  on the basis of the reciprocation of the carriage  50 A as described above. However, the stirring means is not particularly limited thereto. For example, mounting on a carriage including an XY movement mechanism (which moves in the X-Y plane) also may be employed as described in JP-A-2002-225255. In addition, as shown in  FIG. 4 , the container  20  may be disposed beside a line-type ejection head  34 . In this case, as in  FIG. 5A , the container  20  may be installed on a vibration device  35  to move the stirrer  15  in order to perform the stirring. 
     In addition, as shown in  FIG. 5B , an inclination device  36  which alternately inclines the container  20  may be used to move the stirrer  15  in order to perform the stirring. Alternatively, as shown in  FIG. 5C , a magnet  37  may be moved from the outside the container  20  to move the stirrer  15  made of magnetic metal. 
     The stirring means according to this embodiment is not limited to the stirring which is performed by moving the stirrer in one direction. For example, as shown in  FIG. 6 , the container  20  may be installed on a movement device  39  which operates in the X-Y plane to move the stirrer  15  in the container  20  via the movement device  39  in order to perform the stirring. In addition, the liquid stirring device may employ a known stirring means which moves the stirrer  15 . 
     1.5. Relationship Between Container, Stirrer and Precipitates 
     In the liquid stirring device according to this embodiment, the relationship between a height Ht in the vertical direction in the container and a height Hb in the vertical direction of the stirrer satisfies the following Expression 1.
 
0.40 ×Ht≦Hb≦ 0.90 ×Ht   Expression 1
 
     Here, the height Ht in the vertical direction of the interior of the container  20  is the minimum height in the vertical direction in the container  20  when viewed from the cross-section in a predetermined direction (longitudinal direction) in which the height in the vertical direction passes through the highest point. In addition, the height Hb in the vertical direction of the stirrer is the maximum height in the vertical direction of the stirrer  15 . 
       FIG. 7A  is a diagram illustrating a state in which a liquid is supplied into the container  20  and all the components which may precipitate in the liquid have precipitated, including Ht and Hb. 
     As described above, in the container  20  which is included in the liquid stirring device  100  according to this embodiment, the relationship between Ht and Hb satisfies the above Expression 1. Accordingly, the stirrer  15  can be easily moved in the container  20  and precipitates HI and the liquid in the container  20  can be sufficiently stirred. Particularly, when the precipitates HI do not solidify in the bottom surface portion  22  of the container  20  and the stirrer  15  moves while coming into contact with the bottom surface portion  22  of the container  20 , the stirrer  15  can effectively stir the precipitates HI and the liquid in the container  20  when the above Expression 1 is satisfied. 
     On the other hand, when Hb is less than 40% of Ht, Hb becomes too much smaller than Ht, and thus the liquid stirring efficiency is lowered, and the precipitates HI and the liquid cannot be sufficiently stirred in some cases. In addition, when Hb exceeds 90% of Ht, the stirrer  15  easily receives the resistance of the liquid, and thus the precipitates HI and the liquid cannot be sufficiently stirred in some cases. 
     Further, in the container  20  which is included in the liquid stirring device  100  according to this embodiment, the relationship between a height Hi in the vertical direction of the precipitates HI which may generate in the container  20 , Ht and Hb preferably satisfies the following Expressions 2-1 and 2-2, as well as satisfying the above Expression 1.
 
 Hi÷Ht≦ 0.26  Expression 2-1
 
2.50 ×Hi≦Hb≦ 0.90×( Ht−Hi )  Expression 2-2
 
     The height Hi in the vertical direction of the precipitates HI is the maximum height of the precipitates HI when a liquid containing a component which may precipitate at the same predetermined concentration as in the liquid storage portion  10  is subjected to complete precipitation on the bottom surface portion  22  in the container  20  and the upper surface of the precipitates HI in the container is made to be level. 
     In the container  20  which is included in the liquid stirring device  100  according to this embodiment, Hb is preferably equal to or less than [0.90×(Ht−Hi)] as shown in Expression 2-1. Accordingly, even when the stirrer  15  runs onto the precipitates HI when the precipitates HI solidify, the movement of the stirrer  15  is hindered little and the stirrer  15  can easily move in the container  20 , whereby the precipitates HI and the liquid in the container  20  can be sufficiently stirred. The “solidification” is a state in which the stirrer  15  does not come into contact with the bottom surface portion  22  of the container  20  when the stirrer  15  moves on the precipitates HI. The specific positional relationship is shown in  FIG. 7B . 
     On the other hand, when Hb exceeds [0.90×(Ht−Hi)], the stirrer  15  easily receives the resistance of the liquid or the stirrer  15  gets stuck in the container  20  and cannot move therein. Therefore, in some cases, it becomes difficult to stir the liquid and the precipitates HI. 
     The container  20  which is included in the liquid stirring device  100  according to this embodiment satisfies Expression 2-1. When the container  20  does not satisfy Expression 2-1, values having a relationship satisfying Expression 2-2 cannot be obtained. 
     In Expression 2-2, Hb is preferably set to be equal to or greater than 2.50 times Hi. Particularly, when the precipitates HI solidify, when Hb is equal to or greater than 2.50 times Hi, the stirrer  15  can move in the container  20  due to the movement of the carriage  50 A even when the stirrer  15  is partially buried in the precipitates HI. 
     On the other hand, when Hb is less than 2.50 times Hi, the stirrer  15  is buried in the precipitates HI, and thus cannot move in some cases. 
     2. Droplet Ejection Device 
     A droplet ejection device according to the invention includes the above-described liquid stirring device  100 . In this embodiment, a droplet ejection device  300  having the liquid stirring device  100  will be described using an ink jet printer. 
       FIG. 8  is a perspective view schematically showing the droplet ejection device  300  including the liquid stirring device  100 . As shown in  FIG. 8 , the droplet ejection device  300  according to this embodiment includes a control portion  360 , a liquid storage portion  10 , a liquid supply tube  30 , a driving portion  50 , and a transport portion  70 . 
     The driving portion  50  may have a carriage  50 A, a driving belt  50 B, and a carriage motor  50 C. The driving, portion  50  is electrically connected to the control portion via a flexible cable  62  and controlled by the control portion. In addition, the driving portion  50  has a function of reciprocating the carriage  50 A on which an ejection head  33  is mounted. In greater detail, the driving belt  50 B which is connected to the carriage  50 A is driven by power of the carriage motor  50 C which is a driving source for the carriage  50 A, so that the carriage  50 A is reciprocated. 
     The ejection head  33  may have a plurality of nozzles which eject droplets. In addition, a droplet ejection method of the ejection head  33  is not particularly limited, and for example, an ink jet ejection method can be used. As the ink jet ejection method, any known method can be used, and examples thereof include a piezo-type ink jet, thermal-type ink jet and the like. 
     A medium to be ejected is transported by the transport portion  70 , and during the transport, the liquid from the liquid storage portion  10  is ejected by the ejection head  33  which is mounted on the carriage  50 A. After that, the medium to be ejected is discharged to the outside of the device by a discharge portion (not shown). 
     The droplet ejection device  300  of the invention is not only used as an image recording device, such as the exemplified ink jet printer, but also preferably used as a color material spraying device used in manufacturing of a color filter for liquid crystal display, a liquid material spraying device used in the formation of a color filter or an electrode for electrophoretic display, field emission display (FED), and organic EL display, and a bioorganic material spraying device used in bio-chip manufacturing. 
     3. Examples 
     Hereinafter, the invention will be described in detail using examples, but is not limited thereto. 
     3.1. Preparation of White Ink Composition 
     A white ink composition having the following composition was prepared. 
     1. First White Ink Composition 
     titanium dioxide (average particle size: 240 nm): 10 mass % 
     styrene-acrylic acid copolymer: 2 mass % 
     1,2-hexanediol: 5 mass % 
     glycerin: 10 mass % 
     triethanolamine: 0.9 mass % 
     BYK-348 (manufactured by BYK-Chemie Japan KK): 0.5 mass % 
     ultrapure water: remainder 
     total 100 mass % 
     2. Second White Ink Composition 
     The content of titanium dioxide in the first white ink composition was adjusted to 20 mass %, and the other components were the same as those of the first white ink composition. 
     3. Third White Ink Composition 
     The content of titanium dioxide in the first white ink composition was adjusted to 23 mass %, and the other components were the same as those of the first white ink composition. 
     3.2. Creation of Samples for Test 
     3.2.1. Creation of Samples for First Evaluation Test 
     A container having a stirrer disposed therein and having a cylinder shape with a diameter Ht of 15 mm and a height of 65 mm was used and filled with the first white ink composition prepared in the above-described “3.1. (1)”, and then was sealed. Next, a centrifuge (Flexpin Bench-Top Centrifuge LC-131, manufactured by TOMY SEIKO CO., LTD.) was used to separate from the liquid components which were contained in the first white ink composition in the container and which might precipitate. The centrifugation was performed for 2 hours under the conditions of the rotation radius of 21 cm and the centrifugal acceleration of 600 rpm. In addition, after centrifugation, the precipitates were not solidified and the stirrer came into contact with the bottom surface of the container. The stirrer had a spherical stainless steel body (specific gravity 7.9), and its diameter Hb was 95% (14.3 mm) of the diameter Ht of the container. 
     After that, the container was installed in the carriage of an ink jet printer (product name “EPSON PX-G930”, manufactured by Seiko Epson Corp.) so that the longitudinal direction of the container was parallel to the movement direction (horizontal direction) of the carriage. In addition, the container was sealed so that supply of the ink composition into the container and supply of the ink composition to the head from the container were not performed. 
     Next, the carriage reciprocated 100 times a distance of 23 cm at a speed of about 46 cm/sec to stir the first white ink composition in the container. After that, 1 g of the liquid in the container was taken to obtain a sample 1-1 for a first evaluation test. 
     A sample 1-2 for the first evaluation test was the same as the above “sample 1-1”, except for the use of a stirrer with a size 90% (13.5 mm) of the diameter Ht of the container. 
     A sample 1-3 for the first evaluation test was the same as the above “sample 1-1”, except for the use of a stirrer with a size 70% (10.5 mm) of the diameter Ht of the container. 
     A sample 1-4 for the first evaluation test was the same as the above “sample 1-1”, except for the use of a stirrer with a size 50% (7.5 mm) of the diameter Ht of the container. 
     A sample 1-5 for the first evaluation test was the same as the above “sample 1-1”, except for the use of a stirrer with a size 40% (6.0 mm) of the diameter Ht of the container. 
     A sample 1-6 for the first evaluation test was the same as the above “sample 1-1”, except for the use of a stirrer with a size 30% (4.5 mm) of the diameter Ht of the container. 
     A sample 1-7 for the first evaluation test was the same as the above “sample 1-1”, except for not using a stirrer. 
     A sample 1-8 for the first evaluation test was obtained in the same manner as that for the above “sample 1-1”, except for the use of the second white ink composition obtained in the above-described “3.1. (2)”. After centrifugation, the precipitates were not solidified and the stirrer came into contact with the bottom surface of the container. 
     A sample 1-9 for the first evaluation test was obtained in the same manner as that for the above “sample 1-1”, except for the use of a container having a cylinder shape with a diameter Ht of 25 mm and a height of 75 mm and the use of a stirrer with a size 95% (23.8 mm) of the diameter Ht of the container. 
     A sample 1-10 for the first evaluation test was the same as the above “sample 1-9”, except for the use of a stirrer with a size 90% (22.5 mm) of the diameter Ht of the container. 
     A sample 1-11 for the first evaluation test was the same as the above “sample 1-9”, except for the use of a stirrer with a size 40% (10.0 mm) of the diameter Ht of the container. 
     A sample 1-12 for the first evaluation test was the same as the above “sample 1-9”, except for the use of a stirrer with a size 30% (7.5 mm) of the diameter Ht of the container. 
     A sample 1-13 for the first evaluation test was the same as the above “sample 1-1”, except for installation of a container having a rectangular parallelepiped body of vertical 15 mm×horizontal 15 mm×height 65 mm with the direction of the height of the container parallel to the movement direction of the carriage and the use of a stirrer having a spherical body with a size 90% (13.5 mm) of the diameter Ht of the container. 
     A sample 1-14 for the first evaluation test was the same as the above “sample 1-13”, except for the use of a stirrer with a size 40% (6.0 mm) of the diameter Ht of the container. 
     A sample 1-15 for the first evaluation test was the same as the above “sample 1-13”, except for the use of a stirrer having a cubic body with a size 40% (6.0 mm) of the diameter Ht of the container. 
     3.2.2. Creation of Samples for Second Evaluation Test 
     A container having a stirrer disposed therein and having a cylinder shape with a diameter Ht of 15 mm and a height of 65 mm was used and filled with the first white ink composition prepared in the above-described “3.1. (1)”, and then was sealed. Next, a centrifuge was used to separate from the liquid the components which were contained in the first white ink composition in the container and which might precipitate. The centrifugation was performed for 2 hours under the conditions of the rotation radius of 21 cm and the centrifugal acceleration of 600 rpm. After centrifugation, the container was left for a month at 20° C. The precipitates in the container after leaving for a month were solidified. In addition, the stirrer  15  had a spherical stainless steel body (specific gravity 7.9), and its diameter Hb was 95% (14.3 mm) of the diameter Ht of the container. 
     In addition, the volume of the component (titanium dioxide) which was contained in the first white ink composition in the container and which might precipitate was 8% of the volume of the container. In addition, regarding the component (titanium dioxide) which was contained in the first white ink composition in the container and which might precipitate, the height Hi in the vertical direction of precipitates was 2.06 mm (13.3% of the diameter Ht of the container). 
     After leaving the container for a month, the container was installed in the carriage of an ink jet printer (product name “EPSON PX-G930”, manufactured by Seiko Epson Corp.) so that the longitudinal direction of the container was parallel to the movement direction (horizontal direction) of the carriage. In addition, the container was sealed so that supply of the ink composition into the container and supply of the ink composition to the head from the container were not performed. 
     Next, the carriage reciprocated 100 times a distance of 23 cm at a speed of about 46 cm/sec to stir the first white ink composition in the container. After that, 1 g of the liquid in the container was taken to obtain a sample 2-1 for a second evaluation test. 
     A sample 2-2 for the second evaluation test was the same as the above “sample 2-1”, except for the use of a stirrer with a size 90% (13.5 mm) of the diameter Ht of the container. 
     A sample 2-3 for the second evaluation test was the same as the above “sample 2-1”, except for the use of a stirrer with a size 80% (12.0 mm) of the diameter Ht of the container. 
     A sample 2-4 for the second evaluation test was the same as the above “sample 2-1”, except for the use of a stirrer with a size 75% (11.3 mm) of the diameter Ht of the container. 
     A sample 2-5 for the second evaluation test was the same as the above “sample 2-1”, except for the use of a stirrer with a size 70% (10.5 mm) of the diameter Ht of the container. 
     A sample 2-6 for the second evaluation test was the same as the above “sample 2-1”, except for the use of a stirrer with a size 60% (9.0 mm) of the diameter Ht of the container. 
     A sample 2-7 for the second evaluation test was the same as the above “sample 2-1”, except for the use of a stirrer with a size 50% (7.5 mm) of the diameter Ht of the container. 
     A sample 2-8 for the second evaluation test was the same as the above “sample 2-1”, except for the use of a stirrer with a size 40% (6.0 mm) of the diameter Ht of the container. 
     A sample 2-9 for the second evaluation test was the same as the above “sample 2-1”, except for the use of a stirrer with a size 30% (4.5 mm) of the diameter Ht of the container. 
     A sample 2-10 for the second evaluation test was the same as the above “sample 2-1”, except for not using a stirrer. 
     A sample 2-11 for the second evaluation test was the same as the above “sample 2-1”, except for the use of the second white ink composition obtained in the above-described “3.1. (2)”, and using a stirrer having a spherical body with a size 95% (14.3 mm) of the diameter Ht of the container. The volume of the component (titanium dioxide) which was contained in the second white ink composition in the container and which might precipitate was 16% of the volume of the container. In addition, regarding the component (titanium dioxide) which was contained in the second white ink composition in the container and which might precipitate, the height Hi in the vertical direction of precipitates was 3.30 mm (21.3% of the diameter Ht of the container). 
     A sample 2-12 for the second evaluation test was the same as the above “sample 2-11”, except for the use of a stirrer with a size 90% (13.5 mm) of the diameter Ht of the container. 
     A sample 2-13 for the second evaluation test was the same as the above “sample 2-11”, except for the use of a stirrer with a size 75% (11.3 mm) of the diameter Ht of the container. 
     A sample 2-14 for the second evaluation test was the same as the above “sample 2-11”, except for the use of a stirrer with a size 70% (10.5 mm) of the diameter Ht of the container. 
     A sample 2-15 for the second evaluation test was the same as the above “sample 2-11”, except for the use of a stirrer with a size 55% (8.3 mm) of the diameter Ht of the container. 
     A sample 2-16 for the second evaluation test was the same as the above “sample 2-11”, except for the use of a stirrer with a size 50% (7.5 mm) of the diameter Ht of the container. 
     A sample 2-17 for the second evaluation test was the same as the above “sample 2-11”, except for the use of a stirrer with a size 40% (6.0 mm) of the diameter Ht of the container. 
     A sample 2-18 for the second evaluation test was the same as the above “sample 2-11”, except for the use of a stirrer with a size 30% (4.5 mm) of the diameter Ht of the container. 
     A sample 2-19 for the second evaluation test was the same as the above “sample 2-11”, except for not using a stirrer. 
     A sample 2-20 for the second evaluation test was the same as the above “sample 2-1”, except for using the third white ink composition obtained in the above-described “3.1. (3)”, and using a stirrer having a spherical body with a size 95% (14.3 mm) of the diameter Ht of the container. The volume of the component (titanium dioxide) which was contained in the third white ink composition in the container and which might precipitate was 18.5% of the volume of the container. In addition, regarding the component (titanium dioxide) which was contained in the third white ink composition in the container and which might precipitate, the height Hi in the vertical direction of precipitates which were completely precipitated in the container was 3.72 mm (24.0% of the diameter Ht of the container). 
     A sample 2-21 for the second evaluation test was the same as the above “sample 2-20”, except for the use of a stirrer with a size 90% (13.5 mm) of the diameter Ht of the container. 
     A sample 2-22 for the second evaluation test was the same as the above “sample 2-20”, except for the use of a stirrer with a size 70% (10.5 mm) of the diameter Ht of the container. 
     A sample 2-23 for the second evaluation test was the same as the above “sample 2-20”, except for the use of a stirrer with a size 65% (9.8 mm) of the diameter Ht of the container. 
     A sample 2-24 for the second evaluation test was the same as the above “sample 2-20”, except for the use of a stirrer with a size 60% (9.0 mm) of the diameter Ht of the container. 
     A sample 2-25 for the second evaluation test was the same as the above “sample 2-20”, except for the use of a stirrer with a size 50% (7.5 mm) of the diameter Ht of the container. 
     A sample 2-26 for the second evaluation test was the same as the above “sample 2-20”, except for the use of a stirrer with a size 30% (4.5 mm) of the diameter Ht of the container. 
     A sample 2-27 for the second evaluation test was the same as the above “sample 2-20”, except for not using a stirrer. 
     3.3. Evaluation Tests 
     3.3.1. First Evaluation Test 
     Distilled water was added to 1 g of each of the samples 1-1 to 1-15 obtained as described above to dilute the sample 1,000 times. Next, by using a spectrophotometer (product name “Spectrophotometer U-3300”, manufactured by Hitachi, Ltd.), the absorbance (Abs value) of the diluted white ink composition at a wavelength of 500 nm was measured. The absorbances of the samples obtained in this manner were compared to the absorbance of the white ink composition before centrifugation and the recovery rate of the absorbance was obtained using the following Expression 3.
 
Recovery Rate(%) of Absorbance=100×(Absorbance of Sample)/(Absorbance Before Centrifugation Operation)  Expression 3
 
     The higher the recovery rate of the absorbance is, the better the stirring efficiency of the ink composition is. In addition, the evaluation references in the first evaluation test are classified as follows. 
     ⊙: The recovery rate of absorbance is equal to or greater than 80% 
     ◯: The recovery rate of absorbance is equal to or greater than 70% and less than 80% 
     X: The recovery rate of absorbance is less than 70% 
     3.3.2. Second Evaluation Test 
     The recovery rates of the absorbance of the samples 2-1 to 2-27 obtained as described above were obtained in the same manner as in the above “3.3.1. First Evaluation Test”. The evaluation references in the second evaluation test are classified as follows. 
     ⊙: The recovery rate of absorbance is equal to or greater than 80% 
     ◯: The recovery rate of absorbance is equal to or greater than 70% and less than 80% 
     X: The recovery rate of absorbance is less than 70% 
     3.4. Evaluation Results 
     Table 1 shows the results of the first evaluation test and Tables 2 and 3 show the results of the second evaluation test. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Height of 
                 Height 
                   
                 Evaluation Test Results 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Evaluation 
                   
                   
                   
                 Container 
                 of Stirrer 
                 Ratio of 
                 Recovery 
                   
               
               
                 Sample 
                 Used White Ink 
                   
                   
                 (mm) 
                 (mm) 
                 Hb to Ht 
                 Rate 
               
               
                 No. 
                 Composition 
                 Shape of Container 
                 Shape of Stirrer 
                 (Ht) 
                 (Hb) 
                 (Hb/Ht, %) 
                 (%) 
                 Evaluation 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 (1-1) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 15.0 
                 14.30 
                 0.95 
                 40 
                 X 
               
               
                 (1-2) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 15.0 
                 13.50 
                 0.90 
                 82 
                 ⊙ 
               
               
                 (1-3) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 15.0 
                 10.50 
                 0.70 
                 99 
                 ⊙ 
               
               
                 (1-4) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 15.0 
                 7.50 
                 0.50 
                 92 
                 ⊙ 
               
               
                 (1-5) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 15.0 
                 6.00 
                 0.40 
                 86 
                 ⊙ 
               
               
                 (1-6) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 15.0 
                 4.50 
                 0.30 
                 45 
                 X 
               
               
                 (1-7) 
                 First White Ink Composition 
                 Cylinder Shape 
                 — 
                 15.0 
                 — 
                 — 
                 15 
                 X 
               
               
                 (1-8) 
                 Second White Ink 
                 Cylinder Shape 
                 Spherical Body 
                 15.0 
                 7.50 
                 0.50 
                 89 
                 ⊙ 
               
               
                   
                 Composition 
               
               
                 (1-9) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 25.0 
                 23.80 
                 0.95 
                 41 
                 X 
               
               
                 (1-10) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 25.0 
                 22.50 
                 0.90 
                 83 
                 ⊙ 
               
               
                 (1-11) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 25.0 
                 10.00 
                 0.40 
                 87 
                 ⊙ 
               
               
                 (1-12) 
                 First White Ink Composition 
                 Cylinder Shape 
                 Spherical Body 
                 25.0 
                 7.50 
                 0.30 
                 47 
                 X 
               
               
                 (1-13) 
                 First White Ink Composition 
                 Rectangular 
                 Spherical Body 
                 15.0 
                 13.50 
                 0.90 
                 71 
                 ◯ 
               
               
                   
                   
                 Parallelepiped Body 
               
               
                 (1-14) 
                 First White Ink Composition 
                 Rectangular 
                 Spherical Body 
                 15.0 
                 6.00 
                 0.40 
                 72 
                 ◯ 
               
               
                   
                   
                 Parallelepiped Body 
               
               
                 (1-15) 
                 First White Ink Composition 
                 Rectangular 
                 Cubic Body 
                 15.0 
                 6.00 
                 0.40 
                 70 
                 ◯ 
               
               
                   
                   
                 Parallelepiped Body 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
             
            
               
                   
                   
               
               
                   
                   
                   
                   
                 Evaluation 
               
               
                   
                 Height of 
                 Height of 
                   
                 Test Results 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                 Container 
                 Stirrer 
                 Ratio of Hb 
                 Recovery 
                   
               
               
                 Sample 
                   
                   
                 Shape of 
                 (mm) 
                 (mm) 
                 to Ht 
                 Rate 
               
               
                 No. 
                 Used White Ink 
                 Shape of Stirrer 
                 Container 
                 (Ht) 
                 (Hb) 
                 (Hb/Ht, %) 
                 (%) 
                 Evaluation 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 (2-1) 
                 First White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 14.30 
                 0.95 
                 40 
                 X 
               
               
                 (2-2) 
                 Second White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 13.50 
                 0.90 
                 73 
                 ◯ 
               
               
                 (2-3) 
                 Third White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 12.00 
                 0.80 
                 79 
                 ◯ 
               
               
                 (2-4) 
                 Fourth White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 11.30 
                 0.75 
                 81 
                 ⊙ 
               
               
                 (2-5) 
                 First White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 10.50 
                 0.70 
                 95 
                 ⊙ 
               
               
                 (2-6) 
                 First White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 9.00 
                 0.60 
                 99 
                 ⊙ 
               
               
                 (2-7) 
                 First White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 7.50 
                 0.50 
                 92 
                 ⊙ 
               
               
                 (2-8) 
                 First White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 6.00 
                 0.40 
                 86 
                 ⊙ 
               
               
                 (2-9) 
                 First White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 4.50 
                 0.30 
                 45 
                 X 
               
               
                 (2-10) 
                 First White Ink Composition 
                 — 
                 Cylinder Shape 
                 15.0 
                 — 
                 — 
                 15 
                 X 
               
               
                 (2-11) 
                 Second White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 14.30 
                 0.95 
                 38 
                 X 
               
               
                 (2-12) 
                 Second White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 13.50 
                 0.90 
                 70 
                 ◯ 
               
               
                 (2-13) 
                 Second White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 11.30 
                 0.75 
                 75 
                 ◯ 
               
               
                 (2-14) 
                 Second White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 10.50 
                 0.70 
                 98 
                 ⊙ 
               
               
                 (2-15) 
                 Second White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 8.30 
                 0.55 
                 85 
                 ⊙ 
               
               
                 (2-16) 
                 Second White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 7.50 
                 0.50 
                 78 
                 ◯ 
               
               
                 (2-17) 
                 Second White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 6.00 
                 0.40 
                 70 
                 ◯ 
               
               
                 (2-18) 
                 Second White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 4.60 
                 0.31 
                 39 
                 X 
               
               
                 (2-19) 
                 Second White Ink Composition 
                 — 
                 Cylinder Shape 
                 15.0 
                 — 
                 — 
                 21 
                 X 
               
               
                 (2-20) 
                 Third White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 14.30 
                 0.95 
                 36 
                 X 
               
               
                 (2-21) 
                 Third White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 13.50 
                 0.90 
                 72 
                 ◯ 
               
               
                 (2-22) 
                 Third White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 10.50 
                 0.70 
                 79 
                 ◯ 
               
               
                 (2-23) 
                 Third White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 9.80 
                 0.65 
                 83 
                 ⊙ 
               
               
                 (2-24) 
                 Third White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 9.00 
                 0.60 
                 83 
                 ⊙ 
               
               
                 (2-25) 
                 Third White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 7.50 
                 0.50 
                 70 
                 ◯ 
               
               
                 (2-26) 
                 Third White Ink Composition 
                 Spherical Body 
                 Cylinder Shape 
                 15.0 
                 4.50 
                 0.30 
                 36 
                 X 
               
               
                 (2-27) 
                 Third White Ink Composition 
                 — 
                 Cylinder Shape 
                 15.0 
                 — 
                 — 
                 24 
                 X 
               
               
                   
               
            
           
         
       
     
                                         TABLE 3                                      Evaluation           Height of   Height of       Test Results                                                         Container   Precipitates       0.90 ×   Height of Stirrer   Recovery           Sample       (mm)   (mm)   2.50 × Hi   (Ht − Hi)   (mm)   Rate       No.   Used White Ink   (Ht)   (Hi)   (mm)   (mm)   (Hb)   (%)   Evaluation                                                         (2-1)   First White Ink Composition   15.0   2.06   5.15   11.65   14.30   40   X       (2-2)   First White Ink Composition   15.0   2.06   5.15   11.65   13.50   73   ◯       (2-3)   First White Ink Composition   15.0   2.06   5.15   11.65   12.00   79   ◯       (2-4)   First White Ink Composition   15.0   2.06   5.15   11.65   11.30   81   ⊙       (2-5)   First White Ink Composition   15.0   2.06   5.15   11.65   10.50   95   ⊙       (2-6)   First White Ink Composition   15.0   2.06   5.15   11.65   9.00   99   ⊙       (2-7)   First White Ink Composition   15.0   2.06   5.15   11.65   7.50   92   ⊙       (2-8)   First White Ink Composition   15.0   2.06   5.15   11.65   6.00   86   ⊙       (2-9)   First White Ink Composition   15.0   2.06   5.15   11.65   4.50   45   X       (2-10)   First White Ink Composition   15.0   2.06   5.15   11.65   —   15   X       (2-11)   Second White Ink Composition   15.0   3.30   8.25   10.53   14.30   38   X       (2-12)   Second White Ink Composition   15.0   3.30   8.25   10.53   13.50   70   ◯       (2-13)   Second White Ink Composition   15.0   3.30   8.25   10.53   11.30   75   ◯       (2-14)   Second White Ink Composition   15.0   3.30   8.25   10.53   10.50   98   ⊙       (2-15)   Second White Ink Composition   15.0   3.30   8.25   10.53   8.30   85   ⊙       (2-16)   Second White Ink Composition   15.0   3.30   8.25   10.53   7.50   78   ◯       (2-17)   Second White Ink Composition   15.0   3.30   8.25   10.53   6.00   70   ◯       (2-18)   Second White Ink Composition   15.0   3.30   8.25   10.53   4.60   39   X       (2-19)   Second White Ink Composition   15.0   3.30   8.25   10.53   —   21   X       (2-20)   Third White Ink Composition   15.0   3.72   9.30   10.15   14.30   36   X       (2-21)   Third White Ink Composition   15.0   3.72   9.30   10.15   13.50   72   ◯       (2-22)   Third White Ink Composition   15.0   3.72   9.30   10.15   10.50   79   ◯       (2-23)   Third White Ink Composition   15.0   3.72   9.30   10.15   9.80   83   ⊙       (2-24)   Third White Ink Composition   15.0   3.72   9.30   10.15   9.00   83   ⊙       (2-25)   Third White Ink Composition   15.0   3.72   9.30   10.15   7.50   70   ◯       (2-26)   Third White Ink Composition   15.0   3.72   9.30   10.15   4.50   36   X       (2-27)   Third White Ink Composition   15.0   3.72   9.30   10.15   —   24   X                    
3.4.1. Expression 1
 
     In the first evaluation test, from Table 1, it could be confirmed that when using the containers and the stirrers of the samples 1-2 to 1-5, 1-8, 1-10, 1-11, and 1-13 to 1-15, the recovery rate of the absorbance was excellent for any of these cases and a liquid stirring device having excellent stirring efficiency was obtained. On the other hand, it could be confirmed that when using the containers and the stirrers of the samples 1-1, 1-6, 1-7, 1-9 and 1-12, the recovery rate of the absorbance was poor for any of these cases and a liquid stirring device having poor stirring efficiency was obtained. 
     From Table 2 of the results of the second evaluation test, it could be confirmed that when using the containers and the stirrers of the samples 2-2 to 2-8, 2-12 to 2-17, and 2-21 to 2-25, the recovery rate of the absorbance was excellent for any of these cases and a liquid stirring device having excellent stirring efficiency was obtained. On the other hand, it could be confirmed that when using the containers and the stirrers of the samples 2-1, 2-9 to 2-11, 2-18 to 2-20, 2-26, and 2-27, the recovery rate of the absorbance was poor for any of these cases and a liquid stirring device having poor stirring efficiency was obtained. 
     From the above description, it was found that a high stirring efficiency was obtained when satisfying Expression 1.
 
0.40 ×Ht≦Hb≦ 0.90 ×Ht   Expression 1
 
3.4.2. Expressions 2-1 and 2-2
 
     From Table 3 of the results of the second evaluation test, it was shown that when using the containers and the stirrers of the samples 2-4 to 2-8, 2-14, 2-15, 2-23, and 2-24, higher stirring efficiency is obtained even when the precipitates are solidified. On the other hand, it was shown that when using the containers and the stirrers of the samples 2-1 to 2-3, 2-9 to 2-13, 2-16 to 2-22, and 2-25 to 2-27, the movement of the stirrer was extremely hindered due to the precipitates and thus a liquid stirring device having poor stirring efficiency was obtained. 
     From the above description, it was found that higher stirring efficiency is obtained when satisfying Expressions 2-1 and 2-2.