Patent Publication Number: US-2011074870-A1

Title: Liquid ejection head cleaning apparatus and image recording aparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid ejection head cleaning apparatus and an image recording apparatus, and more particularly to technology for cleaning a liquid ejection surface of a liquid ejection head. 
     2. Description of the Related Art 
     As a general image recording apparatus, it is suitable to use an inkjet recording apparatus, which forms a desired image on a recording medium by ejecting and depositing colored inks from a plurality of nozzles provided in an inkjet head. If the inkjet head is operated for a long period of time, adhering matter such as solidified ink or paper dust from the recording medium, and the like, adhere to the nozzle surface. In particular, if adhering matter becomes attached to the vicinity of the nozzles and the nozzle apertures, this gives rise to deflection of the ejection direction of the ink ejected from the nozzles, or reduction in the ejection volume, and so on, and therefore an inkjet recording apparatus is composed in such a manner that cleaning of the nozzle surface is carried out appropriately. 
     Japanese Patent Application Publication No. 2009-006492 discloses a fluid spouting device which applies a cleaning liquid in a non-contact fashion to a nozzle surface of an inkjet head, by spouting the cleaning liquid from a cleaning liquid spouting unit toward the nozzle surface (see  FIGS. 11 and 12 , for example). In this fluid spouting device, the supply of cleaning liquid to the cleaning liquid spouting unit from a cleaning liquid tank is carried out through a pump. 
     The principal methods of supplying the cleaning liquid are a pumping method and a liquid head differential method. With the pumping method, however, pulsation occurs when the cleaning liquid is supplied, and it is not possible to apply the cleaning liquid in a stable and uniform fashion to the inkjet head. Accordingly, the method of supplying cleaning liquid using a liquid head differential (liquid head differential method) is considered to be the most straightforward method, since it does not induce pulsation. 
       FIG. 21  shows an example of the composition of an inkjet head cleaning apparatus in the related art. The inkjet head cleaning apparatus shown in  FIG. 21  includes a cleaning liquid spouting unit  902  having a cleaning liquid spouting surface  902 A in a position opposing a nozzle surface (ejection surface)  900 A of an inkjet head  900 , and a cleaning liquid tank  904  containing the cleaning liquid. The surface of the cleaning liquid in the cleaning liquid tank  904  is disposed higher than the cleaning liquid spouting surface  902 A of the cleaning liquid spouting unit  902 , and the cleaning liquid is supplied from the cleaning liquid tank  904  to the cleaning liquid spouting unit  902  through a supply flow channel  906  by the liquid head differential H between the liquid surface in the cleaning liquid tank  904  and the cleaning liquid spouting surface  902 . The cleaning liquid  908  is spouted from the cleaning liquid spouting surface  902 A of the cleaning liquid spouting unit  902 , the cleaning liquid is thereby applied to the nozzle surface  900 A of the inkjet head  900 , and the nozzle surface  900 A is wiped with a wiping member (web or blade, etc.), which is not illustrated. 
     However, since the viscosity of the cleaning liquid changes with the temperature, then in the inkjet head cleaning apparatus in the related art shown in  FIG. 21 , if a change in the temperature of the cleaning liquid occurs due to change in the ambient temperature, the amount (height h) of the cleaning liquid spouted from the cleaning liquid spouting unit  902  varies, and the cleaning liquid cannot be stably applied. 
       FIG. 22  is a table for describing problems that occur with change in the ambient temperature. In  FIG. 22 , an ambient temperature of normal temperature (25° C.) is taken as a reference temperature. As shown in  FIG. 22 , when the ambient temperature is lower than normal temperature, then the supply rate (flow rate) of the cleaning liquid is reduced because the viscosity of the cleaning liquid becomes higher, and there arises a problem of insufficient height of the cleaning liquid spouted from the cleaning liquid spouting unit  902 . On the other hand, if the ambient temperature is higher than normal temperature, then the supply rate (flow rate) of the cleaning liquid is increased because the viscosity of the cleaning liquid becomes lower, and there arises a problem in that the height of the cleaning liquid spouted from the cleaning liquid unit  902  increases and the consumption of the cleaning liquid increases. 
     SUMMARY OF THE INVENTION 
     The present invention has been contrived in view of these circumstances, an object thereof being to provide a liquid ejection head cleaning apparatus and an image recording apparatus, whereby cleaning liquid can be stably applied to a liquid ejection surface of a liquid ejection head irrespective of the ambient temperature. 
     In order to attain the aforementioned object, the present invention is directed to a liquid ejection head cleaning apparatus, comprising: a cleaning liquid deposition device which spouts cleaning liquid from a plurality of cleaning liquid nozzles and deposits the cleaning liquid onto an ejection surface of a liquid ejection head; a cleaning liquid supply device which supplies the cleaning liquid to the cleaning liquid nozzles by using a liquid head differential with respect to the cleaning liquid deposition device; a temperature measurement device which measures an ambient temperature around the cleaning liquid supply device; and a pressure control device which controls a pressure of the cleaning liquid supplied to the cleaning liquid deposition device from the cleaning liquid supply device in accordance with the ambient temperature measured by the temperature measurement device. 
     According to this aspect of the present invention, it is possible to suppress variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles caused by variation in the ambient temperature, and hence the height of the cleaning liquid spouted from the cleaning liquid nozzles can be kept uniform irrespective of the variation in the ambient temperature. Consequently, it is possible to apply the cleaning liquid stably to the liquid ejection surface of the liquid ejection head. 
     Preferably, the apparatus further comprises a pressure adjustment device which adjusts a pressure inside the cleaning liquid supply device, wherein the pressure control device changes the pressure inside the cleaning liquid supply device by controlling the pressure adjustment device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the apparatus further comprises an elevator device which changes a height of the cleaning liquid supply device with respect to the cleaning liquid deposition device, wherein the pressure control device changes the height of the cleaning liquid supply device by controlling the elevator device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the apparatus further comprises a liquid surface height adjustment device which adjusts a height of a surface of the cleaning liquid inside the cleaning liquid supply device, wherein the pressure control device changes the height of the surface of the cleaning liquid inside the cleaning liquid supply device by controlling the liquid surface height adjustment device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the apparatus further comprises: a supply flow channel which connects the cleaning liquid supply device to the cleaning liquid deposition device; and a flow channel resistance adjustment device which adjusts a flow channel resistance of the supply flow channel, wherein the pressure control device changes the flow channel resistance of the supply flow channel by controlling the flow channel resistance adjustment device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the flow channel resistance adjustment device includes: a plurality of parallel flow channels connected in parallel to the supply flow channel; and a flow channel selecting device which selects at least one of the parallel flow channels; and the pressure control device controls the flow channel selecting device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, at least one of the parallel flow channels has a valve device to open and close the at least one of the parallel flow channels; and the pressure control device selects at least one of the parallel flow channels by controlling the valve device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the parallel flow channels have mutually different lengths. 
     Preferably, the parallel flow channels have restrictor sections, respectively, the restrictor sections having mutually different flow channel cross-sectional areas. 
     Preferably, the pressure control device always selects, apart from the at least one of the parallel flow channels having the valve device, another of the parallel flow channels, and additionally selects the at least one of the parallel flow channels having the valve device by controlling the valve device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, at least two of the parallel flow channels have valve devices to open and close respectively the at least two of the parallel flow channels, the valve devices having mutually different Cv values; and the pressure control device selects at least one of the parallel flow channels by controlling the valve device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the apparatus further comprises a cleaning liquid temperature adjustment device which adjusts a temperature of the cleaning liquid in the cleaning liquid supply device. 
     Preferably, the cleaning liquid deposition device includes a flow rate adjustment device which adjusts a flow rate of the cleaning liquid supplied to each of the cleaning liquid nozzles in such a manner that heights of the cleaning liquid spouted from the cleaning liquid nozzles are uniform. 
     Preferably, the cleaning liquid deposition device includes the cleaning liquid nozzles arranged along a prescribed alignment direction and has a flow channel connecting to the cleaning liquid nozzles; and the flow channel has a restrictor having a width less than a diameter of each of the cleaning liquid nozzles. 
     Preferably, the restrictor includes a groove formed along the alignment direction of the cleaning liquid nozzles. 
     Preferably, the cleaning liquid deposition device has an inlet port through which the cleaning liquid is introduced from the cleaning liquid supply device; a first flow channel resistance from the inlet port to the cleaning liquid nozzles arranged in a first region is larger than a second flow channel resistance from the inlet port to the cleaning liquid nozzles arranged in a second region; and a first interval between the cleaning liquid nozzles arranged in the first region is smaller than a second interval between the cleaning liquid nozzles arranged in the second region. 
     Preferably, the apparatus further comprises a movement device which causes the liquid ejection head and the cleaning liquid deposition device to move relatively to each other, wherein the cleaning liquid deposition device includes the cleaning liquid nozzles arranged through a length not shorter than a breadth of the liquid ejection head. 
     In order to attain the aforementioned object, the present invention is also directed to an image recording apparatus, comprising: a liquid ejection head having an ejection surface in which a plurality of nozzles to eject liquid are arranged; and a liquid ejection head cleaning device which deposits cleaning liquid onto the ejection surface of the liquid ejection head, the liquid ejection head cleaning device including: a cleaning liquid deposition device which spouts the cleaning liquid from a plurality of cleaning liquid nozzles and deposits the cleaning liquid onto the ejection surface of the liquid ejection head; a cleaning liquid supply device which supplies the cleaning liquid to the cleaning liquid nozzles by using a liquid head differential with respect to the cleaning liquid deposition device; a temperature measurement device which measures an ambient temperature around the cleaning liquid supply device; and a pressure control device which controls a pressure of the cleaning liquid supplied to the cleaning liquid deposition device from the cleaning liquid supply device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the liquid ejection head cleaning device further includes a pressure adjustment device which adjusts a pressure inside the cleaning liquid supply device; and the pressure control device changes the pressure inside the cleaning liquid supply device by controlling the pressure adjustment device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the liquid ejection head cleaning device further includes an elevator device which changes a height of the cleaning liquid supply device with respect to the cleaning liquid deposition device; and the pressure control device changes the height of the cleaning liquid supply device by controlling the elevator device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the liquid ejection head cleaning device further includes a liquid surface height adjustment device which adjusts a height of a surface of the cleaning liquid inside the cleaning liquid supply device; and the pressure control device changes the height of the surface of the cleaning liquid inside the cleaning liquid supply device by controlling the liquid surface height adjustment device in accordance with the ambient temperature measured by the temperature measurement device. 
     Preferably, the liquid ejection head cleaning device further includes: a supply flow channel which connects the cleaning liquid supply device to the cleaning liquid deposition device; and a flow channel resistance adjustment device which adjusts a flow channel resistance of the supply flow channel; and the pressure control device changes the flow channel resistance of the supply flow channel by controlling the flow channel resistance adjustment device in accordance with the ambient temperature measured by the temperature measurement device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The nature of this invention, as well as other objects and advantages thereof, will be explained in the following with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures and wherein: 
         FIG. 1  is a general schematic drawing of an inkjet image recording apparatus according to an embodiment of the present invention; 
         FIGS. 2A to 2C  are plan view perspective diagrams showing embodiments of the inkjet head in  FIG. 1 ; 
         FIG. 3  is a cross-sectional diagram showing the inner composition of an ink chamber unit; 
         FIG. 4  is a principal block diagram showing the system configuration of the inkjet image recording apparatus in  FIG. 1 ; 
         FIG. 5  is a schematic drawing showing a composition of a cleaning processing unit according to a first embodiment; 
         FIG. 6  is a plan diagram showing a composition of a cleaning liquid spouting surface of the cleaning liquid application unit; 
         FIGS. 7A and 7B  are illustrative diagrams showing height variations of cleaning liquid pillars formed on the cleaning liquid spouting surface of the cleaning liquid application unit; 
         FIG. 8  is a cross-sectional perspective diagram showing an enlarged view of the vicinity of the cleaning liquid spouting surface of the cleaning liquid application unit; 
         FIG. 9  is a plan diagram showing another composition of the cleaning liquid spouting surface of the cleaning liquid application unit; 
         FIG. 10  is an illustrative diagram showing an embodiment of control performed by the cleaning process control unit; 
         FIG. 11  is a schematic drawing showing the composition of the cleaning processing unit according to a second embodiment; 
         FIG. 12  is a schematic drawing showing the composition of the cleaning processing unit according to a third embodiment; 
         FIG. 13  is a schematic drawing showing the composition of the cleaning processing unit according to a fourth embodiment; 
         FIG. 14  is a schematic drawing showing the composition of the cleaning processing unit according to a fifth embodiment; 
         FIG. 15  is a schematic drawing showing the composition of the cleaning processing unit according to a sixth embodiment; 
         FIG. 16  is a schematic drawing showing a first embodiment of the composition of the flow channel resistance adjustment unit; 
         FIG. 17  is a schematic drawing showing a second embodiment of the composition of the flow channel resistance adjustment unit; 
         FIG. 18  is a schematic drawing showing a third embodiment of the composition of the flow channel resistance adjustment unit; 
         FIG. 19  is a schematic drawing showing a fourth embodiment of the composition of the flow channel resistance adjustment unit; 
         FIG. 20  is a schematic drawing showing a mode where a cleaning liquid temperature adjustment device is arranged in a cleaning liquid tank; 
         FIG. 21  is a schematic drawing showing an example of the composition of an inkjet head cleaning apparatus in the related art; and 
         FIG. 22  is a table for describing problems of the inkjet head cleaning apparatus in the related art. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Entire Configuration of Inkjet Recording Apparatus 
     First, an inkjet recording apparatus will be described as an embodiment of an image formation apparatus according to the present invention. 
       FIG. 1  is a structural diagram illustrating the entire configuration of an inkjet recording apparatus  10  according to an embodiment of the present invention. The inkjet recording apparatus  10  shown in the drawing is an recording apparatus in a two-liquid aggregating system of forming an image on a recording surface of a recording medium  24  by using ink (an aqueous ink) and a treatment liquid (aggregation treatment liquid). The inkjet recording apparatus  10  includes a paper feed unit  12 , a treatment liquid application unit  14 , an image formation unit  16 , a drying unit  18 , a fixing unit  20 , and a discharge unit  22  as the main components. A recording medium  24  (paper sheets) is stacked in the paper feed unit  12 , and the recording medium  24  is fed from the paper feed unit  12  to the treatment liquid application unit  14 . A treatment liquid is applied to the recording surface in the treatment liquid application unit  14 , and then a color ink is applied to the recording surface in the image formation unit  16 . The image is fixed with the fixing unit  20  on the recording medium  24  onto which the ink has been applied, and then the recording medium is discharged with the discharge unit  22 . 
     In the inkjet recording apparatus  10 , intermediate conveyance units  26 ,  28  and  30  are provided between the units, and the recording medium  24  is transferred by these intermediate conveyance units  26 ,  28  and  30 . Thus, a first intermediate conveyance unit  26  is provided between the treatment liquid application unit  14  and image formation unit  16 , and the recording medium  24  is transferred from the treatment liquid application unit  14  to the image formation unit  16  by the first intermediate conveyance unit  26 . Likewise, the second intermediate conveyance unit  28  is provided between the image formation unit  16  and the drying unit  18 , and the recording medium  24  is transferred from the image formation unit  16  to the drying unit  18  by the second intermediate conveyance unit  28 . Further, a third intermediate conveyance unit  30  is provided between the drying unit  18  and the fixing unit  20 , and the recording medium  24  is transferred from the drying unit  18  to the fixing unit  20  by the third intermediate conveyance unit  30 . 
     Each unit (paper feed unit  12 , treatment liquid application unit  14 , image formation unit  16 , drying unit  18 , fixing unit  20 , and discharge unit  22 ) of the inkjet recording apparatus  10  will be described below in greater details. 
     &lt;Paper Feed Unit&gt; 
     The paper feed unit  12  feeds the recording medium  24  to the image formation unit  16 . A paper feed tray  50  is provided in the paper feed unit  12 , and the recording medium  24  is fed, sheet by sheet, from the paper feed tray  50  to the treatment liquid application unit  14 . 
     &lt;Treatment Liquid Application Unit&gt; 
     The treatment liquid application unit  14  is a mechanism that applies a treatment liquid to the recording surface of the recording medium  24 . The treatment liquid includes a coloring material aggregating agent that causes the aggregation of a coloring material (pigment) included in the ink applied in the image formation unit  16 , and the separation of the coloring material and a solvent in the ink is enhanced when the treatment liquid is brought into contact with the ink. 
     As shown in  FIG. 1 , the treatment liquid application unit  14  includes a paper transfer drum  52 , a treatment liquid drum  54 , and a treatment liquid application device  56 . The paper transfer drum  52  is disposed between the paper feed tray  50  of the paper feed unit  12  and the treatment liquid drum  54 . The rotation of the paper transfer drum  52  is driven and controlled by a below-described motor driver  176  (see  FIG. 4 ). The recording medium  24  fed from the paper feed unit  12  is received by the paper transfer drum  52  and transferred to the treatment liquid drum  54 . The below-described intermediate conveyance unit may be also provided instead of the paper transfer drum  52 . 
     The treatment liquid drum  54  is a drum that holds and rotationally conveys the recording medium  24 . The rotation of the treatment liquid drum  54  is driven and controlled by the below-described motor driver  176  (see  FIG. 4 ). Further, the treatment liquid drum  54  is provided on the outer circumferential surface thereof with a hook-shaped holding device, by which the leading end of the recording medium  24  can be held. In a state in which the leading end of the recording medium  24  is held by the holding device, the treatment liquid drum  54  is rotated to rotationally convey the recording medium  24 . In this case, the recording medium  24  is conveyed in a state where the recording surface thereof faces outward. The treatment liquid drum  54  may be provided with suction apertures on the outer circumferential surface thereof and connected to a suction device that performs suction from the suction apertures. As a result, the recording medium  24  can be held in a state of tight adherence to the outer circumferential surface of the treatment liquid drum  54 . 
     The treatment liquid application device  56  is provided on the outside of the treatment liquid drum  54  opposite the outer circumferential surface thereof. The treatment liquid application device  56  applies the treatment liquid onto the recording surface of the recording medium  24 . The treatment liquid application device  56  includes: a treatment liquid container, in which the treatment liquid to be applied is held; an anilox roller, a part of which is immersed in the treatment liquid held in the treatment liquid container; and a rubber roller, which is pressed against the anilox roller and the recording medium  24  that is held by the treatment liquid drum  54 , so as to transfer the treatment liquid metered by the anilox roller  64  to the recording medium  24 . 
     With the treatment liquid application device  56  of the above-described configuration, the treatment liquid is applied onto the recording medium  24 , while being metered. In this case, it is preferred that the film thickness of the treatment liquid be sufficiently smaller than the diameter of ink droplets that are ejected from heads (inkjet heads)  72 M,  72 K,  72 C and  72 Y of the image formation unit  16 . 
     In the present embodiment, the application system using the roller is used to deposit the treatment liquid onto the recording surface of the recording medium  24 ; however, the present invention is not limited to this, and it is possible to employ a spraying method, an inkjet method, or other methods of various types. 
     &lt;Image Formation Unit&gt; 
     The image formation unit  16  is a mechanism which prints an image corresponding to an input image by ejecting and depositing droplets of ink by an inkjet method, and the image formation unit  16  includes an image formation drum  70 , a paper pressing roller  74  and the heads  72 M,  72 K,  72 C and  72 Y. The heads  72 M,  72 K,  72 C and  72 Y correspond to inks of four colors: magenta (M), black (K), cyan (C) and yellow (Y), and are disposed in the order of description from the upstream side in the rotation direction of the image formation drum  70 . 
     The image formation drum  70  is a drum that holds the recording medium  24  on the outer circumferential surface thereof and rotationally conveys the recording medium  24 . The rotation of the image formation drum  70  is driven and controlled by the below-described motor driver  176  (see  FIG. 4 ). 
     Further, the image formation drum  70  is provided on the outer circumferential surface thereof with a hook-shaped holding device, by which the leading end of the recording medium  24  can be held. In a state in which the leading end of the recording medium  24  is held by the holding device, the image formation drum  70  is rotated to rotationally convey the recording medium  24 . In this case, the recording medium  24  is conveyed in a state where the recording surface thereof faces outward, and inks are deposited on the recording surface by the heads  72 M,  72 K,  72 C and  72 Y. 
     The paper pressing roller  74  is a guide member for causing the recording medium  24  to tightly adhere to the outer circumferential surface of the image formation drum  70 , and is arranged so as to face the outer circumferential surface of the image formation drum  70 . More specifically, the paper pressing roller  74  is disposed to the downstream side of the position where transfer of the recording medium  24  is received, and to the upstream side from the heads  72 M,  72 K,  72 C and  72 Y, in terms of the direction of conveyance of the recording medium  24  (the direction of rotation of the image formation drum  70 ). 
     When the recording medium  24  that has been transferred onto the image formation drum  70  from the intermediate conveyance unit  26  is rotationally conveyed in a state where the leading end portion of the recording medium  24  is held by the holding device, the recording medium  24  is pressed by the paper pressing roller  74  to tightly adhere to the outer circumferential surface of the image formation drum  70 . When the recording medium  24  has been made to tightly adhere to the outer circumferential surface of the image formation drum  70  in this way, the recording medium  24  is conveyed to a print region directly below the heads  72 M,  72 K,  72 C and  72 Y in a state where the recording medium  24  does not float up at all from the outer circumferential surface of the image formation drum  70 . 
     The heads  72 M,  72 K,  72 C and  72 Y are inkjet heads (inkjet heads) of the inkjet system of the full line type that have a length corresponding to the maximum width of the image formation region in the recording medium  24 . A nozzle row is formed on the ink ejection surface of the inkjet head. The nozzle row has a plurality of nozzles arranged therein for discharging ink over the entire width of the image recording region. Each of the heads  72 M,  72 K,  72 C and  72 Y is fixedly disposed so as to extend in the direction perpendicular to the conveyance direction (rotation direction of the image formation drum  70 ) of the recording medium  24 . 
     Furthermore, each of the heads  72 M,  72 K,  72 C and  72 Y is disposed at an inclination with respect to the horizontal, in such a manner that each of the nozzle surfaces of the heads  72 M,  72 K,  72 C and  72 Y is substantially parallel to the recording surface of the recording medium  24  held on the outer circumferential surface of the image formation drum  70 . 
     Droplets of corresponding colored inks are ejected from the inkjet heads  72 M,  72 K,  72 C and  72 Y having the above-described configuration toward the recording surface of the recording medium  24  held on the outer circumferential surface of the image formation drum  70 . As a result, the ink comes into contact with the treatment liquid that has been heretofore applied on the recording surface by the treatment liquid application unit  14 , the coloring material (pigment) dispersed in the ink is aggregated, and a coloring material aggregate is formed. Therefore, the coloring material flow on the recording medium  24  is prevented and an image is formed on the recording surface of the recording medium  24 . In this case, because the image formation drum  70  of the image formation unit  16  is structurally separated from the treatment liquid drum  54  of the treatment liquid application unit  14 , the treatment liquid does not adhere to the heads  72 M,  72 K,  72 C and  72 Y, and the number of factors preventing the ejection of ink can be reduced. 
     In the present embodiment, the CMYK standard color (four colors) configuration is described, but combinations of ink colors and numbers of colors are not limited to that of the present embodiment, and if necessary, light inks, dark inks, and special color inks may be added. For example, a configuration is possible in which inkjet heads are added that eject light inks such as light cyan and light magenta. The arrangement order of color heads is also not limited. 
     Furthermore, although not shown in  FIG. 1 , a cleaning processing unit  200  (see  FIG. 5 ) is arranged at a position adjacent to the image formation drum  70  of the image formation unit  16  along the axial direction thereof, and the heads  72 M,  72 K,  72 C and  72 Y are composed so as to be movable between an image formation position opposing the image formation drum  70  and a maintenance position where the cleaning processing unit  200 , and the like, are disposed, by means of a head movement mechanism (not shown). 
     &lt;Drying Unit&gt; 
     The drying unit  18  dries water included in the solvent separated by the coloring material aggregation action. As shown in  FIG. 1 , the drying unit includes a drying drum  76  and a solvent dryer  78 . 
     The drying drum  76  is a drum that holds the recording medium  24  on the outer circumferential surface thereof and rotationally conveys the recording medium  24 . The rotation of the drying drum  76  is driven and controlled by the below-described motor driver  176  (see  FIG. 4 ). Further, the drying drum  76  is provided on the outer circumferential surface thereof with a hook-shaped holding device, by which the leading end of the recording medium  24  can be held. In a state in which the leading end of the recording medium  24  is held by the holding device, the drying drum  76  is rotated to rotationally convey the recording medium. In this case, the recording medium  24  is conveyed in a state where the recording surface thereof faces outward. The drying treatment is carried out by the solvent dryer  78  with respect to the recording surface of the recording medium  24 . The drying drum  76  may be provided with suction apertures on the outer circumferential surface thereof and connected to a suction device that performs suction from the suction apertures. As a result, the recording medium  24  can be held in a state of tight adherence to the outer circumferential surface of the drying drum  76 . 
     The solvent dryer  78  is disposed in a position facing the outer circumferential surface of the drying drum  76 , and includes a halogen heater  80 . The halogen heater  80  is controlled to blow warm air at a prescribed temperature at a constant blowing rate toward the recording medium  24 . 
     With the solvent dryer  78  of the above-described configuration, water included in the ink solvent on the recording surface of the recording medium  24  held by the drying drum  76  is evaporated, and drying treatment is performed. In this case, because the drying drum  76  of the drying unit  18  is structurally separated from the image formation drum  70  of the image formation unit  16 , the number of ink non-ejection events caused by drying of the head meniscus portion by thermal drying can be reduced in the heads  72 M,  72 K,  72 C and  72 Y. Further, there is a degree of freedom in setting the temperature of the drying unit  18 , and the optimum drying temperature can be set. 
     By holding the recording medium  24  in such a manner that the recording surface thereof is facing outward on the outer circumferential surface of the drying drum  76  having this composition (in other words, in a state where the recording surface of the recording medium  24  is curved in a convex shape), and drying while conveying the recording medium in rotation, it is possible to prevent the occurrence of wrinkles or floating up of the recording medium  24 , and therefore drying non-uniformities caused by these phenomena can be prevented reliably. 
     &lt;Fixing Unit&gt; 
     The fixing unit  20  includes a fixing drum  84 , a halogen heater  86 , a fixing roller  88 , and an inline sensor  90 . The halogen heater  86 , the fixing roller  88 , and the inline sensor  90  are arranged in positions opposite the outer circumferential surface of the fixing drum  84  in this order from the upstream side in the rotation direction (counterclockwise direction in  FIG. 1 ) of the fixing drum  84 . 
     The fixing drum  84  a drum that holds the recording medium  24  on the outer circumferential surface thereof and rotationally conveys the recording medium  24 . The rotation of the fixing drum  84  is driven and controlled by the below-described motor driver  176  (see  FIG. 4 ). The fixing drum  84  has a hook-shaped holding device, and the leading end of the recording medium  24  can be held by this holding device. The recording medium  24  is rotationally conveyed by rotating the fixing drum  84  in a state in which the leading end of the recording medium  24  is held by the holding device. In this case, the recording medium  24  is conveyed in a state where the recording surface thereof faces outward, and the preheating by the halogen heater  86 , the fixing treatment by the fixing roller  88  and the inspection by the inline sensor  90  are performed with respect to the recording surface. The fixing drum  84  may be provided with suction apertures on the outer circumferential surface thereof and connected to a suction device that performs suction from the suction apertures. As a result, the recording medium  24  can be held in a state of tight adherence to the outer circumferential surface of the fixing drum  84 . 
     The halogen heater  86  is controlled to a prescribed temperature, by which the preheating is performed with respect to the recording medium  24 . 
     The fixing roller  88  is a roller member which applies heat and pressure to the dried ink to melt and fix the self-dispersible polymer particles in the ink so as to transform the ink into the film. More specifically, the fixing roller  88  is arranged so as to be pressed against the fixing drum  84 , and a nip roller is configured between the fixing roller  88  and the fixing drum  84 . As a result, the recording medium  24  is squeezed between the fixing roller  88  and the fixing drum  84 , nipped under a prescribed nip pressure, and subjected to fixing treatment. 
     Further, the fixing roller  88  is configured by a heating roller in which a halogen lamp is incorporated in a metal pipe, for example made from aluminum, having good thermal conductivity and the rollers are controlled to a prescribed temperature. Where the recording medium  24  is heated with the heating roller, thermal energy not lower than a Tg temperature (glass transition temperature) of a latex included in the ink is applied and latex particles are melted. As a result, fixing is performed by penetration into the projections-recessions of the recording medium  24 , the projections-recessions of the image surface are leveled out, and gloss is obtained. 
     The fixing unit  20  is provided with the single fixing roller  88  in the above-described embodiment; however, it is possible that a plurality of fixing rollers  88  depending on the thickness of image layer and Tg characteristic of latex particles. Furthermore, the surface of the fixing drum  84  may be controlled to a prescribed temperature. 
     On the other hand, the inline sensor  90  is a measuring device which measures the check pattern, moisture amount, surface temperature, gloss, and the like of the image fixed to the recording medium  24 . A CCD sensor or the like can be used for the inline sensor  90 . 
     With the fixing unit  20  of the above-described configuration, the latex particles located within a thin image layer formed in the drying unit  18  are melted by application of heat and pressure by the fixing roller  88 . Thus, the latex particles can be reliably fixed to the recording medium  24 . In addition, with the fixing unit  20 , the fixing drum  84  is structurally separated from other drums. Therefore, the temperature of the fixing unit  20  can be freely set separately from the image formation unit  16  and the drying unit  18 . 
     &lt;Discharge Unit&gt; 
     As shown in  FIG. 1 , the discharge unit  22  is provided after the fixing unit  20 . The discharge unit  22  includes a discharge tray  92 , and a transfer body  94 , a conveying belt  96 , and a tension roller  98  are provided between the discharge tray  92  and the fixing drum  84  of the fixing unit  20  so as to face the discharge tray  92  and the fixing drum  84 . The recording medium  24  is fed by the transfer body  94  onto the conveying belt  96  and discharged onto the discharge tray  92 . 
     &lt;Intermediate Conveyance Unit&gt; 
     The structure of the first intermediate conveyance unit  26  will be described below. The second intermediate conveyance unit  28  and the third intermediate conveyance unit  30  are configured identically to the first intermediate conveyance unit  26  and the explanation thereof will be omitted. 
     The first intermediate conveyance unit  26  is provided with an intermediate conveyance body  32 , which is a drum for receiving the recording medium  24  from a drum of a previous stage, rotationally conveying the recording medium  24 , and transferring it to a drum of the subsequent stage, and is mounted to be capable of rotating freely. The intermediate conveyance body  32  is rotated by a motor  188  (not shown in  FIG. 1  and shown in  FIG. 4 ), and the rotation thereof is driven and controlled by the below-described motor driver  176  (see  FIG. 4 ). Further, the intermediate conveyance body  32  is provided on the outer circumferential surface thereof with a hook-shaped holding device, by which the leading end of the recording medium  24  can be held. In a state in which the leading end of the recording medium  24  is held by the holding device, the intermediate conveyance body  32  is rotated to rotationally convey the recording medium  24 . In this case, the recording medium  24  is conveyed in a state where the recording surface thereof faces inward, whereas the non-recording surface thereof faces outward. 
     The recording medium  24  conveyed by the first intermediate conveyance unit  26  is transferred to a drum of the subsequent stage (that is, the image formation drum  70 ). In this case, the transfer of the recording medium  24  is performed by synchronizing the holding device of the intermediate conveyance unit  26  and the holding device (the gripper  102 ) of the image formation unit  16 . The transferred recording medium  24  is held by the image formation drum  70  and rotationally conveyed. 
     &lt;Structure of Inkjet Heads&gt; 
     Next, the structure of the heads (inkjet heads) is described. The heads  72 M,  72 K,  72 C and  72 Y for the respective colored inks have the same structure, and each of the heads is hereinafter denoted with a reference numeral  150 . 
       FIG. 2A  is a perspective plan view showing an embodiment of the configuration of the head  150 ,  FIG. 2B  is an enlarged view of a portion thereof, and  FIG. 2C  is a perspective plan view showing another embodiment of the configuration of the head  150 .  FIG. 3  is a cross-sectional view taken along the line  3 - 3  in  FIGS. 2A and 2B , showing the inner structure of an ink chamber unit in the head  150 . 
     The nozzle pitch in the head  150  should be minimized in order to maximize the density of the dots printed on the surface of the recording medium  24 . As shown in  FIGS. 2A and 2B , the head  150  according to the present embodiment has a structure in which a plurality of ink chamber units (i.e., droplet ejection units serving as recording units)  153 , each having a nozzle  151  forming an ink ejection aperture, a pressure chamber  152  corresponding to the nozzle  151 , and the like, are disposed two-dimensionally in the form of a staggered matrix, and hence the effective nozzle interval (the projected nozzle pitch) as projected in the lengthwise direction of the head  150  (the main scanning direction: the direction perpendicular to the conveyance direction of the recording medium  24 ) is reduced and high nozzle density is achieved. 
     The mode of forming one or more nozzle rows through a length corresponding to the entire width of the recording medium  24  in the main scanning direction substantially perpendicular to the conveyance direction of the recording medium  24  (the sub-scanning direction) is not limited to the embodiment described above. For example, instead of the configuration in  FIG. 2A , as shown in  FIG. 2C , a line head having nozzle rows of a length corresponding to the entire width of the recording medium  24  can be formed by arranging and combining, in a staggered matrix, short head blocks  150 ′ having a plurality of nozzles  151  arrayed in a two-dimensional fashion. Furthermore, although not shown in the drawings, it is also possible to compose a line head by arranging short heads in one row. 
     The planar shape of the pressure chamber  152  provided for each nozzle  151  is substantially a square, and the nozzle  151  and an ink supply port  154  are disposed in both corners on a diagonal line of the square. The shape of the pressure chamber  152  is not limited to that of the present embodiment, and a variety of planar shapes, for example, a polygon such as a rectangle (rhomb, rectangle, etc.), a pentagon and a heptagon, a circle, and an ellipse can be employed. 
     Each pressure chamber  152  is connected to a common channel  155  through the supply port  154 . The common channel  155  is connected to an ink tank (not shown), which is a base tank for supplying ink, and the ink supplied from the ink tank is delivered through the common flow channel  155  to the pressure chambers  152 . 
     A piezoelectric element  158  provided with an individual electrode  157  is bonded to a diaphragm  156 , which forms a face (the upper face in  FIG. 3 ) of the pressure chamber  152  and also serves as a common electrode. When a drive voltage is applied to the individual electrode  157 , the piezoelectric element  158  is deformed, the volume of the pressure chamber  152  is thereby changed, and the ink is ejected from the nozzle  151  by the variation in pressure that follows the variation in volume. When the piezoelectric element  158  returns to the original state after the ink has been ejected, the pressure chamber  152  is refilled with new ink from the common channel  155  through the supply port  154 . 
     The present embodiment applies the piezoelectric elements  158  as ejection power generation devices to eject the ink from the nozzles  151  arranged in the head  150 ; however, instead, a thermal system that has heaters within the pressure chambers  152  to eject the ink using the pressure resulting from film boiling by the heat of the heaters can be applied. 
     As shown in  FIG. 2B , the high-density nozzle head according to the present embodiment is achieved by arranging the plurality of ink chamber units  153  having the above-described structure in a lattice fashion based on a fixed arrangement pattern, in a row direction which coincides with the main scanning direction, and a column direction which is inclined at a fixed angle of θ with respect to the main scanning direction, rather than being perpendicular to the main scanning direction. 
     More specifically, by adopting a structure in which the ink chamber units  153  are arranged at a uniform pitch d in line with a direction forming the angle of θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to align in the main scanning direction is d×cos θ, and hence the nozzles  151  can be regarded to be equivalent to those arranged linearly at a fixed pitch P along the main scanning direction. Such configuration results in a nozzle structure in which the nozzle row projected in the main scanning direction has a high nozzle density of up to 2,400 nozzles per inch. 
     When implementing the present invention, the arrangement structure of the nozzles is not limited to the embodiments shown in the drawings, and it is also possible to apply various other types of nozzle arrangements, such as an arrangement structure having one nozzle row in the sub-scanning direction. 
     Furthermore, the scope of application of the present invention is not limited to a printing system based on the line type of head, and it is also possible to adopt a serial system where a short head that is shorter than the breadthways dimension of the recording medium  24  is moved in the breadthways direction (main scanning direction) of the recording medium  24 , thereby performing printing in the breadthways direction, and when one printing action in the breadthways direction has been completed, the recording medium  24  is moved through a prescribed amount in the sub-scanning direction perpendicular to the breadthways direction, printing in the breadthways direction of the recording medium  24  is carried out in the next printing region, and by repeating this sequence, printing is performed over the whole surface of the printing region of the recording medium  24 . 
     Description of Control System 
       FIG. 4  is a block diagram of the main portion of a system configuration of the inkjet recording apparatus  10 . The inkjet recording apparatus  10  includes a communication interface  170 , a system controller  172 , a memory  174 , the motor driver  176 , a heater driver  178 , a maintenance control unit  179 , a printing control unit  180 , an image buffer memory  182 , a head driver  184 , a sensor  185 , a program storage unit  190 , a treatment liquid application control unit  196 , a drying control unit  197 , and a fixing control unit  198 . 
     The communication interface  170  is an interface unit that receives image data sent from a host computer  186 . A serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet, and a wireless network, or a parallel interface such as Centronix can be applied as the communication interface  170 . A buffer memory (not shown) may be installed in the part of the interface to increase the communication speed. The image data sent from the host computer  186  are introduced into the inkjet recording apparatus  10  through the communication interface  170  and temporarily stored in the memory  174 . 
     The memory  174  is a storage device that temporarily stores the images inputted through the communication interface  170  and reads/writes the data via the system controller  172 . The memory  174  is not limited to a memory composed of semiconductor elements and may use a magnetic medium such as a hard disk. 
     The system controller  172  includes a central processing unit (CPU) and a peripheral circuitry thereof, functions as a control device that controls the entire inkjet recording apparatus  10  according to a predetermined program, and also functions as an operational unit that performs various computations. Thus, the system controller  172  controls various units such as the communication interface  170 , the memory  174 , the motor driver  176 , the heater driver  178 , the maintenance control unit  179 , the treatment liquid application control unit  196 , the drying control unit  197  and the fixing control unit  198 , performs communication control with the host computer  180 , performs read/write control of the memory  174 , and also generates control signals for controlling the various units. 
     Programs that are executed by the CPU of the system controller  172  and various data necessary for performing the control are stored in the memory  174 . The memory  174  may be a read-only storage device or may be a writable storage device such as EEPROM. The memory  174  can be also used as a region for temporary storing image data, a program expansion region, and a computational operation region of the CPU. 
     Various control programs are stored in the program storage unit  190 , and a control program is read out and executed in accordance with commands from the system controller  172 . The program storage unit  190  may use a semiconductor memory, such as a ROM, EEPROM, or a magnetic disk, or the like. The program storage unit  190  may be provided with an external interface, and a memory card or PC card may also be used. Naturally, a plurality of these storage media may also be provided. The program storage unit  190  may also be combined with a storage device for storing operational parameters, and the like (not shown). 
     The sensor  185  represents the sensors disposed in the respective sections of the inkjet recording apparatus  10 . For example, the sensor  185  includes the inline sensor  90  shown in  FIG. 1 , temperature sensors, position determination sensors, and pressure sensors. The output signals of the sensor  185  are sent to the system controller  172 , and the system controller  172  controls the respective sections of the inkjet recording apparatus  10  by sending the command signals to the respective sections in accordance with the output signals of the sensor  185 . 
     The motor driver  176  drives a motor  188  in accordance with commands from the system controller  172 . In  FIG. 4 , the plurality of motors disposed in the respective sections of the inkjet recording apparatus  10  are represented by the reference numeral  188 . For example, the motor  188  shown in  FIG. 4  includes the motors that drive the paper transfer drum  52 , the treatment liquid drum  54 , the image formation drum  70 , the drying drum  76 , the fixing drum  84  and the transfer body  94  shown in  FIG. 1 , and the motors that drive the intermediate conveyance bodies  32  in the first, second and third intermediate conveyance units  26 ,  28  and  30 . 
     The heater driver  178  is a driver that drives the heater  189  in accordance with commands from the system controller  172 . In  FIG. 4 , the plurality of heaters disposed in the inkjet recording apparatus  10  are represented by the reference numeral  189 . For example, the heater  189  shown in  FIG. 4  includes the halogen heaters  80  in the solvent dryer  78  arranged in the drying unit  18  shown in  FIG. 1 , and the heaters that heat the surfaces of the drying drum  76  and the fixing drum  84  shown in  FIG. 1 . 
     The maintenance control unit  179  controls the operations of the respective sections of a maintenance unit  199 , in accordance with commands from the system controller  172 . The cleaning processing unit  200  (see  FIG. 5 ) described below is included in the maintenance unit  199  shown in  FIG. 4 . Furthermore, a cleaning processing control unit  226  (see  FIG. 5 ), which controls the operations of the respective sections of the cleaning process unit  200 , is a control block corresponding to the system controller  172  and the maintenance control unit  179 . 
     The treatment liquid application control unit  196 , the drying control unit  197  and the fixing control unit  198  control the operations of the treatment liquid application device  56 , the solvent dryer  78  and the fixing roller  88 , respectively, in accordance with commands from the system controller  172 . 
     The printing control unit  180  has a signal processing function for performing a variety of processing and correction operations for generating signals for print control from the image data within the memory  174  according to control of the system controller  172 , and supplies the generated printing data (dot data) to the head driver  184 . The required signal processing is implemented in the printing control unit  180 , and the ejection amount and ejection timing of droplets in the heads  150  are controlled through the head driver  184  based on the image data. As a result, the desired dot size and dot arrangement are realized. 
     The printing control unit  180  is provided with the image buffer memory  182 , and data such as image data or parameters are temporarily stored in the image buffer memory  182  during image data processing in the printing control unit  180 . A mode is also possible in which the printing control unit  180  and the system controller  172  are integrated and configured by one processor. 
     The head driver  184  generates drive signals for driving the piezoelectric elements  158  of the heads  150 , on the basis of the dot data supplied from the print controller  180 , and drives the piezoelectric elements  158  by applying the generated drive signals to the piezoelectric elements  158 . A feedback control system for maintaining constant drive conditions in the inkjet heads  150  may be included in the head driver  184  shown in  FIG. 4 . 
     Description of Cleaning Processing Unit 
     The composition of the cleaning processing unit  200  according to embodiments of the present invention is described below. 
     First Embodiment 
       FIG. 5  is a schematic drawing showing the composition of the cleaning processing unit  200  according to the first embodiment of the present invention. In  FIG. 5 , the lateral direction in the drawing corresponds to the lengthwise direction of the head  150  (the main scanning direction), and the direction perpendicular to the sheet of the drawing corresponds to the breadthways direction of the head  150  (the width direction, the sub-scanning direction, the paper conveyance direction). 
     The cleaning processing unit  200  shown in  FIG. 5  includes: a cleaning liquid application unit  204 , which forms a pillar of the cleaning liquid (a cleaning liquid coating layer)  202 ; and a cleaning liquid tank  206 , which contains the cleaning liquid to be supplied to the cleaning liquid application unit  204 . 
     The cleaning liquid tank  206  is disposed at a position higher than the cleaning liquid application unit  204  so that the cleaning liquid is supplied from the cleaning liquid tank  206  to the cleaning liquid application unit  204  by the liquid head differential H between the liquid surface in the cleaning liquid tank  206  and a cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204 . 
     The cleaning liquid application unit  204  has the cleaning liquid spouting surface  204 A, which is disposed separately and opposingly to the nozzle surface  150 A of the head  150 . The cleaning liquid application unit  204  forms the cleaning liquid pillar  202  from the cleaning liquid spouting surface  204 A, brings the top of the cleaning liquid pillar  202  into contact with the nozzle surface  150 A, and thereby applies the cleaning liquid to the nozzle surface  150 A. 
     The liquid employed as the cleaning liquid has properties capable of dissolving solidified ink adhering to the nozzle surface  150 A, and is a special liquid having enhanced cleaning effects. For example, it is desirable to employ a cleaning liquid containing a solvent, such as DEGmBE (diethylene glycol monobutyl ether). 
     In the case of the inkjet recording apparatus having the plurality of heads  72 M,  72 K,  72 C and  72 Y as shown in  FIG. 1 , it is possible to adopt a composition in which the cleaning processing unit  200  is provided with a plurality of cleaning liquid application units  204  in equal number to the heads  72 M,  72 K,  72 C and  72 Y (namely, respectively for the heads  72 M,  72 K,  72 C and  72 Y), or a composition in which the number of the cleaning liquid application units  204  is fewer than the heads  72 M,  72 K,  72 C and  72 Y. In the former case, it is possible to apply the cleaning liquid to the heads  72 M,  72 K,  72 C and  72 Y by the corresponding cleaning liquid application units  204  in parallel, and hence the cleaning liquid application time can be shortened. On the other hand, in the latter case, the application of the cleaning liquid to the heads  72 M,  72 K,  72 C and  72 Y is progressively carried out while successively moving one or the plurality of cleaning liquid application units  204  fewer than the heads, then in comparison with the former case, although the cleaning liquid application time should be longer, it is possible to arrange the cleaning liquid application unit or units  204  in a smaller space, to miniaturize the cleaning processing unit  200 , and to reduce costs of the cleaning processing unit  200 . 
     Furthermore, although not shown in the drawings, the cleaning processing unit  200  is provided with a recovery tray arranged vertically below the cleaning liquid application unit  204 . The recovery tray receives the cleaning liquid that has dropped down from the head  150  and the cleaning liquid application unit  204 . 
       FIG. 6  is a plan diagram showing the composition of the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204  in an embodiment of the present invention. As shown in  FIG. 6 , a plurality of cleaning liquid nozzles  208  are disposed at a uniform arrangement pitch of Pn through a length corresponding to the breadth of the head  150  (the dimension of the head  150  in the sub-scanning direction), on the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204 . The cleaning liquid nozzles  208  have cleaning liquid spouting ports (opening sections) through which the cleaning liquid supplied from the cleaning liquid tank  206  is spouted. 
     The dimension D of the cleaning liquid application unit  204  in the lengthwise direction thereof corresponds to the dimension of the head  150  in the breadthways direction thereof (see  FIG. 5 ), and the length through which the cleaning liquid nozzles  208  are arranged is equal to or greater than the dimension of the head  150  in the breadthways direction thereof. 
     The dimension W of the cleaning liquid application unit  204  in the breadthways direction thereof is specified in accordance with the arrangement pattern of the cleaning liquid nozzles  208 .  FIG. 6  shows a mode where the cleaning liquid nozzles  208  are arranged in a direction substantially parallel to the lengthwise direction of the cleaning liquid application unit  204  (the breadthways direction of the head  150 ); however, the direction of arrangement of the cleaning liquid nozzles  208  can be an oblique direction which forms a prescribed angle with respect to the lengthwise direction of the cleaning liquid application unit  204 . Furthermore, the cleaning liquid nozzles  208  can be arranged over two or more columns. 
     The arrangement pitch Pn of the cleaning liquid nozzles  208  is specified in such a manner that the cleaning liquid spouted from adjacent cleaning liquid nozzles  208  makes contact and combines together. In other words, the cleaning liquid spouted and caused to spread out from each of the cleaning liquid nozzles  208  joins together with the cleaning liquid spouted from the adjacent cleaning liquid nozzle  208 , and the cleaning liquid pillar  202  which is connected to the cleaning liquid inside the cleaning liquid nozzles  208  and which has the dimension corresponding to the breadthways-direction dimension of the head  150  is formed. When the top of the cleaning liquid pillar  202  makes contact with the nozzle surface  150 A, the surface free energy of the nozzle surface  150 A acts in such a manner that a part of the top portion of the cleaning liquid pillar  202  separates off and adheres to the nozzle surface  150 A. 
     Examples of the dimensions of the respective sections of the cleaning liquid application unit  204  are as follows: the diameter of the cleaning liquid nozzles  208  is 1 mm; the arrangement pitch Pn of the cleaning liquid nozzles  208  is 2 mm; and the width W of the cleaning liquid application unit  204  is 4 mm For example, if sixteen (16) cleaning liquid nozzles of the 1 mm diameter are arranged at the uniform pitch of 2 mm, then the dimension D of the cleaning liquid application unit  204  in the lengthwise direction thereof is approximately 50 mm. 
     The interval between the nozzle surface  150 A of the head  150  and the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204  is specified in such a manner that at least the top of the cleaning liquid pillar  202  formed on the cleaning liquid spouting surface  204 A makes contact with the nozzle surface  150 A (in other words, the interval is set to be less than the maximum height of the cleaning liquid pillar  202 ), and the amount (height) of contact made by the top portion of the cleaning liquid pillar  202  is determined in accordance with the amount of the cleaning liquid to be applied to the nozzle surface  150 A. For example, the interval is set to approximately 1 mm to 2 mm. 
       FIG. 7A  is an illustrative diagram showing the height variations of cleaning liquid pillars  202 A and  202 B formed on the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204 . In  FIG. 7A , the lateral direction in the drawing corresponds to the lengthwise direction of the cleaning liquid application unit  204  (the breadthways direction of the head  150 , the sub-scanning direction), and the direction perpendicular to the sheet of the drawing corresponds to the breadthways direction of the cleaning liquid application unit  204  (the lengthwise direction of the head  150 , the main scanning direction). 
     In the case of the nozzle arrangement structure in which the cleaning liquid nozzles  208  are arranged at uniform pitch as shown in  FIG. 6 , there are induced variations in the shapes of the cleaning liquid pillars  202 A and  202 B as shown in  FIG. 7A  due to the pressure differential caused by the differences in the flow channel lengths (i.e., the flow channel resistances) from a cleaning liquid inlet port  210  to the respective cleaning liquid nozzles  208  (see  FIG. 6 ). 
       FIG. 7A  shows the composition in which the inlet port  210  is arranged in substantially the central portion of the cleaning liquid application unit  204  in the lengthwise direction thereof. In this case, the cleaning liquid nozzles  208 B in the end portions in terms of the lengthwise direction of the cleaning liquid application unit  204  (the direction of arrangement of the cleaning liquid nozzles  208 ) have a greater flow channel length from the inlet port  210  (i.e., a greater flow channel resistance) than the cleaning liquid nozzles  208 A in the central portion, and the height h 2  of the cleaning liquid pillars  202 B in the end portions is thereby made smaller than the height h 1  of the cleaning liquid pillar  202 A in the central portion (h 1 &gt;h 2 ). 
     Hence, the cleaning liquid application unit  204  in the present embodiment is provided with restrictors arranged in the flow channels in connection with the cleaning liquid nozzles  208 , so as to avoid the height variations of the cleaning liquid pillars  202 A and  202 B as shown in  FIG. 7A  due to the variations in the flow channel resistance. Thereby, as shown in  FIG. 7B , the cleaning liquid pillars  202 A and  202 B having a uniform height h are formed throughout the lengthwise direction of the cleaning liquid application unit  204  (the direction of arrangement of the cleaning liquid nozzles  208 ). 
       FIG. 8  is a cross-sectional perspective diagram showing an enlarged view of the vicinity of the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204 . As shown in  FIG. 8 , an aperture  208 C of each cleaning liquid nozzle  208  having a substantially conical shape is formed in a recess section of the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204 , and the cleaning liquid nozzles  208  are provided with a common restrictor  212 , which has a slit shape, directly below the cleaning liquid nozzles  208 . 
     The restrictor  212  is constituted of as a long thin slit formed following the direction of arrangement of the cleaning liquid nozzles  208  in a position opposing the apertures  208 C of the cleaning liquid nozzles  208 , and having a width less than the diameter of the cleaning liquid nozzles  208 . The cleaning liquid nozzles  208  and the flow channel  214  are connected through the restrictor  212 . 
     By arranging the restrictor  212  between the cleaning liquid nozzles  208  and the flow channel  214  in this way, the pressure differential between the respective cleaning liquid nozzles  208  is cancelled out due to the pressure loss induced by the restrictor  212 , whereby a uniform pressure is applied to the respective cleaning liquid nozzles  208 . Thus, the height variations of the cleaning liquid pillars are suppressed, and it is possible to apply the cleaning liquid stably to the nozzle surface  150 A of the head  150 . 
     As a further method of suppressing the height variations of the cleaning liquid pillars, it is possible to adjust the arrangement pitches of the cleaning liquid nozzles  208  in such a manner that the arrangement pitch in the respective end portions in the arrangement of the cleaning liquid nozzles  208  is smaller than the arrangement pitch in the central portion in the arrangement of the cleaning liquid nozzles  208 . 
       FIG. 9  is a plan diagram showing the composition of the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204  in another embodiment, in which the arrangement pitches of the cleaning liquid nozzles  208  are differentiated as described above. 
     In the cleaning liquid application unit  204  shown in  FIG. 9 , the arrangement pitch of the cleaning liquid nozzles  208  in the respective end portions in the lengthwise direction of the cleaning liquid application unit  204  is Pn 1 , and the arrangement pitch of the cleaning liquid nozzles  208  in the central portion is Pn 2 , where Pn 1 &lt;Pn 2 . 
     The ratio between the arrangement pitch Pn 2  of the cleaning liquid nozzles  208  in the central portion and the arrangement pitch Pn 1  of the cleaning liquid nozzles  208  in the end portions (Pn 2 /Pn 1 ) is determined in such a manner that the flow channel resistance is uniform with respect to the cleaning liquid nozzles  208 . 
     According to the mode shown in  FIG. 9 , it is possible to suppress the height variations of the cleaning liquid pillars throughout the lengthwise direction of the cleaning liquid application unit  204  (the direction of arrangement of the cleaning liquid nozzles  208 ). Thus, the amount (size) of the top portion of the cleaning liquid pillar that makes contact with the nozzle surface  150 A of the head  150  is made uniform, and the cleaning liquid can be stably applied to the nozzle surface  150 A. 
       FIG. 9  shows the mode where the arrangement pitches of the cleaning liquid nozzles  208  are differentiated in two levels for example, and the arrangement pitches of the cleaning liquid nozzles  208  can be differentiated in a greater number of levels. According to a mode in which the arrangement pitches of the cleaning liquid nozzles  208  are differentiated in a greater number of levels, it is possible to make the heights of the cleaning liquid pillars even more uniform, and further stabilization of the application of cleaning liquid to the nozzle surface  150 A of the head  150  can be achieved. 
     Referring back to  FIG. 5 , the surface of the cleaning liquid in the cleaning liquid tank  206  is positioned higher than the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204 , and the cleaning liquid is supplied to the cleaning liquid nozzles  208  of the cleaning liquid application unit  204  from the cleaning liquid tank  206  through the supply flow channel  216  by the liquid head differential H produced between the liquid surface in the cleaning liquid tank  206  and the cleaning liquid spouting surface  204 A. 
     The supply flow channel  216  is provided with an electromagnetic valve  218  capable of opening and closing the supply flow channel  216 , and the cleaning liquid flows to the cleaning liquid application unit  204  from the cleaning liquid tank  206  when the electromagnetic valve  218  is open, and the flow of the cleaning liquid is shut off when the electromagnetic valve  218  is closed. The opening and closing of the electromagnetic valve  218  is controlled by the cleaning process control unit  226 . 
     When applying the cleaning liquid to the nozzle surface  150 A of the head  150 , the electromagnetic valve  218  is opened, the cleaning liquid is supplied to the cleaning liquid application unit  204  from the cleaning liquid tank  206  through the supply flow channel  216  by the liquid head differential H, the cleaning liquid is spouted from the cleaning liquid nozzles  208  of the cleaning liquid application unit  204 , and the cleaning liquid pillar  202  is produced on the cleaning liquid spouting surface  204 A. The cleaning liquid can be applied to the whole of the nozzle surface  150 A of the head  150  by moving the head  150  and the cleaning liquid application unit  204  relatively to each other just once in the lengthwise direction of the head  150  (the main scanning direction), while bringing the top of the cleaning liquid pillar  202  produced on the cleaning liquid spouting surface  204 A in contact with the nozzle surface  150 A of the head  150 . 
     On the other hand, when the application of the cleaning liquid to the nozzle surface  150 A of the head  150  is halted, then the electromagnetic valve  218  is closed, and the supply of the cleaning liquid from the cleaning liquid tank  206  to the cleaning liquid application unit  204  is halted. 
     In the supply method for the cleaning liquid by the liquid head differential H as in the present embodiment, if the temperature of the cleaning liquid changes due to change in the ambient temperature around the cleaning processing unit  200  (and in particular, change in the ambient temperature around the cleaning liquid tank  206 ), then change also occurs in the viscosity of the cleaning liquid. This would induce problems such as: change in the flow rate of the cleaning liquid supplied from the cleaning liquid tank  206  to the cleaning liquid nozzles  208  of the cleaning liquid application unit  204 ; change in the height of the cleaning liquid spouted from the cleaning liquid nozzles  208  (i.e., the height of the cleaning liquid pillar  202 ); instability of the application of the cleaning liquid; and increase in the consumption of the cleaning liquid. 
     In order to suppress these problems, the pressure inside the cleaning liquid tank  206  is adjusted in accordance with the ambient temperature around the cleaning processing unit  200  (and desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ) in the present embodiment so that the variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  caused by the variation in the ambient temperature is suppressed, and the height of the cleaning liquid pillar  202  produced on the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204  can be kept stable. A specific composition for achieving this is described below. 
     The cleaning processing unit  200  shown in  FIG. 5  is provided with a pressure adjustment unit  220 , a pressure sensor  222  and a temperature sensor  224 , in addition to the constituents described above. The cleaning process control unit  226  also controls the respective sections of the cleaning processing unit  200 . 
     The pressure adjustment unit  220  adjusts the pressure inside the cleaning liquid tank  206 , and includes a pressurization pump and a depressurization valve, which are connected to the cleaning liquid tank  206 . If pressurization inside the cleaning liquid tank  206  is necessary, then the pressurization pump is driven, and if depressurization is necessary, then the depressurization value is opened. The pressure adjustment unit  220  including the pressurization pump and the depressurization valve is controlled by the cleaning process control unit  226 . 
     The pressure sensor  222  is a pressure measurement device which measures the pressure inside the cleaning liquid tank  206 . The pressure measured by the pressure sensor  222  is reported to the cleaning process control unit  226 . 
     The temperature sensor  224  is a temperature measurement device which measures the ambient temperature around the cleaning processing unit  200  (desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ). The temperature measured by the temperature sensor  224  is reported to the cleaning process control unit  226 . 
     The cleaning process control unit  226  controls the pressure adjustment unit  220  in accordance with the temperature measured by the temperature sensor  224  (the ambient temperature around the cleaning processing unit  200 , and desirably the temperature of the cleaning liquid in the cleaning liquid tank  206 ), in such a manner that the interior of the cleaning liquid tank  206  assumes a prescribed pressure. 
     More specifically, in the case of a high temperature ambience, the cleaning process control unit  226  lowers the pressure inside the cleaning liquid tank  206  so as to reduce the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to suppress the height of the cleaning liquid pillar  202 . 
     On the other hand, in the case of a low temperature ambience, the cleaning process control unit  226  raises the pressure inside the cleaning liquid tank  206  so as to raise the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to push up the height of the cleaning liquid pillar  202 . 
     Furthermore, when adjusting the pressure inside the cleaning liquid tank  206  in accordance with the temperature measured by the temperature sensor  224 , the cleaning process control unit  226  performs feedback control in such a manner that the interior of the cleaning liquid tank  206  assumes a desired pressure in accordance with the pressure measure by the pressure sensor  222  (the pressure inside the cleaning liquid tank  206 ). Thus, it is possible to rapidly adjust the pressure inside the cleaning liquid tank  206 . 
       FIG. 10  is an illustrative diagram showing an embodiment of control performed by the cleaning process control unit  226 . In the embodiment shown in  FIG. 10 , a case where the temperature measured by the temperature sensor  224  is normal temperature (25° C.) is taken as the reference temperature (reference value), and the height of the cleaning liquid pillar  202  in this case is taken to be 1.5 mm. 
     In this case, for example, if the temperature measured by the temperature sensor  224  is higher than normal temperature (e.g., 40° C.), the viscosity of the cleaning liquid declines, so that the height of the cleaning liquid pillar  202  would increase from 1.5 mm at normal temperature to 1.7 mm if there were no compensation. Then, the cleaning process control unit  226  opens the depressurization valve of the pressure adjustment unit  220  so as to lower the pressure inside the cleaning liquid tank  206  to reduce the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208 , and thereby keeps the height of the cleaning liquid pillar  202  to the same value of 1.5 mm as during normal temperature. 
     On the other hand, if the temperature measured by the temperature sensor  224  is lower than normal temperature (e.g., 5° C.), the viscosity of the cleaning liquid increases, so that the height of the cleaning liquid pillar  202  would decrease from 1.5 mm at normal temperature to 1.0 mm if there were no compensation. Then, the cleaning process control unit  226  drives the pressurization pump of the pressure adjustment unit  220  (with the depressurization valve in a closed state) so as to raise the pressure inside the cleaning liquid tank  206  to raise the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208 , and thereby keeps the height of the cleaning liquid pillar  202  to the same value of 1.5 mm as during normal temperature. 
     If the temperature measured by the temperature sensor  224  is normal temperature, the cleaning process control unit  226  does not make change in the pressure adjustment unit  220  and the prevailing state is maintained. 
     The electromagnetic valve  218 , which is arranged in the supply flow channel  216  connecting the cleaning liquid tank  206  and the cleaning liquid application unit  204 , is closed while the pressure inside the cleaning liquid tank  206  is being adjusted by control implemented by the cleaning process control unit  226 . After the pressure adjustment has been completed, the electromagnetic valve  218  is opened, and the cleaning liquid is supplied from the cleaning liquid tank  206  through the supply flow channel  216  to the cleaning liquid nozzles  208  of the cleaning liquid application unit  204 . 
     The relationship between the temperature measured by the temperature sensor  224  (the ambient temperature around the cleaning processing unit  200 , and desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ), the height of the cleaning liquid pillar  202  and the pressure measured by the pressure sensor  222  (the pressure inside the cleaning liquid tank  206 ) can be determined in advance by experimentation, or the like, and this relationship can be stored in a storage device (e.g., the memory  174  shown in  FIG. 4 , or the like), in the form of a data table. The cleaning process control unit  226  is able to control the internal pressure of the cleaning liquid tank  206  rapidly and easily by referring to the data table stored in the storage device. 
     Thus, according to the present embodiment, the supply of the cleaning liquid from the cleaning liquid tank  206  to the cleaning liquid nozzles  208  of the cleaning liquid application unit  204  can be performed by using the liquid head differential H produced between the cleaning liquid tank  206  and the cleaning liquid application unit  204 , rather than a device which generates pulsation, such as a pump, and therefore it is possible to supply the cleaning liquid stably without pulsation. 
     In particular, in the present embodiment, the pressure inside the cleaning liquid tank  206  is controlled in accordance with the ambient temperature around the cleaning processing unit  200  (and desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ), and the relative pressure of the cleaning liquid tank  206  with respect to the cleaning liquid application unit  204  is thereby adjusted. Thus, it is possible to suppress the variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  caused by the variation in the ambient temperature, and the height of the cleaning liquid pillar  202  produced on the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204  can be kept uniform without being affected by variations in the ambient temperature. Hence, it is possible to apply the cleaning liquid stably to the nozzle surface  150 A of the head  150 . 
     Furthermore, in the present embodiment, the cleaning liquid application unit  204  is provided with the flow rate adjustment device (e.g., the restrictor  212  in  FIG. 8 , the nozzle arrangement structure in  FIG. 9 , or the like) for adjusting the flow rate of the cleaning liquid that is supplied to the respective cleaning liquid nozzles  208 , and it is thereby possible to suppress the height variations of the cleaning liquid pillar  202  through the direction of arrangement of the cleaning liquid nozzles  208 . Hence, it is possible to apply the cleaning liquid uniformly without irregularities to the nozzle surface  150 A of the head  150 . 
     Second Embodiment 
       FIG. 11  is a schematic drawing showing the composition of the cleaning processing unit  200  according to the second embodiment of the present invention. In  FIG. 11 , members which are the same as or similar to those in  FIG. 5  are denoted with the same reference numerals and description thereof is omitted here. 
     In the second embodiment, the liquid head differential between the cleaning liquid tank  206  and the cleaning liquid application unit  204  is altered by changing the height of arrangement of the cleaning liquid tank  206  in accordance with the ambient temperature around the cleaning processing unit  200  (desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ). 
     The cleaning processing unit  200  shown in  FIG. 11  is provided with an elevator mechanism  230 , which adjusts the arrangement height of the cleaning liquid tank  206  in the vertical direction. The driving of the elevator mechanism  230  is controlled by the cleaning process control unit  226 . 
     The cleaning process control unit  226  controls the driving of the elevator mechanism  230  in accordance with the temperature measured by the temperature sensor  224  (the ambient temperature around the cleaning processing unit  200 , and desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ). 
     More specifically, in the case of a high temperature ambience where the temperature measured by the temperature sensor  224  is higher than the reference temperature, the cleaning process control unit  226  makes the arrangement height of the cleaning liquid tank  206  lower than the reference height (to set the liquid head differential as H 1  for example) so as to reduce the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to suppress the height of the cleaning liquid pillar  202 . 
     On the other hand, in the case of a low temperature ambience where the temperature measured by the temperature sensor  224  is lower than the reference temperature, the cleaning process control unit  226  makes the arrangement height of the cleaning liquid tank  206  higher than the reference height (to set the liquid head differential as H 2  for example) so as to raise the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to push up the height of the cleaning liquid pillar  202 . 
     According to the second embodiment, the arrangement height of the cleaning liquid tank  206  is changed in accordance with the ambient temperature around the cleaning processing unit  200 , the liquid head differential between the cleaning liquid tank  206  and the cleaning liquid application unit  204  is thereby adjusted, and the relative pressure of the cleaning liquid tank  206  with respect to the cleaning liquid application unit  204  is thereby adjusted. Thus, similarly to the first embodiment, it is possible to restrict variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  caused by variation of the ambient temperature, and the height of the cleaning liquid pillar  202  produced on the cleaning liquid spouting surface  204 A can be made uniform without being affected by variation in the ambient temperature. Hence, it is possible to apply the cleaning liquid stably to the nozzle surface  150 A of the head  150 . 
     Third Embodiment 
       FIG. 12  is a schematic drawing showing the composition of the cleaning processing unit  200  according to the third embodiment of the present invention. In  FIG. 12 , members which are the same as or similar to those in  FIG. 5  are denoted with the same reference numerals and description thereof is omitted here. 
     In the third embodiment, the liquid head differential between the cleaning liquid tank  206  and the cleaning liquid application unit  204  is altered by changing the surface height of the cleaning liquid inside the cleaning liquid tank  206  in accordance with the ambient temperature around the cleaning processing unit  200  (desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ). 
     The cleaning processing unit  200  shown in  FIG. 12  is provided with a main tank  232  and a pump  236  as devices for adjusting the surface height of the cleaning liquid inside the cleaning liquid tank  206 . 
     It is desirable to use a tall tank as the cleaning liquid tank  206  in the third embodiment compared to the first and second embodiments, since the surface height of the cleaning liquid inside the cleaning liquid tank  206  is adjusted in accordance with the ambient temperature around the cleaning processing unit  200 . 
     The main tank  232  serves as a cleaning liquid storage device which stores the cleaning liquid that flows out of and into the cleaning liquid tank  206 . The main tank  232  is connected to the cleaning liquid tank  206  through a connecting flow channel  234 , and the pump  236  is arranged in the connecting flow channel  234 . 
     The pump  236  serves as a liquid conveyance device that is capable of conveying the cleaning liquid bidirectionally between the main tank  232  and the cleaning liquid tank  206 . When the pump  236  is forwardly driven, then the cleaning liquid flows into the cleaning liquid tank  206  from the main tank  232 , and the surface of the cleaning liquid inside the cleaning liquid tank  206  rises. On the other hand, when the pump  236  is reversely driven, then the cleaning liquid flows out from the cleaning liquid tank  206  to the main tank  232 , and the surface of the cleaning liquid inside the cleaning liquid tank  206  falls. The driving of the pump  236  is controlled by the cleaning process control unit  226 . 
     The cleaning liquid tank  206  is provided with a high-temperature liquid surface sensor  238 A, which detects the liquid surface level L 1  corresponding to a high-temperature ambience, and a low-temperature liquid surface sensor  238 B, which detects the liquid surface level L 2  corresponding to a low-temperature ambience. Each of the liquid surface sensors  238 A and  238 B sends a detection signal indicating the detection of the liquid surface to the cleaning process control unit  226 , upon detecting that the cleaning liquid inside the cleaning liquid tank  206  is equal to or greater than the liquid surface height that is the detection object. 
     The cleaning process control unit  226  controls the driving of the pump  236  and thereby adjusts the surface height of the cleaning liquid inside the cleaning liquid tank  206  in accordance with the temperature measured by the temperature sensor  224  (the ambient temperature around the cleaning processing unit  200 , and desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ). 
     More specifically, in the case of a high-temperature ambience where the temperature measured by the temperature sensor  224  is higher than the reference temperature, the cleaning process control unit  226  controls the driving of the pump  236  to adjust the surface height of the cleaning liquid inside the cleaning liquid tank  206  to the detection position (the liquid surface level L 1 ) of the high-temperature liquid surface sensor  238 A (corresponding to the liquid head differential of H 1 ), so as to reduce the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to suppress the height of the cleaning liquid pillar  202 . 
     On the other hand, in the case of a low temperature ambience where the temperature measured by the temperature sensor  224  is lower than the reference temperature, the cleaning process control unit  226  controls the driving of the pump  236  to adjust the surface height of the cleaning liquid inside the cleaning liquid tank  206  to the detection position (the liquid surface level L 2 ) of the low-temperature liquid surface sensor  238 B (corresponding to the liquid head differential of H 2 ), so as to raise the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to push up the height of the cleaning liquid pillar  202 . 
     According to the third embodiment, the surface height of the cleaning liquid inside the cleaning liquid tank  206  is changed in accordance with the ambient temperature around the cleaning processing unit  200 , the liquid head differential between the cleaning liquid tank  206  and the cleaning liquid application unit  204  is thereby adjusted, and the relative pressure of the cleaning liquid tank  206  with respect to the cleaning liquid application unit  204  is thereby adjusted. Thus, similarly to the first and second embodiments, it is possible to restrict variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  caused by variation of the ambient temperature, and the height of the cleaning liquid pillar  202  produced on the cleaning liquid spouting surface  204 A can be made uniform without being affected by variation in the ambient temperature. Hence, it is possible to apply the cleaning liquid stably to the nozzle surface  150 A of the head  150 . 
     Fourth Embodiment 
       FIG. 13  is a schematic drawing showing the composition of the cleaning processing unit  200  according to the fourth embodiment of the present invention. In  FIG. 13 , members which are the same as or similar to those in  FIGS. 5 and 12  are denoted with the same reference numerals and description thereof is omitted here. 
     The cleaning processing unit  200  shown in  FIG. 13  is provided with a main tank  232  and a pump  236  as devices for adjusting the surface height of the cleaning liquid inside the cleaning liquid tank  206 . 
     The pump  236  used in the present embodiment is a liquid conveyance device that is capable of conveying the cleaning liquid in one direction from the main tank  232  to the cleaning liquid tank  206 . Of course, it is also possible to use the liquid conveyance device that is capable of conveying the cleaning liquid bidirectionally between the main tank  232  and the cleaning liquid tank  206  similarly to the third embodiment. 
     The cleaning liquid tank  206  is provided with a high-temperature drain (discharge flow channel)  240 A, which is arranged at a position of the liquid surface level L 1  corresponding to a high temperature ambience, and a low-temperature drain (discharge flow channel)  240 B, which is arranged at a position of the liquid surface level L 2  corresponding to a low temperature ambience. Electromagnetic valves  242 A and  242 B are arranged respectively in the drains  240 A and  240 B. The opening and closing of the electromagnetic valves  242 A and  242 B are controlled by the cleaning process control unit  226 . 
     The cleaning process control unit  226  adjusts the surface height of the cleaning liquid inside the cleaning liquid tank  206  by a combination of controlling the driving of the pump  236  and controlling the opening and closing of the electromagnetic valves  242 A and  242 B, in accordance with the temperature measured by the temperature sensor  224  (the ambient temperature around the cleaning processing unit  200 , and desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ). 
     More specifically, in the case of a high temperature ambience where the temperature measured by the temperature sensor  224  is higher than the reference temperature, the cleaning process control unit  226  opens the high-temperature electromagnetic valve  242 A while driving the pump  236  as required to adjust the surface height of the cleaning liquid inside the cleaning liquid tank  206  to the liquid surface level L 1  (corresponding to the liquid head differential H 1 ), so as to reduce the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to suppress the height of the cleaning liquid pillar  202 . 
     On the other hand, in the case of a low temperature ambience where the temperature measured by the temperature sensor  224  is lower than the reference temperature, the cleaning process control unit  226  opens the low-temperature electromagnetic valve  242 B while driving the pump  236  as required to adjust the surface height of the cleaning liquid inside the cleaning liquid tank  206  to the liquid surface level L 2  (corresponding to the liquid head differential H 2 ), so as to raise the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to push up the height of the cleaning liquid pillar  202 . 
     According to the fourth embodiment, it is possible to change the height of the surface of the cleaning liquid inside the cleaning liquid tank  206  in accordance with the ambient temperature around the cleaning processing unit  200 , and similar beneficial effects to those of the third embodiment described above can be obtained. 
     Fifth Embodiment 
       FIG. 14  is a schematic drawing showing the composition of the cleaning processing unit  200  according to the fifth embodiment of the present invention. In  FIG. 14 , members which are the same as or similar to those in  FIG. 5  are denoted with the same reference numerals and description thereof is omitted here. 
     The cleaning processing unit  200  shown in  FIG. 14  is provided with a cleaning liquid temperature adjustment device  250 , which adjusts the temperature of the cleaning liquid in the cleaning liquid tank  206 . The cleaning liquid temperature adjustment device  250  includes a heater  252 , such as an in-built heater installed inside the cleaning liquid tank  206 , a temperature sensor  254 , which measures the temperature inside the cleaning liquid tank  206 , and a temperature adjustment controller  256 . 
     The temperature adjustment controller  256  controls the temperature of the heater  252  in accordance with the temperature inside the cleaning liquid tank  206 , which is measured by the temperature sensor  254 , in such a manner that the temperature of the cleaning liquid in the cleaning liquid tank  206  is kept uniform. 
     It is desirable that a heat insulating material  258  is arranged on the outer perimeter surfaces (the side faces and the bottom face) of the cleaning liquid tank  206 . By suppressing the exchange of heat with the outside air, it is possible to reduce the change in the temperature of the cleaning liquid in the cleaning liquid tank  206 . 
     It is also desirable that a heat insulating tube is used for the supply flow channel  216 , which connects the cleaning liquid tank  206  and the cleaning liquid application unit  204 . This makes it possible to reduce temperature change in the cleaning liquid flowing through the supply flow channel  216 . 
       FIG. 14  shows one example of a composition in which the cleaning liquid temperature adjustment device  250  is employed in the cleaning processing unit  200  according to the first embodiment (see  FIG. 5 ); however, the present invention is not limited to this and can also be applied similarly to the respective cleaning processing units  200  according to the second to fourth embodiments. 
     According to the fifth embodiment, control is implemented in such a manner that the temperature of the cleaning liquid in the cleaning liquid tank  206  is kept uniform by the cleaning liquid temperature adjustment device  250 , and therefore it is possible reliably to suppress the variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208 , and the application of the cleaning liquid to the nozzle surface  150 A of the head  150  can be made even more stable. 
     Sixth Embodiment 
       FIG. 15  is a schematic drawing showing the composition of the cleaning processing unit  200  according to the sixth embodiment of the present invention. In  FIG. 15 , members which are the same as or similar to those in  FIG. 5  are denoted with the same reference numerals and description thereof is omitted here. 
     In the sixth embodiment, the flow channel resistance from the cleaning liquid tank  206  to the cleaning liquid application unit  204  is adjusted in accordance with the ambient temperature around the cleaning processing unit  200  (and desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ) so as to suppress the variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  caused by the change in the ambient temperature, and the height of the cleaning liquid pillar  202  produced on the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204  can be kept stable. 
     The cleaning processing unit  200  shown in  FIG. 15  is provided with a flow channel resistance adjustment unit  318  instead of the pressure adjustment unit  220  shown in  FIG. 5 . 
     The flow channel resistance adjustment unit  318  adjusts the flow channel resistance from the cleaning liquid tank  206  to the cleaning liquid application unit  204 , and is arranged in the supply flow channel  216  connecting the cleaning liquid tank  206  and the cleaning liquid application unit  204 . The flow channel resistance adjustment unit  318  is controlled by the cleaning process control unit  226 . 
     The cleaning process control unit  226  controls the flow channel resistance adjustment unit  318  in accordance with the temperature measured by the temperature sensor  224 , in such a manner that the supply flow channel  216  connecting the cleaning liquid tank  206  and the cleaning liquid application unit  204  assumes a prescribed flow channel resistance. More specifically, the flow channel resistance of the supply flow channel  216  at normal temperature (25° C.) is taken as the reference resistance, and in the case of a high temperature ambience where the temperature is higher than normal temperature, the cleaning process control unit  226  makes the flow channel resistance of the supply flow channel  216  greater than the reference resistance so as to reduce the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to suppress the height of the cleaning liquid pillar  202 . On the other hand, in the case of a low temperature ambience where the temperature is lower than normal temperature, the cleaning process control unit  226  makes the flow channel resistance of the supply flow channel  216  smaller than the reference resistance so as to raise the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to push up the height of the cleaning liquid pillar  202 . 
     In  FIG. 10  described above, if the temperature measured by the temperature sensor  224  is higher than normal temperature (e.g., 40° C.), the viscosity of the cleaning liquid declines, so that the height of the cleaning liquid pillar  202  would increase from 1.5 mm at normal temperature to 1.7 mm if there were no compensation. Then, the cleaning process control unit  226  in the present embodiment controls the flow channel resistance adjustment unit  318  in such a manner that the flow channel resistance of the supply flow channel  216  becomes greater than the reference resistance, so as to reduce the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to keep the height of the cleaning liquid pillar  202  to the same value of 1.5 mm as in the case of normal temperature. 
     On the other hand, if the temperature measured by the temperature sensor  224  is lower than normal temperature (e.g., 5° C.), the viscosity of the cleaning liquid increases, so that the height of the cleaning liquid pillar  202  would decrease from 1.5 mm at normal temperature to 1.0 mm if there were no compensation. Then, the cleaning process control unit  226  controls the flow channel resistance adjustment unit  318  in such a manner that the flow channel resistance of the supply flow channel  216  becomes smaller than the reference resistance, so as to raise the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  to keep the height of the cleaning liquid pillar  202  to the same value of 1.5 mm as in the case of normal temperature. 
     If the temperature measured by the temperature sensor  224  is normal temperature, the cleaning process control unit  226  does not make change in the flow channel resistance adjustment unit  318  and the prevailing state is maintained. 
     The composition of the flow channel resistance adjustment unit  318  according to embodiments of the present invention is described below. 
     First Embodiment of Flow Channel Resistance Adjustment Unit 
       FIG. 16  is a schematic drawing showing a first embodiment of the composition of the flow channel resistance adjustment unit  318 . 
     As shown in  FIG. 16 , the first embodiment of the composition of the flow channel resistance adjustment unit  318  includes: a high-temperature flow channel  330 H, a normal-temperature flow channel  330 M and a low-temperature flow channel  330 L, which have mutually different lengths and are connected in parallel to the supply flow channel  216 ; and a high-temperature electromagnetic valve  332 H, a normal-temperature electromagnetic valve  332 M and a low-temperature electromagnetic valve  332 L, which are arranged respectively in the flow channels  330 H,  330 M and  330 L. 
     The flow channels  330 H,  330 M and  330 L can be constituted respectively of dedicated flow channels, or may have a composition in which a portion of the flow channels is shared.  FIG. 16  shows one example of a composition where the high-temperature flow channel  330 H and the normal-temperature flow channel  330 M share a portion of the flow channel 
     The flow channel length between a first connection point B 1  and a second connection point B 2 , where the ends of the flow channels  330 H,  330 M and  330 L are connected, becomes shorter progressively from the high-temperature flow channel  330 H, to the normal-temperature flow channel  330 M, to the low-temperature flow channel  330 L. 
     The high-temperature flow channel  330 H has the longest length from the first connection point B 1  to the second connection point B 2 , hence applies the largest flow channel resistance to the supply flow channel  216  among the flow channels  330 H,  330 M and  330 L, and is the flow channel used in a high temperature ambience. 
     The low-temperature flow channel  330 L has the shortest length from the first connection point B 1  to the second connection point B 2 , hence applies the smallest flow channel resistance to the supply flow channel  216  among the flow channels  330 H,  330 M and  330 L, and is the flow channel used in a low temperature ambience. 
     The normal-temperature flow channel  330 M has the length from the first connection point B 1  to the second connection point B 2  that is shorter than the flow channel  330 H and longer than the flow channel  330 L (and desirably, the middle of the lengths of the flow channel  330 H and the flow channel  330 L), and hence applies to the supply flow channel  216  the flow channel resistance that is smaller than the high-temperature flow channel  330 H and greater than the low-temperature flow channel  330 L (and desirably, the middle of the flow channel resistances of the flow channels  330 H and  330 L), and is the flow channel used in a normal temperature ambience. 
     The electromagnetic valves  332 H,  332 M and  332 L are valve devices capable of opening and closing the respectively corresponding flow channels (flow channel opening and closing devices), in such a manner that the cleaning liquid flows from the cleaning liquid tank  206  to the cleaning liquid application unit  204  through the corresponding flow channel when the valve is open, and the flow of the cleaning liquid through the corresponding flow channel is shut off when the valve is closed. The opening and closing of the electromagnetic valves  332 H,  332 M and  332 L are controlled by the cleaning process control unit  226  shown in  FIG. 15 . 
     The cleaning process control unit  226  controls the opening and closing of the electromagnetic valves  332 H,  332 M and  332 L of the flow channel resistance adjustment unit  318  in accordance with the temperature measured by the temperature sensor  224 . 
     More specifically, if the temperature measured by the temperature sensor  224  is normal temperature (normal temperature ambience), then the cleaning process control unit  226  opens the normal-temperature electromagnetic valve  332 M only, of the electromagnetic valves  332 H,  332 M and  332 L, in such a manner that the cleaning liquid is supplied from the cleaning liquid tank  206  to the cleaning liquid application unit  204  through the normal-temperature flow channel  330 M. 
     If the temperature measured by the temperature sensor  224  is higher than normal temperature (a high temperature ambience), then the cleaning process control unit  226  opens the high-temperature electromagnetic valve  332 H only, of the electromagnetic valves  332 H,  332 M and  332 L, in such a manner that the cleaning liquid is supplied from the cleaning liquid tank  206  to the cleaning liquid application unit  204  through the high-temperature flow channel  330 H. Thereby, the flow channel resistance of the supply flow channel  216  is made greater than the reference resistance in the case of normal temperature, and the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  is reduced, thereby making it possible to suppress the height of the cleaning liquid pillar  202 . 
     On the other hand, if the temperature measured by the temperature sensor  224  is lower than normal temperature (a low temperature ambience), then the cleaning process control unit  226  opens the low-temperature electromagnetic valve  332 L only, of the electromagnetic valves  332 H,  332 M and  332 L, in such a manner that the cleaning liquid is supplied from the cleaning liquid tank  206  to the cleaning liquid application unit  204  through the low-temperature flow channel  330 L. Thereby, the flow channel resistance of the supply flow channel  216  is made smaller than the reference resistance in the case of normal temperature, and the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  is raised, thereby making it possible to push up the height of the cleaning liquid pillar  202 . 
     Second Embodiment of Flow Channel Resistance Adjustment Unit 
       FIG. 17  is a schematic drawing showing a second embodiment of the composition of the flow channel resistance adjustment unit  318 . In  FIG. 17 , members which are the same as or similar to those in  FIG. 16  are denoted with the same reference numerals and description thereof is omitted here. 
     As shown in  FIG. 17 , the second embodiment of the composition of the flow channel resistance adjustment unit  318  includes: a high-temperature flow channel  334 H, a normal-temperature flow channel  334 M and a low-temperature flow channel  334 L, which are connected in parallel to the supply flow channel  216 ; and a high-temperature electromagnetic valve  336 H, a normal-temperature electromagnetic valve  336 M and a low-temperature electromagnetic valve  336 L, which have mutually different Cv values and are arranged respectively in the flow channels  334 H,  334 M and  334 L. 
     It is possible that the lengths of all the flow channels  334 H,  334 M and  334 L are the same, or the lengths of some of the flow channels are mutually different. In the latter case, it is desirable that the difference in the lengths of the flow channels  334 H,  334 M and  334 L should be taken into account in setting the Cv values of the electromagnetic valves  336 H,  336 M and  336 L described below, or the thicknesses (cross-sectional areas) of the flow channels  334 H,  334 M and  334 L. 
     The electromagnetic valves  336 H,  336 M and  336 L are flow channel opening and closing devices capable of opening and closing the respectively corresponding flow channels. In the present embodiment, the Cv values of the electromagnetic valves  336 H,  336 M and  336 L are mutually different and the Cv value increases sequentially, from the high-temperature electromagnetic valve  336 H, to the medium-temperature electromagnetic valve  336 M, to the low-temperature electromagnetic valve  336 L. The Cv value of the electromagnetic valve indicates the capacity of the valve, the flow volume becoming larger (i.e., the flow channel resistance becoming smaller), the greater the Cv value. The opening and closing of the electromagnetic valves  336 H,  336 M and  336 L are controlled by the cleaning process control unit  226  shown in  FIG. 15 . The method of control implemented by the cleaning process control unit  226  is similar to that of the first embodiment of the composition of the flow channel resistance adjustment unit  318 , and description thereof is omitted here. 
     Third Embodiment of Flow Channel Resistance Adjustment Unit&gt; 
       FIG. 18  is a schematic drawing showing a third embodiment of the composition of the flow channel resistance adjustment unit  318 . In  FIG. 18 , members which are the same as or similar to those in  FIG. 16  are denoted with the same reference numerals and description thereof is omitted here. 
     As shown in  FIG. 18 , the third embodiment of the composition of the flow channel resistance adjustment unit  318  includes: a high-temperature flow channel  340 H, a normal-temperature flow channel  340 M and a low-temperature flow channel  340 L, which are connected in parallel to the supply flow channel  216 ; a high-temperature electromagnetic valve  342 H, a normal-temperature electromagnetic valve  342 M and a low-temperature electromagnetic valve  342 L, which are arranged respectively in the flow channels  340 H,  340 M and  340 L; and a high-temperature restrictor  344 H, a normal-temperature restrictor  344 M and a low-temperature restrictor  344 L, which have mutually different flow channel cross-sectional areas and are arranged respectively in the flow channels  340 H,  340 M and  340 L. The flow channel cross-sectional areas of the restrictors  344 H,  344 M and  344 L increase successively from the high-temperature restrictor  344 H, to the normal-temperature restrictor  344 M, to the low-temperature restrictor  344 L. 
     It is possible that the lengths of all the flow channels  340 H,  340 M and  340 L are the same, or the lengths of some of the flow channels are mutually different. In the latter case, it is desirable that the difference in the lengths of the flow channels  340 H,  340 M and  340 L should be taken into account in setting the sizes (flow channel cross-sectional areas) of the restrictors  344 H,  344 M and  344 L. 
     It is possible that the Cv values of all of the electromagnetic valves  342 H,  342 M and  342 L are the same, or the Cv values of some of the electromagnetic valves are mutually different. In the latter case, it is desirable that the difference in the Cv values of the electromagnetic valves  342 H,  342 M and  342 L should be taken into account in setting the sizes (flow channel cross-sectional areas) of the restrictors  344 H,  344 M and  344 L. 
     The electromagnetic valves  342 H,  342 M and  342 L are flow channel opening and closing devices capable of opening and closing the respectively corresponding flow channels. The opening and closing of the electromagnetic valves  342 H,  342 M and  342 L are controlled by the cleaning process control unit  226  shown in  FIG. 15 . The method of control implemented by the cleaning process control unit  226  is similar to that of the first embodiment of the composition of the flow channel resistance adjustment unit  318 , and description thereof is omitted here. 
     Fourth Embodiment of Flow Channel Resistance Adjustment Unit 
       FIG. 19  is a schematic drawing showing a fourth embodiment of the composition of the flow channel resistance adjustment unit  318 . In  FIG. 19 , members which are the same as or similar to those in  FIG. 16  are denoted with the same reference numerals and description thereof is omitted here. 
     As shown in  FIG. 19 , the second embodiment of the composition of the flow channel resistance adjustment unit  318  includes: a high-temperature flow channel  350 H, a normal-temperature flow channel  350 M and a low-temperature flow channel  350 L, which are connected in parallel to the supply flow channel  216 ; and a normal-temperature electromagnetic valve  352 M and a low-temperature electromagnetic valve  352 L, which are arranged respectively in the flow channels  350 M and  350 L apart from the high-temperature flow channel  350 H. In other words, no electromagnetic valve is arranged in the high-temperature flow channel  350 H, and the high-temperature flow channel  350 H is always selected regardless of the temperature measured by the temperature sensor  224 , in such a manner that the cleaning liquid is always supplied from the cleaning liquid tank  206  to the cleaning liquid application unit  204  through the high-temperature flow channel  350 H at the least. 
     It is possible that the lengths of all the flow channels  350 H,  350 M and  350 L are the same, or the lengths of some of the flow channels are mutually different. In the latter case, it is desirable that the difference in the lengths of the flow channels  350 H,  350 M and  350 L should be taken into account in setting the thicknesses (cross-sectional areas) of the flow channels  350 H,  350 M and  350 L. 
     Furthermore, the Cv values of the electromagnetic valves  352 M and  352 L can be the same or different. In the latter case, it is desirable that the difference in the Cv values of the electromagnetic valves  352 M and  352 L should be taken into account in setting the lengths and thicknesses of the flow channels  350 H,  350 M and  350 L. 
     The electromagnetic valves  352 M and  352 L are flow channel opening and closing devices capable of opening and closing the respectively corresponding flow channels. The opening and closing of the electromagnetic valves  352 M and  352 L are controlled by the cleaning process control unit  226  shown in  FIG. 15 . 
     The cleaning process control unit  226  controls the opening and closing of the electromagnetic valves  352 M and  352 L of the flow channel resistance adjustment unit  318  in accordance with the temperature measured by the temperature sensor  224 . 
     More specifically, if the temperature measured by the temperature sensor  224  is higher than normal temperature (a high temperature ambience), then the cleaning process control unit  226  opens both the electromagnetic valves  352 M and  352 L, in such a manner that the cleaning liquid is supplied from the cleaning liquid tank  206  to the cleaning liquid application unit  204  through the high-temperature flow channel  350 H only. 
     If the temperature measured by the temperature sensor  224  is normal temperature (a normal temperature ambience), then the cleaning process control unit  226  opens the normal-temperature electromagnetic valve  352 M only, of the electromagnetic valves  352 M and  352 L, in such a manner that the cleaning liquid is supplied from the cleaning liquid tank  206  to the cleaning liquid application unit  204  through the normal-temperature flow channel  350 M, in addition to the high-temperature flow channel  350 H, thereby increasing the supplied amount of the cleaning liquid compared to the high temperature ambience. 
     If the temperature measured by the temperature sensor  224  is lower than normal temperature (a low temperature ambience), then the cleaning process control unit  226  opens both the normal-temperature electromagnetic valve  352 M and the low-temperature electromagnetic valve  352 L, in such a manner that the cleaning liquid is supplied from the cleaning liquid tank  206  to the cleaning liquid application unit  204  through the normal-temperature flow channel  350 M and the low-temperature electromagnetic valve  350 L, in addition to the high-temperature flow channel  350 H, thereby increasing the supplied amount of the cleaning liquid compared to the normal temperature ambience. 
     Thus, in the fourth embodiment of the composition of the flow channel resistance adjustment unit  318 , the cleaning process control unit  226  controls the combination of opening and closing of the electromagnetic valves  352 M and  352 L arranged respectively in the normal-temperature flow channel  350 M and the low-temperature flow channel  350 L, of the plurality of flow channels  350 H,  350 M and  350 L connected in parallel to the supply flow channel  216 , so as to increase the amount of the cleaning liquid supplied from the cleaning liquid tank  206  to the cleaning liquid application unit  204  sequentially, from the high temperature ambience, to the normal temperature ambience, to the low temperature ambience. In other words, since the flow channels  350 H,  350 M and  350 L are connected in parallel to the supply flow channel  216 , then the flow channel resistance of the supply flow channel  216  becomes smaller in sequence, from the high temperature ambience, to the normal temperature ambience, to the low temperature ambience. Consequently, similarly to the first to third embodiments of the composition of the flow channel resistance adjustment unit  318  described above, the flow channel resistance of the supply flow channel  216  can be changed in accordance with the ambient temperature, it is hence possible to suppress the variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  caused by the variation of the ambient temperature, and the height of the cleaning liquid pillar  202  produced on the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204  can be made uniform without being affected by variation in the ambient temperature. 
     In the present sixth embodiment of the invention, by changing the flow channel resistance of the supply flow channel  216  in accordance with the ambient temperature around the cleaning processing unit  200  (and desirably, the temperature of the cleaning liquid in the cleaning liquid tank  206 ), it is possible to suppress the variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208  caused by the variation of the ambient temperature, and the height of the cleaning liquid pillar  202  produced on the cleaning liquid spouting surface  204 A of the cleaning liquid application unit  204  can be made uniform irrespective of variation in the ambient temperature. 
     In the sixth embodiment, the temperature range of the ambient temperature is divided into three stages (the low temperature ambience, the normal temperature ambience and the high temperature ambience); however, the present invention is not limited to this, and the ambient temperature may also be divided into a greater number of stages, in such a manner that the flow channel resistance of the supply flow channel  216  is changed for each temperature range. 
     Furthermore, in the sixth embodiment, the embodiments of the composition of the flow channel resistance adjustment unit  318  have been described in which at least a portion of flow channels is selected from a plurality of flow channels (parallel flow channels) connected in parallel to the supply flow channel  216 ; however, the present invention is not limited to this, and it is also possible that the supply flow channel  216  is provided with, for example, a flow rate control valve capable of altering the degree of opening of the flow channel (the flow channel cross-sectional area) in stepwise, in such a manner that the flow channel resistance of the supply flow channel  216  can be changed by controlling the flow rate control valve in accordance with the ambient temperature. Moreover, it is also possible to change the flow channel resistance by altering the cross-sectional area of the supply flow channel  216  by means of an elastic film. According to these modes, it is possible to control the flow channel resistance of the supply flow channel  216  with good accuracy. 
     On the other hand, according to the first to fourth embodiments of the composition of the flow channel resistance adjustment unit  318  described above with reference to  FIGS. 16 to 19 , it is possible readily to control the flow channel resistance of the supply flow channel  216  by selecting one or more of flow channels from the flow channels connected in parallel to the supply flow channel  216 , and hence the composition is simple and such modes are desirable from a cost viewpoint. 
     Furthermore, a desirable mode of the sixth embodiment is one including a device that adjusts the temperature of the cleaning liquid in the cleaning liquid tank  206  (a cleaning liquid temperature adjustment device). 
       FIG. 20  is a schematic drawing showing a mode where a cleaning liquid temperature adjustment device is arranged in the cleaning liquid tank  206 . In  FIG. 20 , members which are the same as or similar to those in  FIGS. 14 and 15  are denoted with the same reference numerals and description thereof is omitted here. 
     It is desirable that the specific composition of the flow channel resistance adjustment unit  318  arranged in the supply flow channel  216  employs one of the first to fourth embodiments of the composition of the flow channel resistance adjustment unit  318  described above with reference to  FIGS. 16 to 19 . 
     According to the mode shown in  FIG. 20 , control is implemented in such a manner that the temperature of the cleaning liquid in the cleaning liquid tank  206  is kept uniform by the cleaning liquid temperature adjustment device  250 , and therefore it is possible to reliably suppress the variation in the flow rate of the cleaning liquid supplied to the cleaning liquid nozzles  208 , and the application of the cleaning liquid to the nozzle surface  150 A of the head  150  can be made even more stable. 
     In the present embodiments, the modes have been described in which the cleaning processing unit  200  is appended to the inkjet recording apparatus  10 ; however, it is also possible to compose a cleaning apparatus for the inkjet head by separating the cleaning processing unit  200  from the inkjet recording apparatus  10 . 
     Furthermore, in the present embodiments, the inkjet recording apparatus has been described which records a color image by ejecting and depositing color inks onto a recording medium as one example of an image formation apparatus; however, the present invention can also be applied to an image formation apparatus which forms a prescribed pattern shape on a substrate by means of a resin liquid, or the like, in order, for instance, to form a mask pattern or to print wiring of a printed wiring board. 
     It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the invention is to cover all modifications, alternate constructions and equivalents falling within the spirit and scope of the invention as expressed in the appended claims.