Patent Publication Number: US-11655562-B2

Title: Electrospinning head, electrospinning apparatus, and cleaning method of electrospinning head

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-167023, filed Oct. 1, 2020, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate to an electrospinning head, an electrospinning apparatus, and a cleaning method of an electrospinning head. 
     BACKGROUND 
     An electrospinning apparatus that accumulates microfibers on a surface of a collection body or a substrate to form a fiber film with an electrospinning method (sometimes called “electric charge induction spinning method”). In the electrospinning apparatus, an electrospinning head including a nozzle is supplied with a material liquid including a high polymer material. A voltage is applied to the nozzle and a material liquid is supplied to the electrospinning head so as to electrify the material liquid, which is then ejected against the surface of a collection body or a substrate from an ejection port of the nozzle. Fiber is thereby accumulated on the surface of the collection body or the substrate. 
     If the work of fiber film formation is performed by the electrospinning apparatus as described above, the fiber, droplets of the material liquid, and a high polymer material of the material liquid may be deposited in the vicinity of the ejection port on the outer surface of the nozzle. For this reason, after the work of forming a film of the fiber is performed, the deposits on the nozzles are removed so as to clean the electrospinning head. In the electrospinning apparatus, it is demanded to effectively and appropriately perform electrospinning apparatus cleaning through removal of deposits on the nozzles. In other words, it is demanded to effectively and appropriately clean the electrospinning head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram showing a state in which a fiber film is being formed in an electrospinning apparatus according to a first embodiment. 
         FIG.  2    is a schematic diagram showing a state in which an electrospinning head is being cleaned in the electrospinning apparatus according to the first embodiment. 
         FIG.  3    is a perspective view schematically showing a structure of a nozzle in an electrospinning head according to the first embodiment. 
         FIG.  4    is a schematic diagram showing a nozzle and a suction head when suction is being performed with the suction head and a suction unit according to the first embodiment. 
         FIG.  5    is a flowchart showing an example of a process performed by a controller of the electrospinning apparatus according to the first embodiment when a fiber film is formed. 
         FIG.  6    is a flowchart showing an example of a process performed by a controller of the electrospinning apparatus according to the first embodiment when the electrospinning head is cleaned. 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment, an electrospinning head includes a nozzle and an uneven surface. The nozzle is made from an electrically conductive material, and a flow path is formed inside of the nozzle. On the outer surface of the nozzle, an ejection port capable of ejecting a material liquid supplied to the flow path is formed. The uneven surface is formed in the vicinity of the ejection port on the outer surface of the nozzle, and the uneven shape of the uneven surface is arranged around the entire circumference of the nozzle in the circumferential direction and is along the extending direction of the flow path. 
     Hereinafter, the embodiments will be described with reference to the accompanying drawings. 
     First Embodiment 
       FIGS.  1  and  2    show an example of an electrospinning apparatus according to the first embodiment. As shown in  FIGS.  1  and  2   , the electrospinning apparatus  1  includes an electrospinning head  2 , a supplier  3  of a material liquid, a power supply source  4 , a collection body  5 , a suction head  6 , a suction unit  7 , a head mover unit  8 , a controller  9 , and a user interface  10 . 
     The electrospinning head  2  has a head main body  11  and one or more (four in the present embodiment) nozzles  12 . Herein, the center axis of the head main body  11  (electrospinning head  2 ) is defined, and the direction along the center axis of the head main body  11  is defined as a longitudinal direction. The head main body  11  extends along the center axis and extends along the longitudinal direction. In the present embodiment, the head main body  11  and each of the nozzles  12  are made from an electrically conductive material. The number of the nozzles  12  is not limited particularly, and at least one nozzle  12  will suffice. Preferably, the head main body  11  and each of the nozzles  12  are respectively made of materials having resistance against a material liquid and may be made of stainless steel, for example. 
     Each of the nozzles  12  is provided on the outer peripheral surface of the head main body  11 . Each of the nozzles  12  projects from the outer peripheral surface of the head main body  11  toward the outer peripheral side, namely toward the side away from the center axis of the head main body  11 . In the present embodiment, the plurality of nozzles  12  are arranged at the same, or substantially the same, angle positions in a direction around the center axis of the head main body  11 . For this reason, in the present embodiment, the plurality of nozzles  12  are arranged along the longitudinal direction of the electrospinning head  2  and constitute a nozzle row.  FIGS.  1  and  2    show a state viewed in a direction intersecting the center axis (longitudinal direction) of the electrospinning head  2  and intersecting the projecting direction of the nozzles  12 . 
     In the inside of the head main body  11 , an inner hollow  13  is formed. The inner hollow  13  is formed along a longitudinal direction (center axis) of the electrospinning head  2 . In the inside of each nozzle  12 , a flow path  15  is formed. In each nozzle  12 , the flow path  15  extends along the direction in which the nozzle projects from the head main body  11 . Thus, in each nozzle  12 , the direction in which the flow path  15  extends corresponds to, or approximately corresponds to, the projection direction from the head main body  11 . One end (inner-peripheral end) of each flow path  15  is connected to the inner hollow  13 . 
     At the other end (outer-peripheral end) of each flow path  15 , an ejection port  16  is formed. In each nozzle  12 , the ejection port  16  is formed on the outer surface. In the present embodiment, the ejection port  16  is formed at the projection end (distal end) of each nozzle  12  in the head main body  11 . At the ejection port  16 , each flow path  15  opens to the outside of the electrospinning head  2 . In each nozzle  12 , the ejection port  16  communicates with the inner hollow  13  of the head main body  11  via the flow path  15 . For this reason, each nozzle  12  can eject, from the ejection port  16 , a material liquid supplied in the flow path  15  through the inner hollow  13 . In each nozzle  12 , a material liquid can be ejected from the head main body  11  toward the side toward which the nozzle projects, in other words, toward the side to which the ejection port  16  opens. 
       FIG.  3    shows a structure of one of the nozzles  12 . As shown in  FIGS.  1  through  3   , each nozzle  12  includes a nozzle base part  21  and a needle part  22 . In each nozzle  12 , the nozzle base part  21  is connected to the head main body  11  and thereby constitutes the root of the projection from the head main body  11 . In each nozzle  12 , the needle part  22  further projects from the nozzle base part  21  toward the outer peripheral side of the electrospinning head  2 , and constitutes a projecting end from the head main body  11 . Thus, the ejection port  16  is formed at the needle part  22  in each nozzle  12 . Furthermore, in each nozzle  12 , the outer diameter of the needle part  22  is smaller than that of the nozzle base part  21 . In each nozzle  12 , in the cross section perpendicular to, or approximately perpendicular to the extending direction of the flow path  15 , the area size surrounded by the outer periphery of the needle part  22  is smaller than the area size surrounded by the outer periphery of the nozzle base part  21 . 
     In each nozzle  12 , the center axis (nozzle center axis) N is defined. In each nozzle  12 , the center axis N is along the extending direction of the flow path  15  and is coaxial with, or approximately coaxial with, the center axis of the flow path  15 . In each nozzle  12 , the circumferential direction (the direction indicated by arrows R 1  and R 2 ), which is a peri-axial direction of the central axis N, is defined. On the outer surface of each nozzle  12 , an uneven surface  23  is formed in the needle part  22 . In each nozzle  12 , the uneven surface  23  is formed from the projecting end toward the inner peripheral side of the electrospinning head  2 , and is formed in the projecting end and the vicinity thereof. Thus, in each nozzle  12 , the uneven surface  23  is formed in the vicinity of the ejection port  16 . In each nozzle  12 , the uneven surface  23  is formed in an uneven shape (convex-and-concave shape) along the extending direction of the flow path  15  (the projecting direction from the head main body  11 ). In each nozzle  12 , the uneven surface  23  is formed around the entire circumference in the circumferential direction (around the center axis N). For this reason, on the uneven surface  23  of each nozzle  12 , each of the depressions (concave parts) and projections (convex parts) is formed in a ring. 
     The supplier  3  of a material liquid is capable of supplying a material liquid to the electrospinning head  2 . The supplier  3  constitutes a supply source of a material liquid and a supply path for a material liquid from the supply source to the electrospinning head  2 . As shown in  FIG.  1   , etc., the supplier  3  of a material liquid includes a storage unit  31 , a supply driver  32 , a supply adjuster  33 , and a supply pipe  35 . Each of the storage unit  31 , the supply driver  32 , the supply adjuster  33 , and the supply pipe  35  has resistance to a material liquid, and in one example, each of the storage unit  31  and the supply pipe  35  is made of a material having electrically insulating properties, such as a fluorine resin. 
     The storage unit  31  is a reservoir for storing material liquids, for example. A material liquid is a solution of a high-polymer material in a solvent. The high polymer included in the material liquid and the solvent in which the high polymer is dissolved are determined as appropriate in accordance with the type, etc. of fiber  20  to be accumulated on the surface of the collection body  5 . The high polymer material is not limited to a specific type, and any type can be used as appropriate according to material properties of the fiber  20  to be formed. The examples of the high polymer material are: polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, polycarbonate, nylon, aramid, polyimide, and polyamide-imide etc. Any solvent used for a material liquid is used provided a high polymer material can dissolve into the solvent. The solvent can be changed as appropriate in accordance with a high-polymer material to be dissolved. As the solvent, for example, water, methanol, ethanol, isopropyl alcohol, acetone, benzene, toluene, N-methyl-2-pyrrolidone (NMP), and dimethylacetamide (DMAc), etc. can be used. 
     The supply pipe  35  connects the storage unit  31  to the electrospinning head  2  so as to form a supply passage for the material liquid. The supply driver  32  is driven to supply a material liquid to the electrospinning head  2  from the storage unit  31  through the supply pipe  35 . In one example, the supply driver  32  is a pump. The supply adjuster  33  adjusts an amount of flow and a pressure, etc. of the material liquid supplied to the electrospinning head  2 . In one example, the supply adjuster  33  includes a controlling valve capable of controlling an amount of flow and a pressure, etc. of a material liquid. In this case, the supply adjuster  33  adjusts the amount of flow and the pressure, etc. of the material liquid as appropriate based on a viscosity of the material liquid and the structure of the nozzle  12 , and the like. In one example, the supply adjuster  33  is capable of switching between supply and non-supply of the material liquid from the storage unit  31  to the electrospinning head  2 . In this case, the supply adjuster  33  includes, for example, a switching valve. 
     As shown in  FIGS.  1  and  2   , etc., the power supply source is capable of applying voltages to the electrospinning head  2 . Through an application of a voltage to the electrospinning head  2 , a voltage of a predetermined polarity is applied to each nozzle  12  via the head main body  11 . A voltage of the same polarity is applied to respective nozzles  12 . Through an application of a voltage to the electrospinning head  2  by the power supply source  4  as described above, and a supply of a material liquid to the electrospinning head  2  by the supplier  3 , the material liquid is electrified in the same polarity as the nozzles  12  (electrospinning head  2 ). 
     In one example, a terminal (not shown) electrically connected to each nozzle  12  is provided, and the power supply source  4  may apply a voltage to each nozzle  12  through the terminal. In this case, the head main body  11  is not necessarily made of an electrically conductive material. The polarity of the voltage applied to each nozzle  12  may be positive or negative. In the example shown in  FIGS.  1  and  2   , etc., the power supply source  4  is a direct current power source and applies a positive voltage to each nozzle  12 . 
     The collection body  5  is made of an electrically conductive material. The collection body  5  has resistance against the material liquid, and in one example, is made of stainless steel. As shown in  FIG.  1   , etc., the collection body  5  is arranged, with respect to the electrospinning head  2 , on the side where the nozzles  12  project and to which the projection ports  16  are open. Accordingly, with respect to the electrospinning head  2 , the collection body  5  is arranged on the side where the material liquid is ejected from each nozzle  12 . In the example of  FIG.  1   , etc., the collection body  5  is grounded and the voltage of the collection body  5  relative to the ground is 0 V or approximately 0 V. In another example, voltages of a polarity opposite to the polarity of the voltages applied to a material liquid and the electrospinning head  2  (nozzles  12 ) are applied to the collection body  5  by either the power supply source  4  or another power supply source. 
     In the present embodiment, through the application of voltages to the electrospinning head  2  and the supply of a material liquid to the electrospinning head  2 , the material liquid is electrified with the same polarity as the electrospinning head  2 . Furthermore, the material liquid is electrified by the same polarity as the electrospinning head  2  and thereby ejected from the ejection port  16  of each nozzle  12  toward the collection body  5  by an electric potential difference between the electrified material liquid of the electrospinning head  2  (nozzles  12 ) and the collection body  5 . As a result of the ejection of the material liquid from the electrospinning head  2  toward the collection body  5 , fiber  20  is accumulated on the surface of the collection body  5 , and the accumulated fiber  20  is thereby formed into a film of the fiber  20 . In other words, the film of the fiber  20  is formed by an electrospinning method (sometimes referred to as “electric charge induction spinning method”). The voltages applied to the nozzles  12  (electrospinning head  2 ), and the voltage applied to the collection body  5 , and the like are adjusted as appropriate in accordance with a type of the high polymer material contained in the material liquid and a distance between the electrospinning head  2  and the collection body  5 , etc.  FIG.  1    shows a state in which a film of fiber  20  is being formed, with the suction unit  7  omitted. 
     The collection body  5  is formed in a plate-like shape or a sheet-like shape, for example. In the case where the collection body  5  is formed in a sheet-like shape, the fiber  20  may be accumulated on the collection body  5  rolled around the outer peripheral surface of a roll or the like. The collection body  5  may be movable. In one example, a pair of rotating drums, and their drive source, are provided. Driving of the rotating drums by the drive source causes the collection body  5  to be moved between drums in a manner similar to a conveyor belt. Through the moving (transfer) of the collection body  5 , it is possible to change the area where the fiber  20  is accumulated on the surface of the collection body  5  over time. The film of the fiber  20  formed on the surface of the collection body  5  is removed from the collection body  5 . The film of the fiber  20  is used as a nonwoven fabric or a filter, etc., but the usage is not limited thereto. 
     In one example, the collection body  5  is not provided. In this case, a substrate made of an electrically conductive material is used. Through the application of a voltage to the electrospinning head  2  in the above-described manner and the supply of a material liquid to the electrospinning head  2 , the material liquid is ejected from the ejection port  16  of each nozzle  12  toward the substrate. Thus, the fiber  20  is accumulated on the surface of the substrate, and a film of the fiber  20  is formed on the surface of the substrate. In this case, the substrate may be grounded, and a voltage of an opposite polarity to the voltage applied to the electrospinning head  2  (nozzles  12 ) may be applied to the substrate either by the power supply source  4  or another power supply source. 
     In another example, a substrate is placed on the collection body  5 . Through the application of a voltage to the electrospinning head  2  in the above-described manner and the supply of a material liquid to the electrospinning head  2 , the material liquid is ejected from the ejection port  16  of each nozzle  12  toward the collection body  5  and the substrate. Thus, the fiber  20  is accumulated on the surface of the substrate placed on the collection body  5 , and a film of the fiber  20  is formed on the surface of the substrate. In this case, even if the substrate has electrically insulating properties, it is possible to form a film of the fiber  20  on the surface of the substrate. 
     In the case where the substrate is arranged on the collection body  5 , the substrate may be movable on the collection body  5 . In one example, a rotating drum around which the substrate in a sheet-like shape is rolled, and a rotating drum that winds around itself the substrate on which the film of the fiber  20  is formed are provided. Furthermore, the substrate is moved on the collection body  5  by the rotation of each rotating drum. Through the moving (transfer) of the substrate, it is possible to change the area where the fiber  20  is accumulated on the surface of the substrate over time. As an example where the film of the fiber  20  is formed on the surface of the substrate, although not limited thereto, manufacturing of a separator-integrated type electrode for a battery is known. In this case, either one of the negative electrode or the positive electrode of an electrode group may be used as the substrate. The film of the fiber  20  formed on the surface of the substrate serves as a separator integrated with the negative electrode or the positive electrode. 
     In the electrospinning apparatus  1 , when the work to form a film of the fiber  20  is performed as described above, the fiber  20 , droplets of the material liquid and a high polymer material of the material liquid deposited on the outer surface of each nozzle  12 , particularly in the vicinity of the ejection port  16 . For this reason, after the work of forming a film of the fiber  20  is performed, the deposits on the nozzles  12  are removed so as to clean the electrospinning head  2 . The suction head  6  and the suction unit  7  are used to clean the electrospinning head  2 .  FIG.  2    shows the state in which the electrospinning head  2  is being cleaned, with the supplier  3  and the collection body  5  being omitted. The suction head  6  and the suction unit  7  suction the deposits, etc. on the nozzles  12  during the cleaning of the electrospinning head  2 . 
       FIG.  4    shows one of the nozzles  12  and the suction head  6  in a state in which suction is being performed by the suction head  6  and the suction unit  7 . As shown in  FIGS.  1 ,  2 , and  4   , etc., the suction head  6  is formed in the shape of a cylinder, and a suction hollow  61  is formed therein. The suction hollow  61  opens at a suction opening  62  to the outside of the suction head  6 . The suction head  6  is made from a material having electrically insulating properties, for example a resin having electrically insulating properties. The suction head  6  includes head constituent parts  63  and  65 . In the example shown in  FIGS.  2  and  4   , etc., the head constituent part (first head constituent part)  63  has an outer diameter larger than that of the head constituent part (second head constituent part)  65 . In the head constituent part  63 , the suction opening  62  is formed at the end on the side opposite to the head constituent part  65 . 
     The suction unit  7  constitutes a suction source for suctioning from the suction opening  62  of the suction head and a suction passage from the suction head  6  to the suction source. As shown in  FIG.  2   , etc., the suction unit  7  includes a suction driver  71 , a collecting unit  72 , and a suction pipe  73 . Being driven, the suction driver  71  causes matter to be suctioned from the suction opening  62  of the suction head  6 . Through the driving of the suction driver  71  (suction driving) as described above, a suction force is exerted in such a manner that matter on the outside of the suction head  6  are drawn into the suction hollow  61  via the suction opening  62 . The suction driver  71  is a pump or a blower, etc. 
     The collecting unit  72  is a tank for accumulating matter suctioned through the suction opening  62 . In the suction unit  7 , a filter (not shown), etc. is provided between the suction driver  71  and the collecting unit  72 , so that suctioned matter is prevented from flowing into the suction driver  71 . The suction pipe  73  connects the suction head  6  to the collecting unit  72 , thereby forming a suction passage for suctioned matter. As shown in  FIG.  4   , etc., in the suction head  6 , the head constituent part  65  is connected to the suction pipe  73  on the side opposite to the suction opening  62 . 
     The head mover unit  8  constitutes a mechanism for moving the suction head  6  relative to the electrospinning head  2 , etc. Herein, in the electrospinning apparatus  1 , a first direction (the direction indicated by arrows X 1  and X 2 ), a second direction intersecting (perpendicular or approximately perpendicular to) the first direction (the direction indicated by arrows Y 1  and Y 2 ), a third direction intersecting (perpendicular or approximately perpendicular to) the first and second directions (the direction perpendicular or approximately perpendicular in the sheets of  FIGS.  1  and  2   ) are defined. In one example, the third direction corresponds to, or approximately corresponds to, a vertical direction. The suction head  6  is movable in the first direction by the head mover unit  8 . The suction head  6  is also movable in at least one of the second direction or the third direction by the head mover unit  8 . 
     In the example shown in  FIGS.  1  and  2   , etc., the longitudinal direction of the electrospinning head  2  corresponds to, or approximately corresponds to, the first direction. For this reason, the direction in which a plurality of nozzles  12  are arrayed in a nozzle row corresponds to, or approximately corresponds to, the first direction. In the example shown in  FIGS.  1  and  2   , etc., each nozzle  12  projects on one side (the arrow Y 1  side) of the second direction, and each flow path  15  opens to one side (the arrow Y 1  side) of the second direction at the ejection port  16 . For this reason, in each nozzle  12 , a material liquid is ejected from the ejection port  16  toward one side of the second direction. 
     The head mover unit  8  includes a movement driver  81  and a driving force transmitting unit  82 . The movement driver  81  includes a driving member such as an electric motor, etc., and the driving member is supplied with the electric power with which it is driven. The driving force transmitting unit  82  couples the movement driver  81  to the suction head  6 . The driving force transmitting unit  82  transmits a driving force generated in the driving member of the movement driver  81  to the suction head  6  and thereby causes the suction head  6  to be moved. Herein, if the suction head  6  is movable in two directions, two driving members are provided in the movement driver  81 ; if the suction head  6  is movable in three directions, three driving members are provided in the movement driver  81 . Multiple driving members are not necessarily arranged in a single movement driver  81 ; in one example, multiple driving members for moving the suction head  6  may be arranged at positions separate from each other. As the head mover unit  8  is provided in the manner described above, the suction head  6  is movable to a position close to the electrospinning head  2  as shown in  FIG.  2   , etc. The suction head  6  approaches the electrospinning head  2  from the side to which the ejection port  16  of each nozzle  12  opens, namely one side of the second direction (the arrow Y 1  side). As the head mover unit  8  is provided, the suction head  6  is movable to a position separate from the electrospinning head  2  as shown in  FIG.  1   , etc. In the state shown in  FIG.  1   , the suction head  6  is located separate from the electrospinning head  2  in the second direction, and the collecting body  5  is located between the suction head  6  and the electrospinning head  2  according to the second direction. In a state in which the suction head  6  is moved to a position separate from the electrospinning head  2 , the suction head  6  may be located separate from the electrospinning head  2  in the second direction as shown in  FIG.  1   , etc., and the suction head  6  may be located separate from the electrospinning head  2  in the third direction. In a state in which the suction head  6  is moved to a position separate from the electrospinning head  2 , the suction head  6  may be located separate from the electrospinning head  2  in both the second and third directions. 
     The controller  9  is a computer, for example. The controller  9  includes a processor or an integrated circuit (control circuit) including a central processing unit (CPU), an application specific integrated circuit (ASIC), or a field programmable gate array (FPGA), and a storage medium, such as a memory. The controller  9  may include only one integrated circuit, etc., or a plurality of integrated circuits, etc. The controller  9  performs processing by executing a program, etc. stored on the storage medium, etc. The controller  9  controls the driving of the supply driver  32 , the operation of the supply adjuster  33 , the output of the power supply source  4 , and driving of the suction driver  71  etc. The controller  9  controls the driving of the movement driver  81  to thereby control the move of the suction head  6  and adjusts positions of the suction head  6 . 
     When a film of the fiber  20  is formed by an electrospinning method, the controller  9  controls the driving of the movement driver  81  and thereby causes the suction head  6  to be moved to a position separate from the electrospinning head  2 . Then, with the suction head  6  being located at a position separate from the electrospinning head  2 , the controller  9  applies a voltage to the nozzles  12  from the power supply source  4 . Then, the controller  9  controls the driving, etc. of the supply driver  32  to supply a material liquid to the electrospinning head  2 . Thus, the electrified material liquid is ejected from the ejection port  16  of each nozzle  12 , and a film of the fiber  20  is thereby formed. 
     When the electrospinning head  2  is cleaned, the controller  9  controls the driving of the movement driver  81  and thereby causes the suction head  6  to be moved to a position close to the electrospinning head  2 . At this time, the suction head  6  is brought into the proximity of the electrospinning head  2  from the side to which the ejection port  16  of each nozzle  12  opens. Furthermore, the controller controls the driving, etc. of the supply driver  32  to maintain the state of a material liquid not being supplied to the electrospinning head  2 . Then, when the suction head  6  is located at a position close to the electrospinning head and no material liquid is being supplied to the electrospinning head  2  by the supplier  3 , the controller  9  causes the power supply source  4  to apply a voltage to the nozzle  12  and causes the suction driver  71  to be driven (suction driving). Thus, as shown in  FIG.  4   , etc., the deposits on the nozzles  12  are electrified and the electrified deposits are suctioned into the suction hollow through the suction opening  62 . Then, the suctioned deposits (suctioned matters) drawn into the suction hollow  61  are collected by the collecting unit  72  through the suction pipe  73 . 
     When the suction driver  71  is being driven and the suction through the suction opening  62  is being performed, the controller  9  controls the driving of the movement driver  81  to cause the suction head  6  to reciprocates in the direction in which the nozzles  12  are arrayed (the direction indicated by arrow X 1  and arrow X 2 ). At this time, the suction head  6  reciprocates between the positions B 1  and B 2  shown in  FIG.  2   . Hereinafter, the nozzles located at both ends of the array direction among the nozzles  12  constituting the nozzle row will be referred to as the “nozzle  12 α” and “nozzle  12 β”. The suction head  6  moves to the position B 1 , located on the outer side with respect to the nozzle  12 α in the array direction of the nozzles  12 . The suction head  6  then moves to the position B 2 , located on the outer side with respect to the nozzle  12 β in the array direction of the nozzles  12 . In the present embodiment, when a fiber  20  film is being formed or the electrospinning head  2  is being cleaned, a voltage is applied to the electrospinning head  2  by the same power supply source  4 . In one example, however, different power supply sources may be used for applying a voltage to the electrospinning head  2  when a fiber  20  film is formed and for applying a voltage to the electrospinning head  2  when the electrospinning head  2  is cleaned. 
     The user interface  10  includes an operation component. With the operation component, operation commands to commence the formation of a fiber  20  film, operation commands to terminate the forming of a fiber  20  film, operation commands to commence the cleaning of the electrospinning head  2 , and operation commands to terminate the cleaning of the electrospinning head  2  are input by an operator. As the operation component, for example, buttons, a dial, a display, or a touch panel may be adopted. The controller  9  conducts control based on an operation command that is input through the operation component. The user interface  10  may have a notification unit that notifies information to an operator or the like. In this case, the controller  9  causes the notification unit to notify necessary information to an operator or the like. The notification unit makes a notification through display on a screen, generation of sound, or illumination of a light. 
       FIG.  5    shows an example of the processing performed by the controller  9  when a film  20  film is formed. When an operation command to commence the formation of a fiber  20  film is input through the operation component, etc. of the user interface  10 , the controller  9  controls the driving of the movement driver  81  to move the suction head  6  to a position separate from the electrospinning head  2  (S 101 ). Then, the controller  9  causes the power supply source  4  to apply a voltage to the electrospinning head  2  (S 102 ). Then, the controller  9  drives, etc., the supply driver  32  and thereby causes the supply driver  32  to supply a material liquid to the electrospinning head  2  (S 103 ). Thus, the electrified material liquid is ejected from the ejection port  16  of each nozzle  12 , and a film of the fiber  20  is thereby formed. 
     Then, the controller  9  determines whether or not an operation command to terminate the forming of a fiber  20  film is input through the operation member, etc. of the user interface  10  (S 104 ). If an operation command to terminate the forming of a fiber  20  film is not input (No in S 104 ), the process returns to S 102 . Then, the controller  9  performs the process in S 102  and thereafter in order. If an operation command to terminate the forming of a fiber  20  film is input on the other hand (Yes in S 104 ), the controller  9  stops the driving of the supply driver  32  and thereby causes the supply of a material liquid to the electrospinning head  2  to be stopped (S 105 ). Then, the controller  9  causes the application of a voltage to the electrospinning head  2  by the power supply source  4  to be stopped (S 106 ). As a result, a state in which no material liquid is ejected from the ejection port  16  of each nozzle  12  is brought. 
       FIG.  6    shows an example of the process performed by the controller  9  when the electrospinning head  2  is being cleaned. Upon input of an operation command to commence the cleaning of the electrospinning head  2  through the operation component, etc. of the user interface  10 , the controller  9  controls the driving of the movement driver  81  and thereby causes the suction head  6  to move to a position close to the electrospinning head  2  (S 111 ). The controller  9  then, for example, maintains the state in which the driving of the supply driver  32  is stopped so as to maintain the state in which the supply of a material liquid to the electrospinning head  2  is stopped (S 112 ). Then, in a state in which the electrospinning head  2  is not supplied with a material liquid, the controller  9  causes the power supply source  4  to apply a voltage to the electrospinning head  2  (S 113 ) and causes the suction driver  71  to be driven (S 114 ). Thus, the deposits on the nozzles  12  are electrified and then suctioned into the suction hollow  61  through the suction opening  62 . In a state in which the suction driver  71  is being driven (in the suction driving), the controller  9  causes the suction head  6  to reciprocate along the array direction of the nozzles  12 , by controlling the driving of the movement driver (S 115 ). 
     Then, the controller  9  determines whether or not an operation command to terminate the cleaning of the electrospinning head  2  is input through the operation member, etc. of the user interface  10  (S 116 ). If an operation command to terminate the cleaning is not input (No in S 116 ), the process returns to S 113 . Then, the controller  9  performs the process in S 113  and thereafter in order. If an operation command to terminate the cleaning is input on the other hand (Yes in S 116 ), the controller  9  causes the power supply source  4  to stop applying a voltage to the electrospinning head  2  (S 117 ) and causes the suction driver unit  71  to stop driving (suction driving) (S 118 ). As a result, a state in which the suction through the suction opening  62  of the suction head  6  is not performed is brought about. Then, the controller  9  controls the driving of the movement driver  81  so as to cause the reciprocating movement of the suction head  6  to be stopped (S 119 ). 
     In the present embodiment, on the outer surface of each nozzle  12 , an uneven surface  23  is formed in the vicinity of the projection port  16 . In each nozzle  12 , the uneven surface  23  is formed in an uneven shape around the entire periphery of the circumferential direction, and the uneven shape is along the extending direction of the flow path  15 . Since the uneven surface  23  is formed in each nozzle  12  as described above, on the outer surface of each nozzle  12 , even when the fiber  20 , droplets of a material liquid and a high polymer material of the material liquid are deposited in the vicinity of the ejection port  16 , the area of contact between such deposits and the nozzle  12  can be minimized. A small area of contact between deposits and the nozzle  12  makes it easy to remove the deposits from the nozzle  12  appropriately. It is thereby possible to clean the electrospinning head  2  effectively and appropriately. 
     In the present embodiment, in the cleaning of the electrospinning head  2 , the controller  9  causes the power supply source  4  to cause a voltage to the nozzles  12  while the electrospinning head  2  is not being supplied with a material liquid. The deposits on the nozzles  12  are thereby electrified. Thus, the deposits on the nozzles  12  can be removed more appropriately. 
     As described above, in the present embodiment, the deposits on the nozzles  12  are removed appropriately. For this reason, a time required until the ejection of the material liquid from each nozzle  12  becomes stable can be shortened when a film  20  fiber is formed after the electrospinning head  2  is cleaned. Thus, the efficiency in the process of forming a fiber  20  film is improved. 
     In the present embodiment, in a state in which a voltage is being applied to the nozzles  12  by the power supply source  4 , the suction driver  71  is driven, and the deposits on the nozzles  12  are suctioned through the suction opening  62  and thereby removed. For this reason, the deposits on the nozzles  12  are removed, without causing the suction head  6  to be in contact with the nozzles  12 . Since the deposits are removed without the suction head  6 , etc., touching the nozzles  12 , breakage of the nozzles  12  can be effectively prevented. In the present embodiment, a solvent, etc. into which the fiber  20  and a high polymer material of the material liquid are dissolved is not used to remove deposits on the nozzles  12 . For this reason, after the cleaning of the electrospinning head  2 , a solvent, etc. does not remain in the flow path  15  of each nozzle  12 . Thus, when a fiber  20  film is formed after the electrospinning head  2  is cleaned, a time required until the ejection of a material liquid from each nozzle  12  is shortened more appropriately. 
     In the present embodiment, the suction head  6  is made from a material having electrical insulating properties. For this reason, even when a voltage is applied to the nozzle  12  during the cleaning of the electrospinning head  2 , electrical connection of the portion made of an electrically conductive material in the suction unit  7  and the head mover unit  8 , etc., with the nozzles  12  via the suction head  6  can be effectively prevented. 
     Furthermore, in the present embodiment, the controller  9  causes the suction head  6  to reciprocate along the array direction of the nozzles  12  as described above, when the suction driver  71  is being driven. For this reason, deposits can be appropriately suctioned and removed in any of the arrayed nozzles  12 . 
     (Modifications) 
     In a modification, deposits on the nozzles  12  are removed by a rotational brush instead of the suction head  6 . In this modification, an uneven surface  23  is formed on each of the nozzles  12 . In the cleaning of the electrospinning head  2 , the controller  9  causes the power supply source  4  to apply a voltage to the nozzles  12  while the electrospinning head  2  is not supplied with a material liquid from the supplier  3 . While a voltage is being applied to the nozzles  12 , the rotational brush is rotated. While a voltage is being applied to the nozzles  12 , the rotating rotational brush is brought into a contact with each nozzle  12  to remove the deposits thereon. 
     The number of the nozzles  12  and the shape of each nozzle  12  is not limited to those in the forgoing embodiment, etc. In one modification, in the electrospinning head  2 , two nozzle rows are formed on the outer peripheral surface of the head main body  11 , and these nozzle rows are arranged to be shifted from each other around the center axis of the head main body  11  (in the circumferential direction of the electrospinning head  2 ). In each nozzle row, a plurality of nozzles  12  are arrayed in the longitudinal direction of the electrospinning head  2 . In another modification, only one nozzle  12  is provided in the electrospinning head  2 . 
     In any of the modifications, however, one or more nozzles  12  are provided in the electrospinning head  2 . In each nozzle  12 , a flow path  15  is formed therein, and on the outer surface, an ejection port  16  capable of ejecting a material liquid supplied to the flow path  15  is formed. On the outer surface of each nozzle  12 , an uneven surface  23  is formed in the vicinity of the ejection port  16 . In each nozzle  12 , the uneven surface  23  is formed in an uneven shape around the entire periphery of the circumferential direction, and the uneven shape is along the extending direction of the flow path  15 . 
     According to at least one of the foregoing embodiment and modifications, an uneven surface is formed in the vicinity of an ejection port on the outer surface of each nozzle, the uneven surface is formed in an uneven shape around the entire periphery of the circumferential direction of the nozzle, and the uneven shape is along the extending direction of the flow path. It is thereby possible to provide an electrospinning head that can be cleaned effectively and appropriately. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. 
     Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.