Abstract:
The drip irrigation tube ( 100 ) comprises a tube ( 110 ), drippers ( 120 ), and guides ( 140 ). With respect to individual discharge openings ( 130 ), the guides ( 140 ) are disposed on both sides of the discharge opening ( 130 ) in the longitudinal direction of the tube ( 110 ). The guides ( 140 ) protrude from the outer circumferential surface of the tube ( 110 ). The guides ( 140 ) intercept the flow of liquid from the discharge openings ( 130 ) in the longitudinal direction and guide same vertically downward. The liquid is dripped on the soil from the discharge openings ( 130 ) or the vicinity of the discharge openings ( 130 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a drip irrigation tube. 
       BACKGROUND ART 
       [0002]    Drip irrigation methods are known as one of plant cultivating methods. In the drip irrigation methods, a drip irrigation tube is disposed on the soil, and irrigation liquid such as water and liquid fertilizer is slowly supplied from the drip irrigation tube into the soil on which plants are planted, for example. The drip irrigation methods can minimize the liquid consumption, and therefore have increasingly attracted attention in recent years. 
         [0003]    Such a drip irrigation tube typically has a tube and a dripper. Typically, the dripper supplies the irrigation liquid in the tube to the soil at a set rate at which the irrigation liquid drips into the soil. Known examples of the dripper include a dripper which is disposed in such a manner as to stick into a tube from outside, and a dripper which is bonded on an inner wall of a tube. 
         [0004]    The latter dripper has, for example, a channel including a pressure reduction channel that allows liquid, which has flowed from the inside of the tube to the dripper, to flow toward an ejection port opening at a tube wall of the tube while depressurizing the liquid; and a diaphragm that changes the volume of a part, of the channel, where the depressurized irrigation liquid flows in accordance with the liquid pressure in a tube space. The dripper is composed of three members, i.e., a base part bonded to the inner wall of the tube, a coating part disposed on the base part, and a diaphragm disposed between the two members. The base part includes a chimney part having I-shaped cross-sectional shape, for example. The chimney part pushes the wall of the tube from inside. Cutting both the chimney part and the part pushed by the chimney part allows the ejection port to be formed. Further, the chimney part secures a space which serves as a channel of liquid at the ejection port (see, e.g., PTL 1). 
         [0005]    The drippers can suppress variations in the ejection amount of the irrigation liquid regardless of changes in liquid pressure in the tube space. Further, liquid ejected from the ejection port is more likely to drip from the tip of the chimney part. Accordingly, the liquid is more likely to be supplied to the soil immediately below the ejection port. Therefore, the dripper is advantageous from the perspective of growing multiple plants uniformly. 
       CITATION LIST 
     Patent Literature 
     PTL 1 
       [0006]    U.S. Pat. No. 8,302,887 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    The drip irrigation tube is sometimes disposed such that the ejection port faces upward, in order to prevent the soil from attaching to the periphery of an opening of the ejection port to clog the ejection port. When the drip irrigation tube is disposed such that the ejection port faces upward, liquid ejected from the ejection port sometimes runs along the outer wall of the tube in the longitudinal direction of the tube and drips at a position distant from the ejection port to be absorbed into the soil. Therefore, it is desired to supply liquid ejected from the drip irrigation tube to the soil at an intended rate from an intended position at which the ejection port is formed, regardless of the orientation of the ejection port, of the drip irrigation tube, on the soil. 
         [0008]    An object of the present invention is to provide a drip irrigation tube capable of supplying liquid in the tube to the soil from the ejection port or a position in the vicinity of the ejection port in the longitudinal direction of the tube. 
       Solution to Problem 
       [0009]    A drip irrigation tube according to the present invention includes: a tube to which liquid is supplied; an ejection port allowing communication between an inside and an outside of the tube for ejecting the liquid from the inside of the tube; and guide parts for guiding the liquid in a circumferential direction of the tube, provided circumferentially at two locations, for each ejection port, on an outer circumferential surface of the tube such that the ejection port is interposed in a longitudinal direction of the tube. 
       Advantageous Effects of Invention 
       [0010]    Since the drip irrigation tube according to the present invention has the guide part, the flow of liquid running along the outer wall of the tube in the longitudinal direction of the tube is retained at the guide part. Thus, the liquid is likely to be accumulated at the guide part, and the accumulated liquid is likely to be guided downward along the guide part to drip from the guide part. Therefore, according to the drip irrigation tube of the present invention, it is possible to supply liquid in the tube to the soil from a position at least in the vicinity of an ejection port in the longitudinal direction of the tube, even when the liquid ejected from the ejection port runs in the longitudinal direction of the tube. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1A  is a schematic plan view of a drip irrigation tube according to Embodiment 1 of the present invention, and  FIG. 1B  is a cross-sectional view of the drip irrigation tube cut along line A-A in  FIG. 1A ; 
           [0012]      FIG. 2  illustrates an enlarged cross-section of a dripper in the drip irrigation tube according to Embodiment 1; 
           [0013]      FIG. 3A  illustrates an upper surface, a front surface, and a side surface of the dripper according to Embodiment 1, and  FIG. 3B  illustrates a bottom surface, the front surface and the side surface of the dripper of Embodiment 1; 
           [0014]      FIG. 4A  to  FIG. 4D  are a plan view, a front view, a bottom view and a side view of the dripper according to Embodiment 1, respectively; 
           [0015]      FIG. 5A  to  FIG. 5D  are a plan view, a front view, a bottom view and a side view of a dripper body according to Embodiment 1, respectively; 
           [0016]      FIG. 6A  to  FIG. 6D  are a plan view, a front view, a bottom view and a side view of a movable part according to Embodiment 1, respectively; 
           [0017]      FIG. 7A  is a side view schematically illustrating a state before the movement of the movable part of the dripper according to Embodiment 1, and  FIG. 7B  is a side view schematically illustrating a state after the movement of the movable part of the dripper; 
           [0018]      FIG. 8A  is a cross-sectional view schematically illustrating the dripper according to Embodiment 1 cut along line A-A in  FIG. 4C  before the movement of the movable part, and  FIG. 8B  is a cross-sectional view schematically illustrating the dripper cut along line A-A in  FIG. 4C  after the movement of the movable part; 
           [0019]      FIG. 9A  is a cross-sectional view of the drip irrigation tube according to Embodiment 1 cut along line A-A in  FIG. 1A , schematically illustrating liquid being ejected from the drip irrigation tube disposed such that ejection ports face downward, and  FIG. 9B  is a front view schematically illustrating liquid being ejected from the drip irrigation tube according to Embodiment 1 disposed such that ejection ports face upward; 
           [0020]      FIG. 10A  is a schematic front view of a drip irrigation tube according to Embodiment 2 disposed such that ejection ports face upward, and  FIG. 10B  schematically illustrates liquid being ejected from the drip irrigation tube; 
           [0021]      FIG. 11A  is a schematic front view of a drip irrigation tube according to Embodiment 3 of the present invention, and  FIG. 11B  is a schematic front view of a drip irrigation tube according to Embodiment 4 of the present invention; 
           [0022]      FIG. 12A  illustrates an upper surface, a front surface, and a side surface of a dripper according to Embodiment 5 of the present invention, and  FIG. 12B  illustrates a bottom surface, the front surface and the side surface of the dripper; 
           [0023]      FIG. 13A  to  FIG. 13D  are a plan view, a front view, a bottom view and a side view of the dripper according to Embodiment 5, respectively; 
           [0024]      FIG. 14A  is a cross-sectional view schematically illustrating the dripper according to Embodiment 5 cut along line A-A in  FIG. 13C  before the movement of the movable part, and  FIG. 14B  is a cross-sectional view schematically illustrating the dripper cut along line A-A in  FIG. 13C  after the movement of the movable part; and 
           [0025]      FIG. 15A  is a schematic front view of a drip irrigation tube according to Embodiment 6 or 7 disposed such that ejection ports face upward,  FIG. 15B  schematically illustrates liquid being ejected from the drip irrigation tube according to Embodiment 6, and  FIG. 15C  schematically illustrates liquid being ejected from the drip irrigation tube according to Embodiment 7. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       Embodiment 1 
       [0027]      FIG. 1A  is a schematic plan view of a drip irrigation tube according to Embodiment 1 of the present invention, and  FIG. 1B  is a cross-sectional view of the drip irrigation tube cut along line A-A in  FIG. 1A . Drip irrigation tube  100  is composed of tube  110 , drippers  120 , ejection ports  130 , and guide parts  140 . 
         [0028]    Tube  110  is made of, for example, polyethylene, and dripper  120  is made of, for example, polypropylene. 
         [0029]    Drippers  120  are disposed at a predetermined interval (e.g., 200 to 500 mm) in the axis direction of tube  110 . Each dripper  120  is fixed on the inner wall of tube  110  by welding. Dripper  120  is disposed at a position where dripper  120  covers ejection port  130  of tube  110 . Specifically, dripper  120  is disposed such that an ejection part thereof described below covers ejection port  130 . 
         [0030]    Ejection port  130  is a through hole extending through the tube wall of tube  110 . The hole diameter of ejection port  130  is, for example, 1.5 mm. Ejection port  130  is typically formed after dripper  120  is welded. 
         [0031]    Guide part  140  is a different diameter part having an outer diameter different from the outer diameter of the tube. Guide part  140  is disposed at two locations, for single ejection port  130  (a part at which ejection port  130  is to be formed if ejection port  130  has not been formed yet), such that ejection port  130  is interposed between guide parts  140  in the longitudinal direction of tube  110 . That is, each ejection port  130  is disposed between two guide parts  140  in the longitudinal direction. 
         [0032]    The distance from ejection port  130  to guide part  140  is preferably as short as possible, from the perspective of dripping liquid ejected from ejection port  130  from a position near ejection port  130  to the soil. From such a perspective, the distance from ejection port  130  to guide part  140  is preferably 10 to 100 mm, and more preferably 10 to 50 mm. The distance from ejection port  130  to guide part  140  may be constant or different. Note that the distance from ejection port  130  to guide part  140  is the shortest distance from the center of ejection port  130  to guide part  140  in the longitudinal direction. 
         [0033]    Each guide part  140  is provided circumferentially in the circumferential direction of tube  110  on the outer circumferential surface of tube  110 . Guide part  140  constitutes a part having an outer diameter larger than the outer diameter of tube  110  on the outer circumferential surface of tube  110 . Guide part  140  is formed, for example, by winding an adhesive tape. 
         [0034]    Guide part  140  has an outer diameter larger than the outer diameter of tube  110 . Guide part  140  forms a step difference on the outer circumferential surface of tube  110 . The half value of the difference obtained by subtracting the outer diameter of tube  110  from the outer diameter of guide part  140  (height difference equivalent to one step difference; hereinafter, also referred to as “height”) is, for example, 2 mm. The height of guide part  140  can be appropriately determined within such a range as to bring a function of guiding liquid described below downward along the circumferential direction of tube  110  (hereinafter, also referred to as “drip-facilitating function”). The height of guide part  140  is preferably 0.5 to 5 mm, and more preferably 0.5 to 3 mm, from the above-mentioned perspective. The height of guide part  140  may be constant, different, an average value, or the minimum value. 
         [0035]    The width of guide part  140  (length of guide part  140  in the longitudinal direction of tube  110 ) is, for example, 3 mm. The width of guide part  140  can be appropriately determined within a range smaller than the distance between adjacent ejection ports  130  in the longitudinal direction of tube  110 . The width of guide part  140  is preferably 1 to 20 mm, and more preferably 2 to 10 mm, from the above-mentioned perspective. The width of guide part  140  may be constant, different, an average value, or the minimum value. 
         [0036]    Liquid in tube  110  is ejected from ejection port  130  by dripper  120  at a set rate. First, the configuration and function of dripper  120  will be described below. 
         [0037]      FIG. 2  illustrates an enlarged cross-section of the dripper in the drip irrigation tube according to the present embodiment.  FIG. 3A  illustrates an upper surface, a front surface, and a side surface of the dripper according to the present embodiment, and  FIG. 3B  illustrates a bottom surface, the front surface and the side surface of the dripper according to the present embodiment.  FIG. 4A  to  FIG. 4D  are a plan view, a front view, a bottom view and a side view of the dripper according to the present embodiment, respectively. 
         [0038]    Dripper  120  has dripper body  121  and movable part  122  engaged with dripper body  121 , as shown in  FIG. 2 . Dripper  120  forms a liquid channel which is independent from the inner space of tube  110  and allows the inner space of tube  110  to communicate with ejection port  130 . The channel includes inflow part  124 , pressure reduction channel  125  and ejection part  126 . Inflow part  124  communicates with the inner space of tube  110  through inflow ports  123 . Pressure reduction channel  125  is formed by fitting a projection of movable part  122  described below with an open part of dripper body  120  described below. 
         [0039]    A depression (also referred to as “top surface side recess”) is formed on the upper surface (top surface) of dripper  120 , and a plurality of protrusions  1201  are disposed in the top surface side recess, as shown in  FIGS. 3A and 4A . Protrusions  1201  extend in transverse direction Y of dripper  120  and are arranged in parallel in longitudinal direction X of dripper  120 . Both ends of protrusion  1201  are apart from side walls of the top surface side recess in Y direction. The height of protrusion  1201  is, for example, 0.5 mm, and the interval between protrusions  1201  (the distance between the axes of protrusions  1201 ) is, for example, 0.5 mm 
         [0040]    A plurality of inflow ports  123  are disposed on the bottom of the top surface side recess at one end part in X direction, as shown in  FIGS. 3B and 4C . Inflow ports  123  are disposed in lines along protrusions  1201  (in Y direction). Inflow port  123  is a hole extending through the bottom of the top surface side recess and allows the upper side of dripper  120  to communicate with inflow part  124 . The hole diameter of inflow port  123  is, for example, 0.3 mm 
         [0041]    As shown in  FIGS. 3B and 4C , each of inflow part  124  and ejection part  126  is a rectangular depression (also referred to as “bottom surface side recesses”) which is recessed from the bottom surface of dripper body  121  and is disposed at each end part of dripper body  121 . The height of inflow part  124  (the depth of the bottom surface side recess at one end side in X direction) is, for example, 1.0 mm, and the height of ejection part  126  (the depth of the bottom surface side recess at the other end side in X direction) is, for example, 1.0 mm 
         [0042]    Pressure reduction channel  125  allows inflow part  124  to communicate with ejection part  126 , as shown in  FIG. 4C . The shape of pressure reduction channel  125  in plan view is a zigzag shape. The zigzag shape is formed by alternately disposing protrusions each having a substantially triangular shape and protruding from side walls of pressure reduction channel  125  in the longitudinal direction of pressure reduction channel  125 . The protrusion is formed such that the tip end of the protrusion does not go beyond the central axis of pressure reduction channel  125  in plan view. Both end parts of pressure reduction channel  125  are formed only with dripper body  121 , and the other part of pressure reduction channel  125  is formed by fitting a projection of movable part  122  together with an open part formed in dripper body  121  ( FIGS. 4B and 4C ). 
         [0043]      FIG. 5A  to  FIG. 5D  are a plan view, a front view, a bottom view and a side view of the dripper body according to the present embodiment, respectively. 
         [0044]    Dripper body  121  is made of, for example, polypropylene. Dripper body  121  has first end part  1211 , second end part  1212  and connecting part  1213  as shown in  FIGS. 5A to 5C . First end part  1211  includes the top surface side recess, protrusions  1201 , inflow ports  123  and inflow part  124 . Second end part  1212  includes the top surface side recess, protrusions  1201  and ejection part  126 . 
         [0045]    Further, first end part  1211  and second end part  1212  have elastic supporters  1214  and  1215 , respectively, at both end parts of first end part  1211  and second end part  1212 . Both elastic supporters  1214  and  1215  are disposed at relatively high positions on upper surface (top surface) side relative to the center of dripper body  121  in the height (thickness) direction. Elastic supporter  1214  is a plate-shaped elastic member protruding from an end surface of first end part  1211  on second end part  1212  side. Elastic supporter  1215  is a plate-shaped elastic member protruding from an end surface of second end part  1212  on first end part  1211  side. The upper surface (top surface) of each of elastic supporters  1214  and  1215  is parallel with the top surface of dripper body  121 . An inclining surface inclined from top surface side to the bottom surface side is formed at the tip of the upper surface (top surface) of each of elastic supporters  1214  and  1215 . 
         [0046]    Connecting part  1213  connects first end part  1211  with second end part  1212 . The shape of connecting part  1213  in plan view is a substantially cross shape formed by cutting out a rectangle having a shape substantially the same as the shape of elastic supporters  1214  and  1215  in plan view from every corner of a rectangle, as shown in  FIGS. 5A and 5C . Connecting part  1213  has a bottom surface on the same plane as the bottom surfaces of first end part  1211  and second end part  1212 , as shown in  FIG. 5B . The thickness (height) of connecting part  1213  is less than half the height of dripper body  121 , and slightly larger than the height of pressure reduction channel  125 . The height of connecting part  1213  is, for example, about 1.3 times as large as the height of pressure reduction channel  125 . 
         [0047]    Connecting part  1213  includes open part  1216  which opens to the inner space of tube  110  except for both end parts of pressure reduction channel  125 . The shape of open part  1216  in plan view is the same as the zigzag shape of pressure reduction channel  125 , as shown in  FIGS. 5A and 5C . Open part  1216  is configured of a cut extending through connecting part  1213  in the thickness direction of connecting part  1213 . 
         [0048]      FIG. 6A  to  FIG. 6D  are a plan view, a front view, a bottom view and a side view of a movable part according to the present embodiment, respectively. 
         [0049]    Movable part  122  is made of, for example, polypropylene. Movable part  122  has pressure receiving part  1221 , spacer  1222 , engaging part  1223  and projection  1224 , as shown in  FIGS. 6A to 6D . Pressure receiving part  1221  forms the top surface of movable part  122 . Pressure receiving part  1221  includes the depression, and protrusions  1201 . The shape of pressure receiving part  1221  is substantially rectangular, but every corner is slightly cut out by a rectangle. The length of the cutout in X direction is several millimeters, and the length of the cutout in Y direction is substantially the same as the length of elastic supporter  1215  in Y direction. End parts of pressure receiving part  1221  in Y direction have a linear cut formed in X direction from each cutout. 
         [0050]    Spacer  1222  is disposed on the bottom surface side of pressure receiving part  1221 . The shape of spacer  1222  in plan view is rectangular. The length of spacer  1222  in X direction is less than the distance between the tip ends of elastic supporters  1214  and  1215  of dripper body  121 , and the length of spacer  1222  in Y direction is substantially the same as the length of pressure receiving part  1221  in Y direction. The thickness of spacer  1222  is substantially the same as the thickness of elastic supporters  1214  and  1215 . Spacer  1222  is disposed at a center of movable part  122  in X direction where spacer  1222  does not touch the tip end of elastic supporter  1214  or elastic supporter  1215 . 
         [0051]    Engaging part  1223  is connected to the bottom surface side of spacer  1222 . The shape of engaging part  1223  in plan view is rectangular. An inclining surface inclined from bottom surface side to the top surface side is formed at both ends of the bottom surface of engaging part  1223  in X direction. The length of engaging part  1223  in X direction is substantially the same as the length of the remaining part of pressure receiving part  1221  in X direction after the cutout at the both end parts. The length of engaging part  1223  in Y direction is substantially the same as the length of pressure receiving part  1221  in Y direction. 
         [0052]    Projection  1224  is a part connected to the bottom surface side of engaging part  1223  as shown in  FIGS. 6B and 6D . The shape of projection  1224  in plan view is the same as the shape of open part  1216  of dripper body  121  in plan view as shown in  FIG. 6C . The protruding height of projection  1224  is the sum of a movable distance of movable part  122  and an additional distance a. The movable distance is a distance from the bottom surface of spacer  1222  to the top surface of connecting part  1213  of dripper body  121 , and is 0.5 mm for example. The distance a is a distance for slightly fitting the head of projection  1224  with open part  1216  for the positioning of projection  1224 , and is about 0.25 mm for example. 
         [0053]    Dripper  120  is assembled by disposing movable part  122  on connecting part  1213  and by pushing movable part  122  into connecting part  1213 . In response to the pushing, elastic supporters  1214  and  1215  are bent, and the inclining surfaces of the tips of engaging part  1223  slide on the inclining surfaces of the tips of elastic supporters  1214  and  1215 , and thus, elastic supporters  1214  and  1215  are fit in the gap between pressure receiving part  1221  and engaging part  1223 . As a result, elastic supporters  1214  and  1215  support pressure receiving part  1221 , and engage with engaging part  1223 . Movable part  122  is thus supported in dripper body  121  with the elasticity of elastic supporters  1214  and  1215  in a movable manner Projection  1224  of movable part  122  covers open part  1216  from above and is slightly fit with open part  1216  of dripper body  121 . With this fitting, pressure reduction channel  125  is formed. 
         [0054]      FIG. 7A  is a side view schematically illustrating a state before the movement of the movable part of the dripper according to the present embodiment, and  FIG. 7B  is a side view schematically illustrating a state after the movement of the movable part of the dripper.  FIG. 8A  is a cross-sectional view schematically illustrating the dripper according to the present embodiment cut along line A-A in  FIG. 4C  before the movement of the movable part, and  FIG. 8B  is a cross-sectional view schematically illustrating the dripper cut along line A-A in  FIG. 4C  after the movement of the movable part. 
         [0055]    When a sufficient pressure is not exerted on pressure receiving part  1221 , movable part  122  does not move as shown in  FIGS. 7A and 8A . In this case, height h 0  of pressure reduction channel  125  (the distance from the bottom surface of connecting part  1213  to the head of projection  1224 ) is 0.75 mm for example. The cross-sectional area of pressure reduction channel  125  has a maximum value in this case. 
         [0056]    When a sufficient pressure is exerted on pressure receiving part  1221 , movable part  122  is biased to the bottom surface side of dripper  120  and elastic supporters  1214  and  1215  supporting movable part  122  are bent as shown in  FIGS. 7B and 8B . Movable part  122  thus moves toward the bottom surface side to allow projection  1224  to slide further into open part  1216 . Height h 1  of pressure reduction channel  125  in this case is smaller than h 0  and 0.25 mm for example. 
         [0057]    When the pressure on pressure receiving part  1221  is released, movable part  122  slides on open part  1216  upward with the elasticity of elastic supporters  1214  and  1215 , and the height of pressure reduction channel  125  increases. In this case, the height of pressure reduction channel  125  is h 0 . Thus, movable part  122  slides forward or backward on open part  1216  in accordance with the pressure on pressure receiving part  1221 , and the height (cross-sectional area) of pressure reduction channel  125  changes. 
         [0058]    The operation of dripper  120  in drip irrigation tube  100  will be described. Liquid is supplied in drip irrigation tube  100  in  FIG. 2 . The liquid flows in X direction. The liquid fills gaps between protrusions  1201 . Protrusions  1201  are arranged in parallel in the longitudinal direction (direction X) on the top surface of dripper  120 , and gaps are formed between the both ends of protrusions  1201  in Y direction and side walls of the top surface side recess. With this configuration, the gaps between protrusions  1201  are not completely clogged even when a floating object such as a fallen leaf in the liquid sticks to the top surface of dripper  120 . Thus, the gaps to which inflow ports  123  open between protrusions  1201  are filled with liquid at all times. In this manner, protrusions  1201  provide a function as a filter. 
         [0059]    Inflow ports  123  are through holes formed in dripper body  121  made of polypropylene; therefore, inflow ports  123  have water repellency specific to polypropylene. When liquid pressure is at a specific value (e.g., 0.005 MPa, which is also referred to as “burst pressure”) or higher, the liquid filling the gaps overcomes the liquid surface tension of the water repellency, and flows into inflow part  124  from inflow ports  123 . In this manner, inflow ports  123  provide a low-pressure stopping function to inhibit the inflow of liquid whose pressure is lower than a specific value. The low-pressure stopping function can be adjusted by the hole diameter, pitch, number, open part shape, length (thickness of the bottom of the top surface side recess) of inflow ports  123 , and the like. 
         [0060]    Liquid having a pressure equal to or higher than the burst pressure flows into inflow part  124 , and then flows through pressure reduction channel  125 . The liquid flowing through pressure reduction channel  125  is depressurized by pressure drop which is caused by the shape of pressure reduction channel  125  in plan view (zigzag shape). The depressurized liquid is received in ejection part  126 . The liquid received in ejection part  126  is ejected from ejection port  130 . The liquid ejected from ejection port  130  drips from drip irrigation tube  100  into the soil, for example. 
         [0061]    When the liquid pressure in drip irrigation tube  100  is in a range from the burst pressure to a specific pressure higher than the burst pressure (e.g., 0.05 MPa, which is also referred to as “movement starting pressure”), movable part  122  does not move. This is because the elasticity of elastic supporters  1214  and  1215  overcome the liquid pressure on pressure receiving part  1221 . During this time, the liquid ejection rate from ejection port  130  is substantially constant at a set rate. 
         [0062]    When the liquid pressure in drip irrigation tube  100  is equal to or higher than the movement starting pressure, the pressure on pressure receiving part  1221  overcomes the elasticity of elastic supporters  1214  and  1215 , and movable part  122  moves in accordance with the pressure toward the bottom surface side of dripper  120  in a range of less than 0.5 mm. As a result, the height of pressure reduction channel  125  becomes, for example, 0.5 mm, and the amount of liquid flowing through pressure reduction channel  125  is limited. In this manner, the increase of a liquid flow rate due to the pressure increase is offset by the decrease of the liquid flow rate caused by reduction of the cross-sectional area of pressure reduction channel  125 , and thus a supply rate of the liquid to ejection part  126  is maintained at a substantially constant rate. Consequently, the ejection rate of the liquid from ejection port  130  is substantially maintained at the above-mentioned set rate. 
         [0063]    When the liquid pressure in drip irrigation tube  100  is equal to or higher than a specific pressure which is larger than the movement starting pressure (e.g., 0.1 MPa, which is also referred to as “maximum movement pressure”), movable part  122  is further biased by the liquid pressure. As a result, the height of pressure reduction channel  125  minimized (to the above-described fu, e.g., 0.25 mm), and the amount of the liquid flowing through pressure reduction channel  125  is further limited. In this manner, the increase of a liquid flow rate due to the further pressure increase is offset by the decrease of the liquid flow rate caused by the further reduction of the cross-sectional area of pressure reduction channel  125  and thus the supply rate of the liquid to ejection part  126  is still maintained at a substantially constant rate. Consequently, the ejection rate of the liquid from ejection port  130  is substantially maintained at the above-mentioned set rate. 
         [0064]    Next, the functions of guide part  140  will be described. 
         [0065]      FIG. 9A  is a cross-sectional view of drip irrigation tube  100  cut along line A-A in  FIG. 1A , schematically illustrating liquid  150  being ejected from drip irrigation tube  100  disposed such that ejection port  130  faces downward, and  FIG. 9B  is a front view schematically illustrating liquid  150  being ejected from drip irrigation tube  100  disposed such that ejection port  130  faces upward. 
         [0066]    Typically, liquid  150  ejected from ejection port  130  is accumulated at the opening of ejection port  130  and drips. Liquid  150  is ejected from ejection port  130  at a set rate, and thus drips into the soil or the like at a properly set rate. 
         [0067]    When drip irrigation tubes  100  is obliquely disposed partially or entirely, liquid  150  ejected from ejection port  130  runs along the lowest part of tube  110  and flows toward one side along the longitudinal direction of tube  110 , as shown in  FIG. 9A . The flow of liquid  150  along the lowest part is blocked by guide part  140 . Liquid  150  is supplied to guide part  140  at the above-mentioned set rate, and liquid  150  blocked at guide part  140  drips at the above-mentioned set rate from guide part  140  due to its own weight. 
         [0068]    When drip irrigation tube  100  is disposed such that ejection port  130  opens upward, liquid  150  ejected from ejection port  130  is accumulated at the opening of ejection port  130 , as shown in  FIG. 9B . Liquid  150  accumulated at the opening may flow vertically downward from the opening along the outer circumferential surface of tube  110  in one case, whereas in another case liquid  150  may run along the highest part of tube  110  to flow toward one side along the longitudinal direction of tube  110 . The flow of liquid  150  along the highest part is blocked by guide part  140 . 
         [0069]    Liquid  150  is supplied to guide part  140  at the above-mentioned set rate. Therefore, liquid  150  blocked at guide part  140  flows downward on the outer circumferential surface of tube  110  along guide part  140  due to its weight. Thus, liquid  150  is guided to the lowest part of tube  110 , and drips from the lowest part of tube  110  at the above-mentioned set rate. As described above, guide part  140  exhibits a drip-facilitating function of guiding liquid  150  flowing along the longitudinal direction of tube  110  to allow liquid  150  to drip into the soil from guide part  140 . 
         [0070]    Drip irrigation tube  100  according to the present embodiment has guide part  140 , as described above. Thus, according to drip irrigation tube  100 , it is possible to supply liquid  150  in tube  110  into the soil from guide part  140  positioned in the vicinity of ejection port  130  in the longitudinal direction of tube  110  at a rate set by dripper  120 , even when liquid  150  ejected from ejection port  130  runs in the longitudinal direction of tube  110 . 
         [0071]    Further, guide part  140  forms a step difference on the outer circumferential surface of tube  110 . Thus, liquid  150  being blocked is subjected to stronger influence of surface tension at the edge of the step difference. Accordingly, guide part  140  which forms the step difference can further prevent liquid  150  from flowing further in the longitudinal direction of tube  110  beyond guide part  140 . Therefore, guide part  140  is more effective from the perspective of enhancing the above-mentioned drip-facilitating function. 
         [0072]    Dripper  120  according to the present embodiment includes, as described above, dripper body  121  forming a channel having a part of pressure reduction channel  125  (open part  1216 ) opened to the inner space of tube  110 , and movable part  122  disposed to cover open part  1216  from the space side and be movable forward or backward in open part  1216  in accordance with the liquid pressure in drip irrigation tube  100 . Thus, dripper  120  can suppress changes in the ejection amount due to the increase of the pressure of liquid flowing into dripper  120 . Therefore, dripper  120  can eject liquid at a constant flow rate regardless of the change in the pressure. 
         [0073]    Further, dripper  120  can be composed with only two members, i.e., dripper body  121  and movable part  122 . 
         [0074]    As described above, conventional drippers are formed by assembling the three members, and thus an assembly error may occur in the drippers. In particular, the assembly error in the diaphragms may cause variations in operation of the diaphragms, and variations in the ejection amount of irrigation liquid. 
         [0075]    Further, while the dripper is typically formed of an inexpensive resin such as polypropylene, the diaphragm is made of a more expensive elastic material member such as a silicone rubber film. Use of such different materials has a room for improvement in terms of reduction of a material cost. 
         [0076]    In some situation, several hundreds of drippers are disposed in one drip irrigation tube, and in that case pressure drop of the irrigation liquid is large when the drippers bonded on the inner wall of the tube are large. For this reason, in the case where a long drip irrigation tube is used, the pressure for supplying liquid to the tube is required to be high, and as a result the liquid ejection amount of the drippers may be unstabilized. Therefore, it is desired to reduce the size of the drippers from the perspective of suppressing the pressure drop of the liquid in the tube. 
         [0077]    Further, a dripper which can be produced with a single inexpensive material and a smaller number of components is desired from the perspective of suppressing the material cost and the production cost of the dripper. 
         [0078]    Dripper  120  is capable of stabilizing the ejection amount of irrigation liquid and reducing production cost, and is configured for the purpose of providing a drip irrigation tube having the dripper. As described above, dripper  120  can be composed with only two members, i.e., dripper body  121  and movable part  122 , and thus the size (thickness) of dripper  120  can be further reduced in comparison with conventional drippers composed of three members and having a diaphragm. 
         [0079]    Since the size of drippers  120  can be further reduced, drippers  120  can further suppress an increase of liquid pressure drop in tube  110  in comparison with the conventional drippers. As a result, the liquid in drip irrigation tube  100  can be conveyed farther with a low pressure. Therefore, the present embodiment can provide an effect of ejecting liquid at a stable amount even when longer drip irrigation tube  100  is used. 
         [0080]    Dripper  120  can further reduce material cost and production cost (assembling cost) in comparison with the conventional drippers. 
         [0081]    Dripper body  121  further including inflow ports  123  having the low-pressure stopping function is more effective from the perspective of further suppressing the pressure of the liquid flowing into dripper  120  from the inside of drip irrigation tube  100  for the purpose of efficient use of the liquid. 
         [0082]    Dripper  120  does not have a diaphragm in ejection part  126 ; therefore, no diaphragm would be damaged when forming ejection port  130  of drip irrigation tube  100  after welding dripper  120 . This means the pressure regulation function of dripper  120  would not be impaired even when ejection port  130  is formed after welding dripper  120 . The present embodiment thus can produce drip irrigation tube  100  more easily, and further enhance the reliability of drip irrigation tube  100 . 
         [0083]    Dripper body  121  has inflow part  124  and ejection part  126  connected to each other only with pressure reduction channel  125 . This makes it possible to reduce the length of dripper body  121  in X direction. Dripper  120  is thus advantageous also from the perspective of reduction in the size of dripper  120  in X direction. 
       Embodiment 2 
       [0084]      FIG. 10A  is a schematic front view of a drip irrigation tube according to Embodiment 2 disposed such that ejection ports face upward, and  FIG. 10B  schematically illustrates liquid being ejected from the drip irrigation tube. Drip irrigation tube  200  according to the present embodiment is configured in the same manner as drip irrigation tube  100  according to Embodiment 1 except that for the mode of the guide part. 
         [0085]    Drip irrigation tube  200  includes tube  210 , drippers  120  and guide parts  240 . Tube  210  is configured in the same manner as tube  110  except that guide parts  240  are formed in place of guide parts  140 . 
         [0086]    Guide part  240  is a recess provided circumferentially on the outer circumferential surface of tube  210 . The positions of guide parts  240  in the longitudinal direction of tube  210  are the same as the positions of guide parts  140  in tube  110 . The depth of guide part  240  may be constant, different, an average value, or the minimum value. 
         [0087]    The width of guide part  240  is, for example, 3 mm, and the depth of guide part  240  is, for example, 0.1 mm Guide part  240  is formed by cutting with a cutter, for example. 
         [0088]    The width of guide part  240  can be appropriately determined within a range smaller than the distance between ejection ports  130  in the longitudinal direction of tube  210 . The width of guide part  240  is preferably 1 to 20 mm, and more preferably 2 to 10 mm, from the perspective of enhancement of drip-facilitating function brought by the occurrence of capillary phenomenon of liquid  150  flowing into guide part  240 . 
         [0089]    The depth of guide part  240  can be appropriately determined within a range smaller than the wall thickness of tube  210 . The depth of guide part  240  is preferably 10 to 50% of the wall thickness of tube  210 , and more preferably 25 to 50% thereof, from the perspective of durability of tube  210 . The depth of guide part  240  is preferably 0.02 to 0.1 mm, and more preferably 0.05 to 0.1 mm, from the perspective of enhancement of drip-facilitating function due to the occurrence of capillary phenomenon. 
         [0090]    When drip irrigation tube  200  is disposed such that ejection port  130  faces upward, liquid  150  ejected from ejection port  130  and flowing in the longitudinal direction of tube  210  to reach guide part  240  is subjected to the occurrence of stronger surface tension at the edge of a step difference formed by guide part  240 . Accordingly, the flow of liquid  150  in the longitudinal direction is blocked by guide part  240 , and liquid  150  stays on the outer circumferential surface of tube  210  at guide part  240 . 
         [0091]    Staying liquid  150  flows downward on the outer circumferential surface of tube  210  along guide part  240 . Alternatively, liquid  150  flows into guide part  240 . When capillary phenomenon occurs to liquid  150  flowing into guide part  240 , the flow of liquid  150  is accelerated in the circumferential direction of tube  210 . Then, liquid  150  flows downward in guide part  240  and in the vicinity thereof along guide part  240 . Thus, due to the drip-facilitating function of guide part  240 , liquid  150  is guided to the lowest part of tube  210 , and drips from the lowest part of tube  210  at the above-mentioned set rate. 
         [0092]    In drip irrigation tube  200 , guide part  240  can generate at the step difference stronger surface tension in the longitudinal direction of tube  210  for liquid  150  having reached guide part  240  from ejection port  130 . Accordingly, it is possible to enhance the effect of blocking the flow of liquid  150  in the longitudinal direction more than drip irrigation tube  100  according to Embodiment 1. In addition, liquid  150  flowing into guide part  240  is more likely to flow downward in guide part  240  in the circumferential direction of tube  210  than drip irrigation tube  100 . When guide part  240  has such a width as to generate the capillary phenomenon of liquid  150 , the flow of liquid  150  in guide part  240  is further accelerated. Thus, guide part  240  is more effective from the perspective of enhancement of the drip-facilitating function. 
       Embodiments 3 and 4 
       [0093]      FIG. 11A  is a schematic front view of a drip irrigation tube according to Embodiment 3 of the present invention, and  FIG. 11B  is a schematic front view of a drip irrigation tube according to Embodiment 4 of the present invention. Drip irrigation tube  300  according to Embodiment 3 and drip irrigation tube  400  according to Embodiment 4 are both configured in the same manner as drip irrigation tube  100  according to Embodiment 1 except for the mode of the guide part. 
         [0094]    Drip irrigation tube  300  includes tube  310 , drippers  120  and guide parts  340 . Tube  310  is configured in the same manner as tube  110  except that guide parts  340  are formed in place of guide parts  140 . Further, drip irrigation tube  400  includes tube  410 , drippers  120  and guide parts  440 . Tube  410  is also configured in the same manner as tube  110  except that guide parts  440  are formed in place of guide parts  140 . Guide parts  340  in the longitudinal direction of tube  310  and guide parts  440  in the longitudinal direction of tube  410  are both positioned at two locations, for single ejection port  130 , such that dripper  120  is interposed therebetween in the longitudinal direction of tubes  310  and  410 , respectively. 
         [0095]    Guide part  340  is a swelling provided circumferentially on the outer circumferential surface of tube  310 , as shown in  FIG. 11A . The variation in the surface shape of the swelling is continuous in the longitudinal direction of tube  310 . The height of guide part  340  is, for example, about 2 mm, and the width of guide part  340  is, for example, about 3 mm. The height of guide part  340  is the distance from the outer circumferential surface of tube  310  to the apex of the swelling in the radial direction of tube  310  (h 1  in  FIG. 11A ). The width of guide part  340  is a length of a portion, which traverses guide part  340 , of a straight line along the longitudinal direction of tube  310  on the outer circumferential surface of tube  310  (w 1  in  FIG. 11A ). Guide part  340  is formed, for example, by intermittently reducing the extrusion rate of extrusion molding in producing tube  310 . 
         [0096]    Guide part  440  is a depression provided circumferentially on the outer circumferential surface of tube  410 , as shown in  FIG. 11B . The variation in the surface shape of the depression is continuous in the longitudinal direction of tube  410 . The depth of guide part  440  is, for example, about 0.1 mm, and the width of guide part  440  is, for example, about 3 mm. The depth of guide part  440  is the distance from the outer circumferential surface of tube  410  to the bottom of the depression in the radial direction of tube  410  (d 2  in  FIG. 11B ). The width of guide part  440  is a length of a portion, which traverses guide part  440 , of a straight line along the longitudinal direction of tube  410  on the outer circumferential surface of tube  410  (w 2  in  FIG. 11B ). Guide part  440  is formed, for example, by intermittently increasing the extrusion rate of extrusion molding in producing tube  410 . 
         [0097]    When drip irrigation tube  300  is disposed such that ejection port  130  faces upward, liquid  150  having reached guide part  340  from ejection port  130  along the longitudinal direction of tube  310  is blocked by blocking effect due to the swelling of guide part  340 . Accordingly, liquid  150  staying on the outer circumferential surface of tube  310  flows downward along guide part  340 . Thus, liquid  150  is guided to the lowest part of tube  310  by the drip-facilitating function of guide part  340 , and drips from the lowest part at the above-mentioned set rate. 
         [0098]    When drip irrigation tube  400  is disposed such that ejection port  130  faces upward, liquid  150  flowing along the longitudinal direction of tube  410  from ejection port  130  to reach guide part  440  flows into guide part  440 , and stays there. Thus, the flow of liquid  150  in the longitudinal direction on the outer circumferential surface of tube  410  is blocked by blocking effect due to the depression. Liquid  150  staying at guide part  440  flows downward in guide part  440 . Thus, liquid  150  is guided to the lowest part of tube  410  by the drip-facilitating function of guide part  440 , and drips from the lowest part at the above-mentioned set rate. 
         [0099]    Thus, drip irrigation tube  300  according to Embodiment 3 and drip irrigation tube  400  according to Embodiment 4 are both capable of facilitating the drip of liquid  150  in guide parts  340  and  440 , respectively. 
       Embodiment 5 
       [0100]    Embodiment 5 is the same as the above-mentioned Embodiment 1 except for the structure of the dripper. A dripper according to the present embodiment is different from the dripper of Embodiment 1 in that the dripper further has a communication channel for connecting a pressure reduction channel with an ejection part, and that a movable part changes the cross-sectional area of the communication channel. The configurations same as those of Embodiment 1 are given the same symbols as those of Embodiment 1, and the description thereof is omitted. 
         [0101]      FIG. 12A  illustrates an upper surface, a front surface, and a side surface of the dripper according to the present embodiment, and  FIG. 12B  illustrates a bottom surface, the front surface and the side surface of the dripper.  FIG. 13A  to  FIG. 13D  are a plan view, a front view, a bottom view and a side view of the dripper according to the present embodiment, respectively. 
         [0102]    Dripper  220  according to the present embodiment is composed of dripper body  221  and movable part  222 . Dripper body  221  has first end part  2211 , second end part  1212  and connecting part  2213 . First end part  2211  includes inflow ports  123 , inflow part  124  and pressure reduction channel  225 . Pressure reduction channel  225  is configured with a groove recessed from the bottom surface of dripper body  221 . The shape of pressure reduction channel  225  in plan view is the same as the shape of pressure reduction channel  125  in plan view. 
         [0103]    Connecting part  2213  is formed in the same manner as connecting part  1213  except that connecting part  2213  includes open part  2216 , a part of linear shaped communication channel  226  in plan view other than the both ends of communication channel  226 , which opens to the inner space of tube  110 ; and that the shape of bottom surface of connecting part  2213  in plan view is rectangular. Open part  2216  is configured of a cut (slit) extending through connecting part  2213  in the thickness direction of connecting part  2213 . The shape of open part  2216  in plan view is linear. 
         [0104]    Movable part  222  is formed in the same manner as movable part  122  except for projection  2224 . The shape of projection  2224  in plan view is the same as the shape of open part  2216  in plan view, as shown in  FIG. 13C . Projection  2224  covers open part  2216  from above and partially fits with open part  2216 , and thus communication channel  226  for connecting pressure reduction channel  225  to ejection part  126  is formed. 
         [0105]      FIG. 14A  is a cross-sectional view schematically illustrating the dripper according to the present embodiment cut along line A-A in  FIG. 13C  before the movement of the movable part, and  FIG. 14B  is a cross-sectional view schematically illustrating the dripper cut along line A-A in  FIG. 13C  after the movement of the movable part. 
         [0106]    In the same manner as movable part  122  in Embodiment 1, movable part  222  slides at open part  2216  forward or backward from the bottom surface side of dripper  220  in a distance in accordance with the pressure on pressure receiving part  1221  to change the height (cross-sectional area) of communication channel  226  in a range of h 0  to h 1 , for example, from 0.25 to 0.75 mm in accordance with the pressure. 
         [0107]    The present embodiment provides the same effects as those of Embodiment 1. Since dripper  220  according to the present embodiment further has communication channel  226 , dripper  220  can change a cross-sectional area of a part whose shape is simpler than that of pressure reduction channel  225  in the channel formed with dripper  220 . The shape of projection  2224  of movable part  222  in plan view thus can be further simplified. Therefore, the present embodiment is more effective from the perspective of simplifying the production of movable part  222  and assemblage of dripper  220 . 
       Embodiments 6 and 7 
       [0108]      FIG. 15A  is a schematic front view of a drip irrigation tube according to Embodiment 6 or 7 of the present invention disposed such that ejection ports face upward,  FIG. 15B  schematically illustrates liquid being ejected from the drip irrigation tube according to Embodiment 6, and  FIG. 15C  schematically illustrates liquid being ejected from the drip irrigation tube according to Embodiment 7. Drip irrigation tube  600  according to Embodiment 6 and drip irrigation tube  700  according to Embodiment 7 are configured in the same manner as drip irrigation tube  100  according to Embodiment 1 except for the mode of the guide part. 
         [0109]    Drip irrigation tube  600  is configured in the same manner as drip irrigation tube  100  according to Embodiment 1 except that guide parts  640  are formed on the outer circumferential surface of tube  110  in place of guide parts  140 . Further, drip irrigation tube  700  is configured in the same manner as drip irrigation tube  100  according to Embodiment 1 except that guide parts  740  are formed on the outer circumferential surface of tube  110  in place of guide parts  140 . 
         [0110]    Guide part  640  is a part having been subjected to a water-repellent treatment on tube  110 . Guide part  640  has higher water repellency than the outer wall of tube  110 , and is composed of a water-repellent coating film, for example. Examples of the water-repellent coating film include silicone resin coating film and fluorine resin coating film. Guide part  740  is a part having been subjected to a hydrophilic treatment on tube  110 . Guide part  740  has higher hydrophilicity than the outer wall of tube  110 , and is formed by irradiation of UV-rays, for example. The width of guide parts  640  and  740  are, for example, 3 to 20 mm 
         [0111]    When drip irrigation tube  600  is disposed such that ejection port  130  faces upward, liquid  150  ejected from ejection port  130  flows in the longitudinal direction of tube  110  to reach guide part  640 , as shown in  FIG. 15B . The flow of liquid  150  in the longitudinal direction is blocked by guide part  640  having water repellency. Liquid  150  stays on the outer circumferential surface of tube  110  at guide part  640 , and then flows downward on the outer circumferential surface of tube  110  along guide part  640 . Thus, liquid  150  is guided to the lowest part of tube  110  by the drip-facilitating function of guide part  640 , and drips from the lowest part of tube  110  at the above-mentioned set rate. 
         [0112]    When drip irrigation tube  700  is disposed such that ejection port  130  faces upward, liquid  150  ejected from ejection port  130  flows in the longitudinal direction of tube  110  to reach guide part  740 , as shown in  FIG. 15C . Since the outer wall of tube  110  has lower hydrophilicity than guide part  740 , the flow of liquid  150  having reached guide part  740  in the longitudinal direction of tube  110  is blocked by a boundary between guide part  740  and the outer wall of tube  110 . Then, liquid  150  having reached guide part  740  flows along guide part  740 , which is more hydrophilic than the outer wall of tube  110 . In this manner, liquid  150  is guided in the circumferential direction of tube  110 , and flows downward on the outer circumferential surface of tube  110  along guide part  740 . Thus, liquid  150  is guided to the lowest part of tube  110  by the drip-facilitating function of guide part  740 , and drips from the lowest part of tube  110  at the above-mentioned set rate. 
         [0113]    Both guide parts  640  and  740  do not require substantial thickness. Thus, it is possible to dispose them on a tube regardless of the thickness of the tube wall. In addition, since the outer diameter of tube  110  is constant, stress is unlikely to focus on guide parts  640  and  740 . Therefore, guide parts  640  and  740  are more effective from the perspective of suppressing the rupture of tube  110  at a guide part due to stress focusing on the guide part in such cases of storing tube  110  in a wound state or drawing tube  110  when tube  110  is laid. 
         [0114]    While the embodiments of the present invention have been described hereinabove, the scope of the present invention is not limited thereto. 
         [0115]    For example, tube  110  may be a seamless tube, or a tube made by joining slender sheet(s) along the longitudinal direction. 
         [0116]    The ejection port may be a gap formed, at a joint part of the sheet(s), to allow communication between the inside and the outside of tube  110 , or a pipe sandwiched by the sheet(s) at the joint part. Further, the shape of the ejection port in the axis direction can be appropriately determined within such a range as to enable the ejection port to eject liquid in tube  110  at an intended rate, and does not need to be linear. Examples of the tube capable of ejecting liquid from the ejection port at the intended rate include a tube having ejection ports each having a specific hole diameter, and a tube in which the pressure reduction channel is formed at the joint part through the joint of the sheet(s) each having a depression, which serves as the pressure reduction channel, formed on the surface of the sheet. 
         [0117]    While a dripper is disposed in the tube in the above-mentioned embodiments, no dripper needs to be disposed if an ejection port can discharge liquid in tube  110  at an intended rate. While a dripper is disposed such that the inflow part is located on the upstream side in the liquid flow direction in the tube when the dripper is disposed in tube  110 , the dripper may be disposed such that the inflow part is located on a downstream side. The orientations of the drippers may be identical to each other or different from each other. 
         [0118]    While the low-pressure stopping function based on dripper body material (polypropylene) is imparted to the dripper in the above-mentioned embodiments, the low-pressure stopping function may be imparted to the dripper by forming a burr protruding to the inner space of the tube from the open part edge on the top surface side of an inflow port, or by covering the open part edge and internal wall of the inflow port with a hydrophobic film. The low-pressure stopping function can be further enhanced by combining multiple methods of imparting the low-pressure stopping function. 
         [0119]    While the same material (polypropylene) is used for the dripper body and the movable part in the embodiments, different materials may be used. 
         [0120]    Methods other than the method of changing the height of the pressure reduction channel or the communication channel may be employed to change the cross-sectional area of the channel formed in the dripper. For example, the cross-sectional area may be changed using a straightening plate or a baffle plate which is movable forward or backward in the pressure reduction channel or the communication channel 
         [0121]    While the movable part is moved forward or backward in the open part of the dripper body with plate springs formed on the dripper sides in accordance with the liquid pressure in the tube in the above-mentioned embodiments, any other means may be employed to move the movable part in accordance with the pressure. For example, it is also possible to move the movable part forward or backward in the open part by employing a movable part composed of an elastic body and expanding or contracting the elastic body in accordance with the pressure. 
         [0122]    This application claims priority based on Japanese patent Application No. 2013-196945, filed on Sep. 24, 2013, the entire contents of which including the specification, the drawing and the abstract are incorporated herein by reference. 
       INDUSTRIAL APPLICABILITY 
       [0123]    According to the present invention, it is possible to provide a drip irrigation tube capable of dripping liquid to be dripped from the vicinity of an ejection port. Also, it is possible for the present invention to easily provide a drip irrigation tube suitable for dripping liquid to be dripped at a proper rate using the pressure of the liquid. Therefore, further widespread use of such tube in the technical field of drip irrigations and endurance tests where a long term dripping is required can be expected, and further development in the technical field can be expected. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100 ,  200 ,  300 ,  400 ,  600 ,  700  Drip irrigation tube 
           110 ,  210 ,  310 ,  410  Tube 
           120 ,  220  Dripper 
           121 ,  221  Dripper body 
           122 ,  222  movable part 
           123  Inflow port 
           124  Inflow part 
           125 ,  225  Pressure reduction channel 
           126  Ejection part 
           130  Ejection port 
           140 ,  240 ,  340 ,  440 ,  640 ,  740  Guide part 
           150  Liquid 
           226  Communication channel 
           1201  Protrusion 
           1211 ,  2211  First end part 
           1212  Second end part 
           1213 ,  2213  Connecting part 
           1214 ,  1215  Elastic supporter 
           1216 ,  2216  Open part 
           1221  Pressure receiving part 
           1222  Spacer 
           1223  Engaging part 
           1224 ,  2224  Projection