Abstract:
An emitter ( 120 ) forms a flow path that runs to a discharge part ( 250 ) from an intake part ( 220 ) for receiving an irrigation liquid in a tube. The flow path includes a flow volume control part ( 240 ) which includes: an end surface ( 243 ) including a concave inclined surface that faces a film ( 300 ) for receiving the pressure of the liquid inside the tube; a hole ( 244 ) that opens at the center of the flow volume control part ( 240 ) and connects to the discharge part ( 250 ); and a groove ( 245 ) crossing the inclined surface and running to the hole ( 244 ). When the film ( 300 ) adheres to the inclined surface as a result of the pressure of the irrigation liquid inside the tube, the flow volume of the irrigation liquid inside the emitter ( 120 ) is controlled so as to be a volume that can pass through the groove ( 245 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an emitter and a trickle irrigation tube including the emitter. 
       BACKGROUND ART 
       [0002]    A trickle irrigation method is known as a method for culturing plants. In the trickle irrigation method, for example, a trickle irrigation tube is disposed on the soil in which plants are planted, and irrigation liquid such as water and liquid fertilizer is slowly supplied from the trickle irrigation tube to the soil. The trickle irrigation method can minimize the consumption amount of the irrigation liquid, and has been increasingly attracting attention in recent years. 
         [0003]    The trickle irrigation tube typically has a tube and an emitter (also called “dripper”). The emitter typically supplies the soil with the irrigation liquid in the tube at a predetermined rate at which the irrigation liquid is dropped to the soil. Emitters which are pierced into the tube from the outside, and emitters joined to the inner wall surface of the tube are known. 
         [0004]    For example, the latter emitter has a channel including a pressure reduction channel for allowing the liquid having entered the emitter from the internal space of the tube toward the through hole of the tube while reducing the pressure of the liquid, and a diaphragm part configured to change the volume of a portion of the channel where the irrigation liquid having reduced pressure flows in accordance with the pressure of the liquid of the internal space. The emitter is composed of a member which is joined to the inner wall surface of the tube, a member which is disposed on the member joined to the inner wall surface, and a diaphragm part which is disposed between the two members. The diaphragm part is composed of an elastic film such as a silicone rubber film (see, for example, PTL 1). 
         [0005]    The emitter can suppress variation of the discharge rate of the irrigation liquid regardless of change of the pressure of the liquid in the internal space of the tube. Therefore, the emitter is advantageous from the viewpoint of uniformly growing multiple plants. 
       CITATION LIST 
     Patent Literature 
       [0006]    PTL 1 
         [0007]    Japanese Patent Application Laid-Open No. 2010-46094 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0008]    The emitter is formed by assembling three components. In view of this, the emitter may cause assembling error. In particular, the assembling error of the diaphragm part may cause variation of the operation of the diaphragm part, and variation of the discharge rate of the irrigation liquid. 
         [0009]    In addition, the emitter is typically a molded article of an inexpensive resin such as polyethylene and polypropylene, and the diaphragm part is composed of a more expensive elastic material such as a silicone rubber film. The use of components of different materials has a room for improvement in material cost reduction. 
         [0010]    Further, in the case of a trickle irrigation tube, hundreds of emitters are disposed in one tube in some cases. In the case of a long trickle irrigation tube, the supply pressure of liquid to the tube is required to be increased, and consequently the liquid discharge rate of the emitter may not be stable. In view of this, control of the discharge rate of the liquid of the emitter in accordance with the pressure of the liquid in the tube is desired. 
         [0011]    Furthermore, from the viewpoint of reducing the material cost and the manufacturing cost of the emitter, an emitter which can be manufactured with a single inexpensive material and fewer number of components is desired. 
         [0012]    An object of the present invention is to provide an emitter which can stabilize the discharge rate of the irrigation liquid and can further reduce the manufacturing cost. In addition, another object of the present invention is to provide a trickle irrigation tube having the emitter. 
       Solution to Problem 
       [0013]    An emitter according to an embodiment of the present invention is intended for quantitatively discharging irrigation liquid in a tube from a discharge port communicating between an inside and an outside of the tube, the emitter being configured to be joined to an inner wall surface of the tube configured to distribute the irrigation liquid at a position corresponding to the discharge port, the emitter including: a water collecting part for receiving the irrigation liquid in the tube; a pressure reduction channel for allowing the irrigation liquid received from the water collecting part to flow therethrough while reducing a pressure of the irrigation liquid; a flow rate control part for controlling a flow rate of the irrigation liquid supplied from the pressure reduction channel in accordance with the pressure of the irrigation liquid in the tube; and a discharge part to which the irrigation liquid having a flow rate controlled by the flow rate control part, is supplied, the discharge part being to be facing the discharge port, wherein: the water collecting part opens at a first surface which is not joined to the tube in the emitter; the flow rate control part includes: an opening part which opens at the first surface; a film having flexibility and sealing the opening part to block a communication of a channel on a downstream side relative to the pressure reduction channel and the inside of the tube; a recessed surface part depressed with respect to the film and disposed at a position where the recessed surface part faces the film in the channel on a downstream side relative to the pressure reduction channel without making contact with the film, but the recessed surface part being capable of making close contact with the film; a hole opening at the recessed surface part and communicated with the discharge part; and a groove formed on the recessed surface part and configured to communicate between the hole and the channel on outside relative to the recessed surface part; and the film makes close contact with the recessed surface part when the pressure of the irrigation liquid in the tube is equal to or higher than a predetermined value. 
         [0014]    In addition, an emitter according to an embodiment of the present invention includes: a water collecting part for receiving irrigation liquid in a tube, the water collecting part having a cylindrical shape to be inserted to the tube from outside of the tube, the tube being configured to distribute the irrigation liquid; a pressure reduction channel for allowing the irrigation liquid received from the water collecting part to flow therethrough while reducing a pressure of the irrigation liquid; a flow rate control part for controlling a flow rate of the irrigation liquid supplied from the pressure reduction channel in accordance with the pressure of the irrigation liquid in the tube; and a discharge part for discharging the irrigation liquid having a flow rate controlled by the flow rate control part to outside of the tube, wherein: a flange part is disposed at a base end of the water collecting part, the base end representing, when one end of the water collecting part from which the water collecting part is inserted to the tube is defined as a tip end, the other end of the water collecting part; the flange part is composed of a combination of a first disk part disposed at the base end of the water collecting part and a second disk part on which the discharge part is disposed, the flange part including the pressure reduction channel and the flow rate control part; the flow rate control part includes: a film having flexibility and facing a channel on a downstream side relative to the pressure reduction channel; a pressure transmission part for transmitting the pressure of the irrigation liquid in the tube to a rear surface of the film; a recessed surface part depressed with respect to the film and disposed at a position where the recessed surface part faces the film in the channel on a downstream side relative to the pressure reduction channel without making contact with the film, but the recessed surface part being capable of making close contact with the film; a hole opening at the recessed surface part and communicated with the discharge part; and a groove formed on the recessed surface part and configured to communicate between the hole and the channel on outside relative to the recessed surface part; and the film makes close contact with the recessed surface part when the pressure of the irrigation liquid in the tube is equal to or higher than a predetermined value. 
         [0015]    Further, a trickle irrigation tube according to an embodiment of the present invention includes: a tube; and at least one emitter, the emitter being the above-mentioned emitter. 
       Advantageous Effects of Invention 
       [0016]    The emitter according to the present invention controls the discharge rate of the irrigation liquid in accordance with the pressure of the irrigation liquid in the trickle irrigation tube, and thus can stabilize the discharge rate of the irrigation liquid. In addition, since the emitter according to the present invention can be formed with one or two components by injection molding of a resin material, the manufacturing cost can be further reduced in comparison with conventional emitters composed of three parts. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  is a schematic sectional view of a trickle irrigation tube according to Embodiment 1 of the present invention; 
           [0018]      FIG. 2A  illustrates a top surface, a front surface and a side surface of an emitter according to Embodiment 1, and  FIG. 2B  illustrates a bottom surface, a front surface and a side surface of the emitter; 
           [0019]      FIG. 3A  is a plan view of the emitter according to Embodiment 1,  FIG. 3B  is a front view of the emitter,  FIG. 3C  is a back view of the emitter, and  FIG. 3D  is a side view of the emitter; 
           [0020]      FIG. 4  is a bottom view of the emitter according to Embodiment 1; 
           [0021]      FIG. 5A  is a sectional view of the emitter according to Embodiment 1 taken along line A-A of  FIG. 3A ,  FIG. 5B  is a sectional view of the emitter taken along line B-B of  FIG. 3A , and  FIG. 5C  is a sectional view of the emitter taken along line C-C of  FIG. 4 ; 
           [0022]      FIG. 6A  illustrates a top surface, a front surface and a side surface of the emitter of Embodiment 1 in the state before the film is joined to the emitter main body, and  FIG. 6B  illustrates a bottom surface, a front surface and a side surface of the emitter; 
           [0023]      FIG. 7A  is a plan view of the emitter of Embodiment 1 in the state before the film is joined to the emitter main body, and  FIG. 7B  illustrates a bottom view of the emitter; 
           [0024]      FIG. 8A  is a sectional view of the emitter of Embodiment 1 taken along line A-A of  FIG. 7A  in the state before the film is joined to the emitter main body, and  FIG. 8B  is a sectional view of the emitter taken along line B-B of  FIG. 7A , and  FIG. 8C  is a sectional view of the emitter taken along line C-C of  FIG. 7B ; 
           [0025]      FIG. 9A  illustrates part A of  FIG. 5A  in an enlarged manner in the case where the pressure of the irrigation liquid in the tube is equal to or higher than the first pressure value and is lower than the second pressure value,  FIG. 9B  illustrates part A of  FIG. 5A  in an enlarged manner in the case where the pressure of the irrigation liquid in the tube is equal to or higher than the second pressure value and is lower than the third pressure value, and 
           [0026]      FIG. 9C  illustrates part A of  FIG. 5A  in an enlarged manner in the case where the pressure of the irrigation liquid in the tube is equal to or higher than the third pressure value; 
           [0027]      FIG. 10  is a schematic sectional view of a trickle irrigation tube according to Embodiment 2 of the present invention; 
           [0028]      FIG. 11A  is a plan view of an emitter according to Embodiment 2,  FIG. 11B  is a front view of the emitter,  FIG. 11C  is a bottom view of the emitter, and  FIG. 11D  is a side view of the emitter; 
           [0029]      FIG. 12A  is a sectional view of the emitter according to Embodiment 2 taken along line A-A of  FIG. 11A ,  FIG. 12B  is a sectional view of the emitter taken along line B-B of  FIG. 11A ; 
           [0030]      FIG. 13A  is a plan view of a first component of Embodiment 2,  FIG. 13B  is a front view of the first component,  FIG. 13C  is a bottom view of the first component, and  FIG. 13D  is a side view of the first component; 
           [0031]      FIG. 14A  is a sectional view of the first component of Embodiment 2 taken along line A-A of  FIG. 13A ,  FIG. 14B  is a sectional view of the first component taken along line B-B of  FIG. 13A ; 
           [0032]      FIG. 15A  is a plan view of a second component of Embodiment 2,  FIG. 15B  is a front view of the second component,  FIG. 15C  is a bottom view of the second component,  FIG. 15D  is a side view of the second component, and  FIG. 15E  is a sectional view of the second component taken along line A-A of  FIG. 15A ; 
           [0033]      FIG. 16A  schematically illustrates a state of part A of  FIG. 12A  in the case where the pressure of the irrigation liquid in the tube is equal to or higher than the first pressure value and is lower than the second pressure value,  FIG. 16B  schematically illustrates a state of part A of  FIG. 12A  in the case where the pressure of the irrigation liquid in the tube is equal to or higher than the second pressure value and is lower than the third pressure value, and  FIG. 16C  schematically illustrates a state of part A of  FIG. 12A  in the case where the pressure of the irrigation liquid in the tube is equal to or higher than the third pressure value; and 
           [0034]      FIG. 17A  schematically illustrates a first modification of a discharge part of the emitter according to Embodiment 2, and  FIG. 17B  schematically illustrates a second modification of the discharge part. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0035]    In the following, embodiments of the present invention are described in detail with reference to the accompanying drawings. 
       Embodiment 1 
     Configuration 
       [0036]      FIG. 1  is a schematic sectional view of a trickle irrigation tube according to Embodiment 1 of the present invention. Trickle irrigation tube  100  is composed of tube  110  and emitter  120 . Tube  110  is made of polyethylene, for example. Emitter  120  is disposed at a predetermined interval (for example, 200 to 500 mm) in the axial direction of tube  110 . Each emitter  120  is joined on the inner wall surface of tube  110 . Emitter  120  is disposed at a position where emitter  120  covers discharge port  130  of tube  110 . Discharge port  130  is a hole which extends through the tube wall of tube  110 . The hole diameter of discharge port  130  is, for example, 1.5 mm. It is to be noted that arrow F indicates the direction of flow of the irrigation liquid in tube  110 . 
         [0037]      FIG. 2A  illustrates a top surface, a front surface and a side surface of emitter  120 , and  FIG. 2B  illustrates a bottom surface, a front surface and a side surface of emitter  120 .  FIG. 3A  is a plan view of emitter  120 ,  FIG. 3B  is a front view of emitter  120 ,  FIG. 3C  is a back view of emitter  120 ,  FIG. 3D  is a side view of emitter  120 , and  FIG. 4  is a bottom view of emitter  120 .  FIG. 5A  is a sectional view of emitter  120  taken along line A-A of  FIG. 3A ,  FIG. 5B  is a sectional view of emitter  120  taken along line B-B of  FIG. 3A , and  FIG. 5C  is a sectional view of emitter  120  taken along line C-C of  FIG. 4 . It is to be noted that the X direction is the axial direction of tube  110  or the longitudinal direction of emitter  120 , the Y direction is the short (width) direction of emitter  120 , and the Z direction is the height direction of emitter  120 . 
         [0038]    As illustrated in  FIG. 2A  and  FIG. 2B , emitter  120  has a rectangular external shape. For example, the length of emitter  120  is 30 mm in the X direction, 10 mm in the Y direction, and 3 mm in the Z direction. Emitter  120  includes emitter main body  200  to be joined to the inner wall surface of tube  110 , and film  300  which is formed integrally with emitter main body  200 . 
         [0039]      FIG. 6A  illustrates a top surface, a front surface and a side surface of emitter  120  in the state before film  300  is joined to emitter main body  200 , and  FIG. 6B  illustrates a bottom surface, a front surface and a side surface of emitter  120 .  FIG. 7A  is a plan view of emitter  120  in the state before film  300  is joined to emitter main body  200 , and  FIG. 7B  is a bottom view of emitter  120 .  FIG. 8A  is a sectional view of emitter  120  taken along line A-A of  FIG. 7A  in the state before film  300  is joined to emitter main body  200 ,  FIG. 8B  is a sectional view of emitter  120  taken along line B-B of  FIG. 7A , and  FIG. 8C  is a sectional view of emitter  120  taken along line C-C of  FIG. 7B . 
         [0040]    As illustrated in  FIG. 3B  and  FIG. 3C , emitter main body  200  includes first surface  201  and second surface  202 . First surface  201  is one surface which is joined to film  300  in the Z direction. Second surface  202  is the other surface which is joined to the inner wall surface of tube  110  in the Z direction. 
         [0041]    As illustrated in  FIG. 5A ,  FIG. 5B  and  FIG. 5C , emitter main body  200  includes filter part  210  formed on first surface  201 , water collecting part  220  which extends through emitter main body  200  in the Z direction, pressure reduction channel  230  formed on second surface  202 , flow rate control part  240  which opens at first surface  201 , and discharge part  250  formed on second surface  202 . 
         [0042]    As illustrated in  FIG. 6A  and  FIG. 7A , filter part  210  includes first recess  211  which is formed on first surface  201  and has a rectangular shape as the shape viewed from the Z direction (hereinafter also referred to as “shape in plan view”), second recess  212  which is formed on first surface  201  and connects first recess  211  and water collecting part  220  together, a plurality of first protrusion lines  213  which are arranged side by side in the X direction in first recess  211  such that the longitudinal direction thereof is aligned with the Y direction, and a plurality of second protrusion lines  214  which are arranged side by side in the Y direction in second recess  212  such that the longitudinal direction thereof is aligned with the X direction. A gap is formed between first protrusion line  213  and the wall surface of first recess  211  in the Y direction, and a gap is formed between an end portion of second protrusion line  214  in the X direction and first protrusion line  213  adjacent to second protrusion line  214  in the X direction. The distance between the bottom surface of first recess  211  and second recess  212  to the tip end surface of first protrusion line  213  and second protrusion line  214  (the height of first protrusion line  213  and second protrusion line  214 ) is, for example, 0.5 mm 
         [0043]    The opening shape of water collecting part  220  at first surface  201  is a circle as illustrated in  FIG. 7A . The opening diameter of water collecting part  220  is equal to the length of second recess  212  in the Y direction, and is, for example, 5 mm. As illustrated in  FIG. 7B , the opening shape of water collecting part  220  at second surface  202  is a shape (bell shape) which is formed with a semicircle of the above-mentioned circle and a rectangular which has a width of the diameter of the opening and extends in the Y direction from the diameter of the semicircle. 
         [0044]    As illustrated in  FIG. 6A  and  FIG. 6B , water collecting part  220  includes flow rate adjustment valve  221 . Flow rate adjustment valve  221  is composed of four flexible opening-closing parts which cover the circular opening of water collecting part  220 . The opening-closing parts has a form in which a substantially himisphere thin dome protruding from first surface  201  side toward second surface  202  side is divided with slits in a cross shape. The opening-closing part has a thickness of, for example, 0.5 mm, and, normally, the slit has a width of, for example, 0 mm 
         [0045]    As illustrated in  FIG. 4 , pressure reduction channel  230  is formed as a groove on second surface  202 . Pressure reduction channel  230  has a zigzag shape in plan view. In the zigzag shape, substantially triangular protrusions protruding from the side surface of pressure reduction channel  230  are alternately disposed along the longitudinal direction of pressure reduction channel  230 . The protrusions are disposed such that the tip of each protrusion does not exceed the central axis of pressure reduction channel  230  in plan view. The above-mentioned groove has a depth of, for example, 0.5 mm, and the above-mentioned groove has a width (W in  FIG. 4 ) of, for example, 0.5 mm 
         [0046]    As illustrated in  FIG. 4 , one end of pressure reduction channel  230  is connected with water collecting part  220  with linear groove  231  formed on second surface  202 , and the other end of pressure reduction channel  230  is connected with linear groove  232  formed on second surface  202 . Further, groove  232  is connected with flow rate control part  240  with through hole  233  which extends through emitter main body  200  from groove  232  and opens to first surface  201  as illustrated in  FIG. 5B  and  FIG. 5C . Grooves  231  and  232 , and through hole  233  have a width (the length in the Y direction) of, for example, 1 mm 
         [0047]    As illustrated in  FIG. 6A , flow rate control part  240  includes recess  241 , protrusion  242 , end surface  243 , hole  244  and groove  245 . 
         [0048]    As illustrated in  FIG. 6A , recess  241  is a bottomed recess which is provided with an opening part at first surface  201  and is connected with through hole  233 . In plan view, the opening part has a key-hole like shape composed of a combination of a circle and a rectangular. The rectangular is a recess which is shallow relative to recess  241 , and the rectangular recess is connected with through hole  233 , whereby through hole  233  and recess  241  are in communication with each other. The circular shape of the opening part has a diameter of, for example, 6 mm. When the opening part is sealed with film  300 , recess  241  forms a part of a channel of irrigation liquid on the downstream side relative to pressure reduction channel  230 . The distance from the bottom of recess  241  to first surface  201  in the Z direction (the depth of recess  241 ) is, for example, 2 mm 
         [0049]    As illustrated in  FIG. 5A  and  FIG. 5B , protrusion  242  is a substantially cylindrical thick body which is provided in an upright manner. Protrusion  242  includes, at an end thereof, end surface  243  which is disposed at a position where end surface  243  does not make contact with film  300  when the opening part is sealed. 
         [0050]    As illustrated in  FIG. 7A , end surface  243  has a circular shape in plan view, and the diameter thereof is, for example, 3 mm End surface  243  includes outer ring part  2431  which is parallel to the XY plane, and tilted surface  2432  which is tilted to second surface  202  side from the inner periphery edge of outer ring part  2431  toward hole  244  ( FIG. 9A ). The distance from outer ring part  2431  to film  300  in the Z direction is, for example, 0.25 mm 
         [0051]    Tilted surface  2432  is a curved surface which is slightly depressed with respect to first surface  201  side. Tilted surface  2432  coincides with a virtual curve, which is formed between the opening edges of the opening part of recess  241  and is in contact with the opening edges in a cross-section including the central axis of hole  244  of emitter main body  200 . The virtual curve includes a curve which is defined by film  300  when film  300  receives a pressure of the irrigation liquid in tube  110  having a value equal to or higher than a predetermined value in the above-mentioned cross-section ( FIG. 9A  and  FIG. 9C ). The curve has a curvature radius R of, for example, 12 mm 
         [0052]    As illustrated in  FIG. 5A , hole  244  opens at a center of end surface  243 , extends through protrusion  242 , and opens at recess  246  formed on second surface  202 . That is, hole  244  communicates between recess  241  and recess  246 . The hole diameter of hole  244  on end surface  243  side is, for example, 1 mm. The opening on end surface  243  side of hole  244  is smaller than that of the opening on recess  246  side. That is, hole  244  is a tapered hole whose diameter gradually increases from end surface  243  side toward recess  246  side in the Z direction. 
         [0053]    In plan view, recess  246  has a key-hole like shape composed of a combination of a circle with the opening of hole  244  at a center portion thereof and a rectangular having a width smaller than the diameter of the circle as illustrated in  FIG. 4 . 
         [0054]    As illustrated in  FIG. 6A , groove  245  is a groove extending from the outer peripheral edge of end surface  243  to hole  244 . That is, groove  245  communicates between recess  241  and hole  244 . One or more grooves  245  may be provided. For example, groove  245  has a width of 2 mm, and a depth of 0.05 mm 
         [0055]    As illustrated in  FIG. 2B  and  FIG. 4 , discharge part  250  is formed on second surface  202  as a recess which is continuous to recess  246  in the X direction and is deep relative to recess  246 . In plan view, discharge part  250  has a rectangular shape. At the connecting part of recess  246  and the discharge part, the length of discharge part  250  is greater than that of recess  246  in the Y direction. 
         [0056]    As illustrated in  FIG. 4 , slender protrusion line  251  is disposed along the Y direction in discharge part  250 . As illustrated in  FIG. 5A , protrusion line  251  protrudes to second surface  202  from the bottom of the recess forming discharge part  250 . As illustrated in  FIG. 4 , in the X direction, protrusion line  251  is disposed at a position away from recess  246 , and, in the Y direction, the length of protrusion line  251  is smaller than that of discharge part  250  and is substantially equal to that of recess  246  at the connecting part. As described, as viewed from discharge part  250  side along the X direction, protrusion line  251  is disposed at a position where protrusion  251  overlaps recess  246 . 
         [0057]    As illustrated in  FIG. 7A  and  FIG. 7B , film  300  is disposed integrally with emitter main body  200  through hinge part  301 . Hinge part  301  is disposed at an edge of first surface  201  of emitter main body  200  in the Y direction. For example, hinge part  301  is a portion having a thickness equal to that of film  300  and a width of 0.5 mm, and is formed integrally with emitter main body  200  and film  300 . 
         [0058]    As illustrated in  FIG. 7A  and  FIG. 7B , film  300  further includes rectangular opening part  302  at a position corresponding to first recess  211  of filter part  210  in the state where film  300  covers first surface  201 . For example, the thickness of film  300  may be determined by a computer simulation or an experiment using a trial product or the like on the basis of the deformation amount under a pressure described later, and may be, for example, 0.15 mm 
         [0059]    Each of emitter main body  200  and film  300  is molded with one material having flexibility such as polypropylene, for example. Examples of the material include resin and rubber, and examples of the resin include polyethylene and silicone. The flexibility of emitter  120  and film  300  can be adjusted with use of elastic resin materials, and for example, can be adjusted by the type of an elastic resin, the mixing ratio of an elastic resin material to a hard resin material, and the like. Emitter  120  can be manufactured as an integrally molded member by injection molding, for example. 
       (Operation) 
       [0060]    Film  300  turns about hinge part  301 , and is closely joined on first surface  201  of emitter main body  200 . For example, the joining is performed by welding of a resin material of emitter main body  200  or film  300 , by bonding using an adhesive agent, by pressure bonding of film  300  to emitter main body  200  or the like. When film  300  is joined to first surface  201 , a channel extending from filter part  210  to water collecting part  220  is formed, and recess  241  is liquid-tightly sealed with film  300 . 
         [0061]    Second surface  202  is joined to the inner wall surface of tube  110 . The joining is performed by welding of the resin material of emitter main body  200  or tube  110 , by bonding using adhesive agent, by pressure bonding of emitter main body  200  to tube  110 , or the like. When emitter  120  is joined to tube  110 , water collecting part  220 , pressure reduction channel  230 , flow rate control part  240  and discharge part  250  are configured to exhibit their desired functions. Normally, emitter  120  is joined to the inner periphery wall of tube  110  before discharge port  130  is formed, and thereafter, discharge port  130  is formed at a position corresponding to discharge part  250  of tube  110 . Alternatively, emitter  120  may be joined to the inner wall surface of tube  110  such that emitter  120  is located at the position of preliminarily provided discharge port  130 . 
         [0062]    Next, discharge of irrigation liquid by emitter  120  is described.  FIG. 9A  illustrates part A of  FIG. 5A  in an enlarged manner in the case where the pressure of the irrigation liquid in tube  110  is equal to or higher than a first pressure value and lower than a second pressure value.  FIG. 9B  illustrates part A of  FIG. 5A  in an enlarged manner in the case where the pressure of the irrigation liquid in tube  110  is equal to or higher than the second pressure value and lower than a third pressure value.  FIG. 9C  illustrates part A of  FIG. 5A  in an enlarged manner in the case where the pressure of the irrigation liquid in tube  110  is equal to or higher than the third pressure value. 
         [0063]    Supply of irrigation liquid to trickle irrigation tube  100  is performed in a range where the pressure of the irrigation liquid does not exceed 0.1 MPa for the purpose of preventing damaging of tube  110  and emitter  120 . When irrigation liquid is supplied into tube  110 , the irrigation liquid reaches second recess  212  covered with film  300  in the Z direction through a gap between first recess  211  and first protrusion line  213  of filter part  210  and reaches water collecting part  220  through a gap between second recess  212  and second protrusion line  214 . Filter part  210  prevents intrusion of float in the irrigation liquid having a size greater than the gap. 
         [0064]    When the pressure of the irrigation liquid in tube  110  is equal to or higher than the first pressure value (for example, 0.005 MPa), flow rate adjustment valve  221  is pushed to second surface  202  side, and the slit of flow rate adjustment valve  221  is expanded. In this manner, the irrigation liquid reaching water collecting part  220  is received by emitter main body  200  from water collecting part  220 . Flow rate adjustment valve  221  suppresses inflow of the irrigation liquid to emitter main body  200  when the pressure of the irrigation liquid is lower than the first pressure. Thus, high-pressure supply of the irrigation liquid to tube  110  can be achieved, and therefore the configuration where emitter  120  has flow rate adjustment valve  221  is favorable for forming trickle irrigation tube  100  having a greater length, for example. 
         [0065]    The irrigation liquid received from water collecting part  220  is supplied to pressure reduction channel  230  through groove  231 . The pressure of the irrigation liquid flowing through pressure reduction channel  230  is reduced as a result of pressure reduction caused by the shape (zigzag shape) in plan view of reduction channel  230 . In addition, floats in the irrigation liquid are entangled in the turbulent flow generated between the protrusions of pressure reduction channel  230  and are retained in pressure reduction channel  230 . In this manner, the floats are further removed from the irrigation liquid by pressure reduction channel  230 . 
         [0066]    The irrigation liquid having passed through pressure reduction channel  230  in which the pressure is reduced and the floats are removed is supplied into recess  241  of flow rate control part  240  through groove  232  and hole  233 . When recess  241  is filled with the irrigation liquid, the irrigation liquid is supplied to hole  244  of protrusion  242  through a gap between film  300  and end surface  243  as illustrated in  FIG. 9A . 
         [0067]    The irrigation liquid having passed through hole  244  reaches recess  246  and discharge part  250 , and is discharged out of tube  110  through discharge port  130  which opens to discharge part  250 . 
         [0068]    While foreign matters of soil or the like may enter discharge part  250  from discharge port  130 , intrusion of the foreign matters to recess  246  is blocked by protrusion lines  251  of discharge part  250 . 
         [0069]    As the pressure of the irrigation liquid in tube  110  increases, the flow rate of the irrigation liquid flowing into emitter main body  200  from water collecting part  220  increases, and the discharge rate of the irrigation liquid from discharge port  130  increases. 
         [0070]    When the pressure of the irrigation liquid in tube  110  is equal to or higher than the second pressure value (for example, 0.02 MPa), film  300  pushed by the irrigation liquid in tube  110  is deflected as illustrated in  FIG. 9B . Consequently, the distance between film  300  and end surface  243  at flow rate control part  240  is reduced. For example, the distance between end surface  243  and film  300  is changed to 0.15 mm Thus, the amount of the irrigation liquid which passes through flow rate control part  240  is reduced, and the increase of the discharge rate of the irrigation liquid from discharge port  130  is suppressed. 
         [0071]    When the pressure of the irrigation liquid in tube  110  is equal to or higher than the third pressure value (for example, 0.05 MPa), film  300  pushed by the irrigation liquid in tube  110  is further deflected, and is brought into close contact with end surface  243  (tilted surface  2432 ) of protrusion  242  as illustrated in  FIG. 9C . In this manner, film  300  functions as a valve element for sealing a hole which is a channel of the irrigation liquid under high pressure, and end surface  243  functions as a valve seat of the valve element. Meanwhile, since groove  245  is not sealed even when film  300  makes close contact with end surface  243 , the irrigation liquid supplied to recess  241  is supplied from recess  241  to hole  244  through groove  245 . Consequently, the amount of the irrigation liquid which passes through flow rate control part  240  is restricted to a flow rate which can pass through groove  245 , and the discharge rate of the irrigation liquid from discharge port  130  becomes substantially constant. In this manner, emitter  120  quantitatively discharges the irrigation liquid from tube  110  supplied with the irrigation liquid. 
       (Effect) 
       [0072]    As described above, emitter  120  includes water collecting part  220  for receiving the irrigation liquid in tube  110 , pressure reduction channel  230  for allowing the irrigation liquid received from water collecting part  220  to flow therethrough while reducing the pressure of the irrigation liquid, flow rate control part  240  for controlling the flow rate of the irrigation liquid supplied from pressure reduction channel  230  in accordance with the pressure of the irrigation liquid in tube  110 , and discharge part  250  to which the irrigation liquid having a flow rate controlled by flow rate control part  240  supplied, discharge part  250  facing discharge port  130 . Water collecting part  220  opens at first surface  201  of emitter main body  200 . Flow rate control part  240  includes an opening part which opens at first surface  201 , film  300  having flexibility which seals the opening part and blocks communication between a channel on the downstream side relative to pressure reduction channel  23  and the inside of tube  110 , a recessed surface part (tilted surface  2432 ) depressed with respect to film  300  and disposed at a channel on a downstream side relative to pressure reduction channel  230  such that the recessed surface part faces film  300  without making contact with film  300 , but the recessed surface part being capable of making close contact with film  300 ; hole  244  opening at the recessed surface part and communicated with discharge part  250 , and groove  245  formed on the recessed surface part and configured to communicate between hole  244  and the channel on outside relative to the recessed surface part. When emitter  120  is disposed to the inner wall surface of tube  110  at a position corresponding to discharge port  130  of tube  110 , trickle irrigation tube  100  is formed. Film  300  starts to deflect when the pressure of the irrigation liquid in tube  110  is equal to or higher than the above-mentioned second pressure value, and film  300  makes close contact with the recessed surface part when the pressure is equal to or higher than the third pressure value. Therefore, emitter  120  discharges the irrigation liquid such that the amount of the liquid is limited to the amount which passes through groove  245  even when the pressure of the irrigation liquid in tube  110  increases. In this manner, emitter  120  quantitatively discharges the irrigation liquid in tube  110  from discharge port  130  in accordance with the pressure of the irrigation liquid in tube  110 , and thus can stabilize the discharge rate of the irrigation liquid. 
         [0073]    Further, since the above-described components of emitter  120  are composed of a recess or a through hole formed on first surface  201  or second surface  202  of emitter main body  200 , emitter main body  200  can be integrally produced by injection molding. Therefore, emitter  120  can further reduce manufacturing cost in comparison with conventional emitters composed of three parts. 
         [0074]    In addition, with the configuration in which emitter  120  is molded with one material having flexibility and film  300  is integrally molded as a part of emitter  120  such that film  300  can close recess  241 , both of emitter main body  200  and film  300  can be molded as one component by injection molding, and consequently manufacturing error of the joining position of film  300  can be prevented, which is further favorable from the standpoint of further reducing manufacturing cost, for example. 
         [0075]    In addition, with the configuration in which water collecting part  220  further includes water flow rate adjustment valve  221  configured to expand the irrigation liquid channel at collecting part  220  in accordance with the increase of the pressure of the irrigation liquid in tube  110 , the irrigation liquid can be supplied to tube  110  with a higher pressure, which is further favorable from the viewpoint of forming trickle irrigation tube  100  having a greater length. 
       (Modification) 
       [0076]    In trickle irrigation tube  100 , the above-described configurations may be partially changed, or other configurations may be additionally provided as long as the above-described effect is achieved. 
         [0077]    For example, tube  110  may be a seamless tube, or a tube composed of slender sheet(s) joined together along the longitudinal direction. 
         [0078]    In addition, discharge port  130  may be a gap formed at the above-mentioned joining part of the sheet(s) so as to communicate between the inside and the outside of tube  110 , or a pipe sandwiched by the sheets at the joining part. Further, the shape of the discharge port in the axial direction may not be a straight line shape. Examples of the tube having the discharge port include a tube in which a depression having a desired shape and serving as a channel is formed on the surface of the above-mentioned sheet(s), and a discharge port composed of the channel is formed at the joining part when the sheets are joined together. 
         [0079]    While water collecting part  220  is located at a position on the upstream side in the flow direction of the irrigation liquid in tube  110 , water collecting part  220  may be located at a position on the downstream side. In addition, the orientations of a plurality of emitters in one tube  110  may be identical to each other or different from each other. 
         [0080]    In addition, the resin material of emitter main body  200  and the resin material of film  300  may be identical to each other or different from each other. 
         [0081]    While emitter main body  200  is integrally by injection molding of resin, emitter main body  200  may be composed of two components of a first surface  201  side component and a second surface  202  side component. In this case, the first surface  201  side component is integrally molded with film  300 . With the configuration in which emitter main body  200  is composed of the two components, a channel such as a pressure reduction channel can be disposed inside emitter main body  200 . It is to be noted that the two components may be integrally molded through a hinge part. 
         [0082]    In addition, pressure reduction channel  230  may be a groove on first surface  201  which is covered with film  300  in emitter main body  200 . 
         [0083]    While the recessed surface part is tilted surface  2432  in the present embodiment, other suitable configurations may also be adopted as long as it can make close contact with film  300  at a position around hole  244 . For example, the recessed surface part may be a planer part located at a position closer to second surface  202  side than first surface  201  in flow rate control part  240 . 
         [0084]    While second surface  202  is a planer surface in Embodiment 1, second surface  202  may also be a curved surface extending along the inner wall of tube  110  (for example, a surface formed of the arc of the internal diameter of tube  110  in YZ plane). 
       Embodiment 2 
       [0085]    Now Embodiment 2 of the present invention is described. 
       (Configuration) 
       [0086]      FIG. 10  is a schematic sectional view of trickle irrigation tube  500  according to Embodiment 2 of the present invention. Trickle irrigation tube  500  is composed of tube  110  and emitter  620 . The configuration of tube  110  is identical to that of the above-described Embodiment 1. 
         [0087]      FIG. 11A  is a plan view of emitter  620 ,  FIG. 11B  is a front view of emitter  620 ,  FIG. 11C  is a bottom view of emitter  620 , and  FIG. 11D  is a side view of emitter  620 . In addition,  FIG. 12A  is a sectional view of emitter  620  taken along line A-A of  FIG. 11A , and  FIG. 12B  is a sectional view of emitter  620  taken along line B-B of  FIG. 11A . 
         [0088]    As illustrated in  FIG. 11B  and  FIG. 11C , emitter  620  includes water collecting part  720 , pressure transfer pipe  725 , flange part  730  and discharge part  740 . Here, the Z direction is a direction along the axis of water collecting part  720 , and includes a direction in which emitter  620  is inserted to tube  110 . The X direction is one direction orthogonal to the Z direction, and the Y direction is a direction orthogonal to both of the Z direction and the X direction. 
         [0089]    The shape viewed along the Z direction (shape in plan view) of flange part  730  is a circular shape. Flange part  730  has an outer diameter of, for example, 16 mm. As illustrated in  FIG. 11A  and  FIG. 11B , water collecting part  720  is disposed at a center of flange part  730  in plan view, and pressure transfer pipe  725  and discharge part  740  are disposed at positions shifted in the X direction from a center of flange part  730  as illustrated in  FIG. 11B ,  FIG. 11C  and  FIG. 11D . 
         [0090]    Flange part  730  is composed of a combination of first disk part  731  on water collecting part  720  and pressure transfer pipe  725  side and second disk part  732  on discharge part  740  side. Water collecting part  720  and pressure transfer pipe  725  are formed integrally with first disk part  731 , and discharge part  740  is formed integrally with second disk part  732 . Hereinafter, the integrally molded member of water collecting part  720 , pressure transfer pipe  725  and first disk part  731  is also referred to as “first component,” and the integrally molded member of discharge part  740  and second disk part  732  is also referred to as “second component.” 
         [0091]    As illustrated in  FIG. 12A  and  FIG. 12B , water collecting part  720  is a cylindrical member uprightly provided on first surface  7311  of first disk part  731 . Barb  721  is formed at an end portion of water collecting part  720 . Barb  721  is composed of large diameter part  7211  which expands from the outer peripheral surface of water collecting part  720  along the XY plane, and tapered surface  7212  whose outer diameter gradually decreases from large diameter part  7211  toward an end of water collecting part  720 . For example, large diameter part  7211  has an outer diameter of 3.2 mm, and the end of tapered surface  7212  has an outer diameter of 2.6 mm 
         [0092]    As with water collecting part  720 , pressure transfer pipe  725  is a cylindrical member uprightly provided on first surface  7311  of first disk part  731  as illustrated in  FIG. 12A  and  FIG. 12B . Barb  726  is formed at an end portion of pressure transfer pipe  725 . Barb  726  is composed of large diameter part  7261  which expands from the outer peripheral surface of pressure transfer pipe  725  along the XY plane, and tapered surface  7262  whose outer diameter gradually decreases from large diameter part  7261  toward an end of pressure transfer pipe  725 . For example, large diameter part  7261  has an outer diameter of 4 mm, and the end of tapered surface  7262  has an outer diameter of 3.3 mm 
         [0093]      FIG. 13A  is a plan view of the first component,  FIG. 13B  is a front view of the first component,  FIG. 13C  is a bottom view of the first component, and  FIG. 13D  is a side view of the first component. In addition,  FIG. 14A  is a sectional view of the first component taken along line A-A of  FIG. 13A , and  FIG. 14B  is a sectional view of the first component taken along line B-B of  FIG. 13A . 
         [0094]    As illustrated in  FIG. 13A  and  FIG. 13C , first disk part  731  includes recess  7313  on first surface  7311  side, and protrusion line  7314 , first recess  7315 , pressure reduction channel  750 , channel  760 , second recess  7316  and flow rate adjustment valve  780  on second surface  7312  side which is an opposite side of first surface  7311  in the Z direction. 
         [0095]    As illustrated in  FIG. 14A , recess  7313  is a recess formed on first surface  7311 . In plan view, recess  7313  has a circular shape as illustrated in  FIG. 13A . The bottom of recess  7313  composes film  770  described later. Recess  7313  has a diameter of, for example, 3 mm, and recess  7313  has a depth from first surface  7311  of, for example, 0.65 mm Pressure transfer pipe  725  is in communication with recess  7313 . 
         [0096]    As illustrated in  FIG. 13C , protrusion line  7314  is disposed at the peripheral portion of second surface  7312 , and as illustrated in  FIG. 14A  and  FIG. 14B , protrusion line  7314  protrudes from second surface  7312 . The height of protrusion line  7314  from second surface  7312  is, for example, 1 mm 
         [0097]    As illustrated in  FIG. 13C , first recess  7315  is formed at a center of second surface  7312 . In plan view, first recess  7315  has a circular shape. First recess  7315  is in communication with the inside of water collecting part  720 , and the diameter of first recess  7315  is slightly larger than the internal diameter of water collecting part  720 . The depth of first recess  7315  from second surface  7312  is, for example, 0.5 mm 
         [0098]    As illustrated in  FIG. 14B , pressure reduction channel  750  is a portion formed as a groove on second surface  7312 . As illustrated in  FIG. 13C , pressure reduction channel  750  is connected with first recess  7315 , and extends toward the peripheral portion of second surface  7312  along the radial direction of second surface  7312 . In plan view, pressure reduction channel  750  has a zigzag shape as with the above-described pressure reduction channel  230 , and pressure reduction channel  750  has a width (W in  FIG. 13C ) of, for example, 0.45 mm 
         [0099]    As illustrated in  FIG. 14A  and  FIG. 14B , channel  760  is formed as a groove on second surface  7312 . As illustrated in  FIG. 13C , at the peripheral portion of second surface  7312 , the base end of channel  760  is connected with pressure reduction channel  750 , and channel  760  extends along the extending direction of pressure reduction channel  750 . While an end of channel  760  is extended to a region near first recess  7315 , the end portion of channel  760  and first recess  7315  are not in communication with each other. 
         [0100]    As illustrated in  FIG. 14A , second recess  7316  is a recess formed on second surface  7312 . As illustrated in  FIG. 13C , second recess  7316  is adjacent to an end portion of channel  760 , and has a rectangular shape in plan view. In the Z direction, second recess  7316  overlaps recess  7313  on first surface  7311  side, and this overlapping part is thin film  770 . Accordingly, film  770  has a circular shape in plan view. The depth of second recess  7316  from second surface  7312  is, for example, 0.2 mm, and the thickness of film  770  is, for example, 0.15 mm. The thickness of film  770  is determined by a computer simulation or an experiment using a trial product or the like on the basis of the deformation amount under a pressure described later, for example. 
         [0101]    As with the above-described flow rate adjustment valve  221 , flow rate adjustment valve  780  is composed of four opening-closing parts. As illustrated in  FIG. 13C ,  FIG. 14A  and  FIG. 14B , the opening-closing part has a form similar to the form in which a substantially himisphere thin dome protruding from the inner base end of water collecting part  720  toward first recess  7315  is divided with slits in a cross shape. The slit has a width of, for example, 0 mm, and the opening-closing part has a thickness of, for example, 0.2 mm 
         [0102]    As illustrated in  FIG. 12A , discharge part  740  is a cylindrical member uprightly provided on first surface  7321  of second disk part  732 . As with water collecting part  720 , barb  741  is formed at an end portion of discharge part  740 . Barb  741  is composed of large diameter part  7411  which expands from the outer peripheral surface of discharge part  740  along XY plane, and tapered surface  7412  whose outer diameter gradually decreases from large diameter part  7411  toward an end of discharge part  740 . For example, large diameter part  7411  has an outer diameter of 5 mm, and the end of tapered surface  7412  has an outer diameter of 4 mm 
         [0103]      FIG. 15A  is a plan view of the second component,  FIG. 15B  is a front view of the second component,  FIG. 15C  is a bottom view of the second component,  FIG. 15D  is a side view of the second component, and  FIG. 15E  is a sectional view of the second component taken along line A-A of  FIG. 15A . Second disk part  732  includes recessed line  7324 , recessed surface part  810 , hole  820  and groove  830 . 
         [0104]    As illustrated in  FIG. 15A , recessed line  7324  is disposed at the peripheral portion of second surface  7322  which is an opposite side of first surface  7321  in the Z direction, and, as illustrated in  FIG. 15B  and  FIG. 15D , is depressed from second surface  7322 . The depth of recessed line  7324  from second surface  7322  is, for example, 1 mm 
         [0105]    As illustrated in  FIG. 12A , recessed surface part  810  is a recess formed at a position facing film  770  in second surface  7322 . In plan view, recessed surface part  810  has a circular shape as illustrated in  FIG. 15A . Recessed surface part  810  has a diameter of, for example, 1.8 mm Recessed surface part  810  is formed with a curved surface slightly depressed from second surface  7322 , and is formed such that film  770  makes close contact with at least a part surrounding hole  820  of recessed surface part  810  when film  770  is deflected under a pressure of the irrigation liquid having a value equal to or higher than a predetermined value in pressure transfer pipe  725  in pressure transfer pipe  725 . 
         [0106]    As illustrated in  FIG. 15A , hole  820  opens at a center portion of recessed surface part  810 . The opening of hole  820  on recessed surface part  810  side has a circular shape. As illustrated in  FIG. 15E , hole  820  penetrates second disk part  732  along the Z direction, and is in communication with the inside of discharge part  740 . The opening of hole  820  on recessed surface part  810  side has a diameter of, for example, 1 mm, and is smaller than the opening on discharge part  740  side. That is, hole  820  is a tapered hole whose diameter gradually increases from recessed surface part  810  side toward discharge part  740  side along the Z direction. 
         [0107]    As illustrated in  FIG. 15E , groove  830  is formed on second surface  7322  including recessed surface part  810  so as to cross recessed surface part  810  along the radial direction thereof. In emitter  620 , groove  830  communicates between channel  760  and hole  820  as illustrated in  FIG. 12A . Groove  830  has a width of, for example, 0.2 mm, and has a depth from second surface  7322  of, for example, 0.05 mm 
         [0108]    As with emitter main body  200  of Embodiment 1, each of the first component and second component is integrally molded by injection molding using one resin material having flexibility (for example, polypropylene). It is to be noted that examples of the material of the first component and second component include resin and rubber, and examples of the resin include polyethylene and silicone. The flexibility of the material is properly adjusted by the type of the resin material, mixture of two or more resin materials or the like in accordance with the flexibility required for film  770 . 
       (Operation) 
       [0109]    Protrusion line  7314  of first disk part  731  is fitted with recessed line  7324  of second disk part  732 , whereby second surface  7312  of first disk part  731  and second surface  7322  of second disk part  732  make close contact with each other and thus emitter  620  is formed as illustrated in  FIG. 12B . Further, second surfaces  7312  and  7322  may be joined by welding of a resin material, by bonding using an adhesive agent, by pressure bonding of one of them to the other or the like. 
         [0110]    As illustrated in  FIG. 10 , emitter  620  is attached to tube  110  by inserting water collecting part  720  and pressure transfer pipe  725  to the tube wall of tube  110 . Emitter  620  may be attached to tube  110  by penetrating the tube wall of tube  110  with water collecting part  720  and pressure transfer pipe  725 , or by inserting water collecting part  720  and pressure transfer pipe  725  to an opening part for insertion which is preliminarily formed on the tube wall of tube  110 . The former configuration is favorable for freely attaching emitter  620  to tube  110 , and the latter configuration is favorable for preventing leakage of irrigation liquid from tube  110 . Since water collecting part  720  and pressure transfer pipe  725  each has a barb at an end portion thereof, dropping of emitter  620  from tube  110  is prevented. 
         [0111]    Next, discharge of irrigation liquid by emitter  620  is described.  FIG. 16A  schematically illustrates a state of part A of  FIG. 12A  in the case where the pressure of the irrigation liquid in tube  110  is equal to or higher than the first pressure value and is lower than the second pressure value,  FIG. 16B  schematically illustrates a state of part A of  FIG. 12A  in the case where the pressure of the irrigation liquid in tube  110  is equal to or higher than the second pressure value and is lower than the third pressure value, and  FIG. 16C  schematically illustrates a state of part A of  FIG. 12A  in the case where the pressure of the irrigation liquid in tube  110  is equal to or higher than the third pressure value. 
         [0112]    Supply of irrigation liquid to trickle irrigation tube  500  is performed in a range where the pressure of the irrigation liquid does not exceed 0.1 MPa for the purpose of preventing damaging of tube  110  and emitter  620 . When the irrigation liquid is supplied into tube  110 , the irrigation liquid reaches flow rate adjustment valve  780  through water collecting part  720 , and pressure transfer pipe  725  is filled with the irrigation liquid ( FIG. 12B ). 
         [0113]    When the pressure of the irrigation liquid in tube  110  is equal to or higher than the first pressure value (for example, 0.005 MPa), flow rate adjustment valve  780  is pushed to first recess  7315  side, and the slit of flow rate adjustment valve  780  is expanded. In this manner, the irrigation liquid reaching flow rate adjustment valve  780  is supplied to pressure reduction channel  750  via adjustment valve  780  and through first recess  7315  ( FIG. 12B ). Thus, flow rate adjustment valve  780  suppresses distribution of the irrigation liquid in emitter  620  when the pressure of the irrigation liquid is lower than the first pressure. Consequently, the irrigation liquid can be supplied to tube  110  with a high pressure, and therefore the configuration in which emitter  620  has flow rate adjustment valve  780  is favorable for forming trickle irrigation tube  500  having a greater length, for example. 
         [0114]    The pressure of the irrigation liquid flowing through pressure reduction channel  750  is reduced as a result of pressure reduction caused by the shape of reduction channel  750  in plan view (zigzag shape). In addition, floats in the irrigation liquid are entangled in the turbulent flow generated between the above-mentioned protrusions of pressure reduction channel  750 , and retained in pressure reduction channel  750 . In this manner, floats are further removed from irrigation liquid by pressure reduction channel  750 . 
         [0115]    The irrigation liquid having passed through pressure reduction channel  750  in which the pressure is reduced and the floats are removed is supplied to second recess  7316  (the space sandwiched by film  770  and recessed surface part  810 ) through channel  760  and passes through hole  820  as illustrated in  FIG. 16A . Then, the irrigation liquid is discharged out of tube  110  through part  740  ( FIG. 12A ). 
         [0116]    As the pressure of the irrigation liquid in tube  110  increases, the flow rate of the irrigation liquid flowing into emitter  620  from water collecting part  720  increases, and consequently the discharge rate of the irrigation liquid from discharge port  740  increases. 
         [0117]    When the pressure of the irrigation liquid in tube  110  is equal to or higher than the second pressure value (for example, 0.02 MPa), film  770  is pushed by the irrigation liquid in pressure transfer pipe  725  and is deflected as illustrated in  FIG. 16B . Since no structure which causes pressure reduction is provided inside pressure transfer pipe  725 , the pressure of the irrigation liquid in pressure transfer pipe  725  is substantially the same as that of the irrigation liquid in tube  110 . In this manner, pressure transfer pipe  725  transmits the pressure of the irrigation liquid in tube  110  to the rear surface of film  770 . Thus, film  770  is pushed from pressure transfer pipe  725  side by the pressure of the irrigation liquid in the tube, and the distance between film  770  and recessed surface part  810  is reduced. For example, the distance is changed to 0.25 mm to 0.15 mm Consequently, the amount of the irrigation liquid which passes between film  770  and recessed surface part  810  is reduced, and the increase of the discharge rate of the irrigation liquid from discharge port  740  is suppressed. 
         [0118]    When the pressure of the irrigation liquid in tube  110  is equal to or higher than the third pressure value (for example, 0.05 MPa), film  770  is pushed and further deflected by the irrigation liquid in tube  110  and brought into close contact with recessed surface part  810  as illustrated in  FIG. 16C . In this manner, film  770  functions as a valve element for restricting the distribution of irrigation liquid, and recessed surface part  810  functions as a valve seat. Meanwhile, since groove  830  is not sealed even when film  770  makes close contact with recessed surface part  810 , the irrigation liquid having passed through channel  760  is supplied to hole  820  through groove  830 . Consequently, the amount of the irrigation liquid which passes through hole  820  is restricted to a flow rate which can pass through groove  830 , and the discharge rate of the irrigation liquid from discharge port  740  becomes substantially constant. In this manner, emitter  620  quantitatively discharges the irrigation liquid from tube  110  supplied with the irrigation liquid. 
       (Effect) 
       [0119]    As described, emitter  620  includes: water collecting part  720  for receiving irrigation liquid in tube  110 , water collecting part  720  having a cylindrical shape to be inserted to tube  110  from outside of tube  110 , tube  110  being configured to distribute irrigation liquid; pressure reduction channel  750  for allowing the irrigation liquid received from water collecting part  720  to flow therethrough while reducing a pressure of the irrigation liquid; a flow rate control part for controlling a flow rate of the irrigation liquid supplied from pressure reduction channel  750  in accordance with the pressure of irrigation liquid in tube  110 ; and discharge part  740  for discharging from tube  110  the irrigation liquid having a flow rate controlled by the flow rate control part to outside of tube  110 . When one end of water collecting part  720  from which water collecting part  720  is inserted to tube  110  is defined as a tip end and the other end of water collecting part  720  is a base end, a flange part is disposed at the base end of water collecting part  720 . Flange part  730  is composed of a combination of first disk part  731  disposed at the base end of water collecting part  720  and second disk part  732  on which discharge part  740  is disposed, flange part  730  including pressure reduction channel  750  and the flow rate control part. The flow rate control part includes: film  770  having flexibility disposed to face a channel on a downstream side relative to pressure reduction channel  750 ; a pressure transmission part for transmitting the pressure of irrigation liquid in tube  110  to a rear surface of film  770 ; a recessed surface part  810  depressed with respect to film  770  and disposed at a channel on a downstream side relative to pressure reduction channel  750  such that recessed surface part  810  faces film  770  without making contact with film  770 , recessed surface part  810  being capable of making close contact with film  770 , and; a hole opening at recessed surface part  810  and communicated with discharge part  740 ; and groove  830  formed on recessed surface part  810  and configured to communicate between the hole and the channel on outside relative to recessed surface part  810 . When water collecting part  720  is inserted to tube  110 , emitter  620  is disposed to tube  110 , and trickle irrigation tube  500  is formed. Film  700  starts to deflect when the pressure of the irrigation liquid in tube  110  is equal to or higher than the above-mentioned second pressure value, and film  700  makes close contact with the recessed surface part when the pressure is equal to or higher than the third pressure value. Therefore, emitter  620  discharges the irrigation liquid such that the amount of the liquid is limited to the amount which passes through groove  830  even when the pressure of the irrigation liquid in tube  110  increases. In this manner, emitter  620  quantitatively discharges the irrigation liquid in tube  110  from discharge port  740  in accordance with the pressure of the irrigation liquid in tube  110 , and thus can stabilize the discharge rate of the irrigation liquid. 
         [0120]    Further, since the above-described components of emitter  620  are composed of a recess or a through hole formed on the first surface or the second surface of the first component and the second component, each of the first component and the second component can be integrally produced by injection molding. Therefore, emitter  620  can further reduce manufacturing cost in comparison with conventional emitters composed of three parts. 
         [0121]    In addition, with the configuration in which first disk part  731  includes pressure reduction channel  750 , pressure transfer pipe  725  and film  770  and second disk part  732  includes recessed surface part  810 , hole  820  and groove  830 , each of the first component and the second component can be fabricated with a further simplified structure, which is further favorable from the standpoint of further reducing manufacturing cost. 
         [0122]    Further, as described later in the modification, with the configuration in which first disk part  731  and second disk part  732  are integrally formed with the same material, emitter  620  can be produced with one component, which is favorable from the standpoint of further reducing manufacturing cost. 
         [0123]    In addition, with the configuration in which water collecting part  720  further includes flow rate adjustment valve  780  for expanding the channel for the irrigation liquid when the pressure of the irrigation liquid in tube  110  is equal to or higher than a predetermined value, the irrigation liquid can be supplied to tube  110  with a higher pressure, which is favorable from the standpoint of forming trickle irrigation tube  500  having a greater length. 
       (Modification) 
       [0124]    In trickle irrigation tube  500 , the above-described configurations may be partially changed, or other configurations may be additionally provided as long as the above-described effect is achieved. 
         [0125]    For example, discharge part  740  may not have barb  741  as illustrated in  FIG. 17A , and may be an opening part which opens at first surface  7321  of second disk part  732  as illustrated in  FIG. 17B . 
         [0126]    In addition, tube  110  may be a seamless tube, a tube composed of slender sheet(s) joined together along the longitudinal direction, or a tube having a gap formed at the above-mentioned joining part of the sheets so as to communicate between the inside and the outside of tube  110 , or a pipe sandwiched by the sheets at the joining part. 
         [0127]    In addition, the first component and the second component may be integrally formed so as to be turnable about a hinge part integrally formed with the first component and the second component. In this case, the number of components of emitter  620  can be further reduced, that is emitter  620  can be produced with one component. 
         [0128]    In addition, emitter  620  may include, in place of pressure transfer pipe  725 , a part for transmitting to film  770  deflection of film  770  in accordance with the pressure of the irrigation liquid in tube  110 , or, a part capable of directly or indirectly transmitting to the rear surface of film  770  the pressure of the irrigation liquid in the tube. 
         [0129]    While recessed surface part  810  is a curved surface slightly depressed from second surface  7322  in the present embodiment, other suitable configurations may also be adopted as long as close contact with film  770  around hole  820  is achieved. For example, recessed surface part  810  may be a planer part located at a position nearer to first surface  7321  side than second surface  7322 . 
         [0130]    This application is entitled to and claims the benefit of Japanese Patent Application No. 2013-245228 filed on Nov. 27, 2013, the disclosure each of which including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
       INDUSTRIAL APPLICABILITY 
       [0131]    According to the present invention, an emitter which can discharge liquid with an appropriate speed by the pressure of the liquid to be discharged can be easily provided. Accordingly, popularization of the above-mentioned emitter in technical fields such as trickle irrigations and endurance tests where long-term discharging is required, and further development of the technical fields can be expected. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100 ,  500  Trickle irrigation tube 
           110  Tube 
           120 ,  620  Emitter 
           130  Discharge port 
           200  Emitter main body 
           201 ,  7311 ,  7321  First surface 
           202 ,  7312 ,  7322  Second surface 
           210  Filter part 
           211 ,  7315  First recess 
           212 ,  7316  Second recess 
           213  First protrusion line 
           214  Second protrusion line 
           220 ,  720  Water collecting part 
           221 ,  780  Flow rate adjustment valve 
           230 ,  750  Pressure reduction channel 
           231 ,  232 ,  245 ,  830  Groove 
           233  Through hole 
           240  Flow rate control part 
           241 ,  246 ,  7313  Recess 
           242  Protrusion 
           243  End surface 
           244 ,  820  Hole 
           250 ,  740  Discharge part 
           251 ,  7314  Protrusion line 
           300 ,  770  Film 
           301  Hinge part 
           302  Opening part 
           721 ,  726 ,  741  Barb 
           725  Pressure transfer pipe 
           730  Flange part 
           731  First disk part 
           732  Second disk part 
           760  Channel 
           810  Recessed surface part 
           2431  Outer ring part 
           2432  Tilted surface 
           7211 ,  7411 ,  7261  Large diameter part 
           7212 ,  7412 ,  7262  Tapered surface 
           7324  Recessed line