Patent Publication Number: US-2019183074-A1

Title: Emitter and drip-irrigation tube

Description:
TECHNICAL FIELD 
     The present invention relates to an emitter and a drip irrigation tube including the emitter. 
     BACKGROUND ART 
     Conventionally, a drip irrigation method is known as a method for culturing plants. In the drip irrigation method, a drip irrigation tube is disposed on the soil where plants are planted, and irrigation liquid such as water and liquid fertilizer is dropped to the soil from the drip irrigation tube. The drip irrigation method is advantageous at least in that the consumption amount of the irrigation liquid can be minimized. 
     The drip irrigation tube includes a tube having a plurality of through holes for discharging irrigation liquid, and a plurality of emitters (also referred to as “drippers”) joined on the inner wall surface of the tube and configured to discharge irrigation liquid from respective through holes (see, for example, PTL 1). 
       FIG. 1  is a sectional view of emitter  1  disclosed in PTL 1. Emitter  1  disclosed in PTL 1 includes emitter main body  10  and film  13  shaped integrally with emitter main body  10 . Emitter main body  10  and film  13  are formed of polypropylene, for example. Emitter main body  10  includes flow rate adjustment valve  11  and flow rate control valve  12 . 
     Flow rate adjustment valve  11  is composed of four flexible opening-closing parts. The four opening-closing parts deform in accordance with the pressure of the irrigation liquid, and then the widths of the slits between opening-closing parts change. With this configuration, flow rate adjustment valve  11  can adjust the flow rate of the irrigation liquid in emitter  1  in accordance with the pressure of the irrigation liquid. 
     Flow rate control valve  12  includes four opening-closing parts, and the opening-closing parts include a portion that can deform in accordance with the pressure of the irrigation liquid. By the deformation of the portion, widths of the gaps between the opening-closing parts change. With this configuration, flow rate control valve  12  can control the flow rate of the irrigation liquid in emitter  1  in accordance with the pressure of the irrigation liquid. 
     CITATION LIST 
     Patent Literature 
     PTL 1 
     WO2015/050082 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the emitter disclosed in PTL 1, when a portion (in PTL 1, the flow rate adjustment valve and the flow rate control valve) that deforms to adjust the flow rate of the irrigation liquid is deformed due to high temperature, a very long time (e.g. one day) is required for resetting it to the state before the deformation. Consequently, when the emitter disclosed in PTL 1 is used under high temperature, the performance of the emitter is changed in the period until the emitter is reset to the pre-deformation state, and the irrigation liquid cannot be quantitatively discharged for a certain time period. 
     An object of the present invention is to provide an emitter and a drip irrigation tube in which the emitter is not easily deformed even when used under high temperature. 
     Solution to Problem 
     To solve the above-mentioned problems, an emitter according to the present invention is configured to be joined on an inner wall surface of a tube for distributing irrigation liquid at a position corresponding to a discharging port for communicating between inside and outside of the tube, the emitter being configured to quantitatively discharge the irrigation liquid in the tube to the outside of the tube from the discharging port, the emitter including: an emitter main body including a first surface and a second surface disposed opposite each other; a film having flexibility and including a third surface and a fourth surface disposed opposite each other, the film being made of resin, the fourth surface being joined on the first surface of the emitter main body; an intake part disposed in the first surface of the emitter main body, and configured to receive the irrigation liquid; a discharging part disposed in the second surface of the emitter main body, and configured to discharge the irrigation liquid; a channel configured to connect the intake part and the discharging part in the emitter main body and configured to distribute the irrigation liquid; and a flow rate reducing part disposed in the channel, and configured to reduce a flow rate of the irrigation liquid in accordance with deformation of the film under a pressure of the irrigation liquid in the tube. The film includes a protrusion line part having a spiral form, the protrusion line part being disposed at a position corresponding to the flow rate reducing part in the third surface or the fourth surface, or both of the third surface and the fourth surface. 
     To solve the above-mentioned problems, a drip irrigation tube according to the present invention includes: a tube including a discharging port for discharging irrigation liquid; and the above-mentioned emitter joined on the inner wall surface of the tube at a position corresponding to the discharging port. 
     Advantageous Effects of Invention 
     In the emitter and the drip irrigation tube according to the present invention, the emitter is not easily deformed even when used under high temperature, and therefore irrigation liquid can be quantitatively discharged even when used under high temperature. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view of an emitter disclosed in PTL 1; 
         FIG. 2  is a sectional view of a drip irrigation tube according to an embodiment of the present invention; 
         FIGS. 3A to 3C  illustrate a configuration of the emitter or an emitter main body according to the embodiment of the present invention; 
         FIG. 4  illustrates a configuration of the emitter according to the embodiment of the present invention; 
         FIGS. 5A and 5B  illustrate a configuration of a film according to the embodiment of the present invention; 
         FIGS. 6A to 6C  are schematic views illustrating a relationship between operations of a flow rate reducing part and a channel opening-closing part; 
         FIGS. 7A to 7C  illustrate a configuration of a film according to modification  1  of the embodiment of the present invention; and 
         FIGS. 8A to 8C  illustrate a configuration of a film according to modification  2  of the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present invention is described below in detail with reference to the accompanying drawings. 
     Configurations of Drip Irrigation Tube and Emitter 
       FIG. 2  is a sectional view along the axial direction of drip irrigation tube  100  according to the present embodiment. As illustrated in  FIG. 2 , drip irrigation tube  100  includes tube  110  and emitter  120 . 
     Tube  110  is a pipe for carrying irrigation liquid. In the wall of tube  110 , a plurality of discharging ports  112  for discharging irrigation liquid are formed at a predetermined interval (e.g. 200 to 500 mm) in the axial direction of tube  110 . The diameter of the opening of discharging port  112  is not limited as long as irrigation liquid can be discharged. In the present embodiment, the diameter of the opening of discharging port  112  is 1.5 mm. Emitters  120  are joined at respective positions corresponding to discharging ports  112  on the inner wall surface of tube  110 . The cross-sectional shape and the cross-sectional area of tube  110  in the direction perpendicular to the axial direction of tube  110  are not limited as long as emitter  120  can be disposed inside tube  110 . 
     The material of tube  110  is not limited. In the present embodiment, the material of tube  110  is polyethylene. 
     Examples of the irrigation liquid include water, liquid fertilizer, agricultural chemicals and mixtures thereof. 
       FIGS. 3A to 3C  and  FIG. 4  illustrate a configuration of emitter  120  or emitter main body  121  according to the present embodiment.  FIG. 3A  is a plan view of emitter main body  121 ,  FIG. 3B  is a plan view of emitter  120 , and  FIG. 3C  is a bottom view of emitter  120 .  FIG. 4  is a sectional view taken along line A-A of  FIG. 3B . 
     As illustrated in  FIG. 2 , emitter  120  is joined on the inner wall surface of tube  110  to cover discharging port  112 . The shape of emitter  120  is not limited as long as emitter  120  can make intimate contact with the inner wall surface of tube  110  and can cover discharging port  112 . In the present embodiment, in the cross-section of emitter  120  in the direction perpendicular to the axial direction of tube  110 , the rear surface, which is joined to the inner wall surface of tube  110 , of emitter  120  has a substantially arc shape protruding toward the inner wall surface of tube  110  along the inner wall surface of tube  110 . In plan view, emitter  120  has a substantially rectangular shape with chamfered four corners. The size of emitter  120  is not limited. In the present embodiment, emitter  120  has a long side length of 25 mm, a short side length of 8 mm, and a height of 2.5 mm 
     Emitter  120  includes emitter main body  121  including first surface  1211  and second surface  1212  that are opposite to each other, and film  122  including third surface  1223  and fourth surface  1224  that are opposite to each other (see  FIG. 5B ). Fourth surface  1224  is joined on first surface  1211  of emitter main body  121 . In the present embodiment, first surface  1211  of emitter main body  121  is located on the front surface side (irrigation liquid side) of emitter  120 , and second surface  1212  of emitter main body  121  is located on the rear surface side (tube  110  side) of emitter  120 . 
     Emitter main body  121  and film  122  may be integrally formed, or may be formed as separate members. For example, emitter main body  121  and film  122  may be integrally formed with a hinge part therebetween. For example, fourth surface  1224  of film  122  can be joined on first surface  1211  of emitter main body  121  by turning film  122  about the hinge part. In the present embodiment, film  122  is joined on emitter main body  121  at a portion outside diaphragm part (described later). That is, the fourth surface of film  122  is not joined on emitter main body  121  in the diaphragm part. The method of joining emitter main body  121  and film  122  is not limited. Examples of the method of joining emitter main body  121  and film  122  include welding of the resin material of film  122 , bonding with an adhesive agent, and the like. Note that the hinge part may be cut out after emitter main body  121  and film  122  are joined. 
     Emitter main body  121  may be formed of a material having flexibility or a material having no flexibility. Examples of the material of emitter main body  121  include resin and rubber. Examples of the resin include polyethylene and silicone. The flexibility of emitter main body  121  may be adjusted by use of an elastic resin material. Examples of the method of adjusting the flexibility of emitter main body  121  include selection of elastic resins, adjustment of the mixing ratio of an elastic resin material to a hard resin material, and the like. Emitter main body  121  may be produced by injection molding, for example. 
     Film  122  of emitter  120  according to the present embodiment deforms under the pressure of the irrigation liquid. The higher the temperature of film  122 , the more easily film  122  deforms. Film  122  according to the present embodiment includes first film  1221  and second film  1222 . First film  1221  is disposed on emitter main body  121  so as to close the opening of flow rate reducing recess  161  described later. In addition, second film  1222  is disposed on emitter main body  121  so as to close the opening of channel opening-closing recess  171  described later. 
     The shape and the size of film  122  may be appropriately set in accordance with the shape and the size of emitter main body  121 , the shape and the size of an opening a recess (flow rate reducing recess  161  and channel opening-closing recess  171 ) formed in emitter main body  121  and the like. The shape and the size of first film  1221  and the shape and the size of second film  1222  may be identical to each other or different from each other. In the present embodiment, first film  1221  and second film  1222  have the same shape and the same size. 
     Film  122  is formed of a resin material having flexibility except for silicone. The material of film  122  may be appropriately set in accordance with the desired flexibility. Examples of the resin include polyethylene. Also, the flexibility of film  122  may be adjusted by use of an elastic resin material. Examples of the method of adjusting the flexibility of film  122  are identical to those of the method of adjusting the flexibility of emitter main body  121 . The materials of first film  1221  and second film  1222  may be identical to each other or different from each other. 
     In addition, the thickness of film  122  may be appropriately set in accordance with the desired flexibility. The thickness of first film  1221  and the thickness of second film  1222  may be identical to each other or different from each other. In the present embodiment, first film  1221  and second film  1222  have the same thickness. Film  122  may be produced by injection molding, for example. First film  1221  and second film  1222  may be integrally formed, or may be formed as separate members. In the present embodiment, first film  1221  and second film  1222  are formed as separate members. 
       FIGS. 5A and 5B  illustrate a configuration of film  122  (first film  1221  and second film  1222 ) according to the present embodiment.  FIG. 5A  is a plan view of film  122 , and  FIG. 5B  is a sectional view taken along line B-B of  FIG. 5A . 
     In the present embodiment, protrusion line part  123  is disposed in third surface  1223  of film  122 . First protrusion line part  1231  is disposed in third surface  1223  of first film  1221  at a position corresponding to flow rate reducing part  160 , and second protrusion line part  1232  is disposed in third surface  1223  of second film  1222  at a position corresponding to channel opening-closing part  170  (see  FIG. 4  and  FIGS. 5A and 5B ). 
     In the present embodiment, first protrusion line part  1231  is a protrusion line having a spiral form and is disposed in first diaphragm part  167  described later. A portion of first protrusion line part  1231  may be a protrusion line having a shape other than the spiral form as long as a desired elasticity of first film  1221  can be ensured. For example, a portion of first protrusion line part  1231  may have a circular shape. As elaborated later, first protrusion line part  1231  increases the elasticity of first film  1221  while maintaining the ease of deflection of first film  1221 . 
     The width d 1 , the height h 1  and the number of revolutions of first protrusion line part  1231  are not limited as long as a desired elasticity of first film  1221  can be ensured. In addition, width d 1  and height h 1  of first protrusion line part  1231  may or may not be constant. In addition, the revolution direction of first protrusion line part  1231  may be clockwise or counterclockwise. In addition, the distance between first protrusion line part  1231  is not limited as long as a desired elasticity of first film  1221 . Also, dimension D 1  of the region where first protrusion line part  1231  is disposed is not limited as long as a desired elasticity of first film  1221  can be ensured. 
     In the present embodiment, second protrusion line part  1232  is a spiral protrusion line disposed in second diaphragm part  175  described later. A portion of second protrusion line part  1232  may be a protrusion line having a shape other than the spiral form as long as a desired elasticity of second film  1222  can be ensured. For example, a portion of second protrusion line part  1232  may have a circular shape. As elaborated later, second protrusion line part  1232  increases the elasticity of second film  1222  while maintaining the ease of deflection of second film  1222 . 
     Width d 2 , height h 2  and the number of revolutions of second protrusion line part  1232  are not limited as long as a desired elasticity of second film  1222  can be ensured. In addition, width d 1  and height h 1  of first protrusion line part  1231  may or may not be constant. In addition, the revolution direction of second protrusion line part  1232  may be clockwise or counterclockwise. In addition, the distance between adjacent second protrusion line part  1232  is not limited as long as a desired elasticity of second film  1222  can be ensured. Also, dimension D 2  of the region where second protrusion line part  1232  is disposed is not limited as long as a desired elasticity of second film  1222  can be ensured. 
     Preferably, emitter main body  121  and film  122  are formed with one material having flexibility. Also, preferably, the diaphragm part (first diaphragm part  167  and second diaphragm part  175 ) described later may be integrally formed as a portion of emitter  120 . In the present embodiment, emitter main body  121  and film  122  including the diaphragm part are formed as separate members with one material having flexibility. 
     Drip irrigation tube  100  is assembled by joining the rear surface of emitter  120  to the inner wall surface of tube  110 . The method of joining tube  110  and emitter  120  is not limited. Examples of the method of joining tube  110  and emitter  120  include welding of the resin material of tube  110  or emitter  120 , bonding with an adhesive agent and the like. Normally, discharging port  112  is formed after tube  110  and emitter  120  are joined; however, discharging port  112  may be formed before tube  110  and emitter  120  are joined. 
     Next, the components of emitter  120  are described from the viewpoint of its function. Emitter  120  includes intake part  150 , first connecting channel  141 , first pressure reducing channel  142 , second connecting channel  143 , second pressure reducing channel  144 , third pressure reducing channel  145 , flow rate reducing part  160 , channel opening-closing part  170  and discharging part  180 . Intake part  150 , flow rate reducing part  160  and channel opening-closing part  170  are disposed in the front surface (first surface  1211  of emitter main body  121 ) of emitter  120 . In addition, first connecting channel  141 , first pressure reducing channel  142 , second connecting channel  143 , second pressure reducing channel  144 , third pressure reducing channel  145  and discharging part  180  are disposed in the rear surface (second surface  1212  of emitter main body  121 ) of emitter  120 . 
     At least first connecting groove  131 , first pressure reducing groove  132 , second connecting groove  133 , second pressure reducing groove  134  and third pressure reducing groove  135  are formed in second surface  1212  of emitter main body  121 . When emitter  120  and tube  110  are joined to each other, first connecting groove  131 , first pressure reducing groove  132 , second connecting groove  133 , second pressure reducing groove  134  and third pressure reducing groove  135  function as first connecting channel  141 , first pressure reducing channel  142 , second connecting channel  143 , second pressure reducing channel  144  and third pressure reducing channel  145 , respectively. 
     When emitter  120  and tube  110  are joined to each other, a first channel that connects intake part  150  and discharging part  180  in emitter main body  121  is formed. The first channel is composed of intake part  150 , first connecting channel  141 , first pressure reducing channel  142 , second connecting channel  143 , second pressure reducing channel  144 , flow rate reducing part  160  and discharging part  180 . In addition, a second channel that connects intake part  150  and discharging part  180  in emitter main body  121  is formed. The second channel is composed of intake part  150 , first connecting channel  141 , first pressure reducing channel  142 , second connecting channel  143 , third pressure reducing channel  145 , channel opening-closing part  170 , channel reduction section  160  and discharging part  180 . Each of the first channel and the second channel distributes irrigation liquid from intake part  150  to discharging part  180 . In the present embodiment, the first channel and the second channel overlap in the region between intake part  150  and second connecting channel  143 . In addition, the downstream side of channel opening-closing part  170  in the second channel is connected with flow rate reducing part  160 , and the first channel and the second channel also overlap in the region between flow rate reducing part  160  and discharging part  180 . 
     Intake part  150  takes the irrigation liquid into emitter  120 . Intake part  150  is disposed in approximately one-half of first surface  1211  of emitter main body  121  (see  FIGS. 3A and 3B ). In first surface  1211  where intake part  150  is not disposed, flow rate reducing part  160  and channel opening-closing part  170  are disposed. Intake part  150  includes intake side screen part  151  and intake through hole  152 . 
     Intake side screen part  151  prevents entry, into intake recess  153 , of floating matters in the irrigation liquid to be taken into emitter  120 . Intake side screen part  151  opens to the inside of tube  110 , and includes intake recess  153 , a plurality of slits  154  and a plurality of screen projection lines  155 . 
     Intake recess  153  is a recess that is formed in the region where film  122  is not joined in first surface  1211  of emitter main body  121 . The depth of intake recess  153  is not limited, and is appropriately set in accordance with the size of emitter  120 . Slits  154  are formed in the outer periphery wall of intake recess  153 , and screen projection lines  155  are formed on the bottom surface of intake recess  153 . In addition, intake through hole  152  is formed in the bottom surface of intake recess  153 . 
     Slits  154  connect the inner surface of intake recess  153  and the outer surface of emitter main body  121 , and prevent entry, into intake recess  153 , of the floating matters in the irrigation liquid while allowing the irrigation liquid to enter intake recess  153  from the side surface of emitter main body  121 . The shape of slit  154  is not limited as long as the above-described function can be ensured. In the present embodiment, slit  154  is formed in a shape whose width increases from the outer surface of emitter main body  121  toward the inner surface of intake recess  153  (see  FIGS. 3A and 3B ). Thus, slit  154  has a so-called wedge wire structure, and therefore the pressure drop of the irrigation liquid having entered intake recess  153  is suppressed. 
     Screen projection lines  155  are disposed on the bottom surface of intake recess  153 . The placement and the number of screen projection lines  155  are not limited as long as entry of floating matters of irrigation liquid can be prevented while allowing entry of the irrigation liquid from the opening side of intake recess  153 . In the present embodiment, screen projection lines  155  are arranged such that the longitudinal axial direction of screen projection lines  155  matches the minor axial direction of emitter  120 . In addition, each screen projection line  155  is formed such that the width thereof decreases from first surface  1211  of emitter main body  121  toward the bottom surface of intake recess  153 . That is, in the arrangement direction of screen projection lines  155 , the space between screen projection lines  155  adjacent to each other has a so-called wedge wire structure. In addition, the distance between screen projection lines  155  adjacent to each other is not limited as long as the above-described function can be ensured. Since the space between screen projection lines  155  adjacent to each other has a so-called wedge wire structure as described above, the pressure drop of the irrigation liquid having entered intake recess  153  is suppressed. 
     Intake through hole  152  is formed in the bottom surface of intake recess  153 . The shape and the number of intake through hole  152  are not limited as long as the irrigation liquid taken into intake recess  153  can be taken into emitter main body  121 . In the present embodiment, intake through hole  152  is one long hole formed along the longitudinal axial direction of emitter  120  in the bottom surface of intake recess  153 . This long hole is partially covered with screen projection lines  155 , and therefore, intake through hole  152  appears to be divided into a plurality of through holes when viewed from first surface  1211  side. 
     The irrigation liquid that has passed through the inside of tube  110  is taken into emitter main body  121  while the floating matters therein are prevented from entering intake recess  153  by intake side screen part  151 . 
     First connecting groove  131  (first connecting channel  141 ) connects intake through hole  152  (intake part  150 ) and first pressure reducing groove  132  (first pressure reducing channel  142 ). First connecting groove  131  is formed in a linear shape along the longitudinal axial direction of emitter  120  at the outer edge of second surface  1212  of emitter main body  121 . When tube  110  and emitter  120  are joined, first connecting groove  131  and the inner wall surface of tube  110  form first connecting channel  141 . The irrigation liquid taken from intake part  150  flows to first pressure reducing channel  142  through first connecting channel  141 . 
     First pressure reducing groove  132  (first pressure reducing channel  142 ) is disposed in the first channel and the second channel and connects first connecting groove  131  (first connecting channel  141 ) and second connecting groove  133  (second connecting channel  143 ). First pressure reducing groove  132  (first pressure reducing channel  142 ) reduces the pressure of the irrigation liquid taken from intake part  150 , and guides the liquid to second connecting groove  133  (second connecting channel  143 ). First pressure reducing groove  132  is disposed in a linear shape along the longitudinal axial direction of emitter  120  at the outer edge of second surface  1212  of emitter main body  121 . The upstream end of first pressure reducing groove  132  is connected with first connecting groove  131 , and the downstream end of first pressure reducing groove  132  is connected with the upstream end of second connecting groove  133 . 
     The shape of first pressure reducing groove  132  is not limited as long as the above-described function can be ensured. In the present embodiment, in plan view, first pressure reducing groove  132  has a zigzag shape. In first pressure reducing groove  132 , first protrusions  1361 , each of which has a substantially triangular prism shape and protrudes from the inner surface of first pressure reducing groove  132 , are alternately disposed along the flow direction of the irrigation liquid. In plan view, first protrusions  1361  are disposed such that the tip of each first protrusion  1361  does not cross the central axis of first pressure reducing groove  132 . When tube  110  and emitter  120  are joined, first pressure reducing groove  132  and the inner wall surface of tube  110  form first pressure reducing channel  142 . The irrigation liquid taken from intake part  150  is guided to second connecting groove  133  (second connecting channel  143 ) while the pressure thereof is reduced by first pressure reducing channel  142 . 
     Second connecting groove  133  (second connecting channel  143 ) connects first pressure reducing groove  132  (first pressure reducing channel  142 ), second pressure reducing groove  134  (second pressure reducing channel  144 ) and third pressure reducing groove  135  (third pressure reducing channel  145 ). Second connecting groove  133  is formed in a linear shape along the minor axial direction of emitter  120  at the outer edge of second surface  1212  of emitter main body  121 . When tube  110  and emitter  120  are joined, second connecting groove  133  and the inner wall surface of tube  110  form second connecting channel  143 . The irrigation liquid that has been taken from intake part  150  and guided to first connecting channel  141  while the pressure thereof is reduced by first pressure reducing channel  142  is guided to second pressure reducing channel  144  and third pressure reducing channel  145  through second connecting channel  143 . 
     Second pressure reducing groove  134  (second pressure reducing channel  144 ) is disposed upstream of flow rate reducing part  160  in the first channel, and connects second connecting groove  133  (second connecting channel  143 ) and flow rate reducing part  160 . Second pressure reducing groove  134  (second pressure reducing channel  144 ) guides, to flow rate reducing part  160 , the irrigation liquid coming from second connecting groove  133  (second connecting channel  143 ) while reducing the pressure of the liquid. Second pressure reducing groove  134  is disposed along the longitudinal axial direction of emitter  120  at the outer edge of second surface  1212  of emitter main body  121 . The upstream end of second pressure reducing groove  134  is connected with the downstream end of second connecting groove  133 , and the downstream end of second pressure reducing groove  134  is connected with first connecting through hole  165  communicated with flow rate reducing part  160 . 
     The shape of second pressure reducing groove  134  is not limited as long as the above-described function can be ensured. In the present embodiment, in plan view, second pressure reducing groove  134  has a zigzag shape as with the shape of first pressure reducing groove  132 . In second pressure reducing groove  134 , second protrusions  1362 , each of which protrudes from the inner surface of second pressure reducing groove  134  and has a substantially triangular prism shape, are alternately disposed along the flow direction of the irrigation liquid. In plan view, second protrusions  1362  are disposed such that the tip of each second protrusion  1362  does not cross the central axis of second pressure reducing groove  134 . When tube  110  and emitter  120  are joined, second pressure reducing groove  134  and the inner wall surface of tube  110  form second pressure reducing channel  144 . In the present embodiment, second pressure reducing groove  134  (second pressure reducing channel  144 ) is longer than third pressure reducing groove  135  (third pressure reducing channel  145 ) described later. Accordingly, the pressure of the irrigation liquid flowing through second pressure reducing groove  134  (second pressure reducing channel  144 ) is reduced more than the irrigation liquid flowing through third pressure reducing groove  135  (third pressure reducing channel  145 ). A part of the irrigation liquid that has been taken from intake part  150  while the pressure thereof being reduced is guided to flow rate reducing part  160  while the pressure thereof is reduced by second pressure reducing channel  144 . 
     Third pressure reducing groove  135  (third pressure reducing channel  145 ) is disposed upstream of flow rate reducing part  160  and channel opening-closing part  170  in the second channel, and connects second connecting groove  133  (second connecting channel  143 ) and channel opening-closing part  170 . Third pressure reducing groove  135  (third pressure reducing channel  145 ) guides, to channel opening-closing part  170 , the irrigation liquid coming from second connecting groove  133  (second connecting channel  143 ) while reducing the pressure of the liquid. Third pressure reducing groove  135  is disposed along the longitudinal axial direction of emitter  120  at a center portion of second surface  1212  of emitter main body  121 . The upstream end of third pressure reducing groove  135  is connected with the downstream end of second connecting channel  143 , and the downstream end of third pressure reducing groove  135  is connected with third connecting through hole  174  communicated with channel opening-closing part  170 . 
     The shape of third pressure reducing groove  135  is not limited as long as the above-described function can be ensured. In the present embodiment, in plan view, third pressure reducing groove  135  has a zigzag shape as with the shape of first pressure reducing groove  132 . In third pressure reducing groove  135 , third protrusions  1363 , each of which has a substantially triangular prism shape and protrudes from the inner surface of third pressure reducing groove  135 , are alternately disposed along the flow direction of the irrigation liquid. In plan view, third protrusions  1363  are disposed such that the tip of each third protrusion  1363  does not cross the central axis of third pressure reducing groove  135 . When tube  110  and emitter  120  are joined, third pressure reducing groove  135  and the inner wall surface of tube  110  form third pressure reducing channel  145 . Another part of the irrigation liquid that has taken from intake part  150  while the pressure thereof is reduced by first pressure reducing channel  142  is guided to channel opening-closing part  170  while the pressure thereof is reduced by third pressure reducing channel  145 . As elaborated later, the second channel operates only when the pressure of the irrigation liquid is low. 
     In the first channel and the second channel, flow rate reducing part  160  is disposed downstream of first pressure reducing channel  142 , second pressure reducing channel  144  and third pressure reducing channel  145  on the front surface side of emitter  120 . Flow rate reducing part  160  sends the irrigation liquid to discharging part  180  while reducing the flow rate of the irrigation liquid in accordance with the deformation of film  122  under the pressure of the irrigation liquid in tube  110 . 
     The configuration of flow rate reducing part  160  is not limited as long as the above-described function can be ensured. In the present embodiment, flow rate reducing part  160  includes flow rate reducing recess  161 , first valve seat part  162 , communication groove  163 , flow rate reducing through hole  164  communicated with discharging part  180 , first connecting through hole  165  communicated with second pressure reducing groove  134  (second pressure reducing channel  144 ), second connecting through hole  166  communicated with channel opening-closing through hole  173  of channel opening-closing part  170 , and first diaphragm part  167  that is a portion of first film  1221 . At the inner surface of flow rate reducing recess  161 , flow rate reducing through hole  164  communicated with discharging part  180 , first connecting through hole  165  communicated with second pressure reducing groove  134  (second pressure reducing channel  144 ), and second connecting through hole  166  communicated with channel opening-closing through hole  173  of channel opening-closing part  170  open. 
     Flow rate reducing recess  161  is disposed in first surface  1211  of emitter main body  121 . In plan view, flow rate reducing recess  161  has a substantially circular shape. In the bottom surface of flow rate reducing recess  161 , flow rate reducing through hole  164  communicated with discharging part  180 , first connecting through hole  165  communicated with second pressure reducing groove  134  (second pressure reducing channel  144 ), and second connecting through hole  166  communicated with channel opening-closing part  170 , and first valve seat part  162  are disposed. The depth of flow rate reducing recess  161  is not limited as long as the depth of flow rate reducing recess  161  is equal to or greater than the depth of communication groove  163 . 
     Flow rate reducing through hole  164  is disposed at a center portion of the bottom surface of flow rate reducing recess  161 , and is communicated with discharging part  180 . In the bottom surface of flow rate reducing recess  161 , first valve seat part  162  is disposed to surround flow rate reducing through hole  164  such that first valve seat part  162  is opposite to first diaphragm part  167  and is separated from first diaphragm part  167 . First valve seat part  162  is formed such that first valve seat part  162  can make intimate contact with first diaphragm part  167  when the pressure of the irrigation liquid flowing through tube  110  is a predetermined value (second pressure described later) or greater. When first diaphragm part  167  makes contact with first valve seat part  162 , the flow rate of the irrigation liquid flowing from flow rate reducing recess  161  into discharging part  180  is reduced. 
     The shape of first valve seat part  162  is not limited as long as the above-described function can be ensured. In the present embodiment, first valve seat part  162  is a protrusion having a cylindrical shape. In the present embodiment, the height of the end surface of the protrusion from the bottom surface of flow rate reducing recess  161  decreases from the inner side toward the outer side. 
     Communication groove  163 , which communicates between the inside of flow rate reducing recess  161  and flow rate reducing through hole  164  surrounded by flow rate reducing recess  161 , is formed in a portion of the surface of first valve seat part  162  where first diaphragm part  167  can make intimate contact with first valve seat part  162 . First connecting through hole  165  communicated with second pressure reducing groove  134  (second pressure reducing channel  144 ) and second connecting through hole  166  communicated with channel opening-closing through hole  173  of channel opening-closing part  170  are formed in the region where first valve seat part  162  is not disposed in the bottom surface of flow rate reducing recess  161 . Note that first connecting through hole  165  communicated with second pressure reducing groove  134  (second pressure reducing channel  144 ) may be disposed so as to be surrounded by first valve seat part  162 , and flow rate reducing through hole  164  communicated with discharging part  180  may be disposed outside first valve seat part  162 . 
     First diaphragm part  167  is a portion of first film  1221  including first protrusion line part  1231 . First diaphragm part  167  is disposed in such a manner as to close the communication between the inside of flow rate reducing recess  161  and the inside of tube  110 , and to close the opening of flow rate reducing recess  161 . First diaphragm part  167  has flexibility, and deforms in such a manner as to make contact with first valve seat part  162  in accordance with the pressure of the irrigation liquid in tube  110 . For example, first diaphragm part  167  is distorted to flow rate reducing recess  161  side when the pressure of the irrigation liquid flowing in tube  110  is greater than a predetermined value. Specifically, first diaphragm part  167  deforms toward first valve seat part  162  as the pressure of the irrigation liquid increases, and finally makes contact with first valve seat part  162 . Even when first diaphragm part  167  is in intimate contact with first valve seat part  162 , neither of first connecting through hole  165 , flow rate reducing through hole  164  nor communication groove  163  is closed by first diaphragm part  167 , and therefore the irrigation liquid sent from first connecting through hole  165  can be sent to discharging part  180  through communication groove  163  and flow rate reducing through hole  164 . Note that first diaphragm part  167  is disposed next to second diaphragm part  175  described later. 
     Channel opening-closing part  170  is disposed between third pressure reducing channel  145  (third pressure reducing groove  135 ) and discharging part  180  in the second channel on the front surface side of emitter  120 . Channel opening-closing part  170  opens the second channel in accordance with the pressure in tube  110 , and sends the irrigation liquid to discharging part  180 . In the present embodiment, channel opening-closing part  170  is connected with flow rate reducing part  160  through channel opening-closing through hole  173  and second connecting through hole  166 , and the irrigation liquid from third pressure reducing channel  145  (third pressure reducing groove  135 ) reaches discharging part  180  through channel opening-closing part  170  and flow rate reducing part  160 . 
     The configuration of channel opening-closing part  170  is not limited as long as the above-described function can be ensured. In the present embodiment, channel opening-closing part  170  includes channel opening-closing recess  171 , second valve seat part  172 , channel opening-closing through hole  173  communicated with second connecting through hole  166  of flow rate reducing part  160 , third connecting through hole  174  communicated with third pressure reducing channel  145  (third pressure reducing groove  135 ), and second diaphragm part  175  that is a portion of second film  1222 . At the inner surface of channel opening-closing recess  171 , third connecting through hole  174  communicated with third pressure reducing channel  145  (third pressure reducing groove  135 ), and channel opening-closing through hole  173  communicated with flow rate reducing part  160  open. In addition, channel opening-closing recess  171  is communicated with flow rate reducing recess  161  of flow rate reducing part  160 . 
     In plan view, channel opening-closing recess  171  has a substantially circular shape. In the bottom surface of channel opening-closing recess  171 , third connecting through hole  174  connected with third pressure reducing groove  135 , channel opening-closing through hole  173  communicated with flow rate reducing part  160 , and second valve seat part  172  are disposed. The valve seat surface of second valve seat part  172  is disposed on first surface  1211  side of emitter main body  121  (the front surface side of emitter  120 ) relative to the valve seat surface of first valve seat part  162 . That is, second valve seat part  172  is higher than first valve seat part  162 . With this configuration, when film  122  (first film  1221  and second film  1222 ) deforms under the pressure of the irrigation liquid, second film  1222  makes contact with second valve seat part  172  before first film  1221  makes contact with first valve seat part  162 . 
     Third connecting through hole  174  communicated with third pressure reducing groove  135  is disposed in the region where second valve seat part  172  is not disposed in the bottom surface of channel opening-closing recess  171 . Second valve seat part  172  is disposed on the bottom surface of channel opening-closing recess  171  to surround channel opening-closing through hole  173 . In addition, second valve seat part  172  is disposed to face second diaphragm part  175  without making contact with second diaphragm part  175 , and is formed such that second diaphragm part  175  can make intimate contact with second valve seat part  172  when the pressure of the irrigation liquid flowing through tube  110  is a predetermined value (first pressure described later) or greater. When the pressure of the irrigation liquid flowing through tube  110  is the first pressure or greater, second diaphragm part  175  makes intimate contact with second valve seat part  172  to close channel opening-closing through hole  173 , and as a result, the second channel is closed. The shape of second valve seat part  172  is not limited as long as the above-described function can be ensured. In the present embodiment, second valve seat part  172  is an annular-shaped protrusion disposed to surround channel opening-closing through hole  173 . 
     Second diaphragm part  175  is a portion of second film  1222  including second protrusion line part  1232 , and is disposed next to first diaphragm part  167  (first film  1221 ). Second diaphragm part  175  is disposed in such a manner as to prevent the communication between the inside of channel opening-closing recess  171  and the inside of tube  110  and to close the opening of channel opening-closing recess  171 . Second diaphragm part  175  has flexibility, and deforms in such a manner as to make contact with second valve seat part  172  in accordance with the pressure of the irrigation liquid in tube  110 . For example, second diaphragm part  175  is distorted to channel opening-closing recess  171  side when the pressure of the irrigation liquid flowing in tube  110  is greater than a predetermined value. To be more specific, second diaphragm part  175  deforms toward second valve seat part  172  as the pressure of the irrigation liquid increases, and, when the pressure of the irrigation liquid becomes the first pressure, makes contact with second valve seat part  172 . In this manner, the second channel (channel opening-closing through hole  173 ) is closed. 
     Discharging part  180  discharges the irrigation liquid out of emitter  120 . Discharging part  180  is disposed opposite discharging port  112  on second surface  1212  side of emitter main body  121 . Discharging part  180  sends, to discharging port  112  of tube  110 , the irrigation liquid coming from flow rate reducing through hole  164 . With this configuration, discharging part  180  can discharge the irrigation liquid out of emitter  120 . The configuration of discharging part  180  is not limited as long as the above-described function can be ensured. In the present embodiment, discharging part  180  includes discharging recess  181  and entry preventing part  182 . 
     Discharging recess  181  is disposed on second surface  1212  side of emitter main body  121 . In plan view, discharging recess  181  has a substantially rectangular shape. In the bottom surface of discharging recess  181 , flow rate reducing through hole  164  and entry preventing part  182  are disposed. 
     Entry preventing part  182  prevents entry of foreign matters from discharging port  112 . Entry preventing part  182  is not limited as long as the above-described function can be ensured. In the present embodiment, entry preventing part  182  is four protrusions disposed next to each other. The four protrusions are disposed such that the four protrusions are located between flow rate reducing through hole  164  and discharging port  112  when emitter  120  is joined to tube  110 . 
     Operation of Drip Irrigation Tube 
     Next, an operation of drip irrigation tube  100  is described. 
     First, irrigation liquid is fed into tube  110 . Preferably, the pressure of the irrigation liquid that is fed to drip irrigation tube  100  is 0.1 MPa or lower in view of simply implementing the drip irrigation method, or preventing damaging of tube  110  and emitter  120 . The irrigation liquid in tube  110  is taken into emitter  120  from intake part  150 . To be more specific, the irrigation liquid in tube  110  enters intake recess  153  from the gap between slits  154 , or the gap between screen projection lines  155  and passes through intake through hole  152 . At this time, the floating matters in the irrigation liquid can be removed since intake part  150  includes intake side screen part  151  (the gaps between slits  154  and screen projection lines  155 ). In addition, the pressure drop of the irrigation liquid having entered intake part  150  is suppressed since a so-called wedge wire structure is formed in intake part  150 . 
     The irrigation liquid taken from intake part  150  reaches first connecting channel  141 . The irrigation liquid having reached first connecting channel  141  reaches second connecting channel  143  through first pressure reducing channel  142 . The irrigation liquid having reached second connecting channel  143  flows into second pressure reducing channel  144  and third pressure reducing channel  145 . At this time, the irrigation liquid first advances through third pressure reducing channel  145  that causes smaller pressure drop and has a shorter channel length in comparison with second pressure reducing channel  144 . The irrigation liquid having entered third pressure reducing channel  145  flows into channel opening-closing part  170  through third connecting through hole  174 . 
     The irrigation liquid having entered channel opening-closing part  170  flows into flow rate reducing part  160  through channel opening-closing through hole  173  and second connecting through hole  166 . Next, the irrigation liquid having entered flow rate reducing part  160  flows into discharging part  180  through flow rate reducing through hole  164 . Finally, the irrigation liquid having entered discharging part  180  is discharged out of tube  110  from discharging port  112  of tube  110 . 
     On the other hand, the irrigation liquid having entered second pressure reducing channel  144  flows into flow rate reducing part  160  through first connecting through hole  165 . The irrigation liquid having entered flow rate reducing part  160  flows into discharging part  180  through flow rate reducing through hole  164 . The irrigation liquid having entered discharging part  180  is discharged out of tube  110  from discharging port  112  of tube  110 . 
     Operations of Flow Rate Reducing Part and Channel Opening-Closing Part 
     Now, operations of flow rate reducing part  160  and channel opening-closing part  170  in accordance with the pressure of the irrigation liquid in tube  110  is described. 
       FIGS. 6A to 6C  are schematic views illustrating an operational relationship between flow rate reducing part  160  and channel opening-closing part  170 . It is to be noted that  FIGS. 6A to 6C  are schematic cross-sectional views along line A-A of  FIG. 3B .  FIG. 6A  is a sectional view of a state where no irrigation liquid is fed to tube  110 ,  FIG. 6B  is a sectional view of a state where the pressure of the irrigation liquid in tube  110  is a first pressure, and  FIG. 6C  is a sectional view of a state where the pressure of the irrigation liquid in tube  110  is a second pressure greater than the first pressure. 
     Channel opening-closing part  170  and flow rate reducing part  160  are communicated with each other through channel opening-closing through hole  173  and second connecting through hole  166 . In addition, in flow rate reducing part  160 , first diaphragm part  167  deforms in accordance with the pressure of the irrigation liquid in tube  110 , whereby the flow rate of the irrigation liquid is controlled. In channel opening-closing part  170 , second diaphragm part  175  deforms in accordance with the pressure of the irrigation liquid in tube  110 , whereby the flow rate of the irrigation liquid is controlled. 
     In a state before the irrigation liquid is fed into tube  110 , no pressure of the irrigation liquid is applied to film  122 , and therefore neither first diaphragm part  167  nor second diaphragm part  175  deforms (see  FIG. 6A ). 
     When feeding of irrigation liquid into tube  110  is started, deformation of first diaphragm part  167  and second diaphragm part  175  is started. In this state, second diaphragm part  175  is not in intimate contact with second valve seat part  172 , and accordingly the irrigation liquid taken from intake part  150  is discharged out of tube  110  from discharging port  112  through both the first channel (first connecting channel  141 , first pressure reducing channel  142 , second connecting channel  143 , second pressure reducing channel  144 , flow rate reducing part  160  and discharging part  180 ) and the second channel (first connecting channel  141 , first pressure reducing channel  142 , second connecting channel  143 , third pressure reducing channel  145 , channel opening-closing part  170 , flow rate reducing part  160  and discharging part  180 ). In this manner, when feeding of the irrigation liquid to tube  110  is started, and/or when the pressure of the irrigation liquid in tube  110  is lower than a predetermined pressure, the irrigation liquid taken from intake part  150  is discharged through both the first channel and the second channel 
     When the pressure of the irrigation liquid in tube  110  increases, first diaphragm part  167  and second diaphragm part  175  further deform. Then, second diaphragm part  175  makes contact with second valve seat part  172  and closes the second channel (see  FIG. 6B ). At this time, since the valve seat surface of second valve seat part  172  is disposed on first surface  1211  side (the front surface side of emitter  120 ) relative to the valve seat surface of first valve seat part  162 , second diaphragm part  175  makes contact with second valve seat part  172  before first diaphragm part  167  makes contact with first valve seat part  162 . At this time, first diaphragm part  167  is not in contact with first valve seat part  162 . In this manner, when the pressure of the irrigation liquid in tube  110  is so increased as to deform film  122 , second diaphragm part  175  comes closer to second valve seat part  172 , and accordingly the amount of the irrigation liquid that is discharged through the second channel decreases. Then, when the pressure of the irrigation liquid in tube  110  becomes the first pressure, the irrigation liquid in the second channel is not discharged from discharging port  112 . As a result, the irrigation liquid taken from intake part  150  is discharged out of tube  110  from discharging port  112  through only the first channel. 
     When the pressure of the irrigation liquid in tube  110  further increases, first diaphragm part  167  further deforms toward first valve seat part  162 . In a normal configuration, the amount of the irrigation liquid that flows through the first channel increases as the pressure of the irrigation liquid increases; however, in emitter  120  according to the present embodiment, excessive increase in the amount of the liquid that flows through the first channel irrigation is prevented by reducing the distance between first diaphragm part  167  and first valve seat part  162  while the pressure of the irrigation liquid is reduced by first pressure reducing channel  142  and second pressure reducing channel  144 . When the pressure of the irrigation liquid in tube  110  is equal to or greater than the second pressure, which is greater than the first pressure, first diaphragm part  167  makes contact with first valve seat part  162  (see  FIG. 6C ). Even in this state, neither of first connecting through hole  165 , flow rate reducing through hole  164  nor communication groove  163  is closed by first diaphragm part  167 , and accordingly the irrigation liquid taken from intake part  150  is discharged out of tube  110  from discharging port  112  through communication groove  163 . In this manner, in flow rate reducing part  160 , when the pressure of the irrigation liquid in tube  110  is equal to or greater than the second pressure, first diaphragm part  167  makes contact with first valve seat part  162 , and thus increase of the amount of the irrigation liquid that flows through the first channel is suppressed. 
     Thus, flow rate reducing part  160  and channel opening-closing part  170  function to compensate the respective flow rates in accordance with deformation of second film  1222  under the pressure of the irrigation liquid in tube  110 . As a result, drip irrigation tube  100  according to the present embodiment can discharge a certain amount of irrigation liquid out of tube  110  regardless of whether the pressure of the irrigation liquid is low or high. 
     Function of Protrusion Line Part 
     Now a function of protrusion line part  123  in film  122  is described. An emitter including a film provided with no protrusion line part  123  (hereinafter referred to also as “comparison emitter”) is also described for comparison. 
     Also in the comparison emitter, the film deforms to flow rate reducing recess  161  side and channel opening-closing recess  171  side in accordance with the pressure of the irrigation liquid in tube  110 . In the case where the film is made of resin, when irrigation liquid having a high temperature is introduced into the emitter, the temperature of the film exceeds a predetermined value, and the pressure of the irrigation liquid in tube  110  exceeds a predetermined value, deformation of the film that is kept for a long span (hereinafter referred to also as simply “long-span elastic deformation”) is caused. The time taken for resetting film  122  deformed by the long-span elastic deformation to the state before the deformation is, for example, one day. In this manner, when the film is deformed due to the use in a high temperature state, the deformed shape is held over a long period of time. Consequently, the film distorted by the long-span elastic deformation cannot be reset to the original pre-deformation shape for a certain time period, and the distance between first diaphragm part  167  and first valve seat part  162 , and the distance between second diaphragm part  175  and second valve seat part  172  are reduced. As a result, the flow rate of the irrigation liquid that flows into flow rate reducing part  160  from channel opening-closing part  170  and the flow rate of the irrigation liquid that flows into discharging part  180  from flow rate reducing part  160  are reduced. Accordingly, the flow rate of the irrigation liquid that flows into discharging part  180  and is discharged out of tube  110  from discharging port  112  of tube  110  is reduced and becomes insufficient. 
     In contrast, film  122  of emitter  120  according to the present embodiment includes protrusion line part  123  having a spiral form. The thickness of a portion of film  122  where protrusion line part  123  is not disposed is equal to that of the film of the comparison emitter, whereas a portion of film  122  where protrusion line part  123  is disposed is greater than that of the film of the comparison emitter. With this configuration, protrusion line part  123  can increase the elasticity of film  122  while maintaining the ease of deflection of the film  122 . When film  122  deforms to the recess (flow rate reducing recess  161  and channel opening-closing recess  171 ) side, an elastic force of moving film  122  back to the plane where film  122  has been located before the deformation acts on film  122 . As a result, distortion of film  122  due to the long-span elastic deformation is suppressed even when the irrigation liquid having high temperature is introduced into the emitter, the temperature of film  122  exceeds the predetermined value, and the pressure of the irrigation liquid in tube  110  exceeds the predetermined value. 
     Effect 
     As described above, emitter  120  according to the present embodiment includes film  122  in which protrusion line part  123  having a spiral form is disposed on third surface  1223 . Protrusion line part  123  can increase the elasticity of film  122  while maintaining ease of deflection of film  122 . Thus, drip irrigation tube  100  according to the present embodiment causes less deformation resulting from the long-span elastic deformation of film  122 , and as a result, irrigation liquid can be quantitatively discharged even under high temperature. 
     In addition, it is conceivable to increase the thickness of the diaphragm part (first diaphragm part  176  and second diaphragm part  175 ) for the purpose of suppressing reduction of the flow rate of the irrigation liquid due to the long-span elastic deformation of film  122 . If the thickness of the diaphragm part is increased, however, the thickness of emitter  120  is increased, thus resulting in the pressure drop of the irrigation liquid in tube  110 . In addition, the deformation of the diaphragm part is suppressed and the cross-sectional area of the channel is reduced, thus resulting in clogging. In contrast, emitter  120  according to the present embodiment can suppress reduction of the flow rate of the irrigation liquid due to the long-span elastic deformation of film  122  without increasing the entire thickness of film  122 , and therefore does not cause the above-mentioned problems. 
     Modification 
     Note that, in the present embodiment, emitter  120  includes film  122  in which protrusion line part  123  is disposed in third surface  1223 , the emitter according to the present invention is not limited to this configuration. For example, the emitter according to the present invention may include film  122 ′ according to modification  1  or film  122 ″ according to modification  2 . 
       FIGS. 7A to 7C  illustrate a configuration of film  122 ′ according to modification  1 .  FIG. 7A  is a plan view of film  122 ′ according to modification  1 ,  FIG. 7B  is a sectional view taken along line B-B of  FIG. 7A , and  FIG. 7C  is a bottom view of film  122 ′ according to modification  1 . As illustrated in  FIGS. 7A to 7C , protrusion line part  123  may be disposed in fourth surface  1224  of film  122 ′. 
       FIGS. 8A to 8C  illustrate a configuration of film  122 ″ according to modification  2 .  FIG. 8A  is a plan view of film  122 ″ according to modification  2 ,  FIG. 8B  is a sectional view taken along line B-B of  FIG. 8A , and  FIG. 8C  is a bottom view of film  122 ″ according to modification  2 . As illustrated in  FIGS. 8A to 8C , protrusion line part  123  may be disposed on both third surface  1223  and fourth surface  1224  of film  122 ″. 
     In addition, the configurations of the emitter and the drip irrigation tube according to the present invention are not limited to those of emitter  120  and drip irrigation tube  100  according to the embodiment. For example, the emitter may not be provided with first pressure reducing channel  142 , second pressure reducing channel  144 , third pressure reducing channel  145  and channel opening-closing part  170 . 
     In addition, while first connecting channel  141 , first pressure reducing channel  142 , second connecting channel  143 , second pressure reducing channel  144  and third pressure reducing channel  145  are configured to be formed when emitter  120  and tube  110  are joined in the present embodiment, first connecting channel  141 , first pressure reducing channel  142 , second connecting channel  143 , second pressure reducing channel  144  and third pressure reducing channel  145  may be formed in advance as channels in emitter  120 . 
     In addition, while the contact timing of deformed film  122  is adjusted by the difference in heights of first valve seat part  162  and second valve seat part  172  in the present embodiment, the heights of first valve seat part  162  and second valve seat part  172  may be equal to each other. In this case, the contact timing of deformed film  122  may be adjusted by setting different thicknesses and/o by using different materials (materials having different elasticities) between first diaphragm part  167  and second diaphragm part  175 . In this case, the contact timing of deformed film  122  may be adjusted by changing the thicknesses and materials (elasticities) of first diaphragm part  167  and second diaphragm part  175 , and the height and the width of protrusion line part  123 . 
     This application is entitled to and claims the benefit of Japanese Patent Application No. 2016-151366 filed on Aug. 1, 2016, the disclosure each of which including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, it is possible to easily provide an emitter that can drop liquid with an appropriate rate even when used under high temperature. Accordingly, popularization of the emitter in the technical fields of drip irrigations and endurance tests where long-term dropping is required, and development in the technical fields can be expected. 
     REFERENCE SIGNS LIST 
     
         
           1  Emitter 
           10  Emitter main body 
           11  Flow rate adjustment valve 
           12  Flow rate control valve 
           13  Film 
           100  Drip irrigation tube 
           110  Tube 
           112  Discharging port 
           120  Emitter 
           121  Emitter main body 
           1211  First surface 
           1212  Second surface 
           122 ,  122 ′,  122 ″ film 
           1221  First film 
           1222  Second film 
           1223  Third surface 
           1224  Fourth surface 
           123  Protrusion line part 
           1231  First protrusion line part 
           1232  Second protrusion line part 
           131  First connecting groove 
           132  First pressure reducing groove 
           133  Second connecting groove 
           134  Second pressure reducing groove 
           135  Third pressure reducing groove 
           1361  First protrusion 
           1362  Second protrusion 
           1363  Third protrusion 
           141  First connecting channel 
           142  First pressure reducing channel 
           143  Second connecting channel 
           144  Second pressure reducing channel 
           145  Third pressure reducing channel 
           150  Intake part 
           151  Intake side screen part 
           152  Intake through hole 
           153  Intake recess 
           154  Slit 
           155  Screen protrusion line part 
           160  Flow rate reducing part 
           161  Flow rate reducing recess 
           162  First valve seat part 
           163  Communication groove 
           164  Flow rate reducing through hole 
           165  First connecting through hole 
           166  Second connecting through hole 
           167  First diaphragm part 
           170  Channel opening-closing part 
           171  Channel opening-closing recess 
           172  Second valve seat part 
           173  Channel opening-closing through hole 
           174  Third connecting through hole 
           175  Second diaphragm part 
           180  Discharging part 
           181  Discharging recess 
           182  Entry preventing part