Emitter and drip-irrigation tube

An emitter 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 comprising:

• an emitter main body including a first surface and a second surface disposed opposite to each other;
• a first film having flexibility and joined on the first surface of the emitter main body, the first film being made of resin;
• a second film having flexibility and joined on the first surface of the emitter main bode, the second film being made of resin;
• a cover disposed on the emitter main body with the first film sandwiched between the cover and 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;
• a first pressure reducing channel disposed in the channel, and configured to reduce a pressure of the irrigation liquid received by the intake part;
• a second pressure reducing channel disposed downstream of the first pressure reducing channel in the channel, and configured to reduce a pressure of the irrigation liquid received by the intake part;
• and
• a flow rate reducing part disposed downstream of the second pressure reducing channel in the channel, and configured to reduce a flow rate of the irrigation liquid in accordance with deformation of the second film deformed by a pressure of the irrigation liquid in the tube,
• wherein a closed space is formed between a portion of the first film and the cover,
• wherein the channel includes a first through hole and a second through hole, the first through hole being disposed in the first pressure reducing channel, the first through hole opening at the first surface and the second surface of the emitter main body, the second through hole being disposed in the second pressure reducing channel, the second through hole opening at the first surface and the second surface of the emitter main body,
• wherein the first film is disposed to close openings of the first through hole and the second through hole on the first surface side, and
• wherein the first film is distorted in a direction of the closed space by deformation that is caused when a temperature of the first film is greater than a predetermined temperature value and a pressure of the irrigation liquid distributed in the channel is greater than a predetermined first pressure value such that the first through hole and the second through hole communicate with each other through a gap formed between the emitter main body and the first film.