<P>PROBLEM TO BE SOLVED: To provide a ventilation device for a plastic hothouse designed so as to be smoothly moved up and down without applying forcible load on a rotary drive device or a rotary shaft, and enable a transparent sheet to be smoothly wound up or back. ??<P>SOLUTION: The ventilation device for a plastic hothouse is provided with: a guide rod 1 standing close to a plastic hothouse (A); a rotary drive device 2 attached to the guide rod 1 so as to be movable up and down; a shaft 3 horizontally disposed to face the plastic hothouse (A) while its one end is rotatably connected to the device 2; and a transparent sheet 4 one end of which is connected to the shaft 3 and another end of which is connected to the plastic hothouse (A). The ventilation device is structured so that the transparent sheet 4 is wound or backwound around the shaft 3 when the shaft 3 rotates in the device 2 and thereby opening or closing the opening part B of the plastic hothouse (A). In the device, a drum-shaped bobbin 5 is connected to the shaft 3, a wire 6 disposed in parallel to the transparent sheet 4 is wound around the outer periphery of the bobbin 5, and the one end of the wire 6 is fixed to the upper part and the lower part of the plastic hothouse (A). ??<P>COPYRIGHT: (C)2010,JPO&INPIT ??
