Reel-type filter screen improved structure

The present invention relates to an improved structure of reel-type filter screen. It is formed from a filter screen winded round a shaft rod. Said invented improved filter screen structure can be installed in a kitchen ventilator so as to filter oil-smoke impurities. Said filter screen possesses a front end portion, a rear end portion and two side portions. It is characterized by that at least one side portion of said filter screen is equipped with a number of through holes which are equidistantly arranged in turn. Said invented reel-type filter screen can be used in kitchen ventilator whosefilter screen can be automatically changed, and its through holes can be detected by infrared device to define the changed length.