| 摘要 |
PROBLEM TO BE SOLVED: To obtain a low cost filter for a ventilator capable of freely changing a shape of a high performance having directivity in ventilation and to prevent a mounting mistake of a filter as well. SOLUTION: A flexible thin filter medium having a rough tissue at a front side and a dense tissue at a rear side is formed in a bellowlike ring in which ridges and troughs are alternatively continued in a direction of a centerline so that its inside is rough and its outside is dense and flexible frames are mounted at both ends of the filter material in the direction of the centerline. An extendibility and a sealability may be imparted to the frame. Further, a display element for displaying a direction of the rough and dense state of the tissue of the filter medium may be imparted. |
