| 摘要 |
PURPOSE:To reduce the erroneous detection of the progress state of clogging by fixing a reflecting mirror to a front surface panel constituting some of a casing wherein a heat exchanger, etc., are installed and by equipping this reflecting mirror with a light emission part and a photodetection part which oppose to each other across a filter. CONSTITUTION:On the reverse surface of the lattice of a front surface panel 2, a reflecting mirror 11 is provided and to heat exchanger 7, an optical fiber sensor 12 is fitted; and an optical path (l) consisting of the optical fiber sensor 12 and reflecting mirror 11 crosses a filter 5 and the part facing to the suction intake 6 of the panel 2. Namely, the part where the optical path (l) crosses the filter 5 is where the internal air of a chamber sucked from the suction intake 6 comes into direct contact, and the optical path slants to a ventilation direction, thereby substantially increasing the opening area of light passing through the filter 5. |
