| 摘要 |
PROBLEM TO BE SOLVED: To provide a dust sensor unit in which stain at an optical lens caused by air containing floatation particles can be reduced.SOLUTION: A ventilation device including a centrifugal blower within a box-type body having a blowing-out port and a suction port is provided . The ventilation device includes a dust sensor 8 having: a light receiving part 16 including an optical lens 17; and a light-emitting part 14 including an optical lens 15. The dust sensor 8 further includes: a heater 18 below a position where optical axes of the light receiving part 16 and the light-emitting part 14 are crossed to each other. The ventilation device further includes a control part 6 for periodically turning ON/OFF the heater 18. The dust sensor 8 is configured to perform a measurement in conjunction with ON of the heater 18 to thereby shorten a convection flow time of floating particles around the optical lens 15 and the optical lens 17, so that adhesion of stains to the optical lens 15 and the optical lens 17 is suppressed.SELECTED DRAWING: Figure 2 |
