| 摘要 |
PROBLEM TO BE SOLVED: To prevent high humidity hot air in a duct from entering behind a loudspeaker by pressurizing a 1st space enclosed by the loudspeaker and a case higher than B duct pressure. SOLUTION: With an active noise control system, at least while a duct 80 is in operation, a pressure Pe in a 1st space 10 is maintained higher than a pressure Pd in the duct 80 (Pe>Pd). Therefore, humid gas in the duct 80 cannot enter the 1st space 10, a condensation problem is solved. Namely, since it is restricted for high humidity hot air in the duct to enter the space via a route passing through a vibration corn paper itself and reaching the back of the loudspeaker 4, there is an effect of securing condensation prevention measure. Moreover, since the system uses no heater as a condensation prevention means, the loudspeaker 4 is resistant to overheating or mal-operation, and is applicable in a duct in which relatively high temperature gas is flowing. |
