VENTILATION DEVICE

摘要

Disclosed is ventilation device wherein the air volume can be varied, and which is provided with a DC motor for driving blades, and a control circuit for controlling the DC motor. The control circuit is provided with a first current detection unit for detecting the current applied to the DC motor; a rotation speed detection unit for detecting the rotation speed of the DC motor; and a control unit for controlling the DC motor on the basis of the rotation speed detected by the rotation speed detection unit and the current detected by the first current detection unit. The current detection unit is provided with a plurality of low resistors, uses the partial voltage amounts of the low resistors to detect the motor current, and finds a ventilation air volume from the rotation speed detected by the rotation speed detection unit and the current detected by the first current detection unit.