| 摘要 |
PURPOSE:To prevent heating due to stoppage or lowering of rotational speed of a fan by taking out only AC component from a driving current waveform thereby detecting abnormal rotation including stoppage of motor. CONSTITUTION:A lens 5 is driven by a control signal provided from a PU 1 to a motor 6 or a lamp voltage is applied on a light source 3 based on a control signal provided from the PU 1 to a CVR 2. In order to cool a film, electronic circuitry, casing, or the like which are heated by the light source 3, a fan 7 is provided and power is fed to the fan 7 from the CVR 2. When the fan 7 does not operate due to a foreign matter or disconnection, a rotation detecting circuit 8 detects stoppage of the fan and turns a switch 9 OFF to interrupt provision of the control signal to the CVR 2. Consequently, the light source 3 is turned OFF and temperature rise is prevented. |
