| 摘要 |
A diaphragm control angle calculating portion 2 calculates an angle at which a diaphragm is controlled to control an amount of light that reaches from a lamp 6 to a display device 10 according to distribution information of an input video signal, such as the maximum value, the minimum value, the average value and the histogram of the signal, and the control angle is inputted to a fan control signal generating portion 3 and a diaphragm driving portion 8 as control angle information. The diaphragm driving portion 8 controls the angle of the diaphragm 9 based on the control angle information. Light from the lamp 6 driven by a lamp driving portion 5 enters the diaphragm 9, and the amount of light according to the angle of the diaphragm 9 enters the display device 10. The fan control signal generating portion 3 controls the rotation speed of a cooling fan 4 according to a combination of the control angle information and the temperature detected by a temperature sensor. A high-contrast display image can be produced while noise resulting from an increase in the rotation speed of the cooling fan can be suppressed and the reliability of the lamp can be ensured by avoiding the influence of the temperature. |
