| 摘要 |
PURPOSE:To make the emitted light quantity of an LED array constant and to eliminate the irregularity of display by providing a photodetector which detects an LED for monitor and the emitted light quantity thereof and controlling a driving power source based on the output of the photodetector. CONSTITUTION:A whole display screen is constituted of many modules 14. The respective modules 14 are constituted of the LED for monitor 10, a monitor LED driving circuit 11, the photodetector 12 and a trimmer 13 for finely adjusting the intensity of emitted light in addition to the LED array 4. Then, when the emitted light quantity of the LED 10 is detected by the photodetector 12, the driving power sources of the circuit 11 and an LED driving circuit 3 are controlled so as to make the output of the detection equal to a value set by the trimmer 13 and the emitted light quantity of the LED array is made constant. The irregularity of the display is eliminated even when the variance of an LED is generated between the modules.
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