| 摘要 |
In an active matrix electroluminescent display device a storage capacitor (24) is provided in each pixel (10) for storing a voltage to be used for addressing a drive transistor (22) which controls the illumination of the electroluminescent display element (20) and gated discharge photosensitive means (36), for example a phototransistor, are provided for discharging the charge storage capacitor in dependence on the display element's light output. Operation of the gated photosensitive means is controlled by the output of an inverter (50) whose input is coupled to one side of the storage capacitor. Upon the storage capacitor reaching a predetermined discharge voltage, the gated photosensitive means (36) is turned on by switching of the inverter, thereby rapidly discharging the capacitor and turning off the display element. The use of an inverter in this way ensures a fast, robust, and well controlled switching action to terminate light output.
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