In this paper, a new photo device are proposed using gap-typed hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) as backlight sensing circuits. The system employs gap type a-Si TFTs, which has higher photo sensitivity, to sense illumination and increase device dynamic range. Meanwhile, the system with local dimming technologies could attain the purpose for self-adjusting function. It is expected that the integration of this sensing system onto the panel can be implemented without extra process development. Furthermore, the photo leakage characteristics of a-Si TFTs after optical stress are investigated and the corresponding calibration method is proposed to reduce the error in sensing the illumination intensity. This approach would provide the possibility for the sensors array to be integrated into the pixel with the same a-Si TFT device.
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