Active-matrix organic electroluminescent display device
View Patent ↗An organic electroluminescent display device includes scanning lines, signal lines, and pixels formed in a matrix, each pixel being at an intersection of each of the scanning lines and each of the signal lines. Each pixel includes a light-emitting element, a light-emitting circuit composed of a thin-film transistor, and a light-receiving circuit composed of a thin-film transistor. When the light-emitting circuit is selected by the scanning line, the light-emitting circuit drives the light-emitting element according to a video signal that is input from the signal line, thereby displaying an image on the pixels formed in the matrix. The light-receiving circuit is selected in a period of time during which the light-emitting circuit does not operate, and outputs a light-receiving signal in accordance with the amount of light incident on the pixel to a different signal line.
1. An active-matrix organic electroluminescent display device comprising:
scanning lines;
signal lines; and
pixels formed in a matrix, each pixel being at an intersection of each of the scanning lines and each of the signal lines,
wherein each pixel includes a light-emitting element comprising an organic electroluminescent element, a light-emitting circuit comprising a thin-film transistor, and a light-receiving circuit comprising a thin-film transistor,
when the light-emitting circuit is selected by the scanning line, the light-emitting circuit drives the light-emitting element according to a video signal that is input from the signal line, thereby displaying an image on the pixels formed in the matrix, and
the light-receiving circuit is selected in a period of time during which the light-emitting circuit does not operate, and outputs a light-receiving signal in accordance with the amount of light incident on the pixel to a different signal line, wherein the light-receiving circuit includes a resetting unit that resets the light-emitting element to a reverse-bias state, and an amplification unit that amplifies a photo-leakage current that flows in the light-emitting element according to the amount of light incident on the reverse-biased light-emitting element to generate a light-receiving signal,
wherein the light-receiving circuit includes:
an input switch that supplies the photo-leakage current flowing in the light-emitting element according to the amount of incident light to the amplification unit; and
an output switch that reads a light-receiving signal from the amplification unit to the signal line, the light-receiving signal being obtained by amplifying the supplied photo-leakage current and the input switch and the output switch are independently turned on and off.
2. The device according to claim 1 , wherein the light-receiving circuit detects the amount of light incident on the light-emitting element formed on the pixel, and outputs a light-receiving signal corresponding to the detected amount of light.
3. The device according to claim 1 , wherein the light-receiving circuit turns off the input switch and the output switch in a period during which the light-emitting circuit operates, and at non-operating time of the light-emitting circuit, the light-receiving circuit first turns on the input switch to start supplying the photo-leakage current to the amplification unit, and then turns on the output switch when the photo-leakage current is stably supplied.