| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device with a photo sensor that reduces noise from external light and noise due to leak caused by off-state current of a transistor.SOLUTION: A semiconductor device includes a plurality of photo sensors 301 arranged in a matrix-shape. Each of the photo sensors 301 includes a photoelectric conversion element 302 and an amplification circuit 303. The semiconductor device turns on a back-light to radiate light to a detection object, and performs reset operation and storage operation using photo sensors in a specific row, then turns off the back-light and performs reset operation and storage operation using photo sensors in the next row, and then sequentially performs selection operation of photo sensors in all rows. The semiconductor device obtains difference between output signals obtained by photo sensors in adjacent rows, and generates a photographic image of the detection object and detects a region where the detection object is present by using the difference. The amplification circuit includes a transistor 304 that holds accumulated electric charges, and a channel of the transistor 304 is formed in an oxide semiconductor layer.SELECTED DRAWING: Figure 1 |
