| 摘要 |
PURPOSE:To obtain an accurate read signal of an original picture in a high speed, by using a parallel A/D converter in a photodetection sensitivity correcting circuit in the picture reader using a solid image sensor. CONSTITUTION:Before reading an original, switch terminals of an analogue switch 13 are switched to the 1-3 side by a sequence control circuit 22, and a standard original 1 is read by a solid image sensor 3, and the read signal is inputted to a parallel A/D converter 14 and is stored as a correction signal in a memory 18. Next, switch terminals of the analogue switch 13 are switched to the 1-2 side, and an original 2 is read, and the read signal is inputted to a resistance ladder 19. Then, turn-on and off of an analogue switch circuit 20 are set on a basis of the correction signal stored in the memory 18, and the correction signal is converted to an analogue signal and is added to the original read signal by an adder 21, thus correcting the photodetection sensitivity. |
