FIELD: physics, computer engineering.
SUBSTANCE: invention relates to an image forming apparatus. The result is achieved due to that the image forming apparatus includes a pixel for generating a signal through photoelectric conversion; a comparator circuit (30-1) for comparing a pixel-based signal with a time-dependent reference signal; a computing circuit (40-1) which computes the ratio of values between the pixel-based signal and the time-dependent reference signal before inversion; and a selection circuit (30-2) for setting a time-dependent rate of change of the reference signal according to the level of the pixel-based signal.
EFFECT: generating digital data of a high-resolution pixel signal with high rate of reading without increasing the area of the circuit and power consumption.
13 cl, 13 dwg
