Patent ID: 7659931

Claim:
An imaging apparatus, comprising: a photoreceptor element having an output line, the photoreceptor element sending an electric-signal level to the output line in accordance with an intensity of light received by the photoreceptor element, the electric-signal level attenuating from an initial electric-signal level; a comparator coupled with the output line of the photoreceptor element, the comparator comparing the electric-signal level from the output line with a threshold electric-signal level, and sending an output signal when the electric-signal level is lower than the threshold electric-signal level; and a storage unit coupled with the comparator, the storage unit receiving a clock signal and recording a first time period for generating the output signal in the comparator; wherein the threshold electric-signal level monotonically increases from an initial threshold electric-signal level to a final threshold electric-signal level when the electric signal level attenuates, the initial threshold electric-signal level being lower than the electric-signal level and the final threshold electric-signal level approaching the initial electric-signal level.