SEMICONDUCTOR IMAGE READING DEVICE Russian patent published in 2011 - IPC H04N5/335 

FIELD: physics.

SUBSTANCE: signal charge which corresponds to the amount of incident light accumulates in the first node (N1) of each pixel circuit (10). The circuit (20) for tapping off the accumulated charge includes each of the first nodes (N1) of a plurality of pixel circuits (10) belonging to the same group of pixels, and a second node (N2) connected through discharge gates (DG) which operate as variable resistance elements. The second node (N2) operates as a floating drain during the period when the control switch (24) is on, along with accumulation of the signal charge overflowing from each pixel circuit (10) in the capacitor (22) during the period the control switch (24) is off, provided with intermediate timing in one frame scanning period. When light incident on a group of pixels is intense, the value of resistance of each discharge gate (DG) falls in response to the increase in signal charge accumulated in the capacitor (22) so that the signal charge accumulated in each pixel circuit can be tapped once, with the said intermediate timing.

EFFECT: highly accurate and miniature semiconductor image reading device which enables sufficient detection of contrast between a bright part and a dark part, even when there is high spread in brightness in one field of vision.

11 cl, 17 dwg