Image sensor with multiple integration periods

摘要

The invention concerns a method of reading voltages from an image sensor comprising an array of pixels, each pixel comprising at least one photodiode connectable to a storage node, the method comprising: controlling each pixel in a row of pixels to transfer charge accumulated in the photodiode above a first threshold to the storage node at the start and end of a first integration period (T TC ) and reading a first voltage at the storage node of each pixel in the row at the end of the first integration period; controlling of the pixels in the row to transfer charge accumulated in the photodiode above a second threshold to the storage node at the start and end of a second integration period (T C ) longer than the first integration period, and reading a second voltage value at the storage node of each pixel in the row at the end of the second integration period; controlling each pixel in a row of pixels to transfer charge accumulated in the photodiode to the storage node at the end of a third integration period (T L ) longer than the first and second integration periods; comparing for each pixel in the row, the first voltage values with a reference voltage; and based on the comparison, for each pixel in the row, performing one of: determining a pixel output value based on the first and/or second voltage values; and reading a third voltage value at the end of the third integration period, and determining a pixel output value based on the second and/or third voltage values.