DIGITAL CORRELATED DOUBLE SAMPLE CAMERA

摘要

A digital electronic camera, method and circuit for converting an analog image-bearing signal from an electronic imaging device. The image-bearing signal provides both a pixel-reference signal and a pixel-image signal for each one of a plurality of pixels of the imaging device. The circuit includes a voltage clamp that adjusts a level of the image-bearing signal based on a black reference level to produce a clamped image-bearing signal. An analog-to-digital converter (ADC) is coupled to digitize the clamped image-bearing signal and operated to produce a first digital value representative of the pixel-reference signal for a pixel, and operated to produce a second digital value representative of the pixel-image signal. Then, a first digital subtractor generates a first digital difference signal based on the first and second digital values to reduce pixel-to-pixel noise and/or drift. The circuit optionally includes a feedback circuit that adjusts the black-reference level based on a comparison between the digital reference value and a digital black-reference value selected to be near or at one end of a range of values accommodated by the ADC. The circuit further optionally includes a clock-adjustment circuit that adjusts an image-voltage-signal sampling clock and/or a reference-voltage-signal sampling clock to sample the respective signal at substantially an end of a valid sampling interval. The circuit further optionally includes an accumulator/averager which is operated to accumulate and average one or more digital values of non-imaging pixels to produce a third digital value, and a second digital subtractor is operated to generate a second digital difference signal based on the first on the first digital difference signal and the third digital value, to reduce row-to-row noise and/or drift. A dovetail camera mounting system is also disclosed.