Patent ID: 6963060

Claim:
An image sensor, comprising: a pixel array located on a first portion of an integrated circuit and having a plurality of pixels, each pixel having: a photosensor having an electrical property which varies in response to intensity of illumination, comparison means for generating a comparison signal, the comparison means having first and second input nodes and an output node and generating the comparison signal at the output node in response to signals applied to first and second input nodes, and selective connection means for selectively connecting the first input node and the output node so as to convert the comparison means to an op amp; a plurality of storage means displaced from the first portion of the integrated circuit, each of the storage means connected to a respective one of the plurality of pixels, such that a separate storage means of the plurality is connected to each pixel; counter signal means for providing a time-varying, multi-bit counter signal; and reference signal means for providing a reference signal maintainable at a first value and being further configurable to vary the reference signal over time from the first value to a second value; wherein each storage means receives the counter signal, the first input node of the comparison means within each pixel is connected to the photosensor in the same pixel, the second input node of the comparison means within each pixel receives the reference signal, and each storage means is configured to store the value of the multi-bit signal at the time that a comparison signal generated at the storage means' respective pixel transitions from a first value to a second value.