Patent ID: 7038820
Filing Date: 2006-05-02
Classification: H04N

Abstract:
1. An apparatus for adjusting an exposure time for pixels that are arranged in rows and columns in a pixel array, wherein each pixel in the pixel array is associated with a column readout line, the apparatus comprising: a first peak signal detector circuit that includes an input that is arranged to receive a first signal that is associated with a first one of the column readout lines, wherein the first one of the column readout lines is associated with a first column of the pixel array that includes a first selected pixel, and the first peak signal detector circuit is arranged to store a peak signal level that is associated with the first signal; a second peak signal detector circuit that includes an input that is arranged to receive a second signal that is associated with a second one of the column readout lines, wherein the second one of the column readout lines is associated with a second column of the pixel array that includes a second selected pixel, and the second peak signal detector circuit is arranged to store another peak signal level that is associated with the second signal; a digital timing and control circuit that is arranged to reset the peak levels associated with the first and second peak signal detector circuits during a reset time interval, assert a stop exposure signal during the reset time interval, and monitor the stop exposure signal during an exposure time interval; and a threshold detector circuit that includes an input that is selectively coupled to the first detector circuit in a first portion of the exposure time interval, and selectively coupled to the second detector circuit in a second portion of the exposure time interval, wherein the threshold detector circuit is arranged to selectively compare the peak levels associated with the first and second signals to an exposure threshold, and assert the stop exposure signal when at least one of the peak levels associated with the first and second peak signal detector circuits exceeds the exposure threshold.