Agilent Technologies, Inc.

Charles M C Tan

Frederick A Perner

Jeremy Alfred Theil

Min Cao

Francis Joseph

Wayne M Greene

A system and a method for imaging a scene of interest utilize variable exposure periods that have durations based upon detecting a fixed voltage drop in order to determine the scene segment radiance. The rate of voltage drop corresponds to the degree of scene segment radiance, such that high radiant scene segments yield faster voltage drops than lower radiant scene segments. The variable exposure period is determined within each pixel in a pixel array of the system to gather exposure periods from different segments of the scene being imaged. The measured exposure periods are translated into grayscale information that can be used to generate a composite image having various levels of grayscale that is representative of the imaged scene. Each pixel includes a photo sensor, an analog-to-digital converter and a memory to measure, digitize and store the exposure period. The memory contains a number of memory cells having a three-transistor configuration that are each connected to a bi-directional bit line. The bi-directional bit line functions as both a read bit line and a write bit line. The three-transistor configuration allows for non-destructive read-outs of data stored in the memory cells.

CMOS active pixel sensor having in-pixel local exposure control

An image sensor array. The image sensor array includes a substrate. An array of photo diode sensors are electrically interconnected to the substrate. The photo diode sensors conduct charge at a rate proportional to the intensity of light received by the photo diode sensors. A ring of guard diodes are located around the periphery of the array of photo diode sensors. Each guard diode has a guard diode anode connected to a predetermined guard anode voltage and a guard diode cathode connected to a static guard cathode voltage.

Photo diode pixel sensor array having a guard ring

An imaging device includes a Gray Code generator and an array of pixels. Each pixel includes a complimentary metal oxide semiconductor (&ldquo;CMOS&rdquo;) sensor, a comparator and random access memory (e.g., ferroelectric random access memory). The Gray Code generator is started at the beginning of capture mode and begins providing a sequence of code words. Within each pixel, an output of a CMOS sensor is compared to a threshold, and a code word in the sequence is stored in random access memory when the sensor output crosses the threshold. Thus, the random access memory of each pixel stores a code word that represents the intensity of light detected by its associated CMOS sensor.

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Santa Clara, CA, United States of America

Charles M C Tan