Continuously integrating digital pixel imager

Abstract

An imaging device includes an image detector that includes an array of digital pixels, each digital pixel including an output that provides a digital pixel output pulse each time a charge stored in the digital pixel exceeds a threshold and a readout integrated circuit (ROIC) connected to the output of each of the digital pixels to receive the digital pixel output pulse from each pixel, the ROIC including a plurality of accumulators, each of the plurality of accumulators associated with a respective digital pixel. The imaging device also includes a controller that reads the accumulators to determine a number of digital pixel output pulses stored by the accumulators without stopping the generation of digital pixel output pulses.

What is claimed is: 
     
         1 . An imaging device including:
 an image detector that includes an array of digital pixels, each digital pixel including an output that provides a digital pixel output pulse each time a charged stored in the digital pixel exceeds a threshold;   a readout integrated circuit (ROIC) connected to the output of each of the digital pixels and to receive the digital pixel output pulse from each pixel, the ROIC including a serializer that produces a serializer data output each time a digital pixel output pulse is received, the serializer data output including in indication of a position on the image detector of a pixel that produced the received digital pixel output pulse; and   a controller that receives the serializer data output without stopping the generation of digital pixel outputs.   
     
     
         2 . The imaging device of  claim 1 , wherein the indication of the position includes a row and a column. 
     
     
         3 . The imaging device of  claim 2 , further comprising a clock that provides a time to the serializer. 
     
     
         4 . The imaging device of  claim 3 , wherein the serializer data output includes a time stamp based on the time provided to the serializer by the clock when the digital pixel output pulse was received. 
     
     
         5 . The imaging device of  claim 4 , wherein each digital pixel includes:
 a photodiode;   an integration capacitor arranged to receive a photocurrent from the photodiode at an input and to store charge developed from the photocurrent, the integration capacitor coupled between the input and a reset voltage; and   a comparator coupled to the input that generates the digital pixel output pulse when the stored charge exceeds the threshold.   
     
     
         6 . A method of operating an imaging device, the imaging device including: an image detector that includes an array of digital pixels, each digital pixel including an output, a readout integrated circuit (ROIC) including a serializer, and a controller, the method comprising:
 generating digital pixel output pulses, by the array of digital pixels, when a charge stored in the one of the array of digital pixels exceeds a threshold;   receiving, by the serializer, the digital pixel output pulses via the digital pixel outputs;   each time a digital pixel output pulse is received by the serializer, generating the serializer data output, the serializer data output including in indication of a position on the image detector of the digital pixel that produced the received digital pixel output pulse; and   providing the serializer data output to the controller without stopping the generation of additional digital pixel output pulses by the array of digital pixels.   
     
     
         7 . The method of  claim 6 , wherein the indication of the position includes a row and a column. 
     
     
         8 . The method of  claim 6 , further comprising:
 providing a time from a clock to the serializer;   wherein the serializer data output includes a time stamp based on the time provided to the serializer by the clock when the received digital pixel output pulse was received.