Dynamic ROI Reading Circuit for CMOS Image Sensors
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Solution Overview
Problem
Current CMOS image sensors are inefficient in reading out pixels, particularly when the region of interest (ROI) is non-rectangular and changes with each image, leading to unnecessary data download and limited frame rates in applications like laser triangulation.
Innovation Solution
A circuitry and method that allows for dynamic configuration and reading out of ROIs with arbitrary geometries within the sensor array, using a one-bit memory per pixel to store ROI indications and a selection circuit to selectively read out only relevant pixels, thereby reducing data transfer time and increasing frame rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If row-by-row reading out method is used, then all pixels can be read out systematically, but unnecessary pixels are downloaded wasting time
Solution Approach 1:
The pixel array is segmented into regions of interest (ROI) and non-ROI areas. The reading out process is divided into two stages: first reading out ROI pixels immediately, then reading out non-ROI pixels subsequently. This segmentation allows the system to prioritize and extract only the necessary data portions, eliminating the waste of downloading unnecessary pixels while maintaining systematic reading out capability.
2Adaptability or versatility
If rectangular ROI is used, then reading out process is simple, but non-rectangular ROIs cannot be efficiently handled
Solution Approach 1:
The patent introduces a temporal dimension to the reading out process by implementing a two-stage sequential reading mechanism. Instead of attempting to handle complex non-rectangular geometries spatially, the solution reads out pixels in two time phases: first the ROI pixels, then the remaining pixels. This transforms the geometric complexity problem into a temporal sequencing problem, allowing arbitrary ROI shapes to be handled without increasing spatial circuit complexity.
3Productivity
If all pixels are read out, then complete image data is obtained, but frame rate is limited by total data volume
Solution Approach 1:
The invention extracts and separates the region of interest pixels from the complete pixel array. By identifying and extracting only the ROI pixels in the first reading stage, the system reduces the total data transfer volume to only the necessary portion. The remaining non-ROI pixels are read out in a second stage or skipped entirely depending on application requirements, thereby increasing frame rate by minimizing the critical data path volume.
Data Source
AI summary
The present invention relates to reading-out sensor array pixels. In particular, the present invention provides an approach according to which only a region of interest is may be read out from the sensor array, thus leading to substantial time savings. In order to achieve this, a circuitry for configuring a region of interest for the sensor array is provided as well as a reading-out circuitry for reading-out pixels belonging to the region of interest. In addition, the corresponding methods for programming the region of interest and for reading-out the region of interest are provided. The circuitry for programming and/or reading-out the region of interest includes per pixel provided storage elements for storing an indication of whether a pixel belongs to a region of interest (ROI). These are configured by the programming circuitry and using when reading-out the ROI for only reading out the pixels of the ROI.