Automatic Region of Interest Readout Circuit for 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 dynamically, leading to unnecessary data download and limited frame rates in applications like laser triangulation.
Innovation Solution
A circuitry is introduced that automatically determines and reads out a dynamically defined ROI within the sensor array, using a first read-out circuit for fast, low-accuracy pixel acquisition and a processing unit to identify relevant pixels based on predefined conditions, allowing only necessary pixels to be downloaded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If row-by-row reading out is performed to download pixels from the sensor array, then all pixels can be read out systematically, but unnecessary pixels outside the region of interest are downloaded wasting time and bandwidth
Solution Approach 1:
The patent extracts only the relevant pixels within the region of interest from the sensor array, excluding unnecessary pixels outside the ROI. This is achieved by introducing ROI indication storage means that marks which pixels belong to the ROI, and a read-out circuit that selectively reads only marked pixels, thereby eliminating wasted download time and bandwidth.
Solution Approach 2:
The patent segments the sensor array into regions of interest and non-interest areas using ROI indication storage means. Each pixel is individually marked with an ROI indication bit, allowing the read-out circuit to process and download only the segmented ROI portion rather than the entire sensor array, improving frame rate by reducing unnecessary data transfer.
2Productivity
If rectangular ROI covering entire rows is used, then download efficiency is improved by skipping empty rows, but non-rectangular ROIs still require downloading unnecessary pixels
Solution Approach 1:
The patent applies local quality by allowing different pixels to have different ROI indications based on their individual relevance to the region of interest. Instead of treating entire rows uniformly, each pixel can be independently marked, enabling precise extraction of non-rectangular ROIs and eliminating the waste of downloading complete rows when only specific pixels within them are needed.
3Speed
If fast read-out circuit is used for initial pixel acquisition, then processing speed is improved, but accuracy is reduced requiring subsequent verification
Solution Approach 1:
The patent performs preliminary action by using the fast read-out circuit to quickly acquire pixel data and determine the ROI region in advance. This preliminary fast reading allows the system to identify which pixels belong to the ROI, after which the selective read-out circuit can efficiently download only those marked pixels with full accuracy, combining speed and precision in a two-stage process.
Data Source
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Figure 2
Figure 3A~3B
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 with arbitrary geometry may be read out from the sensor array, thus leading to substantial time savings. In order to achieve this, a circuitry is provided for automatic determining of a ROI and reading out the ROI from the sensor array. The circuitry includes a fast reading-out circuitry which is less precise but faster than the accurate reading-out circuitry for reading-out the pixels of the sensor array. The fast reading-out circuitry reads out the pixels with low-level precision and determines by the processing of the fast read-out pixels the ROI which is then provided to an in-pixel ROI programming circuit for storing the ROI identification and by means thereof to the accurate reading-out circuit which then reads out only the pixels determined to belong to the ROI. The accurate read-out circuit is slower than the fast read-out circuit.