CMOS Image Sensor ROI Readout Circuitry for Arbitrary Region Selection
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Solution Overview
Problem
Current CMOS image sensors are inefficient in reading out data, particularly when the region of interest (ROI) is non-rectangular and changes with each image, leading to unnecessary pixel download and reduced frame rates in applications like laser triangulation.
Innovation Solution
A circuitry and method that adaptively configures and reads out a region of interest within a CMOS sensor array, allowing for selective download of pixels with arbitrary geometry, using a rewritable ROI memory and a read-out circuitry that selects only relevant pixels based on an ROI indication, thereby minimizing data readout and increasing frame rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If row-by-row download method is used, then all pixels in selected rows are downloaded, but unnecessary pixels are downloaded when ROI is non-rectangular, leading to increased readout time
Solution Approach 1:
The patent segments the pixel array into multiple independent columnar readout channels, each capable of autonomous operation. This segmentation allows the system to process and transmit data from different columns simultaneously, enabling selective reading of only the pixels within the ROI boundaries rather than downloading entire rows. The segmentation is achieved through dividing the sensor into N columns with independent readout circuitry for each column.
Solution Approach 2:
The patent implements dynamic ROI configuration where the region of interest can be adaptively defined for each frame based on application requirements. The ROI parameters (column start, column end, row start, row end) are programmable and can change dynamically, allowing the system to optimize readout patterns for different scenarios such as laser line detection, rectangular regions, or arbitrary shapes. This dynamic adaptability enables the system to minimize unnecessary pixel downloads by precisely matching the readout pattern to the actual ROI.
2Ease of operation
If rectangular ROI covering entire rows is used, then download process is simplified, but pixels outside the actual ROI are downloaded unnecessarily
Solution Approach 1:
The patent applies local quality by enabling different readout behaviors for different spatial regions. Each column channel can independently configure its readout parameters (start row, end row, pixel selection) based on the local ROI requirements. This allows the system to download only the necessary pixels within the ROI boundaries while skipping unnecessary pixels, even within the same frame. The local quality approach is implemented through independent column channels that can be selectively activated and configured.
Solution Approach 2:
The patent utilizes parameter changes by allowing flexible configuration of ROI parameters (column start, column end, row start, row end) and readout parameters (pixel selection, channel activation). These parameters can be dynamically adjusted to match the specific ROI geometry required by the application. By changing these parameters, the system can optimize the readout process for different ROI shapes and sizes, minimizing unnecessary data transmission while maintaining ease of operation through programmable control.
3Measurement precision
If all pixels are downloaded to determine ROI, then ROI can be accurately determined, but readout time increases significantly
Solution Approach 1:
The patent implements preliminary action by performing a fast preliminary readout of a subset of pixels (such as a reduced-resolution version or key sample pixels) to determine the ROI parameters before performing the complete high-resolution readout. This preliminary step allows the system to identify the ROI boundaries and configure the selective readout parameters in advance, so that only the necessary pixels are then read out at full resolution. This two-stage approach maintains ROI determination accuracy while significantly reducing the overall readout time compared to reading all pixels first.
Data Source
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Figure 2
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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.