Image Sensor Row Averaging Circuit for CMOS Sub-Sampling
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Solution Overview
Problem
Image sensors, particularly CMOS image sensors, face challenges in low-resolution modes such as sub-sampling and binning, where additional line memory is required for averaging pixel information, leading to increased memory usage and decreased sensing speed.
Innovation Solution
An image sensor with a pixel array and a timing control unit that allows simultaneous selection and processing of pixels of the same color from different rows, eliminating the need for additional line memory by using selection, reset, and transfer transistors to perform row averaging without storing previous information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional line memory is used to store previous pixel information for averaging in sub-sampling mode and binning mode, then image quality is improved, but memory area increases and sensing speed decreases
Solution Approach 1:
The patent merges the storage function of line memory with the signal processing function by performing averaging operations directly in the readout circuitry. Multiple pixel signals are combined and averaged in real-time during the readout process, eliminating the need for separate storage memory while maintaining image quality.
Solution Approach 2:
The patent performs preliminary averaging operations on pixel signals before they are fully read out and processed. By pre-averaging signals from multiple pixels (including previous rows in binning mode) during the readout phase, the system prepares processed data in advance, reducing the need for additional memory storage.
2Measurement precision
If additional line memory is used to store previous pixel information for averaging in sub-sampling mode and binning mode, then image quality is improved, but sensing speed decreases
Solution Approach 1:
The patent maintains continuous signal processing by performing averaging operations in real-time during the readout process rather than requiring batch processing after storage. The signal averaging continues uninterrupted as pixels are read out, maintaining high sensing speed while improving image quality through proper signal combination.
Solution Approach 2:
By performing averaging operations preliminarily during readout before final image processing, the system prepares averaged signals in advance, eliminating the need for slower post-processing operations and maintaining high sensing speed.
3Measurement precision
If pixel information from two rows is read separately to obtain averages, then averaging accuracy is improved, but sensing timing decreases to 50% or lower
Solution Approach 1:
The patent combines the readout operations for multiple rows by implementing averaging functionality within the same readout circuitry. Signals from different rows are combined and averaged in a single integrated process rather than requiring separate readout operations, maintaining accuracy while reducing time loss.
Solution Approach 2:
The system performs preliminary combination and averaging of multi-row pixel signals during the readout phase itself, preparing the averaged data in advance before final processing. This eliminates the need for time-consuming separate readout and post-processing operations.
Data Source
AI summary
An image sensor and a row averaging method for an image sensor capable of simultaneously selecting the pixels of the same color in the same column of different rows in a pixel array and performing a signal process, thereby preventing an increase in an area and a decrease in the sensing speed of the pixels in the sub-sampling mode and the binning mode of the image sensor.