Image Sensor Charge Binning and Dual Channel Readout
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Solution Overview
Problem
Existing semiconductor-based image sensors face challenges in achieving high resolution, low noise, and high sensitivity while maintaining a small pixel size, especially in low light environments, and struggle with video rate data production without compromising image quality.
Innovation Solution
A selectable channel readout architecture with shared amplifiers and adjacent color sample averaging is employed, allowing for low noise column storage and readout, and enabling high sensitivity and variable resolution imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is decreased to increase resolution, then the number of pixels in a given size image sensor increases, but the sensitivity decreases and signal levels become inadequate for low light illumination
Solution Approach 1:
The patent combines signals from multiple pixels through charge domain binning, where charge from adjacent pixels is summed together before readout. This merging approach increases the effective signal level for low light conditions while maintaining the high pixel density required for resolution, directly resolving the contradiction between small pixel size and sensitivity.
2Measurement precision
If the pixel size is decreased to increase resolution, then the number of pixels increases, but constructing low noise column storage and readout circuits becomes increasingly difficult
Solution Approach 1:
By merging signals from multiple pixels through charge domain binning before they reach the column readout circuits, the patent reduces the burden on individual column circuits. The combined charge signal is read out through shared amplifiers, simplifying the column circuit design while maintaining low noise performance through the inherent signal integration.
3Measurement precision
If the number of pixels is increased to increase resolution, then the readout time becomes longer, but video rate data production is required
Solution Approach 1:
The patent segments the pixel array into multiple banks that can be read out in parallel through dual channel architecture. This segmentation allows simultaneous readout of different pixel groups, effectively doubling the readout rate and enabling video rate data production from high resolution sensors without requiring sequential readout of all pixels.
Solution Approach 2:
The patent implements selectable channel readout architecture that dynamically configures the readout paths based on operating mode. The system can switch between full resolution mode, binned mode, and dual channel parallel readout mode, providing adaptive readout rates that meet both still image and video production requirements from the same high resolution sensor.
4Productivity
If windowing or sub-sampling is used to achieve video rate data from large resolution sensors, then video rate data is provided, but image quality deteriorates with poor low light performance and aliasing artifacts
Solution Approach 1:
Instead of sub-sampling which discards pixel data, the patent merges charge from multiple pixels through charge domain binning. This combining approach preserves all captured light information while reducing the effective pixel count for video output, eliminating aliasing artifacts and maintaining superior low light performance compared to sub-sampling methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides low noise, high sensitivity, and multiple resolution imaging capabilities from a single image sensor, reducing noise and aliasing artifacts, and eliminating the need for high-performance programmable gain amplifiers.
Implementation Method 1
incident illumination is converted to a signal (either a voltage or current signal). The signal represents the amount of light incident upon a pixel photosite.
Data Source
AI summary
An image sensor includes: (a) a plurality of light measuring elements arranged in an array and at least a portion of the elements have a color filter mated with the light receiving elements which permits selective color reception by the light measuring elements; (b) a plurality of floating diffusions respectively mated with the plurality of light receiving elements; and c) an output structure electrically connected to two or more of the floating diffusions; wherein the at least two light receiving elements receiving the same color are transferred to the output structure substantially simultaneously.