CMOS Image Sensor Resolution Adjustment via Analog Averaging

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Solution Overview

Problem

CMOS image sensors face challenges in maintaining high image quality, especially in low light conditions, due to spatial resolution loss and signal level enhancement issues with existing pixel sub-sampling, binning, and averaging techniques.

Innovation Solution

A photo-sensor image resolution adjustment apparatus that horizontally averages columns and vertically bins or averages rows of image sensors in a Bayer patterned array, using decimation circuits, column and row averaging circuits, and sample and hold circuits to adjust resolution while minimizing signal dilution and fixed pattern noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If pixel sub-sampling is used to reduce resolution, then frame rate increases, but spatial resolution is lost and aliasing is introduced

Engineering Contradiction:

Improveframe rateVSAvoidspatial resolution

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent combines multiple adjacent pixel signals through analog averaging circuits to create a single output signal. By merging signals from multiple pixels (e.g., 2x2, 4x4 blocks) in the analog domain before digital conversion, the system achieves resolution reduction while preserving spatial information through coherent signal combination rather than simple sub-sampling.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent performs analog averaging of pixel signals before the signals are digitized. By pre-processing the analog signals through averaging circuits prior to ADC conversion, the system reduces the data burden early in the signal chain, enabling higher frame rates while maintaining image quality through proper signal combination.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If digital binning is used to reduce resolution, then data processing load decreases, but signal level enhancement is lost

Engineering Contradiction:

Improvedata processing loadVSAvoidsignal level

Core Design Contradiction:

Device complexityVSPower

Solution Approach 1:

The patent replaces digital signal processing operations with analog circuit operations. By performing averaging and binning operations in the analog domain using dedicated hardware circuits rather than digital algorithms, the system achieves both reduced data processing load and signal level enhancement through the inherent properties of analog signal combination.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If analog column averaging is used, then spatial resolution is maintained, but circuit complexity increases

Engineering Contradiction:

Improvespatial resolutionVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the pixel array into distinct blocks or groups (e.g., 2x2, 4x4 pixel blocks) and applies averaging operations within each segment. This segmentation approach allows the circuit to process smaller groups of pixels independently, reducing the overall circuit complexity compared to averaging the entire array while still maintaining spatial resolution through localized signal combination.

Inventive Principle:

Principle #1Segmentation

4Power

If row binning is used in low light conditions, then signal level is enhanced, but resolution is reduced

Engineering Contradiction:

Improvesignal levelVSAvoidresolution

Core Design Contradiction:

PowerVSMeasurement precision

Solution Approach 1:

The patent implements a dynamic resolution adjustment system that can switch between different binning modes (e.g., no binning, 2x2 binning, 4x4 binning) based on lighting conditions. The circuit dynamically adapts its operation to enhance signal level in low light while preserving resolution in bright conditions, optimizing performance across varying environments.

Inventive Principle:

Principle #15Dynamics

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

Achieves high spatial resolution and image quality in both low and high light conditions with reduced power consumption and no additional on-chip memory requirements, scalable to various pixel array decimation ratios.

Implementation Method 1

An array of image sensors (e.g., Complementary Metal Oxide Semiconductor (CMOS) Active Pixel Sensors (APS))

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS7479994B2Image sensor having resolution adjustment employing an analog column averaging/row averaging for high intensity light or row binning for low intensity light

Publication Date: 2009.01.20 GULA CONSULTING LLC

AI summary

A photo-sensor image resolution adjustment apparatus is in communication with an array of image photo-sensors that are organized in columns and rows and have multiple sensor types arranged in a pattern such as a Bayer pattern to detect light. The photo-sensor image resolution adjustment apparatus has a photo-sensor array decimation circuit to partition the array of image photo-sensors into a plurality of sub-groups. A column averaging circuit averages the light conversion electrical signals from common color photo-sensors within the sub-groups. A row averaging circuit averages the common color adjacent light conversion electrical signals from color adjacent rows within the sub-groups in high light intensity condition. In low light conditions, a row binning circuit integrates the common color adjacent light conversion electrical signals from color adjacent rows within the sub-groups.