CMOS Image Sensor Subpixel Groups with Parallel Photocharge Accumulation

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Solution Overview

Problem

CMOS image sensors face challenges in minimizing pixel arrays and driving circuits while maintaining high-definition image quality without distortion, as existing methods fail to effectively control integration time and eliminate photocharge efficiently.

Innovation Solution

The method involves accumulating photocharge in subpixel groups in parallel and sequentially outputting subpixel signals, using control signals to manage photocharge accumulation and elimination, and comparing accumulated potential with a threshold to generate subpixel signals, thereby pixelizing and refining image data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If photocharge accumulation time is extended to improve image quality, then measurement precision is improved, but loss of time increases and productivity decreases

Engineering Contradiction:

Improveimage qualityVSAvoidframe rate

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The pixel array is divided into multiple subpixel groups, each capable of independent photocharge accumulation. This segmentation allows different integration times for different regions, enabling high-quality imaging without requiring extended accumulation time across the entire array, thus maintaining frame rate while improving image quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Photocharge is accumulated in advance in each subpixel group during a predetermined integration time period before readout. This preliminary accumulation ensures sufficient signal strength for high-definition imaging while the predetermined time limit prevents excessive integration time that would reduce frame rate.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If pixel array size is minimized to reduce device complexity, then device complexity is reduced, but measurement precision deteriorates

Engineering Contradiction:

Improvepixel array sizeVSAvoidimage definition

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces a temporal dimension to the pixel structure by implementing multiple subpixel groups that can accumulate photocharge independently over time. This allows the system to achieve high-definition imaging capability without increasing the spatial size of the pixel array, effectively trading temporal processing for spatial compactness.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Multiple subpixel groups are nested within the pixel array structure, with each subpixel group containing multiple subpixels. This nested organization allows the system to maintain a compact overall size while providing multiple accumulation channels that enhance measurement precision through parallel processing.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If integration time is controlled to reduce image distortion, then reliability is improved, but loss of time increases

Engineering Contradiction:

Improveimage distortion controlVSAvoidintegration time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The integration time is made dynamic and controllable for each subpixel group independently. By adjusting the integration time of each subpixel group according to specific imaging requirements, the system can minimize image distortion while avoiding excessive integration time that would reduce frame rate. The row driver block dynamically controls the start and end of integration periods.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system incorporates feedback mechanisms where the row driver block monitors and controls the integration time of each subpixel group. This feedback control ensures that integration is terminated at the optimal moment to prevent image distortion from excessive accumulation, while maintaining efficient timing to preserve frame rate.

Inventive Principle:

Principle #23Feedback

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 enables efficient photocharge management, reducing image distortion and improving high-definition image quality by synchronizing photocharge accumulation and output across subpixel groups, enhancing the performance of CMOS image sensors.

Implementation Method 1

each of the plurality of subpixels being configured to generate a subpixel signal corresponding to at least one photocharge accumulated in response to at least one photon

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS9357142B2Image sensor and image processing system including subpixels having a transfer circuit, comparator and counter for outputting the count value as the subpixel signal

Publication Date: 2016.05.31 SAMSUNG ELECTRONICS CO LTD

AI summary

An image sensor includes a pixel array and a row driver block. The pixel array includes a plurality of subpixel groups, each including a plurality of subpixels. Each of the plurality of subpixels is configured to generate a subpixel signal corresponding to photocharge accumulated in response to a photon. The row driver block is configured to generate a first control signal to control the subpixels included in each of the plurality of subpixel groups to accumulate the photocharge in parallel from a first time point to a second time point.