Analog Image Sensor Ambient Light Noise Elimination

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Solution Overview

Problem

Conventional image sensors using global shutters require digital buffer storage for differential operations to eliminate ambient light noise, leading to increased power consumption and complexity.

Innovation Solution

An image sensor and operating method that utilize analog differencing to eliminate ambient light noise by comparing charges stored during periods with and without a light source, eliminating the need for digital buffer storage and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If digital buffer storage is used for differential operations to eliminate ambient light noise, then noise elimination is achieved, but power consumption increases and device complexity increases

Engineering Contradiction:

Improveambient light noiseVSAvoidpower consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent replaces the digital buffer storage system with an analog differential circuit system. Instead of storing digital image frames in a digital buffer and performing subtraction digitally, the invention uses analog circuits to directly subtract the ambient light component from the total light signal in the analog domain, thereby eliminating the need for power-hungry digital buffer storage while achieving the same noise elimination effect

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameter from digital domain processing to analog domain processing. By performing differential operations on analog signals before digital conversion, the system avoids the power consumption associated with storing and processing digital frames, thus reducing overall power consumption while maintaining noise elimination capability

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If digital buffer storage is used for differential operations to eliminate ambient light noise, then noise elimination is achieved, but device complexity increases

Engineering Contradiction:

Improveambient light noiseVSAvoiddevice complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent substitutes the complex digital buffer storage and digital processing system with a simpler analog differential circuit system. The analog approach requires only basic circuit components to perform subtraction in the analog domain, significantly reducing device complexity compared to implementing digital frame storage and processing

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If digital buffer storage is used for differential operations, then ambient light noise is eliminated, but processing time increases due to sequential frame output requirement

Engineering Contradiction:

Improveambient light noiseVSAvoidprocessing time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent enables continuous operation by performing analog differential subtraction in real-time as signals are being processed, rather than requiring sequential output of complete frames. This allows the system to continuously eliminate ambient light noise without interrupting the imaging process, thereby reducing processing time delays

Inventive Principle:

Principle #20Continuity of useful action

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

The solution effectively removes ambient light noise from analog image signals, reducing power consumption by half and simplifying the image processing workflow, while enabling motion detection with a single image frame.

Implementation Method 1

an optoelectronic conversion circuit (10) configured to store a first charge corresponding to a first exposure period and store the first charge for a storing period, successively output the first charge and store a second charge corresponding to a second exposure period

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS9661250B2Image sensor and operating method thereof, motion sensor including the same

Publication Date: 2017.05.23 SAMSUNG ELECTRONICS CO LTD

AI summary

There is provided an operating method of an image sensor including: storing a first charge from an optoelectronic element to a pixel buffer circuit within a first exposure period; transferring the first charge from the pixel buffer circuit to a first storage circuit within a second exposure period; storing a second charge from the optoelectronic element to the pixel buffer circuit within the second exposure period after the first charge is transferred; transferring the second charge from the pixel buffer circuit to a second storage circuit; and comparing charges stored in the first storage circuit and in the second storage circuit to output an analog image signal.