Image Sensing Structure With Analog Signal Storage for Event Detection

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Solution Overview

Problem

Current CMOS image sensors used in self-driving cars and other applications face challenges in miniaturization due to the need for digital frame buffers, which increase volume and cost, while also requiring additional space and power for image capture operations.

Innovation Solution

An image sensing structure that generates and stores sensing signals of different periods using a sensing circuit, storage circuit, and processing circuit, allowing for direct analog subtraction without a digital frame buffer, thereby reducing space and cost, and enhancing power efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a digital frame buffer is added to store sensing signals, then the image sensor can maintain and process images, but the volume and cost of the device increase

Engineering Contradiction:

Improveimage sensing capabilityVSAvoiddevice volume

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent extracts the frame buffer function from the traditional digital processing path and implements it directly in the pixel circuit using analog storage. The sensing signal is stored in an analog format within the pixel's floating diffusion node, eliminating the need for a separate digital frame buffer component, thereby reducing device volume while maintaining image sensing capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/digital storage system (digital frame buffer) with an analog electrical storage mechanism (floating diffusion node in the pixel circuit). By performing analog subtraction directly in the pixel domain before digital conversion, the system eliminates the need for large digital memory structures, significantly reducing device volume

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a digital frame buffer is added to store sensing signals, then the image sensor can maintain and process images, but the manufacturing cost increases

Engineering Contradiction:

Improveimage sensing capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts the frame buffer function from the digital processing path and implements it directly in the pixel circuit using analog storage. The sensing signal is stored in an analog format within the pixel's floating diffusion node, eliminating the need for a separate digital frame buffer component, thereby reducing device volume while maintaining image sensing capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the frame buffer function with the pixel circuit itself by using the floating diffusion node for both signal generation and temporary storage. This integration eliminates the need for separate memory structures and reduces the overall component count, leading to lower manufacturing costs

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If sensing signals are processed in digital format, then processing flexibility is improved, but power consumption and processing time increase

Engineering Contradiction:

Improveprocessing flexibilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces digital signal processing with analog signal processing in the pixel domain. By performing subtraction operations directly on the analog sensing signals before digital conversion, the system reduces the amount of data that needs to be processed digitally, thereby lowering power consumption while maintaining processing flexibility

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent performs the subtraction operation preliminarily in the analog domain before digital conversion. By calculating the difference between current and previous frame signals at the pixel level before ADC conversion, the system reduces the computational burden on subsequent digital processing stages, lowering overall power consumption

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20230388679A1Image sensing structure and image sensing device comprising the same

Publication Date: 2023.11.30 GUANGZHOU TYRAFOS SEMICON TECH CO LTD

AI summary

The present invention relates to an image sensing structure, including: a sensing circuit, a storage circuit and a processing circuit. The sensing circuit is used to generate multiple sensing signals in different periods; the storage circuit is used to store the sensing signals. The storage circuit sequentially outputs a first sensing signal of a target object in a first period and a second sensing signal of the target object in a second period to the processing circuit. The processing circuit performs dynamic event detection processing through the first sensing signal and the second sensing signal. Also, the present invention relates to an image sensing device including the image sensing structure.