Imaging Pixel Switching Circuit for Event Detection and Sensitivity

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Solution Overview

Problem

In imaging elements capable of both event detection and imaging, the area of photodiodes is narrowed due to the presence of two transfer gates, leading to reduced light use efficiency, deteriorated pixel characteristics, and decreased sensitivity, especially as miniaturization progresses, resulting in poor image quality and erroneous low-illuminance event detection.

Innovation Solution

An imaging element with a light receiving section, an event detecting section, and a pixel signal generating section, where a switching element controls the flow of charge between these sections, eliminating the need for two transfer gates and optimizing the use of photodiode area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If two transfer gates are mounted for one photodiode to perform both event detection and imaging, then the imaging element can perform both functions, but the area of the photodiode is narrowed and light use efficiency is reduced

Engineering Contradiction:

Improvedual function capabilityVSAvoidphotodiode area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The pixel circuit is divided into two operational modes: event detection mode using one transfer gate and imaging mode using another transfer gate. By segmenting the functionality and activating only the necessary transfer gate for each mode, the photodiode area is preserved while maintaining dual function capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The imaging element dynamically switches between event detection and imaging modes by controlling which transfer gate is active. This dynamic operation allows the system to adapt its functionality based on the required task, preventing the need for both transfer gates to be permanently present and occupying photodiode area.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If two transfer gates are mounted for one photodiode to perform both event detection and imaging, then the imaging element can perform both functions, but pixel characteristics deteriorate

Engineering Contradiction:

Improvedual function capabilityVSAvoidpixel characteristics

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

By segmenting the circuit into distinct event detection and imaging pathways with separate transfer gates, each pathway can be optimized for its specific function without interference from the other, maintaining pixel characteristics in both modes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The switching element acts as an intermediary that directs charge to either the event detection circuit or the imaging circuit based on the operational mode, preventing signal interference and maintaining the integrity of pixel characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Volume of moving object

If miniaturization progresses to reduce pixel size, then the device can be more compact, but pixel sensitivity decreases

Engineering Contradiction:

Improvepixel sizeVSAvoidpixel sensitivity

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

By segmenting the pixel circuit to use only one transfer gate at a time based on operational mode, the effective area available for photoelectric conversion is maximized even in miniaturized pixels, preserving sensitivity despite reduced overall pixel size.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes operational parameters by switching between event detection and imaging modes, allowing miniaturized pixels to maintain sensitivity through optimized charge transfer pathways appropriate for each mode rather than requiring both transfer gates to be present.

Inventive Principle:

Principle #35Parameter changes

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 configuration enhances light use efficiency, improves pixel characteristics, and maintains sensitivity even with miniaturization, reducing image quality deterioration and erroneous event detection at low illuminance.

Implementation Method 1

a light receiving section that includes a photoelectric conversion element that generates a charge

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS20240171878A1Imaging element, imaging device, and method for controlling imaging element

Publication Date: 2024.05.23 SONY SEMICON SOLUTIONS CORP

AI summary

An imaging element of an aspect according to the present disclosure includes a light receiving section (61) including a photoelectric conversion element that generates a charge, an event detecting section (63) that generates an event detection signal on the basis of the charge supplied from the light receiving section (61), a pixel signal generating section (62) that generates a pixel signal on the basis of the charge supplied from the light receiving section (61), and a switching transistor (253) that is an example of a single switching element that switches between a first electric path through which the charge is supplied from the light receiving section (61) to the event detecting section (63) and a second electric path through which the charge is supplied from the light receiving section (61) to the pixel signal generating section (62).