Solid-State Imaging Device Dynamic Storage Capacitance for Wide Dynamic Range

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Solution Overview

Problem

Existing image sensors face challenges in achieving a wide dynamic range while maintaining high sensitivity and high signal-to-noise ratio, especially in applications requiring both low-illumination and high-illumination imaging without degrading animation quality.

Innovation Solution

A solid-state imaging device with a photodiode, transfer transistor, and multiple storage capacitance elements that store overflowing photocharges, allowing for sequential storage and signal processing to enhance dynamic range without dividing storage time between illumination conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple storage capacitance elements are used to store overflowing photocharges, then the dynamic range is widened, but the device complexity increases

Engineering Contradiction:

Improvedynamic rangeVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The storage capacitance is divided into multiple segments (first storage capacitance element, second storage capacitance element, etc.) that can be independently controlled. Each segment can store photocharges separately, allowing the system to handle a wider range of illumination levels while maintaining manageable complexity through modular architecture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The storage capacitance elements are dynamically switched in and out of operation based on illumination conditions. Transfer transistors control the connection between photodiodes and specific storage capacitance elements, allowing the system to adapt its storage capacity dynamically rather than requiring all capacitance elements to be permanently connected.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If photocharges are stored in multiple storage capacitance elements, then the signal-to-noise ratio is improved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidmanufacturing precision

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

By segmenting the storage capacitance into multiple elements, the patent reduces the burden on any single element, allowing for more relaxed manufacturing tolerances while still achieving the required overall precision through the combined operation of multiple elements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system uses transfer transistors that can be precisely controlled to direct photocharges to appropriate storage capacitance elements based on illumination levels. This feedback mechanism ensures that signals are stored in the most appropriate capacitance element, maintaining high signal-to-noise ratio while compensating for manufacturing variations.

Inventive Principle:

Principle #23Feedback

3Reliability

If sequential storage operation is used, then the animation quality is maintained, but the operation complexity increases

Engineering Contradiction:

Improveanimation qualityVSAvoidoperation complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system dynamically switches between different storage capacitance elements in sequence based on illumination conditions, allowing continuous operation without interruption. This dynamic switching maintains animation quality by ensuring that photocharges are always being stored, while the sequential nature simplifies control compared to simultaneous multi-element operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The sequential storage operation ensures continuous useful action by always having at least one storage capacitance element active and ready to receive photocharges. This continuity maintains animation quality without requiring complex simultaneous coordination of multiple storage operations.

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 maintains high sensitivity and signal-to-noise ratio across a wide dynamic range, preventing image quality degradation in animation imaging and enabling efficient miniaturization of image sensors.

Implementation Method 1

a photodiode for receiving light and producing photocharges

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS7821560B2Optical sensor, solid-state imaging device, and operating method of solid-state imaging device

Publication Date: 2010.10.26 TOHOKU UNIV

AI summary

In an optical device such as an optical sensor or a solid-state imaging device having a photodiode for receiving light and producing photocharges and a transfer transistor (or an overflow gate) for transferring the photocharge, it is configured that photocharges overflowing from the photo diode in storage operation are stored into a plurality of storage capacitance elements through the transfer transistor or the overflow gate, thereby obtaining the optical device adapted to maintain a high sensitivity and a high S/N ratio and having a wide dynamic range.