Imaging Device Charge Accumulation Node Potential Control

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Solution Overview

Problem

Existing imaging devices face image-quality deterioration due to potential changes at the opposing electrode, causing brightness variations and signal charge leakage, which affect sensitivity and saturation levels.

Innovation Solution

An imaging device with a photoelectric converter, a capacitor, and voltage supply circuits that selectively apply different voltages to reduce potential variations at the charge accumulation node, ensuring stable voltage phases to minimize image-quality deterioration and maintain sensitivity and saturation levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If voltage is applied between pixel electrode and opposing electrode for sensitivity control, then sensitivity is controlled, but potential changes at opposing electrode cause image-quality deterioration

Engineering Contradiction:

Improvesensitivity controlVSAvoidimage-quality deterioration

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A capacitor is introduced as an intermediary element connected between the pixel electrode and the charge accumulation node. This capacitor isolates the charge accumulation node from potential changes at the opposing electrode, allowing sensitivity control voltage to be applied without transmitting harmful potential variations to the accumulated signal charge.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The circuit is segmented into distinct functional regions: the pixel electrode region for sensitivity control, the capacitor as an isolation barrier, and the charge accumulation node for signal storage. This segmentation allows independent optimization of sensitivity control while protecting the charge accumulation region from adverse potential changes.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If voltage is adjusted for sensitivity control, then sensitivity level is controlled, but saturation level is affected

Engineering Contradiction:

Improvesensitivity levelVSAvoidsaturation level

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The capacitor serves as a mediator that decouples the sensitivity control voltage from the charge accumulation node. This allows the saturation level at the charge accumulation node to remain stable and independent of voltage adjustments made for sensitivity control, resolving the trade-off between sensitivity and saturation stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If potential changes occur at opposing electrode, then sensitivity control is achieved, but signal charge leakage occurs

Engineering Contradiction:

Improvesensitivity controlVSAvoidsignal charge retention

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The capacitor acts as a protective intermediary between the pixel electrode and the charge accumulation node. It allows the application of sensitivity control voltages while blocking the transmission of potential changes that would otherwise cause signal charge leakage, thereby maintaining both sensitivity control and charge retention reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The capacitor provides beforehand protection by being positioned in advance between the pixel electrode and charge accumulation node. It cushions the charge accumulation node against potential changes before they can cause signal charge leakage, ensuring reliable charge retention during sensitivity control operations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 reduces image-quality deterioration by controlling potential variations at the charge accumulation node, maintaining consistent sensitivity and saturation levels, and preventing signal charge leakage.

Implementation Method 1

a photoelectric converter that includes a first electrode, a second electrode, and a photoelectric conversion layer between the first electrode and the second electrode and that generates a signal charge

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS11451726B2Imaging device and drive method therefor

Publication Date: 2022.09.20 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An imaging device includes: a photoelectric converter including a first electrode, a second electrode, and a photoelectric conversion layer that generates a signal charge; a charge accumulator connected to the first electrode to accumulate the signal charge; a first voltage supply circuit connected to the second electrode and that selectively supplies at least two different voltages including a first voltage and a third voltage greater than the first voltage; and a second voltage supply circuit that is connected to the charge accumulator via capacitance and that selectively supplies at least two different voltages including a second voltage and a fourth voltage less than the second voltage, where in a first period in which the first voltage supply circuit supplies the first voltage, the first period being included in an accumulation period for accumulating the signal charge in the charge accumulator, the second voltage supply circuit supplies the second voltage.