CMOS Image Sensor Global Drive Layout for Uniform Exposure

Solution Overview

Problem

CMOS image sensors face exposure time unevenness due to IR drop and wiring delays, leading to reduced image quality, especially in high-speed operations.

Innovation Solution

A solid-state imaging element with a global drive portion and a rolling drive portion, where the global drive circuit is placed on multiple sides of the pixel array region, reducing waveform rounding and ensuring uniform exposure time across all pixels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the global drive circuit is placed on one side of the pixel array region, then the device complexity is reduced, but exposure time unevenness increases due to IR drop and wiring delays

Engineering Contradiction:

Improvecircuit configurationVSAvoidexposure time uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The global drive circuit is divided into multiple independent drive circuits positioned on different sides of the pixel array region. Each drive circuit independently drives a portion of the pixel array, which segments the current paths and reduces the cumulative effect of IR drop and wiring delays across the entire array, thereby improving exposure time uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the pixel array are driven by locally positioned drive circuits. The drive circuits are strategically placed on multiple sides to provide localized driving, which reduces the distance that signals must travel and minimizes the impact of wiring delays and IR drop on exposure time uniformity across different regions.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If the global drive circuit is placed on multiple sides of the pixel array region, then exposure time uniformity is improved, but the device complexity increases

Engineering Contradiction:

Improveexposure time uniformityVSAvoidcircuit configuration

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The global drive circuit is divided into multiple independent drive circuits positioned on different sides of the pixel array region. Each drive circuit independently drives a portion of the pixel array, which segments the current paths and reduces the cumulative effect of IR drop and wiring delays across the entire array, thereby improving exposure time uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple drive circuits perform the same global shutter driving function but are distributed across different sides of the pixel array. This multi-functional arrangement allows each circuit to serve its local region while collectively achieving uniform exposure time across the entire array, balancing complexity with performance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If the global drive circuit is placed on multiple sides of the pixel array region, then image quality is improved, but the manufacturing cost increases

Engineering Contradiction:

Improveimage qualityVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The global drive circuit is divided into multiple independent drive circuits positioned on different sides of the pixel array region. Each drive circuit independently drives a portion of the pixel array, which segments the current paths and reduces the cumulative effect of IR drop and wiring delays across the entire array, thereby improving exposure time uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the spatial distribution parameter of the drive circuits from a single-side configuration to a multi-side configuration. This parameter change improves image quality by reducing exposure time unevenness, and the cost increase is offset by the ability to use standard manufacturing processes for creating multiple identical circuit blocks.

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 minimizes exposure time unevenness, enabling higher image quality even in high-speed operations by distributing instantaneous current paths and ensuring all pixels are driven at the same timing.

Implementation Method 1

charges generated by photoelectric conversion in a photodiode

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS11910117B2Solid-state imaging element and electronic apparatus

Publication Date: 2024.02.20 SONY SEMICON SOLUTIONS CORP

AI summary

The present disclosure relates to a solid-state imaging element and an electronic apparatus that can achieve a higher image quality. The imaging element includes a pixel having a global drive portion in which all rows are driven at a same timing and a rolling drive portion in which each row is driven at a corresponding timing, a pixel array region in which a plurality of the pixels is placed in an array, a global drive circuit configured to supply a drive signal to the global drive portion, and a rolling drive circuit configured to supply a drive signal to the rolling drive portion. Further, the global drive circuit is placed on each of at least three or more sides of four sides surrounding the pixel array region. The present technology is applicable to a stacked CMOS image sensor, for example.