TOF Image Sensor Driving Circuitry for Depth Accuracy

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Time-of-flight (TOF) sensing systems face challenges in achieving high resolution and accuracy due to distance differences between pixels in the image sensor array and delays in driving voltage transfer, leading to distortion and reduced image quality, especially as the size of the image sensor increases.

Innovation Solution

The implementation of a driving voltage supply mechanism that compensates for distance differences between driving circuitry and pixels by alternating the driving control signal between odd and even columns, and using dual driving circuitry on opposite sides of the pixel array to minimize delay and resistance, ensuring consistent voltage delivery across the pixel array.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the image sensor size is increased to improve resolution, then the resolution and accuracy of depth information are improved, but the distance difference between pixels and driving circuitry increases, causing greater voltage transfer delays and distortion

Engineering Contradiction:

Improvedepth information accuracyVSAvoidvoltage transfer delay

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The pixel array is divided into multiple column groups (first column groups and second column groups) with different driving signal supply timings. This segmentation allows each group to be driven at optimized times, compensating for the increased distance from the driving circuitry in larger sensors and reducing voltage transfer delays across the array.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The driving signal supply timing is predetermined and optimized for each column group based on its position and distance from the driving circuitry. By pre-calculating and applying the appropriate timing offsets, the system compensates for voltage transfer delays before they cause distortion, enabling accurate depth measurement in high-resolution sensors.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the image sensor size is increased to improve resolution, then the resolution and accuracy of depth information are improved, but the resistance in voltage transfer paths increases, causing distortion

Engineering Contradiction:

Improvedepth information accuracyVSAvoidvoltage delivery consistency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The pixel array is segmented into multiple column groups that are driven at different timings. This segmentation reduces the effective driving distance and resistance for each group, ensuring consistent voltage delivery even in high-resolution sensors where the overall array size is large.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different column groups are assigned different driving signal supply timings based on their specific positions and resistance characteristics. This local optimization ensures that each group receives the driving signal at the optimal time, compensating for variations in resistance and maintaining reliable voltage delivery across the entire array.

Inventive Principle:

Principle #3Local quality

3Device complexity

If conventional driving control signal supply is used, then the device complexity is low, but distortion occurs due to distance differences between pixels and driving circuitry

Engineering Contradiction:

Improvedriving circuit structureVSAvoidimage quality consistency

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The pixel array is divided into multiple column groups with different driving signal supply timings. This segmentation approach maintains relatively simple driving circuitry while significantly reducing distortion by accounting for distance differences between pixels and the driving circuitry through timing-based compensation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The driving signal supply timing is pre-optimized for each column group based on its position relative to the driving circuitry. This preliminary timing adjustment compensates for distance-induced distortion without requiring complex additional circuitry, maintaining image quality consistency while keeping the device structure relatively simple.

Inventive Principle:

Principle #10Preliminary 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

This approach enhances the resolution and accuracy of depth information in 3D images by reducing distortion caused by pixel position and voltage transfer delays, improving the overall performance of the TOF sensing system.

Implementation Method 1

each pixel generating an amount of charge in response to an incident light

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11709271B2Time of flight sensing system and image sensor used therein

Publication Date: 2023.07.25 SK HYNIX INC

AI summary

An image sensor, employed in a time-of-flight (TOF) sensing system, includes a pixel array including a plurality of pixels arranged in plural rows and plural columns, each pixel generating an amount of charge in response to an incident light, and first driving circuitry configured to supply a driving control signal to each pixel via the plural columns. The first driving circuitry is configured to supply the driving control signal via one of odd and even columns.