Vehicle Image Sensor Pixel Layout With Uneven Photodiode Areas
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Solution Overview
Problem
Current image sensors for vehicles face challenges in optimizing pixel design and layout to enhance light collection efficiency and image quality, particularly in balancing the area of photodiodes and transfer transistors within pixels.
Innovation Solution
The image sensor incorporates a pixel group with a first region and a second region, where the first region has a larger photodiode area than the second region, and both regions are connected by transfer transistors and floating diffusion regions, arranged in a specific m*n layout to improve light conversion and signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the photodiode area is increased to enhance light collection efficiency, then the light collection efficiency is improved, but the pixel density and resolution are reduced
Solution Approach 1:
The patent applies local quality by creating different photodiode areas within different pixel types. Specifically, first pixels have a first photodiode area while second pixels have a second photodiode area, where the areas are deliberately made different to optimize local light collection characteristics for different color channels or functional requirements, thereby improving overall image quality without uniformly sacrificing pixel density
Solution Approach 2:
The patent employs asymmetry by designing an uneven distribution of photodiode areas across the pixel array. Rather than using uniform photodiode sizes, the invention creates an asymmetric pattern where certain pixels (first pixels) have larger photodiodes for better light collection while others (second pixels) have smaller photodiodes, allowing the system to achieve both high light collection efficiency and high pixel density through strategic asymmetry
2Measurement precision
If the pixel area is increased to improve signal conversion efficiency, then the signal conversion efficiency is enhanced, but the field of view and scene coverage are reduced
Solution Approach 1:
The patent applies segmentation by dividing the pixel array into multiple types of pixels with different photodiode areas. This segmentation allows the system to have both large photodiodes for high signal conversion efficiency and small photodiodes for wide field of view coverage, with each segment serving a specific functional role in the overall imaging system
Solution Approach 2:
The patent resolves the contradiction by transitioning from a single-dimensional approach (uniform photodiode size) to a multi-dimensional approach (varying photodiode sizes across different pixel types). By adding the dimension of photodiode area variation, the system can simultaneously optimize for both signal conversion efficiency and field of view coverage in different regions of the sensor array
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 design enhances light collection efficiency and image quality by optimizing the area distribution of photodiodes and transfer transistors, leading to improved performance in vehicle image sensing applications.
Implementation Method 1
The photodiode may serve to convert incident light into electrical signals
Data Source
AI summary
An image sensor includes a pixel group including a first region and a second region; and a color filter having a first color on the pixel group, wherein the first region includes a first pixel including a first photodiode, a first floating diffusion region on the first photodiode, and a first transfer transistor on the first photodiode, the second region includes a second pixel including a second photodiode, a second floating diffusion region, and a second transfer transistor connected to the second photodiode and the second floating diffusion region, at least one of the first pixel and the second pixel is arranged in m*n (m and n are natural numbers of 2 or more), and from a planar point of view, a total area of the first photodiode included in the first region is greater than a total area of the second photodiode included in the second region.