Image Sensor Auto-Focusing Pixel Array with Segmented Photo Diodes
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Solution Overview
Problem
Current CMOS image sensors face challenges in implementing auto-focusing functionality without additional optical systems, requiring efficient methods to generate auto-focusing information using existing pixel structures.
Innovation Solution
The image sensor incorporates a pixel array with first to fourth pixels arranged in a Bayer pattern, featuring two photo diodes separated in different directions, which accumulate light intensity and convert it into sub-pixel signals for calculating auto-focusing information, allowing for auto-focusing operations in both vertical and horizontal directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four photo diodes are used per pixel for auto-focusing, then auto-focusing information can be obtained, but the size and power consumption of the pixel array increase
Solution Approach 1:
The pixel array is segmented into different pixel types (first-type pixels with two photo diodes separated in a first direction, and second-type pixels with two photo diodes separated in a second direction). This segmentation allows the system to obtain auto-focusing information in multiple directions without requiring four photo diodes in every pixel, thereby reducing the overall pixel array size while maintaining auto-focusing capability.
2Measurement precision
If four photo diodes are used per pixel for auto-focusing, then auto-focusing information can be obtained, but power consumption increases
Solution Approach 1:
By segmenting the pixel array into different pixel types with varying numbers of photo diodes, the total number of photo diodes in the array is reduced. Fewer photo diodes mean lower power consumption while still providing sufficient auto-focusing information through the combination of first-type and second-type pixels.
Solution Approach 2:
The patent changes the parameter of photo diode quantity from four per pixel to two per pixel for certain pixel types. This parameter change reduces the overall power consumption of the pixel array while maintaining the capability to generate auto-focusing information through differential measurement between pixels with different photo diode configurations.
3Adaptability or versatility
If two photo diodes are separated in different directions, then auto-focusing information for multiple directions can be calculated, but the data processing complexity increases
Solution Approach 1:
The pixel array is divided into first-type pixels and second-type pixels with photo diodes separated in different directions. This segmentation allows the system to process data in a structured manner, where first-type pixels provide auto-focusing information in one direction and second-type pixels provide information in another direction, simplifying the overall data processing compared to having all pixels with complex multi-directional photo diode arrangements.
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 enables effective auto-focusing and depth information calculation, reducing the size and power consumption of the pixel array while maintaining efficient data rates, compared to structures with four photo diodes per pixel.
Implementation Method 1
each pixel includes a photoelectric conversion element. The photoelectric conversion element may generate an electrical signal that changes according to the amount of light incident thereon
Data Source
AI summary
An image sensor includes a pixel array including first to fourth pixels having an R, G, and B Bayer pattern. An analog-to-digital converter (ADC) block converts a pixel signal of each of the first to fourth pixels into a digital pixel signal. At least one among the first to fourth pixels includes two photo diodes separated in a first direction, and at least one other of the first to fourth pixels includes two photo diodes separated in a second direction which is different from the first direction.