Image Sensor Pixel Grouping for Phase Detection and Sensitivity
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Solution Overview
Problem
Current phone camera sensors face challenges in improving imaging sensitivity and signal noise ratio (SNR) due to decreasing pixel unit size and the inability to distinguish light direction, which hinders phase detection and focusing capabilities.
Innovation Solution
A pixel information output method where multiple photosensitive pixels share a micro-lens, allowing for combined signal output to enhance sensitivity and SNR, and individual output for phase difference detection, utilizing a Bayer filter array structure to process image signals without major hardware adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel unit size is reduced to increase the number of pixels, then the resolution is improved, but the imaging sensitivity and signal noise ratio deteriorate
Solution Approach 1:
Multiple photosensitive pixels (e.g., 2x2=4 pixels) share a common micro-lens, merging their light collection capabilities. This allows the system to maintain high resolution through multiple pixels while improving imaging sensitivity and SNR by combining their signals through additive integration, effectively creating a larger light-gathering area for each shared lens.
Solution Approach 2:
The shared micro-lens structure serves multiple functions: it acts as a light gathering element for multiple pixels simultaneously, enabling both high-resolution imaging and enhanced sensitivity. The same optical structure supports both standard imaging mode and phase detection mode, making the system multi-functional without requiring separate hardware for each function.
2Device complexity
If a conventional micro-lens structure is used where one micro-lens corresponds to one pixel unit, then the structure is simple, but the ability to distinguish light direction and perform phase detection is lost
Solution Approach 1:
The pixel array is segmented into groups where multiple pixels share a common micro-lens. This segmentation allows the system to maintain simple micro-lens structures while enabling phase detection through the spatial arrangement and signal comparison of multiple pixels within each group, distinguishing light directions based on which pixels receive light from different angles.
Solution Approach 2:
The shared micro-lens structure enables dual functionality: standard imaging mode where pixel signals are additively integrated for high sensitivity, and phase detection mode where pixel signals are compared to determine light direction. The same hardware configuration supports both functions by switching between different signal processing modes.
3Reliability
If multiple photosensitive pixels share one micro-lens, then the imaging sensitivity and SNR are improved, but the structure becomes more complex
Solution Approach 1:
The pixel array is organized into groups (e.g., 2x2 grids) where each group shares a common micro-lens. This segmentation strategy improves SNR by combining signals from multiple pixels while limiting the complexity increase to manageable groups rather than requiring complete structural redesign of the entire sensor array.
Solution Approach 2:
The patent changes the organizational parameter from one-to-one pixel-lens mapping to many-to-one mapping (multiple pixels per lens). This parameter change improves imaging sensitivity through signal integration while the complexity increase is controlled by the regular grouping pattern, which can be implemented through standard semiconductor fabrication processes.
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 improves image quality by enhancing sensitivity and SNR and enables phase focusing by distinguishing light direction, providing a basis for depth information and focusing adjustments without altering the structure of ordinary photosensitive pixels.
Implementation Method 1
Each micro-lens 31 covers a corresponding filter cell 21 and a corresponding photosensitive unit 11
Implementation Method 2
a plurality of photosensitive pixels form a group sharing one micro-lens, pixel information of each photosensitive pixel of a group of the photosensitive pixel is respectively read
Data Source
AI summary
The present disclosure discloses a pixel information output method of an image sensor. The image sensor includes a photosensitive unit array including a plurality of photosensitive units, a filter cell array including a plurality of filter cells, and a micro-lens array including a plurality of micro-lenses. The filter cell array is located between the photosensitive unit array and the micro-lens array. Each micro-lens covers a filter cell and a photosensitive unit. Each photosensitive unit includes a plurality of photosensitive pixels. The method includes: determining an output mode according to a mode selection instruction; controlling exposure of the photosensitive unit array and reading outputs of the photosensitive unit array, pixel information of the plurality of photosensitive pixels of a same photosensitive unit being combined to be output when selecting a first output mode. The present disclosure also discloses a phase focusing method, an image sensor, an imaging device, and a terminal.