Quad Photodiode Microlens Layout for Autofocus and Resolution
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Solution Overview
Problem
Image sensors face a trade-off between autofocusing and resolution, as larger lenses improve autofocusing but degrade pixel resolution, and existing systems struggle to balance both effectively.
Innovation Solution
The use of different-sized microlenses over pixels, where large microlenses cover groups of photodiodes for autofocusing and small microlenses cover individual photodiodes for resolution, particularly using large lenses over red and green pixels for autofocusing and small lenses over clear pixels to maintain resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large microlenses are used to cover photodiodes, then autofocusing is improved, but pixel resolution is degraded
Solution Approach 1:
The patent applies local quality by assigning different microlens sizes to different pixel types based on their functional requirements. Clear pixels (used for phase detection autofocus) are equipped with large microlenses to maximize light collection and autofocus accuracy, while color pixels (used for image formation) use small microlenses to preserve resolution. This localized differentiation resolves the contradiction by optimizing each pixel type for its specific purpose rather than using a uniform approach.
2Reliability
If dedicated pixels are used for phase detection autofocus, then autofocusing is improved, but overall image sensor resolution is compromised
Solution Approach 1:
The patent implements multi-functionality by enabling clear pixels to serve dual purposes: they participate in image formation during normal operation and switch to dedicated autofocus measurement during phase detection autofocus mode. The image sensor can dynamically utilize all pixels for imaging while dedicating specific clear pixels for autofocus when needed, eliminating the need for permanently dedicated autofocus pixels that would reduce overall resolution.
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 achieves an acceptable balance between autofocusing and resolution by preserving image sensor resolution while enhancing autofocusing capabilities, particularly by utilizing large microlenses for red and green pixels and small lenses for clear pixels.
Implementation Method 1
Each pixel of the pixel array includes a plurality of photodiodes... incident light 50... focus and appropriately color-filter the incident light for a given photodiode (210) inside a semiconductor material (60)
Data Source
AI summary
Quad photodiode microlens arrangements, and associated systems and methods. In one embodiment, a plurality of pixels are arranged in rows and columns of a pixel array disposed in a semiconductor material. The plurality of pixels includes green (G) pixels, red (R) pixels, blue (B) pixels and clear (C) pixels. Each pixel comprises a plurality of photodiodes that are configured to receive incoming light through an illuminated surface of the semiconductor material. A plurality of small microlenses are distributed over individual photodiodes of clear (C) pixels. A plurality of large microlenses are distributed over individual green (G) pixels. A diameter of the small microlenses is smaller than a diameter of the large microlenses.