Panchromatic Pixel Array for Low Light Phase Detection
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Solution Overview
Problem
Current focusing methods in mobile terminals, such as contrast detection auto focus and phase detection auto focus (PDAF), face challenges in low light environments where the signal-to-noise ratio is low, leading to inaccurate focusing.
Innovation Solution
A control method implemented by an image sensor with a two-dimensional pixel array comprising both color and panchromatic pixels, where the panchromatic pixels are arranged in a first diagonal direction and the color pixels in a second diagonal direction, allowing for the calculation of phase differences for focusing based on phase information from different pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional color sensors are used for focusing, then the device structure is simple, but the signal-to-noise ratio is low in low light environments leading to inaccurate focusing
Solution Approach 1:
The pixel array is segmented into multiple types of pixels (color pixels and panchromatic pixels) with different spectral response characteristics. By dividing the pixel array into functional segments, the patent enables selective use of panchromatic pixels for phase detection in low light conditions, thereby improving signal-to-noise ratio while maintaining focusing accuracy.
2Measurement precision
If panchromatic pixels are added to increase luminous flux, then focusing accuracy in low light improves, but the device complexity increases
Solution Approach 1:
The patent merges color pixels and panchromatic pixels into a unified pixel array structure where both types coexist and work together. The panchromatic pixels are strategically integrated into the array to provide additional luminous flux for phase detection without requiring separate imaging systems, thus improving focusing accuracy while controlling overall device complexity.
Solution Approach 2:
The pixel array is designed with multi-functionality where panchromatic pixels serve dual purposes: they contribute to phase detection for focusing accuracy while also adding luminous flux for improved low light performance. This universal design allows a single structure to address multiple requirements simultaneously.
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 solution enhances focusing performance in low light conditions by increasing luminous flux and improving signal-to-noise ratio, achieving more accurate focusing compared to conventional color sensors.
Implementation Method 1
obtaining phase information of different pixels of the corresponding one sub-unit covered by the lens; and calculating a phase difference according to the phase information of the different pixels, to perform focusing
Data Source
AI summary
Provided are a control method, a camera assembly, and a mobile terminal. The control method is implemented by an image sensor including a two-dimensional pixel array and a lens array. The two-dimensional pixel array includes multiple color pixels and multiple panchromatic pixels. The color pixels have narrower spectral responses than the panchromatic pixels. The two-dimensional pixel array includes minimum repeating units, each of which includes multiple sub-units, and each of the multiple sub-units includes at least two color pixels of the multiple color pixels and at least two panchromatic pixels of the multiple panchromatic pixels. The lens array includes multiple lenses, each of which covers a corresponding one sub-unit of the sub-units. The control method includes: obtaining phase information of different pixels of the corresponding one sub-unit covered by the lens; and calculating a phase difference according to the phase information of the different pixels, to perform focusing.