Image Sensor Light Shielding for Uniform PDAF Pixel Sensitivity
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Solution Overview
Problem
The integration of Phase Difference Auto Focus (PDAF) pixels in image sensors leads to non-uniform light sensitivity due to the disruption of the traditional cycling effect caused by micro-lenses of different dimensions, resulting in precision issues and affected overall performance.
Innovation Solution
A light shielding structure is arranged between autofocus sensor units and neighboring sensor units, with an extra light shielding structure extending laterally on both sides, ensuring uniform light distribution and sensitivity by blocking excessive light and maintaining the cycling effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If micro-lenses of different dimensions are used for PDAF pixels, then focus detection capability is improved, but light sensitivity uniformity deteriorates
Solution Approach 1:
The patent applies local quality by introducing a light shielding structure specifically at the boundaries between PDAF pixels and neighboring pixels. This localized modification allows the micro-lenses to maintain different dimensions for focus detection while the light shielding structure compensates for the resulting light sensitivity non-uniformity by blocking excess light from adjacent pixels, thus resolving the contradiction between focus detection precision and light sensitivity uniformity.
2Area of moving object
If pixel size is reduced, then device integration is improved, but measurement precision deteriorates
Solution Approach 1:
The light shielding structure is strategically positioned at the boundaries between pixels, allowing the central sensing region to maintain sufficient size for precision while the overall pixel dimensions are reduced for higher integration. The local light shielding compensates for the reduced light gathering area, preserving measurement precision despite smaller pixel size.
Solution Approach 2:
The patent segments the pixel structure into a central sensing region and boundary regions. The light shielding structure is applied specifically to the boundary regions, allowing the central region to optimize for light reception and precision while the boundaries are managed separately to prevent light leakage and maintain focus detection accuracy in miniaturized pixels.
3Reliability
If light shielding structure is added, then light sensitivity uniformity is improved, but device complexity increases
Solution Approach 1:
The light shielding structure is segmented and positioned only at the boundaries between pixels rather than being applied universally across the entire sensor array. This selective segmentation reduces the overall complexity by limiting the light shielding structures to only where they are needed, while still achieving light sensitivity uniformity across the sensor.
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
The solution enhances uniformity in light sensitivity among sensor units, maintaining image focus and precision by regulating light reception, thereby improving the overall performance of the image sensor.
Implementation Method 1
A light shielding structure is arranged between autofocus sensor units and neighboring sensor units, with an extra light shielding structure extending laterally on both sides, ensuring uniform light distribution and sensitivity by blocking excessive light
Data Source
AI summary
An image sensor includes: a group of autofocus sensor units; neighboring sensor units adjacent to and surrounding the group of autofocus sensor units, wherein each of the neighboring sensor units has a first side close to the group of autofocus sensor units, and a second side away from the group of autofocus sensor units. The image sensor further includes: a first light shielding structure disposed between the group of autofocus sensor units and the neighboring sensor units; a first extra light shielding structure laterally extending from the first light shielding structure and disposed on at least one of the first side and the second side of one or more of the neighboring sensor units.