Phase Detection Pixels Asymmetric Optical Structures
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Solution Overview
Problem
Conventional imaging systems with phase detection capabilities face limitations due to asymmetric angular response, leading to reduced spatial resolution, increased complexity, and higher costs in applications requiring depth sensing and automatic focusing.
Innovation Solution
The implementation of phase detection pixel arrangements with asymmetric optical structures, such as concave lenses formed by dielectric layers with different refractive indices, to enhance the asymmetric angular response and improve phase detection data sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional phase detection pixels are used, then depth sensing and automatic focusing capabilities are provided, but the asymmetric angular response limits measurement precision and spatial resolution
Solution Approach 1:
The patent applies asymmetry by configuring different optical structures over first and second photosensitive regions. Specifically, a first optical structure (such as a microlens) is placed over the first photosensitive region while a second optical structure with different geometric or optical properties is placed over the second photosensitive region. This asymmetric configuration creates different angular response characteristics for light incident on each region, enabling enhanced phase detection sensitivity and improved measurement precision for depth sensing and automatic focusing applications.
2Reliability
If multiple image sensors and complex lens arrays are used, then depth sensing and stereo capabilities are achieved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple functions into a single image sensor by integrating phase detection pixels with different optical structures directly into the sensor array. Instead of using separate depth sensing sensors or complex external lens arrays, the invention combines depth sensing, automatic focusing, and image capture capabilities into one unified sensor structure. This integration reduces the total number of components, simplifies the optical system, and lowers device complexity while maintaining reliable depth sensing functionality.
Solution Approach 2:
The image sensor achieves multi-functionality by enabling a single sensor to perform both standard image capture and phase-based depth sensing simultaneously. The different optical structures over the photosensitive regions allow the sensor to extract both spatial image information and depth/phase information from the same incident light, eliminating the need for separate dedicated depth sensing sensors and enabling versatile functionality within a compact single-sensor architecture.
3Measurement precision
If lenticular arrays are added to focus incident light, then automatic focusing capability is improved, but spatial resolution and manufacturing simplicity are reduced
Solution Approach 1:
The patent segments the optical functionality by providing different optical structures for different photosensitive regions rather than using a single uniform lenticular array. Each photosensitive region can be equipped with optical structures optimized for its specific function (e.g., one region for capturing focused light from a specific direction, another region for capturing light from a different direction). This segmentation allows for improved focusing accuracy in each region while using simpler, more manufacturable optical structures compared to a complete lenticular array, as each optical structure can be designed and fabricated independently using standard semiconductor manufacturing 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 solution enhances the quality of phase detection data, improving the accuracy and efficiency of automatic focusing and depth sensing capabilities while reducing complexity and cost by increasing the sensitivity and dynamic range of phase detection pixels.
Implementation Method 1
an optical structure that is interposed between the color filter layer and the at least first and second photodiodes. The optical structure redirects incident light between the color filter layer and the at least first and second photodiodes
Implementation Method 2
a microlens that covers the at least first and second photodiodes
Data Source
AI summary
In order to increase angular response or otherwise customize the response of phase detection pixels to incident light, phase detection pixels may include optical structures. The optical structures may be formed between a microlens and at least first and second photodiodes to redirect incident light between the microlens and the photodiodes. The optical structures may include two or more layers with different indices of refraction. For example, a layer of silicon dioxide and a layer of silicon nitride may form a concave lens that increases the angular response of phase detection pixels. The optical structures may have any desired shape to customize the response of the photodiodes to incident light.