Phase Detect Pixel Sensor Layout for Wide-Angle Light Capture
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Solution Overview
Problem
Existing imaging array technologies face challenges in capturing light from large angles without compromising resolution, as current methods either increase pixel size at the cost of resolution or suffer from leakage current and crosstalk issues with light pipes.
Innovation Solution
A pixel sensor array design featuring tapered light pipes with reflective lining and a filler material transparent to visible light, along with FPPD pixels created by metal layers, allows for efficient light capture from large angles while maintaining high resolution by aligning apertures with inner reflective walls and microlenses to direct light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If pixel sensors are increased in size to capture light from large angles, then light acceptance angle is improved, but resolution deteriorates
Solution Approach 1:
The patent divides the pixel sensor structure into multiple functional segments: microlenses for light collection, tapered light pipes for light guidance, reflective linings for light redirection, and aperture structures for angular selection. This segmentation allows each component to optimize its function, enabling large angle acceptance without increasing overall pixel size, thus maintaining resolution while improving light acceptance from oblique angles
Solution Approach 2:
The patent introduces vertical dimensionality through tapered light pipes that extend from the surface into the substrate. By utilizing the depth dimension rather than increasing lateral pixel size, the structure captures light from large angles while maintaining the same planar footprint, thereby preserving resolution while enhancing angular acceptance
2Illumination intensity
If light pipes are used to capture light from large angles, then light acceptance angle is improved, but leakage current and crosstalk increase
Solution Approach 1:
The patent introduces reflective linings as intermediary surfaces within the light pipe structure. These reflective surfaces redirect oblique light rays back toward the pixel aperture, preventing light from escaping laterally and causing crosstalk. The reflective intermediary ensures that light from large angles is properly guided to the intended pixel sensor, reducing both leakage current and inter-pixel crosstalk
Solution Approach 2:
The patent converts potentially harmful oblique light rays that would normally cause crosstalk or leakage into beneficial signals by using reflective linings to redirect them back toward the pixel aperture. What would be harmful (light escaping at large angles) is converted into useful light that reaches the intended sensor, thereby reducing leakage current and crosstalk while maintaining large angle acceptance
3Adaptability or versatility
If opaque silicide layers are deposited to shadow selected portions of FPPD pixels, then phase detection functionality is achieved, but leakage current increases significantly
Solution Approach 1:
The patent changes the optical parameters of the light pipe structure by introducing reflective linings with high reflectivity in the visible spectrum. This parameter change allows the structure to achieve phase detection functionality through controlled light redirection rather than opaque blocking, thereby maintaining functionality while significantly reducing leakage current compared to silicide layer approaches
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 design enhances light acceptance angles without the drawbacks of previous solutions, maintaining high resolution and minimizing crosstalk, thus improving the performance of imaging arrays in capturing light at increased angles.
Implementation Method 1
relying upon total internal reflection (TIR)
Implementation Method 2
Microlenses 16a and 16b are formed, respectively, over pixel sensors 10a and 10b
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3C
AI summary
A focal plane phase detect pixel sensor is formed on a substrate and includes a surface pixel sensor formed in a pixel sensor area at a surface of the substrate. The surface pixel sensor has a sensing area occupying no more than an adjacent pair of quadrants centered in the pixel sensor area. A microlens is disposed over the surface pixel sensor.