Image Detector Pixel Array with Variable Light Shielding Openings
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Solution Overview
Problem
Image detectors face issues with lateral diffusion of light, leading to blurred images and reduced spatial resolution due to light emitted in large angles, causing crosstalk and decreased image quality in both radiation and fingerprint image sensors.
Innovation Solution
The image detector incorporates a pixel array with a photoelectric conversion layer and a light shielding layer featuring openings that vary in size from the center to the edge, allowing only light within a specific angle range to reach the conversion layer, thereby blocking large-angle light and reducing crosstalk and blurring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a light shielding layer with uniform openings is used, then the structure is simple and easy to manufacture, but light emitted in large angles still diffuses laterally causing blurred images and reduced spatial resolution
Solution Approach 1:
The light shielding layer employs openings of varying sizes distributed across the pixel area, with smaller openings near pixel edges and larger openings toward the center. This local variation in opening size optimizes light collection efficiency at different spatial locations while maintaining effective lateral diffusion blocking, thereby improving spatial resolution without requiring a completely different structural approach
Solution Approach 2:
The light shielding layer is segmented into multiple regions with different opening characteristics. By dividing the uniform structure into zones with varying opening sizes, the design achieves differentiated light management for different spatial positions, improving image sharpness while keeping the overall layer structure relatively simple
2Illumination intensity
If openings in the light shielding layer are made larger to increase light transmission, then more light reaches the photoelectric conversion layer improving signal strength, but lateral diffusion increases causing more crosstalk and blurring
Solution Approach 1:
Different regions of the light shielding layer have different opening sizes optimized for their specific functions: central regions have larger openings to maximize light transmission and signal strength, while peripheral regions have smaller openings to minimize lateral diffusion and maintain image sharpness. This local optimization resolves the contradiction between light transmission and image quality
Solution Approach 2:
The opening size parameter is varied spatially across the light shielding layer rather than maintaining a uniform value. This parameter change allows the system to achieve both high light transmission (through larger central openings) and high image sharpness (through smaller peripheral openings), resolving the contradiction between these two requirements
3Manufacturing precision
If the light shielding layer blocks all large angle light, then crosstalk and blurring are reduced improving image quality, but the overall light transmission efficiency decreases
Solution Approach 1:
The light shielding layer implements location-dependent opening sizes that optimize the balance between blocking large-angle light and transmitting useful light. Central regions with larger openings maintain high light transmission efficiency for on-axis light, while peripheral regions with smaller openings effectively block oblique light that would cause crosstalk, thus achieving both high image quality and acceptable transmission efficiency
Solution Approach 2:
Rather than uniformly blocking all large-angle light across the entire light shielding layer, the design applies partial blocking only where necessary (peripheral regions), allowing excessive light transmission in central regions where it is beneficial. This partial action approach maintains overall light transmission efficiency while achieving sufficient crosstalk reduction for high image quality
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 image resolution and quality by minimizing light diffusion, improving the signal-to-noise ratio and reducing crosstalk, resulting in sharper images with increased spatial modulation transfer function.
Implementation Method 1
a photoelectric conversion layer configured to convert incident light into signal charges
Implementation Method 2
a light shielding layer positioned above light incident surface of the photoelectric conversion layer and comprising a plurality of openings to pass the incident light to the photoelectric conversion layer
Data Source
AI summary
An image detector comprises a plurality of photosensitive pixels that each pixel includes a photoelectric conversion layer and a light shielding layer overlapped each other. A plurality of openings are made on the light shielding layer in a manner that its light passing area is substantially proportional to a distance from the opening to a border of the pixel.