Solid-state imaging device light-collecting element oblique incident angle
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Solution Overview
Problem
Solid-state imaging devices face a decrease in sensitivity due to changes in the incident angle of light from different lenses, such as when switching between wide-angle and telephoto lenses, as the light collection efficiency varies significantly across the imaging area, leading to reduced performance in peripheral regions.
Innovation Solution
A solid-state imaging device with unit pixels featuring a light-collecting element having a concentric structure with a true-circle shape at the center and an oval shape towards the periphery, where the effective refractive index decreases gradually, allowing for improved light collection across a wide range of incident angles by bending oblique light towards the light-receiving element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional microlens structure is used in unit pixels, then light collection efficiency is relatively high at the middle portion of the imaging region, but light collection efficiency decreases significantly in the peripheral portion due to oblique incident angles
Solution Approach 1:
The patent applies local quality by making the light-collecting element have different structural characteristics in different regions: a first region with a first curvature radius and a second region with a second curvature radius. This allows the optical properties to be optimized locally for different incident angle conditions, improving light collection efficiency in the peripheral portion while maintaining performance at the middle portion.
Solution Approach 2:
The patent introduces asymmetry by designing the light-collecting element with non-uniform curvature distribution, where the curvature radius varies between the first region (closer to the incident surface) and the second region (farther from the incident surface). This asymmetric curvature design enables better handling of oblique incident light compared to conventional symmetric microlens structures.
2Adaptability or versatility
If the incident angle of light increases in the peripheral portion of the imaging region, then the light is intercepted by the Al wire and cannot reach the light-receiving element, but shifting the Al wire and light-receiving element outward to capture oblique light reduces light collection efficiency for vertical light
Solution Approach 1:
The patent changes the optical parameters by varying the curvature radius of the light-collecting element across different regions. The first curvature radius in the first region and the second curvature radius in the second region are specifically designed to optimize light collection for oblique incident angles without requiring physical shifting of the Al wire or light-receiving element, thus maintaining proper alignment for vertical light while capturing oblique light effectively.
3Adaptability or versatility
If interchangeable lenses with different focal lengths are used (wide-angle to telephoto), then the incident angle of light varies significantly, but conventional solid-state imaging devices cannot maintain consistent sensitivity across different incident angles
Solution Approach 1:
The patent achieves universality by designing the light-collecting element with a multi-region curvature structure that can handle a wide range of incident angles. The first region with its first curvature radius and the second region with its second curvature radius work together to make the solid-state imaging device compatible with various lenses (wide-angle, standard, telephoto) while maintaining consistent sensitivity, eliminating the need for lens-specific optimization.
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 configuration enhances light collection efficiency and maintains sensitivity across varying incident angles, preventing image darkening in peripheral regions, even when using interchangeable lenses, thereby ensuring consistent image quality in digital cameras and single-lens reflex cameras.
Implementation Method 1
a light-collecting element having a concentric structure with a true-circle shape at the center and an oval shape towards the periphery, where the effective refractive index decreases gradually, allowing for improved light collection across a wide range of incident angles by bending oblique light towards the light-receiving element
Data Source
AI summary
A solid-state imaging device includes: unit pixels each having a light-receiving element which is divided into line widths shorter than or equal to a wavelength of light; a plurality of light-transmissive films in a concentric structure; and an effective refractive index distribution. Among the light-transmissive films, a light-transmissive film closest to a center of the concentric structure has an outer edge in a shape of a true circle, and a light-transmissive film far from the center of the concentric structure has an outer edge in a shape of an oval, a ratio of a long axis to a short axis of the oval increases as the light-transmissive film is farther away from the center of the concentric structure, and a direction of the long axis of the oval is orthogonal to a vector which connects the center of the concentric structure and a center of the solid-state imaging device.