Asymmetric Light Guiding Path Reduces Pixel Signal Mixing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing imaging devices face challenges in reducing light entry from the light guiding path into the charge accumulation portion, leading to decreased image quality due to signal mixing from different time periods.
Innovation Solution
The imaging device is designed with a specific layout where the exit surface of the light guiding path is longer in one direction than the other, and the charge accumulation portion is positioned between the photoelectric converters to maximize distance from the exit surface, reducing light leakage into the capacitive element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the charge accumulation portion is positioned close to the light guiding path for compact layout, then device area is reduced, but light leakage from the light guiding path into the charge accumulation portion increases causing signal mixing
Solution Approach 1:
The light guiding path is designed with an asymmetric rectangular cross-section where the width in the first direction (dimension along the row of photoelectric converters) is smaller than the width in the second direction (dimension perpendicular to the row). This asymmetric geometry reduces the projection area of the light guiding path in the first direction, thereby minimizing light leakage into the charge accumulation portion while maintaining compact pixel layout.
Solution Approach 2:
The patent utilizes the second direction (perpendicular to the row of photoelectric converters) as an additional spatial dimension to position the charge accumulation portion. By extending the light guiding path width in the second direction while keeping it narrow in the first direction, the design achieves compact layout in the critical first direction while providing sufficient separation in the second direction to prevent light leakage.
2Reliability
If the light guiding path is made longer to improve light guidance efficiency, then light collection is improved, but light leakage into the charge accumulation portion increases
Solution Approach 1:
The light guiding path employs asymmetric dimensions where it is extended in the second direction (perpendicular to the photoelectric converter row) to improve light guidance efficiency, while maintaining a narrow width in the first direction (along the row) to minimize light leakage into the charge accumulation portion. This asymmetric design allows the light guiding path to be effectively long for light collection without being wide in the critical leakage direction.
3Ease of manufacture
If the exit surface of the light guiding path is made symmetric, then manufacturing is simplified, but light leakage control is reduced
Solution Approach 1:
The exit surface of the light guiding path is designed with asymmetric dimensions (narrower in the first direction, wider in the second direction) to optimize light leakage control. While this asymmetric design increases manufacturing complexity compared to a symmetric shape, it provides precise control over the light guidance path's projection area, thereby effectively minimizing light leakage into the charge accumulation portion.
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 the sensitivity of the photodiode while minimizing image degradation by reducing light entry into the capacitive element, thereby improving image quality.
Implementation Method 1
Each of the pixels includes a photodiode that generates an electrical signal in accordance with light entered into the photodiode
Data Source
AI summary
In an imaging device, a photoelectric converter of a first pixel and a photoelectric converter of a second pixel are arranged along a first direction. At least part of a charge accumulation portion of the first pixel is disposed between the photoelectric converter of the first pixel and the photoelectric converter of the second pixel. An exit surface of a light guiding path of the first pixel is longer in a second direction orthogonal to the first direction in plan view than in the first direction.