Multisection Light Guide for Image Sensor Alignment
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Solution Overview
Problem
Conventional image sensor pixels suffer from light loss due to misalignment between light guides and photosensitive elements, and face challenges in achieving desired spectral characteristics.
Innovation Solution
The implementation of a multisection light guide configuration with staggered and tapered light guides of varying refractive indices and lateral dimensions, which improves light gathering efficiency and accommodates spectral filtering by aligning light guides with microlenses and photosensitive elements, and allows for integral color filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional single light guide is used, then the structure is simple, but light is lost due to misalignment between the light guide and photosensitive element
Solution Approach 1:
The light guide is divided into multiple sections (first light guide section and second light guide section) with different lateral dimensions. The first section has a larger lateral dimension to collect more light, while the second section has a smaller lateral dimension to align precisely with the photosensitive element, thereby reducing light loss while maintaining structural feasibility
Solution Approach 2:
The patent introduces lateral dimension variation along the light propagation direction (vertical dimension) to solve the alignment problem. By changing the lateral dimensions of light guide sections at different vertical positions, the structure accommodates both light collection efficiency and precise alignment requirements
2Reliability
If light guides with uniform lateral dimensions are used, then manufacturing is easier, but spectral characteristics cannot be optimized
Solution Approach 1:
Different sections of the light guide are assigned different lateral dimensions tailored to their specific functions. The first section has larger dimensions optimized for light collection, while the second section has smaller dimensions optimized for alignment and spectral filtering, allowing each region to have properties suited to its local requirement
3Productivity
If light guides are aligned with microlenses, then light collection is maximized, but alignment with photosensitive elements becomes difficult
Solution Approach 1:
The light guide is segmented into two sections with different lateral dimensions. The first section aligns with the microlens for optimal light collection, while the second section aligns with the photosensitive element for precise positioning. This segmentation allows each section to serve its specific alignment requirement without compromising the other
Solution Approach 2:
The patent uses vertical positioning of different lateral dimension sections to resolve the alignment conflict. By varying the lateral dimensions at different vertical levels, the structure enables simultaneous alignment with both the microlens (at the top) and the photosensitive element (at the bottom)
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 reception efficiency and enables precise spectral filtering, improving the overall performance of image sensors by maximizing light collection and accommodating the point spread function of imaging lenses.
Implementation Method 1
A microlens and light guide may be associated with each image sensor pixel to help concentrate light onto the photosensitive element
Implementation Method 2
Light guides for image sensor pixels... light guide configuration with staggered and tapered light guides of varying refractive indices
Implementation Method 3
light guide may be associated with each image sensor pixel to help concentrate light onto the photosensitive element
Data Source
AI summary
Image sensors may contain arrays of image sensor pixels, each of which includes a microlens and a photosensitive element. A multisection light guide that is made up of multiple light guide layers may be interposed between the microlens and the photosensitive element. The light guide layers may have alternating indicies of refraction to form a spectral filter. The lateral dimensions of the light guide layers may also be configured so that the light guide layers perform spectral filtering. Light guide shapes and sizes may be altered as a function of the lateral position of each image sensor pixel within the image sensor array. The uppermost light guide may be aligned with the microlens and the lowermost light guide may be aligned with the photosensitive element. The lateral positions of each light guide may be laterally shifted with respect to the next to form a staggered stack of light guides.